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Compiler/virtual machine interpreter

From Rosetta Code
Task
Compiler/virtual machine interpreter
You are encouraged to solve this task according to the task description, using any language you may know.
Virtual Machine Interpreter

A virtual machine implements a computer in software.

Task[edit]

Write a virtual machine interpreter. This interpreter should be able to run virtual assembly language programs created via the task. This is a byte-coded, 32-bit word stack based virtual machine.

The program should read input from a file and/or stdin, and write output to a file and/or stdout.

Input format:

Given the following program:

count = 1;
while (count < 10) {
    print("count is: ", count, "\n");
    count = count + 1;
}

The output from the Code generator is a virtual assembly code program:

Output from gen, input to VM
Datasize: 1 Strings: 2
"count is: "
"\n"
    0 push  1
    5 store [0]
   10 fetch [0]
   15 push  10
   20 lt
   21 jz     (43) 65
   26 push  0
   31 prts
   32 fetch [0]
   37 prti
   38 push  1
   43 prts
   44 fetch [0]
   49 push  1
   54 add
   55 store [0]
   60 jmp    (-51) 10
   65 halt

The first line of the input specifies the datasize required and the number of constant strings, in the order that they are reference via the code.

The data can be stored in a separate array, or the data can be stored at the beginning of the stack. Data is addressed starting at 0. If there are 3 variables, the 3rd one if referenced at address 2.

If there are one or more constant strings, they come next. The code refers to these strings by their index. The index starts at 0. So if there are 3 strings, and the code wants to reference the 3rd string, 2 will be used.

Next comes the actual virtual assembly code. The first number is the code address of that instruction. After that is the instruction mnemonic, followed by optional operands, depending on the instruction.

Registers:

sp:

   the stack pointer - points to the next top of stack.  The stack is a 32-bit integer
   array.

pc:

   the program counter - points to the current instruction to be performed.  The code is an
   array of bytes.

Data:

   data
   string pool

Instructions:

Each instruction is one byte. The following instructions also have a 32-bit integer operand:

fetch [index]

where index is an index into the data array.

store [index]

where index is an index into the data array.

push n

where value is a 32-bit integer that will be pushed onto the stack.

jmp (n) addr

where (n) is a 32-bit integer specifying the distance between the current location and the desired location. addr is an unsigned value of the actual code address.

jz (n) addr

where (n) is a 32-bit integer specifying the distance between the current location and the desired location. addr is an unsigned value of the actual code address.

The following instructions do not have an operand. They perform their operation directly against the stack:

For the following instructions, the operation is performed against the top two entries in the stack:

add
sub
mul
div
mod
lt
gt
le
ge
eq
ne
and
or

For the following instructions, the operation is performed against the top entry in the stack:

neg
not

Print the word at stack top as a character.

prtc

Print the word at stack top as an integer.

prti

Stack top points to an index into the string pool. Print that entry.

prts

Unconditional stop.

halt
A simple example virtual machine
def run_vm(data_size)
int stack[data_size + 1000]
set stack[0..data_size - 1] to 0
int pc = 0
while True:
op = code[pc]
pc += 1
 
if op == FETCH:
stack.append(stack[bytes_to_int(code[pc:pc+word_size])[0]]);
pc += word_size
elif op == STORE:
stack[bytes_to_int(code[pc:pc+word_size])[0]] = stack.pop();
pc += word_size
elif op == PUSH:
stack.append(bytes_to_int(code[pc:pc+word_size])[0]);
pc += word_size
elif op == ADD: stack[-2] += stack[-1]; stack.pop()
elif op == SUB: stack[-2] -= stack[-1]; stack.pop()
elif op == MUL: stack[-2] *= stack[-1]; stack.pop()
elif op == DIV: stack[-2] /= stack[-1]; stack.pop()
elif op == MOD: stack[-2] %= stack[-1]; stack.pop()
elif op == LT: stack[-2] = stack[-2] < stack[-1]; stack.pop()
elif op == GT: stack[-2] = stack[-2] > stack[-1]; stack.pop()
elif op == LE: stack[-2] = stack[-2] <= stack[-1]; stack.pop()
elif op == GE: stack[-2] = stack[-2] >= stack[-1]; stack.pop()
elif op == EQ: stack[-2] = stack[-2] == stack[-1]; stack.pop()
elif op == NE: stack[-2] = stack[-2] != stack[-1]; stack.pop()
elif op == AND: stack[-2] = stack[-2] and stack[-1]; stack.pop()
elif op == OR: stack[-2] = stack[-2] or stack[-1]; stack.pop()
elif op == NEG: stack[-1] = -stack[-1]
elif op == NOT: stack[-1] = not stack[-1]
elif op == JMP: pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == JZ: if stack.pop() then pc += word_size else pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == PRTC: print stack[-1] as a character; stack.pop()
elif op == PRTS: print the constant string referred to by stack[-1]; stack.pop()
elif op == PRTI: print stack[-1] as an integer; stack.pop()
elif op == HALT: break
Additional examples

Your solution should pass all the test cases above and the additional tests found Here.

Reference

The C and Python versions can be considered reference implementations.

Related Tasks

Aime[edit]

integer n, pc, sp;
file f;
text s;
index code, Data;
list l, stack, strings;
 
f.affix(argv(1));
 
f.list(l, 0);
 
n = atoi(l[-1]);
while (n) {
f.lead(s);
strings.append(erase(s, -1, 0));
n -= 1;
}
 
while (f.list(l, 0) ^ -1) {
code.put(atoi(lf_x_text(l)), l);
}
 
pc = sp = 0;
while (1) {
l = code[pc];
s = l[0];
if (s == "jz") {
if (lb_pick(stack)) {
isk_greater(code, pc, pc);
} else {
pc = atoi(l[-1]);
}
} elif (s == "jmp") {
pc = atoi(l[-1]);
} else {
if (s == "push") {
lb_push(stack, atoi(l[1]));
} elif (s == "fetch") {
lb_push(stack, Data[atoi(erase(l[1], -1, 0))]);
} elif (s == "neg") {
stack[-1] = -stack[-1];
} elif (s == "not") {
stack[-1] = !stack[-1];
} elif (s == "halt") {
break;
} else {
n = lb_pick(stack);
if (s == "store") {
Data[atoi(erase(l[1], -1, 0))] = n;
} elif (s == "add") {
stack[-1] = stack[-1] + n;
} elif (s == "sub") {
stack[-1] = stack[-1] - n;
} elif (s == "mul") {
stack[-1] = stack[-1] * n;
} elif (s == "div") {
stack[-1] = stack[-1] / n;
} elif (s == "mod") {
stack[-1] = stack[-1] % n;
} elif (s == "lt") {
stack[-1] = stack[-1] < n;
} elif (s == "gt") {
stack[-1] = stack[-1] > n;
} elif (s == "le") {
stack[-1] = stack[-1] <= n;
} elif (s == "ge") {
stack[-1] = stack[-1] >= n;
} elif (s == "eq") {
stack[-1] = stack[-1] == n;
} elif (s == "ne") {
stack[-1] = stack[-1] != n;
} elif (s == "and") {
stack[-1] = stack[-1] && n;
} elif (s == "or") {
stack[-1] = stack[-1] || n;
} elif (s == "prtc") {
o_byte(n);
} elif (s == "prti") {
o_(n);
} elif (s == "prts") {
o_(strings[n]);
} else {
}
}
 
isk_greater(code, pc, pc);
}
}

ALGOL W[edit]

begin % virtual machine interpreter %
 % string literals %
string(256) array stringValue ( 0 :: 256 );
integer array stringLength ( 0 :: 256 );
integer MAX_STRINGS;
 % op codes %
integer oFetch, oStore, oPush
, oAdd, oSub, oMul, oDiv, oMod, oLt, oGt, oLe, oGe, oEq, oNe
, oAnd, oOr, oNeg, oNot, oJmp, oJz, oPrtc, oPrts, oPrti, oHalt
 ;
string(6) array opName ( 1 :: 24 );
integer OP_MAX;
 % code %
string(1) array byteCode ( 0 :: 4096 );
integer nextLocation, MAX_LOCATION;
 % data %
integer array data ( 0 :: 4096 );
integer dataSize, MAX_DATA, MAX_STACK;
 % tracing %
logical trace;
 
 % reports an error and stops %
procedure rtError( string(80) value message ); begin
integer errorPos;
write( s_w := 0, "**** Runtime error: " );
errorPos := 0;
while errorPos < 80 and message( errorPos // 1 ) not = "." do begin
writeon( s_w := 0, message( errorPos // 1 ) );
errorPos := errorPos + 1
end while_not_at_end_of_message ;
writeon( s_w := 0, "." );
assert( false )
end genError ;
 
oFetch := 1; opName( oFetch ) := "fetch"; oStore := 2; opName( oStore ) := "store"; oPush := 3; opName( oPush ) := "push";
oAdd  := 4; opName( oAdd ) := "add"; oSub  := 5; opName( oSub ) := "sub"; oMul  := 6; opName( oMul ) := "mul";
oDiv  := 7; opName( oDiv ) := "div"; oMod  := 8; opName( oMod ) := "mod"; oLt  := 9; opName( oLt ) := "lt";
oGt  := 10; opName( oGt ) := "gt"; oLe  := 11; opName( oLe ) := "le"; oGe  := 12; opName( oGe ) := "ge";
oEq  := 13; opName( oEq ) := "eq"; oNe  := 14; opName( oNe ) := "ne"; oAnd  := 15; opName( oAnd ) := "and";
oOr  := 16; opName( oOr ) := "or"; oNeg  := 17; opName( oNeg ) := "neg"; oNot  := 18; opName( oNot ) := "not";
oJmp  := 19; opName( oJmp ) := "jmp"; oJz  := 20; opName( oJz ) := "jz"; oPrtc := 21; opName( oPrtc ) := "prtc";
oPrts  := 22; opName( oPrts ) := "prts"; oPrti  := 23; opName( oPrti ) := "prti"; oHalt := 24; opName( oHalt ) := "halt";
OP_MAX := oHalt;
 
trace  := false;
MAX_STACK  := 256;
MAX_LOCATION := 4096;
for pc := 0 until MAX_LOCATION do byteCode( pc ) := code( 0 );
MAX_DATA := 4096;
for dPos := 0 until MAX_DATA do data( dPos ) := 0;
MAX_STRINGS := 256;
for sPos := 0 until MAX_STRINGS do begin
stringValue( sPos ) := " ";
stringLength( sPos ) := 0
end for_sPos ;
 
 % load thge output from syntaxc analyser %
begin % readCode %
 
 % skips spaces on the source line %
procedure skipSpaces ; begin
while line( lPos // 1 ) = " " do lPos := lPos + 1
end skipSpaces ;
 
 % parses a string from line and stores it in the string literals table %
procedure readString ( integer value stringNumber ) ; begin
string(256) str;
integer sLen;
str  := " ";
sLen := 0;
lPos := lPos + 1; % skip the opening double-quote %
while lPos <= 255 and line( lPos // 1 ) not = """" do begin
str( sLen // 1 ) := line( lPos // 1 );
sLen := sLen + 1;
lPos := lPos + 1
end while_more_string ;
if lPos > 255 then rtError( "Unterminated String." );
 % store the string %
stringValue( stringNumber ) := str;
stringLength( stringNumber ) := sLen
end readString ;
 
 % gets an integer from the line - checks for valid digits %
integer procedure readInteger ; begin
integer n;
skipSpaces;
n := 0;
while line( lPos // 1 ) >= "0" and line( lPos // 1 ) <= "9" do begin
n  := ( n * 10 ) + ( decode( line( lPos // 1 ) ) - decode( "0" ) );
lPos := lPos + 1
end while_not_end_of_integer ;
n
end readInteger ;
 
 % reads the next line from standard input %
procedure readALine ; begin
lPos := 0;
readcard( line );
if trace then write( s_w := 0, ">> ", line( 0 // 32 ) )
end readALine ;
 
 % loads an instruction from the current source line %
procedure loadCodeFromLine ; begin
integer pc, opCode, operand, oPos;
string(256) op;
logical haveOperand;
 % get the code location %
pc := readInteger;
if pc > MAX_LOCATION then rtError( "Code too large." );
 % get the opCode %
skipSpaces;
oPos := 0;
op := " ";
while lPos <= 255 and line( lPos // 1 ) not = " " do begin
op( oPos // 1 ) := line( lPos // 1 );
oPos := oPos + 1;
lPos := lPos + 1
end while_more_opName ;
 % lookup the op code %
opCode := 0;
oPos  := 1;
while oPos <= OP_MAX and opCode = 0 do begin
if opName( oPos ) = op then opCode := oPos
else oPos  := oPos + 1
end while_op_not_found ;
if opCode = 0 then rtError( "Unknown op code." );
 % get the operand if there is one %
operand  := 0;
haveOperand := false;
if opCode = oFetch or opCode = oStore then begin
 % fetch or store - operand is enclosed in square brackets %
skipSpaces;
if line( lPos // 1 ) not = "[" then rtError( """["" expected after fetch/store." );
lPos  := lPos + 1;
operand  := readInteger;
if operand > dataSize then rtError( "fetch/store address out of range." );
haveOperand := true
end
else if opCode = oPush then begin
 % push integer literal instruction %
operand  := readInteger;
haveOperand := true
end
else if opCode = oJmp or opCode = oJz then begin
 % jump - the operand is the relative address enclosed in parenthesis %
 % followed by the absolute address - we use the absolute address so  %
 % the opewrand will be >= 0 %
skipSpaces;
if line( lPos // 1 ) not = "(" then rtError( """("" expected after jmp/jz." );
lPos  := lPos + 1;
if line( lPos // 1 ) = "-" then % negative relative address % lPos := lPos + 1;
operand  := readInteger;
if line( lPos // 1 ) not = ")" then rtError( """)"" expected after jmp/jz." );
lPos  := lPos + 1;
operand  := readInteger;
haveOperand := true
end if_various_opcodes ;
 % store the code %
byteCode( pc ) := code( opCode );
if haveOperand then begin
 % have an operand for the op code %
if ( pc + 4 ) > MAX_LOCATION then rtError( "Code too large." );
for oPos := 1 until 4 do begin
pc := pc + 1;
byteCode( pc ) := code( operand rem 256 );
operand := operand div 256;
end for_oPos
end if_have_operand ;
end loadCodeFromLine ;
 
string(256) line;
string(16) name;
integer lPos, tPos, stringCount;
 
 % allow us to detect EOF %
ENDFILE := EXCEPTION( false, 1, 0, false, "EOF" );
 
 % first line should be "Datasize: d Strings: s" where d = number variables %
 % and s = number of strings  %
readALine;
if line = "trace" then begin
 % extension - run in trace mode %
trace := true;
readALine
end if_line_eq_trace ;
if XCPNOTED(ENDFILE) then rtError( "Empty program file." );
if line( 0 // 10 ) not = "Datasize: " then rtError( "Header line missing." );
lPos := 10;
dataSize := readInteger;
if dataSize > MAX_DATA then rtError( "Datasize too large." );
skipSpaces;
if line( lPos // 9 ) not = "Strings: " then rtError( """Strings: "" missing on header line." );
lPos := lPos + 9;
stringCount := readInteger;
if stringCount > MAX_STRINGS then rtError( "Too many strings." );
 % read the string table %
for stringNumber := 0 until stringCount - 1 do begin
string(256) str;
integer sLen, sPos;
readALine;
if XCPNOTED(ENDFILE) then rtError( "End-of-file in string table." );
if line( lPos // 1 ) not = """" then rtError( "String literal expected." );
str  := " ";
sLen := 0;
lPos := lPos + 1; % skip the opening double-quote %
while lPos <= 255 and line( lPos // 1 ) not = """" do begin
str( sLen // 1 ) := line( lPos // 1 );
sLen := sLen + 1;
lPos := lPos + 1
end while_more_string ;
if lPos > 255 then rtError( "Unterminated String." );
 % store the string %
stringValue( stringNumber ) := str;
stringLength( stringNumber ) := sLen
end for_sPos ;
 % read the code %
readALine;
while not XCPNOTED(ENDFILE) do begin
if line not = " " then loadCodeFromLine;
readALine
end while_not_eof
end;
 % run the program %
begin
integer pc, opCode, operand, sp;
integer array st ( 0 :: MAX_STACK );
logical halted;
 % prints a string from the string pool, escape sequences are interpreted %
procedure writeOnString( integer value stringNumber ) ;
begin
integer cPos, sLen;
string(256) text;
if stringNumber < 0 or stringNumber > MAX_STRINGS then rtError( "Invalid string number." );
cPos := 0;
sLen := stringLength( stringNumber );
text := stringValue( stringNumber );
while cPos < stringLength( stringNumber ) do begin
string(1) ch;
ch := text( cPos // 1 );
if ch not = "\" then writeon( s_w := 0, ch )
else begin
 % escaped character %
cPos := cPos + 1;
if cPos > sLen then rtError( "String terminates with ""\""." );
ch := text( cPos // 1 );
if ch = "n" then % newline % write()
else writeon( s_w := 0, ch )
end;
cPos := cPos + 1
end while_not_end_of_string
end writeOnString ;
 
pc  := 0;
sp  := -1;
halted := false;
while not halted do begin;
 % get the next op code and operand %
opCode  := decode( byteCode( pc ) );
pc  := pc + 1;
operand := 0;
if opCode = oFetch or opCode = oStore or opCode = oPush or opCode = oJmp or opCode = oJz then begin
 % this opCode has an operand %
pc := pc + 4;
for bPos := 1 until 4 do begin
operand := ( operand * 256 ) + decode( byteCode( pc - bPos ) );
end for_bPos
end if_opCode_with_an_operand ;
if trace then begin
write( i_w:= 1, s_w := 0, pc, " op(", opCode, "): ", opName( opCode ), " ", operand );
write()
end if_trace ;
 % interpret the instruction %
if opCode = oFetch then begin sp := sp + 1; st( sp ) := data( operand ) end
else if opCode = oStore then begin data( operand ) := st( sp ); sp := sp - 1 end
else if opCode = oPush then begin sp := sp + 1; st( sp ) := operand end
else if opCode = oHalt then halted := true
else if opCode = oJmp then pc  := operand
else if oPCode = oJz then begin
if st( sp ) = 0 then pc := operand;
sp := sp - 1
end
else if opCode = oPrtc then begin writeon( i_w := 1, s_w := 0, code( st( sp ) ) ); sp := sp - 1 end
else if opCode = oPrti then begin writeon( i_w := 1, s_w := 0, st( sp ) ); sp := sp - 1 end
else if opCode = oPrts then begin writeonString( st( sp ) ); sp := sp - 1 end
else if opCode = oNeg then st( sp ) := - st( sp )
else if opCode = oNot then st( sp ) := ( if st( sp ) = 0 then 1 else 0 )
else begin
operand := st( sp );
sp  := sp - 1;
if opCode = oAdd then st( sp ) := st( sp ) + operand
else if opCode = oSub then st( sp ) := st( sp ) - operand
else if opCode = oMul then st( sp ) := st( sp ) * operand
else if opCode = oDiv then st( sp ) := st( sp ) div operand
else if opCode = oMod then st( sp ) := st( sp ) rem operand
else if opCode = oLt then st( sp ) := if st( sp ) < operand then 1 else 0
else if opCode = oGt then st( sp ) := if st( sp ) > operand then 1 else 0
else if opCode = oLe then st( sp ) := if st( sp ) <= operand then 1 else 0
else if opCode = oGe then st( sp ) := if st( sp ) >= operand then 1 else 0
else if opCode = oEq then st( sp ) := if st( sp ) = operand then 1 else 0
else if opCode = oNe then st( sp ) := if st( sp ) not = operand then 1 else 0
else if opCode = oAnd then st( sp ) := if st( sp ) not = 0 and operand not = 0 then 1 else 0
else if opCode = oOr then st( sp ) := if st( sp ) not = 0 or operand not = 0 then 1 else 0
else rtError( "Unknown opCode." )
end if_various_opCodes
end while_not_halted
end
end.

AWK[edit]

Tested with gawk 4.1.1 and mawk 1.3.4.

 
function error(msg) {
printf("%s\n", msg)
exit(1)
}
 
function bytes_to_int(bstr, i, sum) {
sum = 0
for (i=word_size-1; i>=0; i--) {
sum *= 256
sum += code[bstr+i]
}
return sum
}
 
function emit_byte(x) {
code[next_free_code_index++] = x
}
 
function emit_word(x, i) {
for (i=0; i<word_size; i++) {
emit_byte(int(x)%256);
x = int(x/256)
}
}
 
function run_vm(data_size) {
sp = data_size + 1
pc = 0
while (1) {
op = code[pc++]
if (op == FETCH) {
stack[sp++] = stack[bytes_to_int(pc)]
pc += word_size
} else if (op == STORE) {
stack[bytes_to_int(pc)] = stack[--sp]
pc += word_size
} else if (op == PUSH) {
stack[sp++] = bytes_to_int(pc)
pc += word_size
} else if (op == ADD ) { stack[sp-2] += stack[sp-1]; sp--
} else if (op == SUB ) { stack[sp-2] -= stack[sp-1]; sp--
} else if (op == MUL ) { stack[sp-2] *= stack[sp-1]; sp--
} else if (op == DIV ) { stack[sp-2] = int(stack[sp-2] / stack[sp-1]); sp--
} else if (op == MOD ) { stack[sp-2] %= stack[sp-1]; sp--
} else if (op == LT ) { stack[sp-2] = stack[sp-2] < stack[sp-1]; sp--
} else if (op == GT ) { stack[sp-2] = stack[sp-2] > stack[sp-1]; sp--
} else if (op == LE ) { stack[sp-2] = stack[sp-2] <= stack[sp-1]; sp--
} else if (op == GE ) { stack[sp-2] = stack[sp-2] >= stack[sp-1]; sp--
} else if (op == EQ ) { stack[sp-2] = stack[sp-2] == stack[sp-1]; sp--
} else if (op == NE ) { stack[sp-2] = stack[sp-2] != stack[sp-1]; sp--
} else if (op == AND ) { stack[sp-2] = stack[sp-2] && stack[sp-1]; sp--
} else if (op == OR ) { stack[sp-2] = stack[sp-2] || stack[sp-1]; sp--
} else if (op == NEG ) { stack[sp-1] = - stack[sp-1]
} else if (op == NOT ) { stack[sp-1] = ! stack[sp-1]
} else if (op == JMP ) { pc += bytes_to_int(pc)
} else if (op == JZ ) { if (stack[--sp]) { pc += word_size } else { pc += bytes_to_int(pc) }
} else if (op == PRTC) { printf("%c", stack[--sp])
} else if (op == PRTS) { printf("%s", string_pool[stack[--sp]])
} else if (op == PRTI) { printf("%d", stack[--sp])
} else if (op == HALT) { break
}
} # while
}
 
function str_trans(srce, dest, i) {
dest = ""
for (i=1; i <= length(srce); ) {
if (substr(srce, i, 1) == "\\" && i < length(srce)) {
if (substr(srce, i+1, 1) == "n") {
dest = dest "\n"
i += 2
} else if (substr(srce, i+1, 1) == "\\") {
dest = dest "\\"
i += 2
}
} else {
dest = dest substr(srce, i, 1)
i += 1
}
}
return dest
}
 
function load_code( n, i) {
getline line
if (line == "")
error("empty line")
n=split(line, line_list)
data_size = line_list[2]
n_strings = line_list[4]
for (i=0; i<n_strings; i++) {
getline line
gsub(/\n/, "", line)
gsub(/"/ , "", line)
string_pool[i] = str_trans(line)
}
while (getline) {
offset = int($1)
instr = $2
opcode = code_map[instr]
if (opcode == "
")
error("
Unknown instruction " instr " at " offset)
emit_byte(opcode)
if (opcode == JMP || opcode == JZ) {
p = int($4)
emit_word(p - (offset + 1))
} else if (opcode == PUSH) {
value = int($3)
emit_word(value)
} else if (opcode == FETCH || opcode == STORE) {
gsub(/\[/, "
", $3)
gsub(/\]/, "
", $3)
value = int($3)
emit_word(value)
}
}
return data_size
}
 
BEGIN {
code_map["
fetch"] = FETCH = 1
code_map["
store"] = STORE = 2
code_map["
push" ] = PUSH = 3
code_map["
add" ] = ADD = 4
code_map["
sub" ] = SUB = 5
code_map["
mul" ] = MUL = 6
code_map["
div" ] = DIV = 7
code_map["
mod" ] = MOD = 8
code_map["
lt" ] = LT = 9
code_map["
gt" ] = GT = 10
code_map["
le" ] = LE = 11
code_map["
ge" ] = GE = 12
code_map["
eq" ] = EQ = 13
code_map["
ne" ] = NE = 14
code_map["
and" ] = AND = 15
code_map["
or" ] = OR = 16
code_map["
neg" ] = NEG = 17
code_map["
not" ] = NOT = 18
code_map["
jmp" ] = JMP = 19
code_map["
jz" ] = JZ = 20
code_map["
prtc" ] = PRTC = 21
code_map["
prts" ] = PRTS = 22
code_map["
prti" ] = PRTI = 23
code_map["
halt" ] = HALT = 24
 
next_free_node_index = 1
next_free_code_index = 0
word_size = 4
input_file = "
-"
if (ARGC > 1)
input_file = ARGV[1]
data_size = load_code()
run_vm(data_size)
}
Output  —  count:

count is: 1
count is: 2
count is: 3
count is: 4
count is: 5
count is: 6
count is: 7
count is: 8
count is: 9

C[edit]

Tested with gcc 4.81 and later, compiles warning free with -Wall -Wextra

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
#include <string.h>
#include <stdint.h>
#include <ctype.h>
 
#define NELEMS(arr) (sizeof(arr) / sizeof(arr[0]))
 
#define da_dim(name, type) type *name = NULL; \
int _qy_ ## name ## _p = 0; \
int _qy_ ## name ## _max = 0

 
#define da_redim(name) do {if (_qy_ ## name ## _p >= _qy_ ## name ## _max) \
name = realloc(name, (_qy_ ## name ## _max += 32) * sizeof(name[0]));} while (0)

 
#define da_rewind(name) _qy_ ## name ## _p = 0
 
#define da_append(name, x) do {da_redim(name); name[_qy_ ## name ## _p++] = x;} while (0)
 
typedef unsigned char uchar;
typedef uchar code;
 
typedef enum { FETCH, STORE, PUSH, ADD, SUB, MUL, DIV, MOD, LT, GT, LE, GE, EQ, NE, AND,
OR, NEG, NOT, JMP, JZ, PRTC, PRTS, PRTI, HALT
} Code_t;
 
typedef struct Code_map {
char *text;
Code_t op;
} Code_map;
 
Code_map code_map[] = {
{"fetch", FETCH},
{"store", STORE},
{"push", PUSH },
{"add", ADD },
{"sub", SUB },
{"mul", MUL },
{"div", DIV },
{"mod", MOD },
{"lt", LT },
{"gt", GT },
{"le", LE },
{"ge", GE },
{"eq", EQ },
{"ne", NE },
{"and", AND },
{"or", OR },
{"neg", NEG },
{"not", NOT },
{"jmp", JMP },
{"jz", JZ },
{"prtc", PRTC },
{"prts", PRTS },
{"prti", PRTI },
{"halt", HALT },
};
 
FILE *source_fp;
da_dim(object, code);
 
void error(const char *fmt, ... ) {
va_list ap;
char buf[1000];
 
va_start(ap, fmt);
vsprintf(buf, fmt, ap);
va_end(ap);
printf("error: %s\n", buf);
exit(1);
}
 
/*** Virtual Machine interpreter ***/
void run_vm(const code obj[], int32_t data[], int g_size, char **string_pool) {
int32_t *sp = &data[g_size + 1];
const code *pc = obj;
 
again:
switch (*pc++) {
case FETCH: *sp++ = data[*(int32_t *)pc]; pc += sizeof(int32_t); goto again;
case STORE: data[*(int32_t *)pc] = *--sp; pc += sizeof(int32_t); goto again;
case PUSH: *sp++ = *(int32_t *)pc; pc += sizeof(int32_t); goto again;
case ADD: sp[-2] += sp[-1]; --sp; goto again;
case SUB: sp[-2] -= sp[-1]; --sp; goto again;
case MUL: sp[-2] *= sp[-1]; --sp; goto again;
case DIV: sp[-2] /= sp[-1]; --sp; goto again;
case MOD: sp[-2] %= sp[-1]; --sp; goto again;
case LT: sp[-2] = sp[-2] < sp[-1]; --sp; goto again;
case GT: sp[-2] = sp[-2] > sp[-1]; --sp; goto again;
case LE: sp[-2] = sp[-2] <= sp[-1]; --sp; goto again;
case GE: sp[-2] = sp[-2] >= sp[-1]; --sp; goto again;
case EQ: sp[-2] = sp[-2] == sp[-1]; --sp; goto again;
case NE: sp[-2] = sp[-2] != sp[-1]; --sp; goto again;
case AND: sp[-2] = sp[-2] && sp[-1]; --sp; goto again;
case OR: sp[-2] = sp[-2] || sp[-1]; --sp; goto again;
case NEG: sp[-1] = -sp[-1]; goto again;
case NOT: sp[-1] = !sp[-1]; goto again;
case JMP: pc += *(int32_t *)pc; goto again;
case JZ: pc += (*--sp == 0) ? *(int32_t *)pc : (int32_t)sizeof(int32_t); goto again;
case PRTC: printf("%c", sp[-1]); --sp; goto again;
case PRTS: printf("%s", string_pool[sp[-1]]); --sp; goto again;
case PRTI: printf("%d", sp[-1]); --sp; goto again;
case HALT: break;
default: error("Unknown opcode %d\n", *(pc - 1));
}
}
 
char *read_line(int *len) {
static char *text = NULL;
static int textmax = 0;
 
for (*len = 0; ; (*len)++) {
int ch = fgetc(source_fp);
if (ch == EOF || ch == '\n') {
if (*len == 0)
return NULL;
break;
}
if (*len + 1 >= textmax) {
textmax = (textmax == 0 ? 128 : textmax * 2);
text = realloc(text, textmax);
}
text[*len] = ch;
}
text[*len] = '\0';
return text;
}
 
char *rtrim(char *text, int *len) { // remove trailing spaces
for (; *len > 0 && isspace(text[*len - 1]); --(*len))
;
 
text[*len] = '\0';
return text;
}
 
char *translate(char *st) {
char *p, *q;
if (st[0] == '"') // skip leading " if there
++st;
p = q = st;
 
while ((*p++ = *q++) != '\0') {
if (q[-1] == '\\') {
if (q[0] == 'n') {
p[-1] = '\n';
++q;
} else if (q[0] == '\\') {
++q;
}
}
if (q[0] == '"' && q[1] == '\0') // skip trialing " if there
++q;
}
 
return st;
}
 
/* convert an opcode string into its byte value */
int findit(const char text[], int offset) {
for (size_t i = 0; i < sizeof(code_map) / sizeof(code_map[0]); i++) {
if (strcmp(code_map[i].text, text) == 0)
return code_map[i].op;
}
error("Unknown instruction %s at %d\n", text, offset);
return -1;
}
 
void emit_byte(int c) {
da_append(object, (uchar)c);
}
 
void emit_int(int32_t n) {
union {
int32_t n;
unsigned char c[sizeof(int32_t)];
} x;
 
x.n = n;
 
for (size_t i = 0; i < sizeof(x.n); ++i) {
emit_byte(x.c[i]);
}
}
 
/*
Datasize: 5 Strings: 3
" is prime\n"
"Total primes found: "
"\n"
154 jmp (-73) 82
164 jz (32) 197
175 push 0
159 fetch [4]
149 store [3]
*/

 
/* Load code into global array object, return the string pool and data size */
char **load_code(int *ds) {
int line_len, n_strings;
char **string_pool;
char *text = read_line(&line_len);
text = rtrim(text, &line_len);
 
strtok(text, " "); // skip "Datasize:"
*ds = atoi(strtok(NULL, " ")); // get actual data_size
strtok(NULL, " "); // skip "Strings:"
n_strings = atoi(strtok(NULL, " ")); // get number of strings
 
string_pool = malloc(n_strings * sizeof(char *));
for (int i = 0; i < n_strings; ++i) {
text = read_line(&line_len);
text = rtrim(text, &line_len);
text = translate(text);
string_pool[i] = strdup(text);
}
 
for (;;) {
int len;
 
text = read_line(&line_len);
if (text == NULL)
break;
text = rtrim(text, &line_len);
 
int offset = atoi(strtok(text, " ")); // get the offset
char *instr = strtok(NULL, " "); // get the instruction
int opcode = findit(instr, offset);
emit_byte(opcode);
char *operand = strtok(NULL, " ");
 
switch (opcode) {
case JMP: case JZ:
operand++; // skip the '('
len = strlen(operand);
operand[len - 1] = '\0'; // remove the ')'
emit_int(atoi(operand));
break;
case PUSH:
emit_int(atoi(operand));
break;
case FETCH: case STORE:
operand++; // skip the '['
len = strlen(operand);
operand[len - 1] = '\0'; // remove the ']'
emit_int(atoi(operand));
break;
}
}
return string_pool;
}
 
void init_io(FILE **fp, FILE *std, const char mode[], const char fn[]) {
if (fn[0] == '\0')
*fp = std;
else if ((*fp = fopen(fn, mode)) == NULL)
error(0, 0, "Can't open %s\n", fn);
}
 
int main(int argc, char *argv[]) {
init_io(&source_fp, stdin, "r", argc > 1 ? argv[1] : "");
int data_size;
char **string_pool = load_code(&data_size);
int data[1000 + data_size];
run_vm(object, data, data_size, string_pool);
}

COBOL[edit]

Code by Steve Williams (with changes to work around code highlighting issues). Tested with GnuCOBOL 2.2.

        >>SOURCE FORMAT IS FREE
identification division.
*> this code is dedicated to the public domain
*> (GnuCOBOL) 2.3-dev.0
program-id. vminterpreter.
environment division.
configuration section.
repository. function all intrinsic.
input-output section.
file-control.
select input-file assign using input-name
status is input-status
organization is line sequential.
data division.
 
file section.
fd input-file.
01 input-record pic x(64).
 
working-storage section.
01 program-name pic x(32).
01 input-name pic x(32).
01 input-status pic xx.
 
01 error-record pic x(64) value spaces global.
 
01 v-max pic 99.
01 parameters.
03 offset pic 999.
03 opcode pic x(8).
03 parm0 pic x(16).
03 parm1 pic x(16).
03 parm2 pic x(16).
 
01 opcodes.
03 opFETCH pic x value x'00'.
03 opSTORE pic x value x'01'.
03 opPUSH pic x value x'02'.
03 opADD pic x value x'03'.
03 opSUB pic x value x'04'.
03 opMUL pic x value x'05'.
03 opDIV pic x value x'06'.
03 opMOD pic x value x'07'.
03 opLT pic x value x'08'.
03 opGT pic x value x'09'.
03 opLE pic x value x'0A'.
03 opGE pic x value x'0B'.
03 opEQ pic x value x'0C'.
03 opNE pic x value x'0D'.
03 opAND pic x value x'0E'.
03 opOR pic x value x'0F'.
03 opNEG pic x value x'10'.
03 opNOT pic x value x'11'.
03 opJMP pic x value x'13'.
03 opJZ pic x value x'14'.
03 opPRTC pic x value x'15'.
03 opPRTS pic x value x'16'.
03 opPRTI pic x value x'17'.
03 opHALT pic x value x'18'.
 
01 filler.
03 s pic 99.
03 s-max pic 99 value 0.
03 s-lim pic 99 value 16.
03 filler occurs 16.
05 string-length pic 99.
05 string-entry pic x(48).
 
01 filler.
03 v pic 99.
03 v-lim pic 99 value 16.
03 variables occurs 16 usage binary-int.
 
01 generated-code global.
03 c pic 999 value 1.
03 pc pic 999.
03 c-lim pic 999 value 512.
03 kode pic x(512).
 
01 filler.
03 stack1 pic 999 value 2.
03 stack2 pic 999 value 1.
03 stack-lim pic 999 value 998.
03 stack occurs 998 usage binary-int.
 
01 display-definitions global.
03 ascii-character.
05 numeric-value usage binary-char.
03 display-integer pic -(9)9.
03 word-x.
05 word usage binary-int.
03 word-length pic 9.
03 string1 pic 99.
03 length1 pic 99.
03 count1 pic 99.
03 display-pending pic x.
 
procedure division.
start-vminterpreter.
display 1 upon command-line *> get arg(1)
accept program-name from argument-value
move length(word) to word-length
perform load-code
perform run-code
stop run
.
run-code.
move 1 to pc
perform until pc >= c
evaluate kode(pc:1)
when opFETCH
perform push-stack
move kode(pc + 1:word-length) to word-x
add 1 to word *> convert offset to subscript
move variables(word) to stack(stack1)
add word-length to pc
when opPUSH
perform push-stack
move kode(pc + 1:word-length) to word-x
move word to stack(stack1)
add word-length to pc
when opNEG
compute stack(stack1) = -stack(stack1)
when opNOT
if stack(stack1) = 0
move 1 to stack(stack1)
else
move 0 to stack(stack1)
end-if
when opJMP
move kode(pc + 1:word-length) to word-x
move word to pc
when opHALT
if display-pending = 'Y'
display space
end-if
exit perform
when opJZ
if stack(stack1) = 0
move kode(pc + 1:word-length) to word-x
move word to pc
else
add word-length to pc
end-if
perform pop-stack
when opSTORE
move kode(pc + 1:word-length) to word-x
add 1 to word *> convert offset to subscript
move stack(stack1) to variables(word)
add word-length to pc
perform pop-stack
when opADD
add stack(stack1) to stack(stack2)
perform pop-stack
when opSUB
subtract stack(stack1) from stack(stack2)
perform pop-stack
when opMUL
multiply stack(stack1) by stack(stack2)
*>rounded mode nearest-toward-zero *> doesn't match python
perform pop-stack
when opDIV
divide stack(stack1) into stack(stack2)
*>rounded mode nearest-toward-zero *> doesn'
t match python
perform pop-stack
when opMOD
move mod(stack(stack2),stack(stack1)) to stack(stack2)
perform pop-stack
when opLT
if stack(stack2) < stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when opGT
if stack(stack2) > stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when opLE
if stack(stack2) <= stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when opGE
if stack(stack2) >= stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when opEQ
if stack(stack2) = stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when opNE
if stack(stack2) <> stack(stack1)
move 1 to stack(stack2)
else
move 0 to stack(stack2)
end-if
perform pop-stack
when opAND
call "CBL_AND" using stack(stack1) stack(stack2) by value word-length
perform pop-stack
when opOR
call "CBL_OR" using stack(stack1) stack(stack2) by value word-length
perform pop-stack
when opPRTC
move stack(stack1) to numeric-value
if numeric-value = 10
display space
move 'N' to display-pending
else
display ascii-character with no advancing
move 'Y' to display-pending
end-if
perform pop-stack
when opPRTS
add 1 to word *> convert offset to subscript
move 1 to string1
move string-length(word) to length1
perform until string1 > string-length(word)
move 0 to count1
inspect string-entry(word)(string1:length1)
tallying count1 for characters before initial '\' *> ' workaround code highlighter problem
evaluate true
when string-entry(word)(string1 + count1 + 1:1) = 'n' *> \n
display string-entry(word)(string1:count1)
move 'N' to display-pending
compute string1 = string1 + 2 + count1
compute length1 = length1 - 2 - count1
when string-entry(word)(string1 + count1 + 1:1) = '\' *> ' \\
display string-entry(word)(string1:count1 + 1) with no advancing
move 'Y' to display-pending
compute string1 = string1 + 2 + count1
compute length1 = length1 - 2 - count1
when other
display string-entry(word)(string1:count1) with no advancing
move 'Y' to display-pending
add count1 to string1
subtract count1 from length1
end-evaluate
end-perform
perform pop-stack
when opPRTI
move stack(stack1) to display-integer
display trim(display-integer) with no advancing
move 'Y' to display-pending
perform pop-stack
end-evaluate
add 1 to pc
end-perform
.
push-stack.
if stack1 >= stack-lim
string 'in vminterpreter at ' pc ' stack overflow at ' stack-lim into error-record
perform report-error
end-if
add 1 to stack1 stack2
>>d display ' push at ' pc space stack1 space stack2
.
pop-stack.
if stack1 < 2
string 'in vminterpreter at ' pc ' stack underflow' into error-record
perform report-error
end-if
>>d display ' pop at ' pc space stack1 space stack2
subtract 1 from stack1 stack2
.
load-code.
perform read-input
if input-status <> '00'
string 'in vminterpreter no input data' into error-record
perform report-error
end-if
 
unstring input-record delimited by all spaces into parm1 v-max parm2 s-max
if v-max > v-lim
string 'in vminterpreter datasize exceeds ' v-lim into error-record
perform report-error
end-if
if s-max > s-lim
string 'in vminterpreter number of strings exceeds ' s-lim into error-record
perform report-error
end-if
 
perform read-input
perform varying s from 1 by 1 until s > s-max
or input-status <> '00'
compute string-length(s) string-length(word) = length(trim(input-record)) - 2
move input-record(2:string-length(word)) to string-entry(s)
perform read-input
end-perform
if s <= s-max
string 'in vminterpreter not all strings found' into error-record
perform report-error
end-if
 
perform until input-status <> '00'
initialize parameters
unstring input-record delimited by all spaces into
parm0 offset opcode parm1 parm2
evaluate opcode
when 'fetch'
call 'emitbyte' using opFETCH
call 'emitword' using parm1
when 'store'
call 'emitbyte' using opSTORE
call 'emitword' using parm1
when 'push'
call 'emitbyte' using opPUSH
call 'emitword' using parm1
when 'add' call 'emitbyte' using opADD
when 'sub' call 'emitbyte' using opSUB
when 'mul' call 'emitbyte' using opMUL
when 'div' call 'emitbyte' using opDIV
when 'mod' call 'emitbyte' using opMOD
when 'lt' call 'emitbyte' using opLT
when 'gt' call 'emitbyte' using opGT
when 'le' call 'emitbyte' using opLE
when 'ge' call 'emitbyte' using opGE
when 'eq' call 'emitbyte' using opEQ
when 'ne' call 'emitbyte' using opNE
when 'and' call 'emitbyte' using opAND
when 'or' call 'emitbyte' using opOR
when 'not' call 'emitbyte' using opNOT
when 'neg' call 'emitbyte' using opNEG
when 'jmp'
call 'emitbyte' using opJMP
call 'emitword' using parm2
when 'jz'
call 'emitbyte' using opJZ
call 'emitword' using parm2
when 'prtc' call 'emitbyte' using opPRTC
when 'prts' call 'emitbyte' using opPRTS
when 'prti' call 'emitbyte' using opPRTI
when 'halt' call 'emitbyte' using opHALT
when other
string 'in vminterpreter unknown opcode ' trim(opcode) ' at ' offset into error-record
perform report-error
end-evaluate
perform read-input
end-perform
.
read-input.
if program-name = spaces
move '00' to input-status
accept input-record on exception move '10' to input-status end-accept
exit paragraph
end-if
if input-name = spaces
string program-name delimited by space '.gen' into input-name
open input input-file
if input-status <> '00'
string 'in vminterpreter ' trim(input-name) ' file open status ' input-status
into error-record
perform report-error
end-if
end-if
read input-file into input-record
evaluate input-status
when '00'
continue
when '10'
close input-file
when other
string 'in vminterpreter unexpected input-status: ' input-status into error-record
perform report-error
end-evaluate
.
report-error.
display error-record upon syserr
stop run with error status -1
.
identification division.
program-id. emitbyte.
data division.
linkage section.
01 opcode pic x.
procedure division using opcode.
start-emitbyte.
if c >= c-lim
string 'in vminterpreter emitbyte c exceeds ' c-lim into error-record
call 'reporterror'
end-if
move opcode to kode(c:1)
add 1 to c
.
end program emitbyte.
 
identification division.
program-id. emitword.
data division.
working-storage section.
01 word-temp pic x(8).
linkage section.
01 word-value any length.
procedure division using word-value.
start-emitword.
if c + word-length >= c-lim
string 'in vminterpreter emitword c exceeds ' c-lim into error-record
call 'reporterror'
end-if
move word-value to word-temp
inspect word-temp converting '[' to ' '
inspect word-temp converting ']' to ' '
move numval(trim(word-temp)) to word
move word-x to kode(c:word-length)
add word-length to c
.
end program emitword.
 
end program vminterpreter.
Output  —  Count:
prompt$ ./lexer <testcases/Count | ./parser | ./generator | ./vminterpreter 
count is: 1
count is: 2
count is: 3
count is: 4
count is: 5
count is: 6
count is: 7
count is: 8
count is: 9

Forth[edit]

Tested with Gforth 0.7.3

CREATE BUF 0 ,              \ single-character look-ahead buffer
: PEEK BUF @ 0= IF KEY BUF ! THEN BUF @ ;
: GETC PEEK 0 BUF ! ;
: SPACE? DUP BL = SWAP 9 14 WITHIN OR ;
: >SPACE BEGIN PEEK SPACE? WHILE GETC DROP REPEAT ;
: DIGIT? 48 58 WITHIN ;
: >INT ( -- n) >SPACE 0
BEGIN PEEK DIGIT?
WHILE GETC [CHAR] 0 - SWAP 10 * + REPEAT ;
CREATE A 0 ,
: [email protected] ( -- c) A @ [email protected] ;
: [email protected]+ ( -- c) [email protected] 1 CHARS A +! ;
: C!A+ ( c --) A @ C! 1 CHARS A +! ;
: WORD ( -- c-addr) >SPACE PAD 1+ A !
BEGIN PEEK SPACE? INVERT WHILE GETC C!A+ REPEAT
>SPACE PAD A @ OVER - 1- PAD C! ;
: >STRING ( -- c-addr) >SPACE GETC DROP PAD 1+ A !
BEGIN PEEK [CHAR] " <> WHILE GETC C!A+ REPEAT
GETC DROP PAD A @ OVER - 1- PAD C! ;
: \INTERN ( c-addr -- c-addr) HERE >R A ! [email protected]+ DUP C,
BEGIN DUP WHILE [email protected]+
DUP [CHAR] \ = IF DROP -1 [email protected] +! [email protected]+
[CHAR] n = IF 10 ELSE [CHAR] \ THEN
THEN C, 1-
REPEAT DROP R> ;
: . 0 .R ;
 
CREATE DATA 0 ,
CREATE STRINGS 0 ,
: >DATA HERE DATA !
WORD DROP >INT 4 * BEGIN DUP WHILE 0 C, 1- REPEAT DROP ;
: >STRINGS HERE STRINGS !
WORD DROP >INT DUP >R CELLS ALLOT
0 BEGIN DUP [email protected] < WHILE
DUP CELLS >STRING \INTERN STRINGS @ ROT + ! 1+
REPEAT R> DROP DROP ;
: >HEADER >DATA >STRINGS ;
: i32! ( n addr --)
OVER $FF AND OVER C! 1+
OVER 8 RSHIFT $FF AND OVER C! 1+
OVER 16 RSHIFT $FF AND OVER C! 1+
SWAP 24 RSHIFT $FF AND SWAP C! ;
: [email protected] ( addr -- n) >R \ This is kinda slow... hmm
[email protected] [email protected]
[email protected] 1 + [email protected] 8 LSHIFT OR
[email protected] 2 + [email protected] 16 LSHIFT OR
R> 3 + [email protected] 24 LSHIFT OR
DUP $7FFFFFFF AND SWAP $80000000 AND - ; \ sign extend
: i32, ( n --) HERE 4 ALLOT i32! ;
: [email protected]+ ( -- n) A @ [email protected] A @ 4 + A ! ;
CREATE BYTECODE 0 ,
: @fetch [email protected]+ 4 * DATA @ + [email protected] ;
: @store [email protected]+ 4 * DATA @ + i32! ;
: @jmp [email protected]+ BYTECODE @ + A ! ;
: @jz IF 4 A +! ELSE @jmp THEN ;
: @prts CELLS STRINGS @ + @ COUNT TYPE ;
: @div >R S>D R> SM/REM SWAP DROP ;
CREATE OPS
' @fetch , ' @store , ' [email protected]+ , ' @jmp , ' @jz ,
' EMIT , ' . , ' @prts , ' NEGATE , ' 0= ,
' + , ' - , ' * , ' @div , ' MOD ,
' < , ' > , ' <= , ' >= ,
' = , ' <> , ' AND , ' OR , ' BYE ,
CREATE #OPS 0 ,
: OP: CREATE #OPS @ , 1 #OPS +! DOES> @ ;
OP: fetch OP: store OP: push OP: jmp OP: jz
OP: prtc OP: prti OP: prts OP: neg OP: not
OP: add OP: sub OP: mul OP: div OP: mod
OP: lt OP: gt OP: le OP: ge
OP: eq OP: ne OP: and OP: or OP: halt
: >OP WORD FIND
0= IF ." Unrecognized opcode" ABORT THEN EXECUTE ;
: >i32 >INT i32, ;
: >[i32] GETC DROP >i32 GETC DROP ;
: >OFFSET WORD DROP ( drop relative offset) >i32 ;
CREATE >PARAM ' >[i32] DUP , , ' >i32 , ' >OFFSET DUP , ,
: >BYTECODE HERE >R
BEGIN >INT DROP >OP >R [email protected] C,
[email protected] 5 < IF [email protected] CELLS >PARAM + @ EXECUTE THEN
R> halt = UNTIL R> BYTECODE ! ;
: RUN BYTECODE @ A !
BEGIN [email protected]+ CELLS OPS + @ EXECUTE AGAIN ;
>HEADER >BYTECODE RUN

Go[edit]

Translation of: Python
package main
 
import (
"bufio"
"encoding/binary"
"fmt"
"log"
"math"
"os"
"strconv"
"strings"
)
 
type code = byte
 
const (
fetch code = iota
store
push
add
sub
mul
div
mod
lt
gt
le
ge
eq
ne
and
or
neg
not
jmp
jz
prtc
prts
prti
halt
)
 
var codeMap = map[string]code{
"fetch": fetch,
"store": store,
"push": push,
"add": add,
"sub": sub,
"mul": mul,
"div": div,
"mod": mod,
"lt": lt,
"gt": gt,
"le": le,
"ge": ge,
"eq": eq,
"ne": ne,
"and": and,
"or": or,
"neg": neg,
"not": not,
"jmp": jmp,
"jz": jz,
"prtc": prtc,
"prts": prts,
"prti": prti,
"halt": halt,
}
 
var (
err error
scanner *bufio.Scanner
object []code
stringPool []string
)
 
func reportError(msg string) {
log.Fatalf("error : %s\n", msg)
}
 
func check(err error) {
if err != nil {
log.Fatal(err)
}
}
 
func btoi(b bool) int32 {
if b {
return 1
}
return 0
}
 
func itob(i int32) bool {
if i != 0 {
return true
}
return false
}
 
func emitByte(c code) {
object = append(object, c)
}
 
func emitWord(n int) {
bs := make([]byte, 4)
binary.LittleEndian.PutUint32(bs, uint32(n))
for _, b := range bs {
emitByte(code(b))
}
}
 
/*** Virtual Machine interpreter ***/
func runVM(dataSize int) {
stack := make([]int32, dataSize+1)
pc := int32(0)
for {
op := object[pc]
pc++
switch op {
case fetch:
x := int32(binary.LittleEndian.Uint32(object[pc : pc+4]))
stack = append(stack, stack[x])
pc += 4
case store:
x := int32(binary.LittleEndian.Uint32(object[pc : pc+4]))
ln := len(stack)
stack[x] = stack[ln-1]
stack = stack[:ln-1]
pc += 4
case push:
x := int32(binary.LittleEndian.Uint32(object[pc : pc+4]))
stack = append(stack, x)
pc += 4
case add:
ln := len(stack)
stack[ln-2] += stack[ln-1]
stack = stack[:ln-1]
case sub:
ln := len(stack)
stack[ln-2] -= stack[ln-1]
stack = stack[:ln-1]
case mul:
ln := len(stack)
stack[ln-2] *= stack[ln-1]
stack = stack[:ln-1]
case div:
ln := len(stack)
stack[ln-2] = int32(float64(stack[ln-2]) / float64(stack[ln-1]))
stack = stack[:ln-1]
case mod:
ln := len(stack)
stack[ln-2] = int32(math.Mod(float64(stack[ln-2]), float64(stack[ln-1])))
stack = stack[:ln-1]
case lt:
ln := len(stack)
stack[ln-2] = btoi(stack[ln-2] < stack[ln-1])
stack = stack[:ln-1]
case gt:
ln := len(stack)
stack[ln-2] = btoi(stack[ln-2] > stack[ln-1])
stack = stack[:ln-1]
case le:
ln := len(stack)
stack[ln-2] = btoi(stack[ln-2] <= stack[ln-1])
stack = stack[:ln-1]
case ge:
ln := len(stack)
stack[ln-2] = btoi(stack[ln-2] >= stack[ln-1])
stack = stack[:ln-1]
case eq:
ln := len(stack)
stack[ln-2] = btoi(stack[ln-2] == stack[ln-1])
stack = stack[:ln-1]
case ne:
ln := len(stack)
stack[ln-2] = btoi(stack[ln-2] != stack[ln-1])
stack = stack[:ln-1]
case and:
ln := len(stack)
stack[ln-2] = btoi(itob(stack[ln-2]) && itob(stack[ln-1]))
stack = stack[:ln-1]
case or:
ln := len(stack)
stack[ln-2] = btoi(itob(stack[ln-2]) || itob(stack[ln-1]))
stack = stack[:ln-1]
case neg:
ln := len(stack)
stack[ln-1] = -stack[ln-1]
case not:
ln := len(stack)
stack[ln-1] = btoi(!itob(stack[ln-1]))
case jmp:
x := int32(binary.LittleEndian.Uint32(object[pc : pc+4]))
pc += x
case jz:
ln := len(stack)
v := stack[ln-1]
stack = stack[:ln-1]
if v != 0 {
pc += 4
} else {
x := int32(binary.LittleEndian.Uint32(object[pc : pc+4]))
pc += x
}
case prtc:
ln := len(stack)
fmt.Printf("%c", stack[ln-1])
stack = stack[:ln-1]
case prts:
ln := len(stack)
fmt.Printf("%s", stringPool[stack[ln-1]])
stack = stack[:ln-1]
case prti:
ln := len(stack)
fmt.Printf("%d", stack[ln-1])
stack = stack[:ln-1]
case halt:
return
default:
reportError(fmt.Sprintf("Unknown opcode %d\n", op))
}
}
}
 
func translate(s string) string {
var d strings.Builder
for i := 0; i < len(s); i++ {
if s[i] == '\\' && (i+1) < len(s) {
if s[i+1] == 'n' {
d.WriteByte('\n')
i++
} else if s[i+1] == '\\' {
d.WriteByte('\\')
i++
}
} else {
d.WriteByte(s[i])
}
}
return d.String()
}
 
func loadCode() int {
var dataSize int
firstLine := true
for scanner.Scan() {
line := strings.TrimRight(scanner.Text(), " \t")
if len(line) == 0 {
if firstLine {
reportError("empty line")
} else {
break
}
}
lineList := strings.Fields(line)
if firstLine {
dataSize, err = strconv.Atoi(lineList[1])
check(err)
nStrings, err := strconv.Atoi(lineList[3])
check(err)
for i := 0; i < nStrings; i++ {
scanner.Scan()
s := strings.Trim(scanner.Text(), "\"\n")
stringPool = append(stringPool, translate(s))
}
firstLine = false
continue
}
offset, err := strconv.Atoi(lineList[0])
check(err)
instr := lineList[1]
opCode, ok := codeMap[instr]
if !ok {
reportError(fmt.Sprintf("Unknown instruction %s at %d", instr, opCode))
}
emitByte(opCode)
switch opCode {
case jmp, jz:
p, err := strconv.Atoi(lineList[3])
check(err)
emitWord(p - offset - 1)
case push:
value, err := strconv.Atoi(lineList[2])
check(err)
emitWord(value)
case fetch, store:
value, err := strconv.Atoi(strings.Trim(lineList[2], "[]"))
check(err)
emitWord(value)
}
}
check(scanner.Err())
return dataSize
}
 
func main() {
codeGen, err := os.Open("codegen.txt")
check(err)
defer codeGen.Close()
scanner = bufio.NewScanner(codeGen)
runVM(loadCode())
}
Output:

Using the 'while count' example:

count is: 1
count is: 2
count is: 3
count is: 4
count is: 5
count is: 6
count is: 7
count is: 8
count is: 9

Julia[edit]

mutable struct VM32
code::Vector{UInt8}
stack::Vector{Int32}
data::Vector{Int32}
strings::Vector{String}
offsets::Vector{Int32}
lastargs::Vector{Int32}
ip::Int32
VM32() = new(Vector{UInt8}(), Vector{Int32}(), Vector{Int32}(),
Vector{String}(), Vector{Int32}(), Vector{Int32}(), 1)
end
 
halt, add, sub, mul, Div, mod, not, neg, and, or, lt, gt, le, ge, ne, eq, prts,
prti, prtc, store, Fetch, push, jmp, jz = UInt8.(collect(1:24))
 
function assemble(io)
vm = VM32()
header = readline(io)
datasize, nstrings = match(r"\w+:\s*(\d+)\s+\w+:\s*(\d+)", header).captures
vm.data = zeros(Int32, parse(Int, datasize) + 4)
for i in 1:parse(Int, nstrings)
line = replace(strip(readline(io), ['"', '\n']), r"\\." => x -> x[end] == 'n' ? "\n" : string(x[end]))
push!(vm.strings, line)
end
while !eof(io)
line = readline(io)
offset, op, arg1, arg2 = match(r"(\d+)\s+(\w+)\s*(\S+)?\s*(\S+)?", line).captures
op = op in ["fetch", "div"] ? uppercasefirst(op) : op
push!(vm.code, eval(Symbol(op)))
if arg1 != nothing
v = parse(Int32, strip(arg1, ['[', ']', '(', ')']))
foreach(x -> push!(vm.code, x), reinterpret(UInt8, [v]))
end
if arg2 != nothing
push!(vm.lastargs, (x = tryparse(Int32, arg2)) == nothing ? 0 : x)
end
push!(vm.offsets, parse(Int32, offset))
end
vm
end
 
function runvm(vm)
value() = (x = vm.ip; vm.ip += 4; reinterpret(Int32, vm.code[x:x+3])[1])
tobool(x) = (x != 0)
ops = Dict(
halt => () -> exit(),
add => () -> begin vm.stack[end-1] += vm.stack[end]; pop!(vm.stack); vm.stack[end] end,
sub => () -> begin vm.stack[end-1] -= vm.stack[end]; pop!(vm.stack); vm.stack[end] end,
mul => () -> begin vm.stack[end-1] *= vm.stack[end]; pop!(vm.stack); vm.stack[end] end,
Div => () -> begin vm.stack[end-1] /= vm.stack[end]; pop!(vm.stack); vm.stack[end] end,
mod => () -> begin vm.stack[end-1] %= vm.stack[1]; pop!(vm.stack); vm.stack[end] end,
not => () -> vm.stack[end] = vm.stack[end] ? 0 : 1,
neg => () -> vm.stack[end] = -vm.stack[end],
and => () -> begin vm.stack[end-1] = tobool(vm.stack[end-1]) && tobool(vm.stack[end]) ? 1 : 0; pop!(vm.stack); vm.stack[end] end,
or => () -> begin vm.stack[end-1] = tobool(vm.stack[end-1]) || tobool(vm.stack[end]) ? 1 : 0; pop!(vm.stack); vm.stack[end] end,
lt => () -> begin x = (vm.stack[end-1] < vm.stack[end] ? 1 : 0); pop!(vm.stack); vm.stack[end] = x end,
gt => () -> begin x = (vm.stack[end-1] > vm.stack[end] ? 1 : 0); pop!(vm.stack); vm.stack[end] = x end,
le => () -> begin x = (vm.stack[end-1] <= vm.stack[end] ? 1 : 0); pop!(vm.stack); vm.stack[end] = x end,
ge => () -> begin x = (vm.stack[end-1] >= vm.stack[end] ? 1 : 0); pop!(vm.stack); vm.stack[end] = x end,
ne => () -> begin x = (vm.stack[end-1] != vm.stack[end] ? 1 : 0); pop!(vm.stack); vm.stack[end] = x end,
eq => () -> begin x = (vm.stack[end-1] == vm.stack[end] ? 1 : 0); pop!(vm.stack); vm.stack[end] = x end,
prts => () -> print(vm.strings[pop!(vm.stack) + 1]),
prti => () -> print(pop!(vm.stack)),
prtc => () -> print(Char(pop!(vm.stack))),
store => () -> vm.data[value() + 1] = pop!(vm.stack),
Fetch => () -> push!(vm.stack, vm.data[value() + 1]),
push => () -> push!(vm.stack, value()),
jmp => () -> vm.ip += value(),
jz => () -> if pop!(vm.stack) == 0 vm.ip += value() else vm.ip += 4 end)
vm.ip = 1
while true
op = vm.code[vm.ip]
vm.ip += 1
ops[op]()
end
end
 
const testasm = """
Datasize: 1 Strings: 2
"count is: "
"\\n"
0 push 1
5 store [0]
10 fetch [0]
15 push 10
20 lt
21 jz (43) 65
26 push 0
31 prts
32 fetch [0]
37 prti
38 push 1
43 prts
44 fetch [0]
49 push 1
54 add
55 store [0]
60 jmp (-51) 10
65 halt """
 
const iob = IOBuffer(testasm)
const vm = assemble(iob)
runvm(vm)
 
Output:

count is: 1
count is: 2
count is: 3
count is: 4
count is: 5
count is: 6
count is: 7
count is: 8
count is: 9

M2000 Interpreter[edit]

Using Select Case[edit]

 
Module Virtual_Machine_Interpreter (a$){
\\ function to extract string, replacing escape codes.
Function GetString$(a$) {
s=instr(a$, chr$(34))
m=rinstr(a$,chr$(34))-s
if m>1 then
\\ process escape codes
=format$(mid$(a$, s+1, m-1))
else
=""
end if
}
\\ module to print a string to console using codes, 13, 10, 9
Module printsrv (a$) {
for i=1 to len(a$)
select case chrcode(Mid$(a$,i,1))
case 13
cursor 0
case 10
cursor 0 : Print
case 9
cursor ((pos+tab) div tab)*tab
else case
{
m=pos :if pos>=width then Print : m=pos
Print Mid$(a$,i,1);
if m<=width then cursor m+1
}
end select
next i
}
const nl$=chr$(13)+chr$(10)
\\ we can set starting value to any number n where 0<=n<=232
enum op { halt_=232, add_, sub_, mul_, div_, mod_, not_, neg_, and_, or_, lt_,
gt_, le_, ge_, ne_, eq_, prts_, prti_, prtc_, store_, fetch_, push_,
jmp_, jz_
}
Rem : Form 120, 60 ' change console width X height to run Ascii Mandlebrot examlpe
Report "Virtual Assembly Code:"+{
}+a$
Print "Prepare Byte Code"
 
\\ get datasize
a$=rightpart$(a$, "Datasize:")
m=0
data_size=val(a$, "int", m)
a$=mid$(a$, m)
\\ make stack
if data_size>0 then Buffer Clear stack_ as long*data_size
\\ dim or redim buffer append 1000 long as is.
Buffer stack_ as long*(1000+data_size)
\\ get strings
a$=rightpart$(a$, "Strings:")
m=0
strings=val(a$, "int", m)
a$=rightpart$(a$, nl$)
 
if strings>0 then
Dim strings$(strings)
for i=0 to strings-1
strings$(i)=GetString$(leftpart$(a$, nl$))
a$=rightpart$(a$, nl$)
Next i
End if
buffer clear code_ as byte*1000
do
m=0
offset=val(a$,"int", m)
if m<0 then exit
a$=mid$(a$,m)
line$=trim$(leftpart$(a$,nl$))
if line$="" then line$=trim$(a$) else a$=trim$(rightpart$(a$, nl$))
op$=if$(instr(line$," ")>0->leftpart$(line$," "), line$)
if not valid(eval(op$+"_")) then exit
opc=eval(op$+"_")
Return code_, offset:=opc
if opc>=store_ then
line$=rightpart$(line$," ")
select case opc
case store_, fetch_
Return code_, offset+1:=val(rightpart$(leftpart$(line$,"]"),"[")) as long : offset+=4
case push_
Return code_, offset+1:=uint(val(line$)) as long : offset+=4
case jz_, jmp_
Return code_, offset+1:=val(rightpart$(line$,")")) as long : offset+=4
end select
end if
Always
Print "Press any key" : Push key$ : Drop
\\ Prepare VM
let pc=0, sp=len(stack_) div 4
do {
func=eval(code_, pc)
pc++
select case func
case halt_
exit
case push_
sp--:return stack_, sp:=eval(code_, pc as long):pc+=4
case jz_
sp++: if eval(stack_, sp-1)=0 then pc=eval(code_, pc as long) else pc+=4
case jmp_
pc=eval(code_, pc as long)
case fetch_
sp--:Return stack_, sp:=eval(stack_, eval(code_, pc as long)):pc+=4
case store_
Return stack_, eval(code_, pc as long):=eval(stack_, sp):sp++:pc+=4
case add_
Return stack_, sp+1:=uint(sint(eval(stack_, sp+1))+sint(eval(stack_, sp))):sp++
case sub_
Return stack_, sp+1:=uint(sint(eval(stack_, sp+1))-sint(eval(stack_, sp))):sp++
case mul_
Return stack_, sp+1:=uint(sint(eval(stack_, sp+1))*sint(eval(stack_, sp))):sp++
case div_
Return stack_, sp+1:=uint(sint(eval(stack_, sp+1)) div sint(eval(stack_, sp))):sp++
case mod_
Return stack_, sp+1:=uint(sint(eval(stack_, sp+1)) mod sint(eval(stack_, sp))) :sp++
case not_
Return stack_, sp:=if(eval(stack_, sp)=0->uint(-1),0)
case neg_ \\ we can use neg(sint(value))+1 or uint(-sint(value))
Return stack_, sp:=uint(-sint(eval(stack_, sp)))
case and_
Return stack_, sp+1:=binary.and(eval(stack_, sp+1),eval(stack_, sp)):sp++
case or_
Return stack_, sp+1:=binary.or(eval(stack_, sp+1),eval(stack_, sp)):sp++
case lt_
Return stack_, sp+1:=uint(if(sint(eval(stack_, sp+1))<sint(eval(stack_, sp))->-1, 0)):sp++
case gt_
Return stack_, sp+1:=uint(if(sint(eval(stack_, sp+1))>sint(eval(stack_, sp))->-1, 0)):sp++
case le_
Return stack_, sp+1:=uint(if(sint(eval(stack_, sp+1))<=sint(eval(stack_, sp))->-1, 0)):sp++
case ge_
Return stack_, sp+1:=uint(if(sint(eval(stack_, sp+1))>=sint(eval(stack_, sp))->-1, 0)):sp++
case ne_
Return stack_, sp+1:=uint(if(eval(stack_, sp+1)<>eval(stack_, sp)->-1, 0)):sp++
case eq_
Return stack_, sp+1:=uint(if(eval(stack_, sp+1)=eval(stack_, sp)->-1, 0)):sp++
case prts_
printsrv strings$(eval(stack_,sp)):sp++
case prti_
printsrv str$(sint(eval(stack_,sp)),0):sp++
case prtc_
printsrv chrcode$(eval(stack_,sp)):sp++
else case
Error "Unkown op "+str$(func)
end select
} always
Print "done"
}
Virtual_Machine_Interpreter {
Datasize: 1 Strings: 2
"count is: "
"\n"
0 push 1
5 store [0]
10 fetch [0]
15 push 10
20 lt
21 jz (43) 65
26 push 0
31 prts
32 fetch [0]
37 prti
38 push 1
43 prts
44 fetch [0]
49 push 1
54 add
55 store [0]
60 jmp (-51) 10
65 halt
}
 

Using Lambda functions[edit]

A call local to function pass the current scope to function, so it's like a call to subroutine, but faster.

 
Module Virtual_Machine_Interpreter (a$){
\\ function to extract string, replacing escape codes.
Function GetString$(a$) {
s=instr(a$, chr$(34))
m=rinstr(a$,chr$(34))-s
if m>1 then
\\ process escape codes
=format$(mid$(a$, s+1, m-1))
else
=""
end if
}
\\ module to print a string to console using codes, 13, 10, 9
Module printsrv (a$) {
for i=1 to len(a$)
select case chrcode(Mid$(a$,i,1))
case 13
cursor 0
case 10
cursor 0 : Print
case 9
cursor ((pos+tab) div tab)*tab
else case
{
m=pos :if pos>=width then Print : m=pos
Print Mid$(a$,i,1);
if m<=width then cursor m+1
}
end select
next i
}
const nl$=chr$(13)+chr$(10)
\\ we can set starting value to any number n where 0<=n<=232
enum op { halt_=232, add_, sub_, mul_, div_, mod_, not_, neg_, and_, or_, lt_,
gt_, le_, ge_, ne_, eq_, prts_, prti_, prtc_, store_, fetch_, push_,
jmp_, jz_
}
exit_now=false
Inventory func=halt_:=lambda->{exit_now=true}
Append func, push_:=lambda->{sp--:return stack_, sp:=eval(code_, pc as long):pc+=4}
Append func, jz_:=lambda->{
sp++: if eval(stack_, sp-1)=0 then pc=eval(code_, pc as long) else pc+=4
}
Append func, jmp_:=lambda->{pc=eval(code_, pc as long)}
Append func, fetch_:=lambda->{sp--:Return stack_, sp:=eval(stack_, eval(code_, pc as long)):pc+=4}
Append func, store_:=lambda->{Return stack_, eval(code_, pc as long):=eval(stack_, sp):sp++:pc+=4}
Append func, add_:=lambda->{Return stack_, sp+1:=uint(sint(eval(stack_, sp+1))+sint(eval(stack_, sp))):sp++}
Append func, sub_:=lambda->{Return stack_, sp+1:=uint(sint(eval(stack_, sp+1))-sint(eval(stack_, sp))):sp++}
Append func, mul_:=lambda->{Return stack_, sp+1:=uint(sint(eval(stack_, sp+1))*sint(eval(stack_, sp))):sp++}
Append func, div_:=lambda->{Return stack_, sp+1:=uint(sint(eval(stack_, sp+1)) div sint(eval(stack_, sp))):sp++}
Append func, mod_:=lambda->{Return stack_, sp+1:=uint(sint(eval(stack_, sp+1)) mod sint(eval(stack_, sp))) :sp++}
Append func, not_:=lambda->{Return stack_, sp:=if(eval(stack_, sp)=0->uint(-1),0)}
Append func, neg_:=lambda->{Return stack_, sp:=uint(-sint(eval(stack_, sp)))}
Append func, and_:=lambda->{Return stack_, sp+1:=binary.and(eval(stack_, sp+1),eval(stack_, sp)):sp++ }
Append func, or_:=lambda->{Return stack_, sp+1:=binary.or(eval(stack_, sp+1),eval(stack_, sp)):sp++ }
Append func, lt_:=lambda->{Return stack_, sp+1:=uint(if(sint(eval(stack_, sp+1))<sint(eval(stack_, sp))->-1, 0)):sp++}
Append func, gt_:=lambda->{Return stack_, sp+1:=uint(if(sint(eval(stack_, sp+1))>sint(eval(stack_, sp))->-1, 0)):sp++}
Append func, le_:=lambda->{Return stack_, sp+1:=uint(if(sint(eval(stack_, sp+1))<=sint(eval(stack_, sp))->-1, 0)):sp++}
Append func, ge_:=lambda->{Return stack_, sp+1:=uint(if(sint(eval(stack_, sp+1))>=sint(eval(stack_, sp))->-1, 0)):sp++}
Append func, ne_:=lambda->{Return stack_, sp+1:=uint(if(eval(stack_, sp+1)<>eval(stack_, sp)->-1, 0)):sp++}
Append func, eq_:=lambda->{Return stack_, sp+1:=uint(if(eval(stack_, sp+1)=eval(stack_, sp)->-1, 0)):sp++}
Append func, prts_:=lambda->{printsrv strings$(eval(stack_,sp)):sp++}
Append func, prti_:=lambda->{printsrv str$(sint(eval(stack_,sp)),0):sp++}
Append func, prtc_:=lambda->{printsrv chrcode$(eval(stack_,sp)):sp++}
Rem : Form 120, 60 ' change console width X height to run Ascii Mandlebrot examlpe
Report "Virtual Assembly Code:"+{
}+a$
Print "Prepare Byte Code"
 
\\ get datasize
a$=rightpart$(a$, "Datasize:")
m=0
data_size=val(a$, "int", m)
a$=mid$(a$, m)
\\ make stack
if data_size>0 then Buffer Clear stack_ as long*data_size
\\ dim or redim buffer append 1000 long as is.
Buffer stack_ as long*(1000+data_size)
\\ get strings
a$=rightpart$(a$, "Strings:")
m=0
strings=val(a$, "int", m)
a$=rightpart$(a$, nl$)
 
if strings>0 then
Dim strings$(strings)
for i=0 to strings-1
strings$(i)=GetString$(leftpart$(a$, nl$))
a$=rightpart$(a$, nl$)
Next i
End if
buffer clear code_ as byte*1000
do
m=0
offset=val(a$,"int", m)
if m<0 then exit
a$=mid$(a$,m)
line$=trim$(leftpart$(a$,nl$))
if line$="" then line$=trim$(a$) else a$=trim$(rightpart$(a$, nl$))
op$=if$(instr(line$," ")>0->leftpart$(line$," "), line$)
if not valid(eval(op$+"_")) then exit
opc=eval(op$+"_")
Return code_, offset:=opc
if opc>=store_ then
line$=rightpart$(line$," ")
select case opc
case store_, fetch_
Return code_, offset+1:=val(rightpart$(leftpart$(line$,"]"),"[")) as long : offset+=4
case push_
Return code_, offset+1:=uint(val(line$)) as long : offset+=4
case jz_, jmp_
Return code_, offset+1:=val(rightpart$(line$,")")) as long : offset+=4
end select
end if
Always
Print "Press any key" : Push key$ : Drop
\\ Prepare VM
let pc=0, sp=len(stack_) div 4
do
b=func(eval(code_, pc))
pc++
call local b()
until exit_now
Print "done"
}
Virtual_Machine_Interpreter {
Datasize: 1 Strings: 2
"count is: "
"\n"
0 push 1
5 store [0]
10 fetch [0]
15 push 10
20 lt
21 jz (43) 65
26 push 0
31 prts
32 fetch [0]
37 prti
38 push 1
43 prts
44 fetch [0]
49 push 1
54 add
55 store [0]
60 jmp (-51) 10
65 halt
}
 

Nim[edit]

import os, parseutils, strutils, strscans, strformat
 
type
 
Value = int32
BytesValue = array[4, byte]
Address = int32
 
OpCode = enum
opFetch = "fetch"
opStore = "store"
opPush = "push"
opJmp = "jmp"
opJz = "jz"
opAdd = "add"
opSub = "sub"
opMul = "mul"
opDiv = "div"
opMod = "mod"
opLt = "lt"
opgt = "gt"
opLe = "le"
opGe = "ge"
opEq = "eq"
opNe = "ne"
opAnd = "and"
opOr = "or"
opNeg = "neg"
opNot = "not"
opPrtc = "prtc"
opPrti = "prti"
opPrts = "prts"
opHalt = "halt"
opInvalid = "invalid"
 
# Virtual machine description.
VM = object
stack: seq[Value] # Evaluation stack.
memory: seq[byte] # Memory to store program.
data: seq[Value] # Data storage.
strings: seq[string] # String storage.
pc: Address # Program counter.
 
# Exceptions.
LoadingError = object of CatchableError
RuntimeError = object of CatchableError
 
 
####################################################################################################
# Running program.
 
proc checkStackLength(vm: VM; minLength: int) {.inline.} =
## Check that evaluation stack contains at least "minLength" elements.
if vm.stack.len < minLength:
raise newException(RuntimeError, &"not enough operands on the stack (pc = {vm.pc}).")
 
#---------------------------------------------------------------------------------------------------
 
proc getOperand(vm: var VM): Value =
## Get a 32 bits operand.
 
type Union {.union.} = object
value: Value
bytes: BytesValue
 
if vm.pc + 4 >= vm.memory.len:
raise newException(RuntimeError, &"out of memory (pc = {vm.pc}).")
 
var aux: Union
let address = vm.pc + 1
for idx in 0..3:
aux.bytes[idx] = vm.memory[address + idx]
result = aux.value
 
#---------------------------------------------------------------------------------------------------
 
proc run(vm: var VM) =
## Run a program loaded in VM memory.
 
vm.pc = 0
 
while true:
 
if vm.pc notin 0..vm.memory.high:
raise newException(RuntimeError, &"out of memory (pc = {vm.pc}).")
 
let opcode = OpCode(vm.memory[vm.pc])
case opcode
 
of opFetch, opStore:
let index = vm.getOperand()
if index notin 0..vm.data.high:
raise newException(RuntimeError, &"wrong memory index (pc = {vm.pc}).")
if opcode == opFetch:
vm.stack.add(vm.data[index])
else:
vm.checkStackLength(1)
vm.data[index] = vm.stack.pop()
inc vm.pc, 4
 
of opPush:
let value = vm.getOperand()
vm.stack.add(value)
inc vm.pc, 4
 
of opJmp:
let offset = vm.getOperand()
inc vm.pc, offset
 
of opJz:
let offset = vm.getOperand()
vm.checkStackLength(1)
let value = vm.stack.pop()
inc vm.pc, if value == 0: offset else: 4
 
of opAdd..opOr:
# Two operands instructions.
vm.checkStackLength(2)
let op2 = vm.stack.pop()
let op1 = vm.stack.pop()
case range[opAdd..opOr](opcode)
of opAdd:
vm.stack.add(op1 + op2)
of opSub:
vm.stack.add(op1 - op2)
of opMul:
vm.stack.add(op1 * op2)
of opDiv:
vm.stack.add(op1 div op2)
of opMod:
vm.stack.add(op1 mod op2)
of opLt:
vm.stack.add(Value(op1 < op2))
of opgt:
vm.stack.add(Value(op1 > op2))
of opLe:
vm.stack.add(Value(op1 <= op2))
of opGe:
vm.stack.add(Value(op1 >= op2))
of opEq:
vm.stack.add(Value(op1 == op2))
of opNe:
vm.stack.add(Value(op1 != op2))
of opAnd:
vm.stack.add(op1 and op2)
of opOr:
vm.stack.add(op1 or op2)
 
of opNeg..opPrts:
# One operand instructions.
vm.checkStackLength(1)
let op = vm.stack.pop()
case range[opNeg..opPrts](opcode)
of opNeg:
vm.stack.add(-op)
of opNot:
vm.stack.add(not op)
of opPrtc:
stdout.write(chr(op))
of opPrti:
stdout.write(op)
of opPrts:
if op notin 0..vm.strings.high:
raise newException(RuntimeError, &"wrong string index (pc = {vm.pc}).")
stdout.write(vm.strings[op])
 
of opHalt:
break
 
of opInvalid:
discard # Not possible.
 
inc vm.pc
 
 
####################################################################################################
# Loading assembly file.
 
proc parseHeader(line: string): tuple[dataSize, stringCount: int] =
## Parse the header.
 
if not line.scanf("Datasize: $s$i $sStrings: $i", result.dataSize, result.stringCount):
raise newException(LoadingError, "Wrong header in code.")
 
#---------------------------------------------------------------------------------------------------
 
import re
 
proc parseString(line: string; linenum: int): string =
## Parse a string.
 
if not line.startsWith('"'):
raise newException(LoadingError, "Line $1: incorrect string.".format(linenum))
# Can't use "unescape" as it is confused by "\\n" and "\n".
result = line.replacef(re"([^\\])(\\n)", "$1\n").replace(r"\\", r"\").replace("\"", "")
 
#---------------------------------------------------------------------------------------------------
 
proc parseValue(line: string; linenum: int; pos: var int; msg: string): int32 =
## Parse an int32 value.
 
var value: int
 
pos += line.skipWhitespace(pos)
let parsed = line.parseInt(value, pos)
if parsed == 0:
raise newException(LoadingError, "Line $1: ".format(linenum) & msg)
pos += parsed
result = int32(value)
 
#---------------------------------------------------------------------------------------------------
 
proc parseOpcode(line: string; linenum: int; pos: var int): OpCode =
## Parse an opcode.
 
var opstring: string
 
pos += line.skipWhitespace(pos)
let parsed = line.parseIdent(opstring, pos)
if parsed == 0:
raise newException(LoadingError, "Line $1: opcode expected".format(linenum))
pos += parsed
 
result = parseEnum[OpCode](opstring, opInvalid)
if result == opInvalid:
raise newException(LoadingError, "Line $1: invalid opcode encountered".format(linenum))
 
#---------------------------------------------------------------------------------------------------
 
proc parseMemoryIndex(line: string; linenum: int; pos: var int): int32 =
## Parse a memory index (int32 value between brackets).
 
var memIndex: int
 
pos += line.skipWhitespace(pos)
let str = line.captureBetween('[', ']', pos)
if str.parseInt(memIndex) == 0 or memIndex < 0:
raise newException(LoadingError, "Line $1: invalid memory index".format(lineNum))
pos += str.len + 2
result = int32(memIndex)
 
#---------------------------------------------------------------------------------------------------
 
proc parseOffset(line: string; linenum: int; pos: var int): int32 =
## Parse an offset (int32 value between parentheses).
 
var offset: int
 
pos += line.skipWhitespace(pos)
let str = line.captureBetween('(', ')', pos)
if str.parseInt(offset) == 0:
raise newException(LoadingError, "Line $1: invalid offset".format(linenum))
pos += str.len + 2
result = int32(offset)
 
#---------------------------------------------------------------------------------------------------
 
proc load(vm: var VM; code: string) =
## Load an assembly code into VM memory.
 
# Analyze header.
let lines = code.splitlines()
let (dataSize, stringCount) = parseHeader(lines[0])
vm.data.setLen(dataSize)
vm.strings.setLen(stringCount)
 
# Load strings.
for idx in 1..stringCount:
vm.strings[idx - 1] = lines[idx].parseString(idx + 1)
 
# Load code.
var pc: Address = 0
for idx in (stringCount + 1)..lines.high:
var pos = 0
let line = lines[idx]
if line.len == 0: continue
 
# Process address.
let address = line.parseValue(idx + 1, pos, "address expected")
if address != pc:
raise newException(LoadingError, "Line $1: wrong address".format(idx + 1))
 
# Process opcode.
let opcode = line.parseOpcode(idx + 1, pos)
vm.memory.add(byte(opcode))
 
# Process operand.
case opcode
 
of opFetch, opStore:
# Find memory index.
let memIndex = line.parseMemoryIndex(idx + 1, pos)
vm.memory.add(cast[BytesValue](Value(memIndex)))
inc pc, 5
 
of opJmp, opJz:
# Find offset.
let offset = line.parseOffset(idx + 1, pos)
vm.memory.add(cast[BytesValue](Value(offset)))
# Find and check branch address.
let branchAddress = line.parseValue(idx + 1, pos, "branch address expected")
if branchAddress != pc + offset + 1:
raise newException(LoadingError, "Line $1: wrong branch address".format(idx + 1))
inc pc, 5
 
of opPush:
# Find value.
let value = line.parseValue(idx + 1, pos, "value expected")
vm.memory.add(cast[BytesValue](Value(value)))
inc pc, 5
 
else:
inc pc
 
#———————————————————————————————————————————————————————————————————————————————————————————————————
 
let code = if paramCount() == 0: stdin.readAll() else: paramStr(1).readFile()
var vm: VM
 
vm.load(code)
vm.run()

All tests passed.

Perl[edit]

Tested with perl v5.26.1

#!/usr/bin/perl
 
# http://www.rosettacode.org/wiki/Compiler/virtual_machine_interpreter
use strict; # vm.pl - run rosetta code
use warnings;
use integer;
 
my ($binary, $pc, @stack, @data) = ('', 0);
 
<> =~ /Strings: (\d+)/ or die "bad header";
my @strings = map <> =~ tr/\n""//dr =~ s/\\(.)/$1 eq 'n' ? "\n" : $1/ger, 1..$1;
 
sub value { unpack 'l', substr $binary, ($pc += 4) - 4, 4 }
 
my @ops = (
[ halt => sub { exit } ],
[ add => sub { $stack[-2] += pop @stack } ],
[ sub => sub { $stack[-2] -= pop @stack } ],
[ mul => sub { $stack[-2] *= pop @stack } ],
[ div => sub { $stack[-2] /= pop @stack } ],
[ mod => sub { $stack[-2] %= pop @stack } ],
[ not => sub { $stack[-1] = $stack[-1] ? 0 : 1 } ],
[ neg => sub { $stack[-1] = - $stack[-1] } ],
[ and => sub { $stack[-2] &&= $stack[-1]; pop @stack } ],
[ or => sub { $stack[-2] ||= $stack[-1]; pop @stack } ],
[ lt => sub { $stack[-1] = $stack[-2] < pop @stack ? 1 : 0 } ],
[ gt => sub { $stack[-1] = $stack[-2] > pop @stack ? 1 : 0 } ],
[ le => sub { $stack[-1] = $stack[-2] <= pop @stack ? 1 : 0 } ],
[ ge => sub { $stack[-1] = $stack[-2] >= pop @stack ? 1 : 0 } ],
[ ne => sub { $stack[-1] = $stack[-2] != pop @stack ? 1 : 0 } ],
[ eq => sub { $stack[-1] = $stack[-2] == pop @stack ? 1 : 0 } ],
[ prts => sub { print $strings[pop @stack] } ],
[ prti => sub { print pop @stack } ],
[ prtc => sub { print chr pop @stack } ],
[ store => sub { $data[value()] = pop @stack } ],
[ fetch => sub { push @stack, $data[value()] // 0 } ],
[ push => sub { push @stack, value() } ],
[ jmp => sub { $pc += value() - 4 } ],
[ jz => sub { $pc += pop @stack ? 4 : value() - 4 } ],
);
my %op2n = map { $ops[$_][0], $_ } 0..$#ops; # map name to op number
 
while(<>)
{
/^ *\d+ +(\w+)/ or die "bad line $_"; # format error
$binary .= chr( $op2n{$1} // die "$1 not defined" ) . # op code
(/\((-?\d+)\)|(\d+)]?$/ and pack 'l', $+); # 4 byte value
}
 
$ops[vec($binary, $pc++, 8)][1]->() while 1; # run it

Passes all tests.

Phix[edit]

Reusing cgen.e from the Code Generator task

--
-- demo\rosetta\Compiler\vm.exw
-- ============================
--
-- Since we have generated executable machine code, the virtual machine, such as it is, is just
-- the higher level implementations of printc/i/s, see setbuiltins() in cgen.e
-- Otherwise the only difference between this and cgen.exw is call(code_mem) instead of decode().
--
-- A quick test (calculating fib(44) 10^6 times) suggests ~500 times faster than interp.exw -
-- which is to be expected given that a single add instruction (1 clock) here is implemented as
-- at least three (and quite possibly five!) resursive calls to interp() in the other.
 
 
format PE32
--format ELF32
-- Note: cgen generates 32-bit machine code, which cannot be executed directly from a 64-bit interpreter.
-- You can however, via the magic of either the above format directives, use a 64-bit version of
-- Phix to compile this (just add a -c command line option) to a 32-bit executable, which can.
-- It would not be particularly difficult to emit 32 or 64 bit code, but some source code files
-- would, fairly obviously, then be very nearly twice as long, and a fair bit harder to read.
 
include cgen.e
 
procedure main(sequence cl)
open_files(cl)
toks = lex()
object t = parse()
code_gen(t)
fixup()
if machine_bits()=32 then
-- ^ as per note above
call(code_mem)
end if
free({var_mem,code_mem})
close_files()
end procedure
 
--main(command_line())
main({0,0,"count.c"})
Output:
count is: 1
count is: 2
count is: 3
count is: 4
count is: 5
count is: 6
count is: 7
count is: 8
count is: 9

Python[edit]

Tested with Python 2.7 and 3.x

from __future__ import print_function
import sys, struct
 
FETCH, STORE, PUSH, ADD, SUB, MUL, DIV, MOD, LT, GT, LE, GE, EQ, NE, AND, OR, NEG, NOT, \
JMP, JZ, PRTC, PRTS, PRTI, HALT = range(24)
 
code_map = {
"fetch": FETCH,
"store": STORE,
"push": PUSH,
"add": ADD,
"sub": SUB,
"mul": MUL,
"div": DIV,
"mod": MOD,
"lt": LT,
"gt": GT,
"le": LE,
"ge": GE,
"eq": EQ,
"ne": NE,
"and": AND,
"or": OR,
"not": NOT,
"neg": NEG,
"jmp": JMP,
"jz": JZ,
"prtc": PRTC,
"prts": PRTS,
"prti": PRTI,
"halt": HALT
}
 
input_file = None
code = bytearray()
string_pool = []
word_size = 4
 
#*** show error and exit
def error(msg):
print("%s" % (msg))
exit(1)
 
def int_to_bytes(val):
return struct.pack("<i", val)
 
def bytes_to_int(bstr):
return struct.unpack("<i", bstr)
 
#***
def emit_byte(x):
code.append(x)
 
#***
def emit_word(x):
s = int_to_bytes(x)
for x in s:
code.append(x)
 
#***
def run_vm(data_size):
stack = [0 for i in range(data_size + 1)]
pc = 0
while True:
op = code[pc]
pc += 1
 
if op == FETCH:
stack.append(stack[bytes_to_int(code[pc:pc+word_size])[0]]);
pc += word_size
elif op == STORE:
stack[bytes_to_int(code[pc:pc+word_size])[0]] = stack.pop();
pc += word_size
elif op == PUSH:
stack.append(bytes_to_int(code[pc:pc+word_size])[0]);
pc += word_size
elif op == ADD: stack[-2] += stack[-1]; stack.pop()
elif op == SUB: stack[-2] -= stack[-1]; stack.pop()
elif op == MUL: stack[-2] *= stack[-1]; stack.pop()
# use C like division semantics
elif op == DIV: stack[-2] = int(float(stack[-2]) / stack[-1]); stack.pop()
elif op == MOD: stack[-2] = int(float(stack[-2]) % stack[-1]); stack.pop()
elif op == LT: stack[-2] = stack[-2] < stack[-1]; stack.pop()
elif op == GT: stack[-2] = stack[-2] > stack[-1]; stack.pop()
elif op == LE: stack[-2] = stack[-2] <= stack[-1]; stack.pop()
elif op == GE: stack[-2] = stack[-2] >= stack[-1]; stack.pop()
elif op == EQ: stack[-2] = stack[-2] == stack[-1]; stack.pop()
elif op == NE: stack[-2] = stack[-2] != stack[-1]; stack.pop()
elif op == AND: stack[-2] = stack[-2] and stack[-1]; stack.pop()
elif op == OR: stack[-2] = stack[-2] or stack[-1]; stack.pop()
elif op == NEG: stack[-1] = -stack[-1]
elif op == NOT: stack[-1] = not stack[-1]
elif op == JMP: pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == JZ:
if stack.pop():
pc += word_size
else:
pc += bytes_to_int(code[pc:pc+word_size])[0]
elif op == PRTC: print("%c" % (stack[-1]), end=''); stack.pop()
elif op == PRTS: print("%s" % (string_pool[stack[-1]]), end=''); stack.pop()
elif op == PRTI: print("%d" % (stack[-1]), end=''); stack.pop()
elif op == HALT: break
 
def str_trans(srce):
dest = ""
i = 0
while i < len(srce):
if srce[i] == '\\' and i + 1 < len(srce):
if srce[i + 1] == 'n':
dest += '\n'
i += 2
elif srce[i + 1] == '\\':
dest += '\\'
i += 2
else:
dest += srce[i]
i += 1
 
return dest
 
#***
def load_code():
global string_pool
 
line = input_file.readline()
if len(line) == 0:
error("empty line")
 
line_list = line.split()
data_size = int(line_list[1])
n_strings = int(line_list[3])
 
for i in range(n_strings):
string_pool.append(str_trans(input_file.readline().strip('"\n')))
 
while True:
line = input_file.readline()
if len(line) == 0:
break
line_list = line.split()
offset = int(line_list[0])
instr = line_list[1]
opcode = code_map.get(instr)
if opcode == None:
error("Unknown instruction %s at %d" % (instr, offset))
emit_byte(opcode)
if opcode in [JMP, JZ]:
p = int(line_list[3])
emit_word(p - (offset + 1))
elif opcode == PUSH:
value = int(line_list[2])
emit_word(value)
elif opcode in [FETCH, STORE]:
value = int(line_list[2].strip('[]'))
emit_word(value)
 
return data_size
 
#*** main driver
input_file = sys.stdin
if len(sys.argv) > 1:
try:
input_file = open(sys.argv[1], "r", 4096)
except IOError as e:
error(0, 0, "Can't open %s" % sys.argv[1])
 
data_size = load_code()
run_vm(data_size)

Raku[edit]

(formerly Perl 6) Non-standard size of instructions (not byte-coded, 'Datasize' is 3 not 1) required adjusting the jump offsets.

NOTE: I don't think you are allowed to change the jump offsets. They come from another program from another company from another planet from another galaxy.

WIP: discovered 'P5pack' module, this may allow for completing the task properly, using correct offsets

Translation of: Perl
my @CODE = q:to/END/.lines;
Datasize: 3 Strings: 2
"count is: "
"\n"
0 push 1
5 store [0]
10 fetch [0]
15 push 10
20 lt
21 jz (68) 65 # jump value adjusted
26 push 0
31 prts
32 fetch [0]
37 prti
38 push 1
43 prts
44 fetch [0]
49 push 1
54 add
55 store [0]
60 jmp (-87) 10 # jump value adjusted
65 halt
END
 
my (@stack, @strings, @data, $memory);
my $pc = 0;
 
(@CODE.shift) ~~ /'Datasize:' \s+ (\d+) \s+ 'Strings:' \s+ (\d+)/ or die "bad header";
my $w = $0; # 'wordsize' of op-codes and 'width' of data values
@strings.push: (my $s = @CODE.shift) eq '"\n"' ?? "\n" !! $s.subst(/'"'/, '', :g) for 1..$1;
 
sub value { substr($memory, ($pc += $w) - $w, $w).trim }
 
my %ops = (
'no-op' => sub { },
'add' => sub { @stack[*-2] += @stack.pop },
'sub' => sub { @stack[*-2] -= @stack.pop },
'mul' => sub { @stack[*-2] *= @stack.pop },
'div' => sub { @stack[*-2] /= @stack.pop },
'mod' => sub { @stack[*-2] %= @stack.pop },
'neg' => sub { @stack[*-1] = - @stack[*-1] },
'and' => sub { @stack[*-2] &&= @stack[*-1]; @stack.pop },
'or' => sub { @stack[*-2] ||= @stack[*-1]; @stack.pop },
'not' => sub { @stack[*-1] = @stack[*-1] ?? 0 !! 1 },
'lt' => sub { @stack[*-1] = @stack[*-2] < @stack.pop ?? 1 !! 0 },
'gt' => sub { @stack[*-1] = @stack[*-2] > @stack.pop ?? 1 !! 0 },
'le' => sub { @stack[*-1] = @stack[*-2] <= @stack.pop ?? 1 !! 0 },
'ge' => sub { @stack[*-1] = @stack[*-2] >= @stack.pop ?? 1 !! 0 },
'ne' => sub { @stack[*-1] = @stack[*-2] != @stack.pop ?? 1 !! 0 },
'eq' => sub { @stack[*-1] = @stack[*-2] == @stack.pop ?? 1 !! 0 },
'store' => sub { @data[&value] = @stack.pop },
'fetch' => sub { @stack.push: @data[&value] // 0 },
'push' => sub { @stack.push: value() },
'jmp' => sub { $pc += value() - $w },
'jz' => sub { $pc += @stack.pop ?? $w !! value() - $w },
'prts' => sub { print @strings[@stack.pop] },
'prti' => sub { print @stack.pop },
'prtc' => sub { print chr @stack.pop },
'halt' => sub { exit }
);
 
my %op2n = %ops.keys.sort Z=> 0..*;
my %n2op = %op2n.invert;
%n2op{''} = 'no-op';
 
for @CODE -> $_ {
next unless /\w/;
/^ \s* \d+ \s+ (\w+)/ or die "bad line $_";
$memory ~= %op2n{$0}.fmt("%{$w}d");
/'(' ('-'?\d+) ')' | (\d+) ']'? $/;
$memory ~= $0 ?? $0.fmt("%{$w}d") !! ' ' x $w;
}
 
loop {
my $opcode = substr($memory, $pc, $w).trim;
$pc += $w;
%ops{%n2op{ $opcode }}();
}
Output:
count is: 1
count is: 2
count is: 3
count is: 4
count is: 5
count is: 6
count is: 7
count is: 8
count is: 9

Scala[edit]

The complete implementation for the compiler tasks can be found in a GitHub repository at github.com/edadma/rosettacodeCompiler which includes full unit testing for the samples given in Compiler/Sample programs.

The following code implements a virtual machine for the output of the code generator.

 
package xyz.hyperreal.rosettacodeCompiler
 
import java.io.{BufferedReader, FileReader, Reader, StringReader}
 
import scala.collection.mutable
import scala.collection.mutable.ArrayBuffer
 
object VirtualMachine {
 
private object Opcodes {
val FETCH: Byte = 0
val STORE: Byte = 1
val PUSH: Byte = 2
val JMP: Byte = 3
val JZ: Byte = 4
val ADD: Byte = 5
val SUB: Byte = 6
val MUL: Byte = 7
val DIV: Byte = 8
val MOD: Byte = 9
val LT: Byte = 10
val GT: Byte = 11
val LE: Byte = 12
val GE: Byte = 13
val EQ: Byte = 14
val NE: Byte = 15
val AND: Byte = 16
val OR: Byte = 17
val NEG: Byte = 18
val NOT: Byte = 19
val PRTC: Byte = 20
val PRTI: Byte = 21
val PRTS: Byte = 22
val HALT: Byte = 23
}
 
import Opcodes._
 
private val HEADER_REGEX = "Datasize: ([0-9]+) Strings: ([0-9]+)" r
private val STRING_REGEX = "\"([^\"]*)\"" r
private val PUSH_REGEX = " *[0-9]+ push +([0-9]+|'(?:[^'\\n]|\\\\n|\\\\\\\\)')" r
private val PRTS_REGEX = " *[0-9]+ prts" r
private val PRTI_REGEX = " *[0-9]+ prti" r
private val PRTC_REGEX = " *[0-9]+ prtc" r
private val HALT_REGEX = " *[0-9]+ halt" r
private val STORE_REGEX = " *[0-9]+ store +\\[([0-9]+)\\]" r
private val FETCH_REGEX = " *[0-9]+ fetch +\\[([0-9]+)\\]" r
private val LT_REGEX = " *[0-9]+ lt" r
private val GT_REGEX = " *[0-9]+ gt" r
private val LE_REGEX = " *[0-9]+ le" r
private val GE_REGEX = " *[0-9]+ ge" r
private val NE_REGEX = " *[0-9]+ ne" r
private val EQ_REGEX = " *[0-9]+ eq" r
private val JZ_REGEX = " *[0-9]+ jz +\\((-?[0-9]+)\\) [0-9]+" r
private val ADD_REGEX = " *[0-9]+ add" r
private val SUB_REGEX = " *[0-9]+ sub" r
private val MUL_REGEX = " *[0-9]+ mul" r
private val DIV_REGEX = " *[0-9]+ div" r
private val MOD_REGEX = " *[0-9]+ mod" r
private val AND_REGEX = " *[0-9]+ and" r
private val OR_REGEX = " *[0-9]+ or" r
private val NOT_REGEX = " *[0-9]+ not" r
private val NEG_REGEX = " *[0-9]+ neg" r
private val JMP_REGEX = " *[0-9]+ jmp +\\((-?[0-9]+)\\) [0-9]+" r
 
def fromStdin = fromReader(Console.in)
 
def fromFile(file: String) = fromReader(new FileReader(file))
 
def fromString(src: String) = fromReader(new StringReader(src))
 
def fromReader(r: Reader) = {
val in = new BufferedReader(r)
val vm =
in.readLine match {
case HEADER_REGEX(datasize, stringsize) =>
val strings =
for (_ <- 1 to stringsize.toInt)
yield
in.readLine match {
case STRING_REGEX(s) => unescape(s)
case null => sys.error("expected string constant but encountered end of input")
case s => sys.error(s"expected string constant: $s")
}
var line: String = null
val code = new ArrayBuffer[Byte]
 
def addShort(a: Int) = {
code += (a >> 8).toByte
code += a.toByte
}
 
def addInstIntOperand(opcode: Byte, operand: Int) = {
code += opcode
addShort(operand >> 16)
addShort(operand)
}
 
def addInst(opcode: Byte, operand: String) = addInstIntOperand(opcode, operand.toInt)
 
while ({ line = in.readLine; line ne null }) line match {
case PUSH_REGEX(n) if n startsWith "'" =>
addInstIntOperand(PUSH, unescape(n.substring(1, n.length - 1)).head)
case PUSH_REGEX(n) => addInst(PUSH, n)
case PRTS_REGEX() => code += PRTS
case PRTI_REGEX() => code += PRTI
case PRTC_REGEX() => code += PRTC
case HALT_REGEX() => code += HALT
case STORE_REGEX(idx) => addInst(STORE, idx)
case FETCH_REGEX(idx) => addInst(FETCH, idx)
case LT_REGEX() => code += LT
case GT_REGEX() => code += GT
case LE_REGEX() => code += LE
case GE_REGEX() => code += GE
case NE_REGEX() => code += NE
case EQ_REGEX() => code += EQ
case JZ_REGEX(disp) => addInst(JZ, disp)
case ADD_REGEX() => code += ADD
case SUB_REGEX() => code += SUB
case MUL_REGEX() => code += MUL
case DIV_REGEX() => code += DIV
case MOD_REGEX() => code += MOD
case AND_REGEX() => code += AND
case OR_REGEX() => code += OR
case NOT_REGEX() => code += NOT
case NEG_REGEX() => code += NEG
case JMP_REGEX(disp) => addInst(JMP, disp)
}
 
new VirtualMachine(code, datasize.toInt, strings)
case _ => sys.error("expected header")
}
 
in.close
vm
}
 
}
 
class VirtualMachine(code: IndexedSeq[Byte], datasize: Int, strings: IndexedSeq[String]) {
 
import VirtualMachine.Opcodes._
 
var pc = 0
val stack = new mutable.ArrayStack[Int]
val data = new Array[Int](datasize)
var running = false
 
def getByte = {
val byte = code(pc) & 0xFF
 
pc += 1
byte
}
 
def getShort = getByte << 8 | getByte
 
def getInt = getShort << 16 | getShort
 
def pushBoolean(b: Boolean) = stack push (if (b) 1 else 0)
 
def popBoolean = if (stack.pop != 0) true else false
 
def operator(f: (Int, Int) => Int) = {
val y = stack.pop
 
stack.push(f(stack.pop, y))
}
 
def relation(r: (Int, Int) => Boolean) = {
val y = stack.pop
 
pushBoolean(r(stack.pop, y))
}
 
def connective(c: (Boolean, Boolean) => Boolean) = pushBoolean(c(popBoolean, popBoolean))
 
def execute: Unit =
getByte match {
case FETCH => stack push data(getInt)
case STORE => data(getInt) = stack.pop
case PUSH => stack push getInt
case JMP => pc = pc + getInt
case JZ => if (stack.pop == 0) pc = pc + getInt else pc += 4
case ADD => operator(_ + _)
case SUB => operator(_ - _)
case MUL => operator(_ * _)
case DIV => operator(_ / _)
case MOD => operator(_ % _)
case LT => relation(_ < _)
case GT => relation(_ > _)
case LE => relation(_ <= _)
case GE => relation(_ >= _)
case EQ => relation(_ == _)
case NE => relation(_ != _)
case AND => connective(_ && _)
case OR => connective(_ || _)
case NEG => stack push -stack.pop
case NOT => pushBoolean(!popBoolean)
case PRTC => print(stack.pop.toChar)
case PRTI => print(stack.pop)
case PRTS => print(strings(stack.pop))
case HALT => running = false
}
 
def run = {
pc = 0
stack.clear
running = true
 
for (i <- data.indices) data(i) = 0
 
while (running) execute
}
 
}
 

The above code depends on the function unescape() to perform string escape sequence translation. That function is defined in the following separate source file.

 
package xyz.hyperreal
 
import java.io.ByteArrayOutputStream
 
package object rosettacodeCompiler {
 
val escapes = "\\\\b|\\\\f|\\\\t|\\\\r|\\\\n|\\\\\\\\|\\\\\"" r
 
def unescape(s: String) =
escapes.replaceAllIn(s, _.matched match {
case "\\b" => "\b"
case "\\f" => "\f"
case "\\t" => "\t"
case "\\r" => "\r"
case "\\n" => "\n"
case "\\\\" => "\\"
case "\\\"" => "\""
})
 
def capture(thunk: => Unit) = {
val buf = new ByteArrayOutputStream
 
Console.withOut(buf)(thunk)
buf.toString
}
 
}
 

Scheme[edit]

The interpreter uses recursion, representing the stack as a list; the stack pointer is the reference to the top of the list. This is a more natural solution in Scheme than a fixed stack array, and removes the danger of stack overflow. Operations on or returning booleans have been adapted to use integers, 0 for false and anything else for true.

All of the "Compiler/Sample programs" are correctly interpreted.

 
(import (scheme base)
(scheme char)
(scheme file)
(scheme process-context)
(scheme write)
(only (srfi 13) string-contains string-delete string-filter
string-replace string-tokenize))
 
(define *word-size* 4)
 
;; Mappings from operation symbols to internal procedures.
;; We define operations appropriate to virtual machine:
;; e.g. division must return an int, not a rational
;; boolean values are treated as numbers: 0 is false, other is true
(define *unary-ops*
(list (cons 'neg (lambda (a) (- a)))
(cons 'not (lambda (a) (if (zero? a) 1 0)))))
(define *binary-ops*
(let ((number-comp (lambda (op) (lambda (a b) (if (op a b) 1 0)))))
(list (cons 'add +)
(cons 'sub -)
(cons 'mul *)
(cons 'div (lambda (a b) (truncate (/ a b)))) ; int division
(cons 'mod modulo)
(cons 'lt (number-comp <))
(cons 'gt (number-comp >))
(cons 'le (number-comp <=))
(cons 'ge (number-comp >=))
(cons 'eq (lambda (a b) (if (= a b) 1 0)))
(cons 'ne (lambda (a b) (if (= a b) 0 1)))
(cons 'and (lambda (a b) ; make "and" work on numbers
(if (and (not (zero? a)) (not (zero? b))) 1 0)))
(cons 'or (lambda (a b) ; make "or" work on numbers
(if (or (not (zero? a)) (not (zero? b))) 1 0))))))
 
;; read information from file, returning vectors for data and strings
;; and a list of the code instructions
(define (read-code filename)
(define (setup-definitions str)
(values ; return vectors for (data strings) of required size
(make-vector (string->number (list-ref str 1)) #f)
(make-vector (string->number (list-ref str 3)) #f)))
(define (read-strings strings) ; read constant strings into data structure
(define (replace-newlines chars) ; replace newlines, obeying \\n
(cond ((< (length chars) 2) ; finished list
chars)
((and (>= (length chars) 3) ; preserve \\n
(char=? #\\ (car chars))
(char=? #\\ (cadr chars))
(char=? #\n (cadr (cdr chars))))
(cons (car chars)
(cons (cadr chars)
(cons (cadr (cdr chars))
(replace-newlines (cdr (cdr (cdr chars))))))))
((and (char=? #\\ (car chars)) ; replace \n with newline
(char=? #\n (cadr chars)))
(cons #\newline (replace-newlines (cdr (cdr chars)))))
(else ; keep char and look further
(cons (car chars) (replace-newlines (cdr chars))))))
(define (tidy-string str) ; remove quotes, map newlines to actual newlines
(list->string
(replace-newlines
(string->list
(string-delete #\" str))))) ; " (needed to satisfy rosettacode's scheme syntax highlighter)
;
(do ((i 0 (+ i 1)))
((= i (vector-length strings)) )
(vector-set! strings i (tidy-string (read-line)))))
(define (read-code)
(define (cleanup-code opn) ; tidy instructions, parsing numbers
(let ((addr (string->number (car opn)))
(instr (string->symbol (cadr opn))))
(cond ((= 2 (length opn))
(list addr instr))
((= 3 (length opn))
(list addr
instr
(string->number
(string-filter char-numeric? (list-ref opn 2)))))
(else ; assume length 4, jump instructions
(list addr instr (string->number (list-ref opn 3)))))))
;
(let loop ((result '()))
(let ((line (read-line)))
(if (eof-object? line)
(reverse (map cleanup-code result))
(loop (cons (string-tokenize line) result))))))
;
(with-input-from-file
filename
(lambda ()
(let-values (((data strings)
(setup-definitions (string-tokenize (read-line)))))
(read-strings strings)
(values data
strings
(read-code))))))
 
;; run the virtual machine
(define (run-program data strings code)
(define (get-instruction n)
(if (assq n code)
(cdr (assq n code))
(error "Could not find instruction")))
;
(let loop ((stack '())
(pc 0))
(let ((op (get-instruction pc)))
(case (car op)
((fetch)
(loop (cons (vector-ref data (cadr op)) stack)
(+ pc 1 *word-size*)))
((store)
(vector-set! data (cadr op) (car stack))
(loop (cdr stack)
(+ pc 1 *word-size*)))
((push)
(loop (cons (cadr op) stack)
(+ pc 1 *word-size*)))
((add sub mul div mod lt gt le eq ne and or)
(let ((instr (assq (car op) *binary-ops*)))
(if instr
(loop (cons ((cdr instr) (cadr stack) ; replace top two with result
(car stack))
(cdr (cdr stack)))
(+ pc 1))
(error "Unknown binary operation"))))
((neg not)
(let ((instr (assq (car op) *unary-ops*)))
(if instr
(loop (cons ((cdr instr) (car stack)) ; replace top with result
(cdr stack))
(+ pc 1))
(error "Unknown unary operation"))))
((jmp)
(loop stack
(cadr op)))
((jz)
(loop (cdr stack)
(if (zero? (car stack))
(cadr op)
(+ pc 1 *word-size*))))
((prtc)
(display (integer->char (car stack)))
(loop (cdr stack)
(+ pc 1)))
((prti)
(display (car stack))
(loop (cdr stack)
(+ pc 1)))
((prts)
(display (vector-ref strings (car stack)))
(loop (cdr stack)
(+ pc 1)))
((halt)
#t)))))
 
;; create and run virtual machine from filename passed on command line
(if (= 2 (length (command-line)))
(let-values (((data strings code) (read-code (cadr (command-line)))))
(run-program data strings code))
(display "Error: pass a .asm filename\n"))
 

Wren[edit]

Translation of: Go
Library: Wren-dynamic
Library: Wren-crypto
Library: Wren-fmt
Library: Wren-ioutil
import "/dynamic" for Enum
import "/crypto" for Bytes
import "/fmt" for Conv
import "/ioutil" for FileUtil
 
var codes = [
"fetch",
"store",
"push",
"add",
"sub",
"mul",
"div",
"mod",
"lt",
"gt",
"le",
"ge",
"eq",
"ne",
"and",
"or",
"neg",
"not",
"jmp",
"jz",
"prtc",
"prts",
"prti",
"halt"
]
 
var Code = Enum.create("Code", codes)
 
var codeMap = {
"fetch": Code.fetch,
"store": Code.store,
"push": Code.push,
"add": Code.add,
"sub": Code.sub,
"mul": Code.mul,
"div": Code.div,
"mod": Code.mod,
"lt": Code.lt,
"gt": Code.gt,
"le": Code.le,
"ge": Code.ge,
"eq": Code.eq,
"ne": Code.ne,
"and": Code.and,
"or": Code.or,
"neg": Code.neg,
"not": Code.not,
"jmp": Code.jmp,
"jz": Code.jz,
"prtc": Code.prtc,
"prts": Code.prts,
"prti": Code.prti,
"halt": Code.halt
}
 
var object = []
var stringPool = []
 
var reportError = Fn.new { |msg| Fiber.abort("error : %(msg)") }
 
var emitByte = Fn.new { |c| object.add(c) }
 
var emitWord = Fn.new { |n|
var bs = Bytes.fromIntLE(n)
for (b in bs) emitByte.call(b)
}
 
// Converts the 4 bytes starting at object[pc] to an unsigned 32 bit integer
// and thence to a signed 32 bit integer
var toInt32LE = Fn.new { |pc|
var x = Bytes.toIntLE(object[pc...pc+4])
if (x >= 2.pow(31)) x = x - 2.pow(32)
return x
}
 
/* Virtual Machine interpreter */
 
var runVM = Fn.new { |dataSize|
var stack = List.filled(dataSize + 1, 0)
var pc = 0
while (true) {
var op = object[pc]
pc = pc + 1
if (op == Code.fetch) {
var x = toInt32LE.call(pc)
stack.add(stack[x])
pc = pc + 4
} else if (op == Code.store) {
var x = toInt32LE.call(pc)
var ln = stack.count
stack[x] = stack[ln-1]
stack = stack[0...ln-1]
pc = pc + 4
} else if (op == Code.push) {
var x = toInt32LE.call(pc)
stack.add(x)
pc = pc + 4
} else if (op == Code.add) {
var ln = stack.count
stack[ln-2] = stack[ln-2] + stack[ln-1]
stack = stack[0...ln-1]
} else if (op == Code.sub) {
var ln = stack.count
stack[ln-2] = stack[ln-2] - stack[ln-1]
stack = stack[0...ln-1]
} else if (op == Code.mul) {
var ln = stack.count
stack[ln-2] = stack[ln-2] * stack[ln-1]
stack = stack[0...ln-1]
} else if (op == Code.div) {
var ln = stack.count
stack[ln-2] = (stack[ln-2] / stack[ln-1]).truncate
stack = stack[0...ln-1]
} else if (op == Code.mod) {
var ln = stack.count
stack[ln-2] = stack[ln-2] % stack[ln-1]
stack = stack[0...ln-1]
} else if (op == Code.lt) {
var ln = stack.count
stack[ln-2] = Conv.btoi(stack[ln-2] < stack[ln-1])
stack = stack[0...ln-1]
} else if (op == Code.gt) {
var ln = stack.count
stack[ln-2] = Conv.btoi(stack[ln-2] > stack[ln-1])
stack = stack[0...ln-1]
} else if (op == Code.le) {
var ln = stack.count
stack[ln-2] = Conv.btoi(stack[ln-2] <= stack[ln-1])
stack = stack[0...ln-1]
} else if (op == Code.ge) {
var ln = stack.count
stack[ln-2] = Conv.btoi(stack[ln-2] >= stack[ln-1])
stack = stack[0...ln-1]
} else if (op == Code.eq) {
var ln = stack.count
stack[ln-2] = Conv.btoi(stack[ln-2] == stack[ln-1])
stack = stack[0...ln-1]
} else if (op == Code.ne) {
var ln = stack.count
stack[ln-2] = Conv.btoi(stack[ln-2] != stack[ln-1])
stack = stack[0...ln-1]
} else if (op == Code.and) {
var ln = stack.count
stack[ln-2] = Conv.btoi(Conv.itob(stack[ln-2]) && Conv.itob(stack[ln-1]))
stack = stack[0...ln-1]
} else if (op == Code.or) {
var ln = stack.count
stack[ln-2] = Conv.btoi(Conv.itob(stack[ln-2]) || Conv.itob(stack[ln-1]))
stack = stack[0...ln-1]
} else if (op == Code.neg) {
var ln = stack.count
stack[ln-1] = -stack[ln-1]
} else if (op == Code.not) {
var ln = stack.count
stack[ln-1] = Conv.btoi(!Conv.itob(stack[ln-1]))
} else if (op == Code.jmp) {
var x = toInt32LE.call(pc)
pc = pc + x
} else if (op == Code.jz) {
var ln = stack.count
var v = stack[ln-1]
stack = stack[0...ln-1]
if (v != 0) {
pc = pc + 4
} else {
var x = toInt32LE.call(pc)
pc = pc + x
}
} else if (op == Code.prtc) {
var ln = stack.count
System.write(String.fromByte(stack[ln-1]))
stack = stack[0...ln-1]
} else if (op == Code.prts) {
var ln = stack.count
System.write(stringPool[stack[ln-1]])
stack = stack[0...ln-1]
} else if (op == Code.prti) {
var ln = stack.count
System.write(stack[ln-1])
stack = stack[0...ln-1]
} else if (op == Code.halt) {
return
} else {
reportError.call("Unknown opcode %(op)")
}
}
}
 
var translate = Fn.new { |s|
var d = ""
var i = 0
while (i < s.count) {
if (s[i] == "\\" && (i+1) < s.count) {
if (s[i+1] == "n") {
d = d + "\n"
i = i + 1
} else if (s[i+1] == "\\") {
d = d + "\\"
i = i + 1
}
} else {
d = d + s[i]
}
i = i + 1
}
return d
}
 
var lines = []
var lineCount = 0
var lineNum = 0
 
var loadCode = Fn.new {
var dataSize
var firstLine = true
while (lineNum < lineCount) {
var line = lines[lineNum].trimEnd(" \t")
lineNum = lineNum + 1
if (line.count == 0) {
if (firstLine) {
reportError.call("empty line")
} else {
break
}
}
var lineList = line.split(" ").where { |s| s != "" }.toList
if (firstLine) {
dataSize = Num.fromString(lineList[1])
var nStrings = Num.fromString(lineList[3])
for (i in 0...nStrings) {
var s = lines[lineNum].trim("\"\n")
lineNum = lineNum + 1
stringPool.add(translate.call(s))
}
firstLine = false
continue
}
var offset = Num.fromString(lineList[0])
var instr = lineList[1]
var opCode = codeMap[instr]
if (!opCode) {
reportError.call("Unknown instruction %(instr) at %(opCode)")
}
emitByte.call(opCode)
if (opCode == Code.jmp || opCode == Code.jz) {
var p = Num.fromString(lineList[3])
emitWord.call(p - offset - 1)
} else if (opCode == Code.push) {
var value = Num.fromString(lineList[2])
emitWord.call(value)
} else if (opCode == Code.fetch || opCode == Code.store) {
var value = Num.fromString(lineList[2].trim("[]"))
emitWord.call(value)
}
}
return dataSize
}
 
lines = FileUtil.readLines("codegen.txt")
lineCount = lines.count
runVM.call(loadCode.call())
Output:
count is: 1
count is: 2
count is: 3
count is: 4
count is: 5
count is: 6
count is: 7
count is: 8
count is: 9

Zig[edit]

 
const std = @import("std");
 
pub const VirtualMachineError = error{OutOfMemory};
 
pub const VirtualMachine = struct {
allocator: *std.mem.Allocator,
stack: [stack_size]i32,
program: std.ArrayList(u8),
sp: usize, // stack pointer
pc: usize, // program counter
string_pool: std.ArrayList([]const u8), // all the strings in the program
globals: std.ArrayList(i32), // all the variables in the program, they are global
output: std.ArrayList(u8), // Instead of outputting to stdout, we do it here for better testing.
 
const Self = @This();
const stack_size = 32; // Can be arbitrarily increased/decreased as long as we have enough.
const word_size = @sizeOf(i32);
 
pub fn init(
allocator: *std.mem.Allocator,
program: std.ArrayList(u8),
string_pool: std.ArrayList([]const u8),
globals: std.ArrayList(i32),
) Self {
return VirtualMachine{
.allocator = allocator,
.stack = [_]i32{std.math.maxInt(i32)} ** stack_size,
.program = program,
.sp = 0,
.pc = 0,
.string_pool = string_pool,
.globals = globals,
.output = std.ArrayList(u8).init(allocator),
};
}
 
pub fn interp(self: *Self) VirtualMachineError!void {
while (true) : (self.pc += 1) {
switch (@intToEnum(Op, self.program.items[self.pc])) {
.push => self.push(self.unpackInt()),
.store => self.globals.items[@intCast(usize, self.unpackInt())] = self.pop(),
.fetch => self.push(self.globals.items[@intCast(usize, self.unpackInt())]),
.jmp => self.pc = @intCast(usize, self.unpackInt() - 1),
.jz => {
if (self.pop() == 0) {
// -1 because `while` increases it with every iteration.
// This doesn't allow to jump to location 0 because we use `usize` for `pc`,
// just arbitrary implementation limitation.
self.pc = @intCast(usize, self.unpackInt() - 1);
} else {
self.pc += word_size;
}
},
.prts => try self.out("{s}", .{self.string_pool.items[@intCast(usize, self.pop())]}),
.prti => try self.out("{d}", .{self.pop()}),
.prtc => try self.out("{c}", .{@intCast(u8, self.pop())}),
.lt => self.binOp(lt),
.le => self.binOp(le),
.gt => self.binOp(gt),
.ge => self.binOp(ge),
.eq => self.binOp(eq),
.ne => self.binOp(ne),
.add => self.binOp(add),
.mul => self.binOp(mul),
.sub => self.binOp(sub),
.div => self.binOp(div),
.mod => self.binOp(mod),
[email protected]"and" => self.binOp(@"and"),
[email protected]"or" => self.binOp(@"or"),
.not => self.push(@boolToInt(self.pop() == 0)),
.neg => self.push(-self.pop()),
.halt => break,
}
}
}
 
fn push(self: *Self, n: i32) void {
self.sp += 1;
self.stack[self.sp] = n;
}
 
fn pop(self: *Self) i32 {
std.debug.assert(self.sp != 0);
self.sp -= 1;
return self.stack[self.sp + 1];
}
 
fn unpackInt(self: *Self) i32 {
const arg_ptr = @ptrCast(*[4]u8, self.program.items[self.pc + 1 .. self.pc + 1 + word_size]);
self.pc += word_size;
var arg_array = arg_ptr.*;
const arg = @ptrCast(*i32, @alignCast(@alignOf(i32), &arg_array));
return arg.*;
}
 
pub fn out(self: *Self, comptime format: []const u8, args: anytype) VirtualMachineError!void {
try self.output.writer().print(format, args);
}
 
fn binOp(self: *Self, func: fn (a: i32, b: i32) i32) void {
const a = self.pop();
const b = self.pop();
// Note that arguments are in reversed order because this is how we interact with
// push/pop operations of the stack.
const result = func(b, a);
self.push(result);
}
 
fn lt(a: i32, b: i32) i32 {
return @boolToInt(a < b);
}
fn le(a: i32, b: i32) i32 {
return @boolToInt(a <= b);
}
fn gt(a: i32, b: i32) i32 {
return @boolToInt(a > b);
}
fn ge(a: i32, b: i32) i32 {
return @boolToInt(a >= b);
}
fn eq(a: i32, b: i32) i32 {
return @boolToInt(a == b);
}
fn ne(a: i32, b: i32) i32 {
return @boolToInt(a != b);
}
fn add(a: i32, b: i32) i32 {
return a + b;
}
fn sub(a: i32, b: i32) i32 {
return a - b;
}
fn mul(a: i32, b: i32) i32 {
return a * b;
}
fn div(a: i32, b: i32) i32 {
return @divTrunc(a, b);
}
fn mod(a: i32, b: i32) i32 {
return @mod(a, b);
}
fn @"or"(a: i32, b: i32) i32 {
return @boolToInt((a != 0) or (b != 0));
}
fn @"and"(a: i32, b: i32) i32 {
return @boolToInt((a != 0) and (b != 0));
}
};
 
pub fn main() !void {
var arena = std.heap.ArenaAllocator.init(std.heap.page_allocator);
defer arena.deinit();
var allocator = &arena.allocator;
 
var arg_it = std.process.args();
_ = try arg_it.next(allocator) orelse unreachable; // program name
const file_name = arg_it.next(allocator);
// We accept both files and standard input.
var file_handle = blk: {
if (file_name) |file_name_delimited| {
const fname: []const u8 = try file_name_delimited;
break :blk try std.fs.cwd().openFile(fname, .{});
} else {
break :blk std.io.getStdIn();
}
};
defer file_handle.close();
const input_content = try file_handle.readToEndAlloc(allocator, std.math.maxInt(usize));
 
var string_pool = std.ArrayList([]const u8).init(allocator);
var globals = std.ArrayList(i32).init(allocator);
const bytecode = try loadBytecode(allocator, input_content, &string_pool, &globals);
var vm = VirtualMachine.init(allocator, bytecode, string_pool, globals);
try vm.interp();
const result: []const u8 = vm.output.items;
_ = try std.io.getStdOut().write(result);
}
 
pub const Op = enum(u8) {
fetch,
store,
push,
add,
sub,
mul,
div,
mod,
lt,
gt,
le,
ge,
eq,
ne,
@"and",
@"or",
neg,
not,
jmp,
jz,
prtc,
prts,
prti,
halt,
 
const from_string = std.ComptimeStringMap(Op, .{
.{ "fetch", .fetch },
.{ "store", .store },
.{ "push", .push },
.{ "add", .add },
.{ "sub", .sub },
.{ "mul", .mul },
.{ "div", .div },
.{ "mod", .mod },
.{ "lt", .lt },
.{ "gt", .gt },
.{ "le", .le },
.{ "ge", .ge },
.{ "eq", .eq },
.{ "ne", .ne },
.{ "and", [email protected]"and" },
.{ "or", [email protected]"or" },
.{ "neg", .neg },
.{ "not", .not },
.{ "jmp", .jmp },
.{ "jz", .jz },
.{ "prtc", .prtc },
.{ "prts", .prts },
.{ "prti", .prti },
.{ "halt", .halt },
});
 
pub fn fromString(str: []const u8) Op {
return from_string.get(str).?;
}
};
 
// 100 lines of code to load serialized bytecode, eh
fn loadBytecode(
allocator: *std.mem.Allocator,
str: []const u8,
string_pool: *std.ArrayList([]const u8),
globals: *std.ArrayList(i32),
) !std.ArrayList(u8) {
var result = std.ArrayList(u8).init(allocator);
var line_it = std.mem.split(str, "\n");
while (line_it.next()) |line| {
if (std.mem.indexOf(u8, line, "halt")) |_| {
var tok_it = std.mem.tokenize(line, " ");
const size = try std.fmt.parseInt(usize, tok_it.next().?, 10);
try result.resize(size + 1);
break;
}
}
 
line_it.index = 0;
const first_line = line_it.next().?;
const strings_index = std.mem.indexOf(u8, first_line, " Strings: ").?;
const globals_size = try std.fmt.parseInt(usize, first_line["Datasize: ".len..strings_index], 10);
const string_pool_size = try std.fmt.parseInt(usize, first_line[strings_index + " Strings: ".len ..], 10);
try globals.resize(globals_size);
try string_pool.ensureCapacity(string_pool_size);
var string_cnt: usize = 0;
while (string_cnt < string_pool_size) : (string_cnt += 1) {
const line = line_it.next().?;
var program_string = try std.ArrayList(u8).initCapacity(allocator, line.len);
var escaped = false;
// Skip double quotes
for (line[1 .. line.len - 1]) |ch| {
if (escaped) {
escaped = false;
switch (ch) {
'\\' => try program_string.append('\\'),
'n' => try program_string.append('\n'),
else => {
std.debug.print("unknown escape sequence: {c}\n", .{ch});
std.os.exit(1);
},
}
} else {
switch (ch) {
'\\' => escaped = true,
else => try program_string.append(ch),
}
}
}
try string_pool.append(program_string.items);
}
while (line_it.next()) |line| {
if (line.len == 0) break;
 
var tok_it = std.mem.tokenize(line, " ");
const address = try std.fmt.parseInt(usize, tok_it.next().?, 10);
const op = Op.fromString(tok_it.next().?);
result.items[address] = @enumToInt(op);
switch (op) {
.fetch, .store => {
const index_bracketed = tok_it.rest();
const index = try std.fmt.parseInt(i32, index_bracketed[1 .. index_bracketed.len - 1], 10);
insertInt(&result, address + 1, index);
},
.push => {
insertInt(&result, address + 1, try std.fmt.parseInt(i32, tok_it.rest(), 10));
},
.jmp, .jz => {
_ = tok_it.next();
insertInt(&result, address + 1, try std.fmt.parseInt(i32, tok_it.rest(), 10));
},
else => {},
}
}
return result;
}
 
fn insertInt(array: *std.ArrayList(u8), address: usize, n: i32) void {
const word_size = @sizeOf(i32);
var i: usize = 0;
var n_var = n;
var n_bytes = @ptrCast(*[4]u8, &n_var);
while (i < word_size) : (i += 1) {
array.items[@intCast(usize, address + i)] = n_bytes[@intCast(usize, i)];
}
}
 

zkl[edit]

Translation of: Python

File rvm.zkl:

// This is a little endian machine
const WORD_SIZE=4;
const{ var _n=-1; var[proxy]N=fcn{ _n+=1 } } // enumerator
const FETCH=N, STORE=N, PUSH=N, ADD=N, SUB=N, MUL=N, DIV=N, MOD=N,
LT=N, GT=N, LE=N, GE=N, EQ=N, NE=N, AND=N, OR=N, NEG=N, NOT=N,
JMP=N, JZ=N, PRTC=N, PRTS=N, PRTI=N, HALT=N;
 
var [const]
bops=Dictionary(ADD,'+, SUB,'-, MUL,'*, DIV,'/, MOD,'%,
LT,'<, GT,'>, LE,'<=, GE,'>=, NE,'!=, EQ,'==, NE,'!=),
strings=List(); // filled in by the loader
;
 
// do a binary op
fcn bop(stack,op){ a,b:=stack.pop(),stack.pop(); stack.append(bops[op](b,a)) }
 
fcn run_vm(code,stackSz){
stack,pc := List.createLong(stackSz,0), 0;
while(True){
op:=code[pc]; pc+=1;
switch(op){
case(FETCH){
stack.append(stack[code.toLittleEndian(pc,WORD_SIZE,False)]);
pc+=WORD_SIZE;
}
case(STORE){
stack[code.toLittleEndian(pc,WORD_SIZE)]=stack.pop();
pc+=WORD_SIZE;
}
case(PUSH){
stack.append(code.toLittleEndian(pc,WORD_SIZE,False)); // signed
pc+=WORD_SIZE;
}
case(ADD,SUB,MUL,DIV,MOD,LT,GT,LE,GE,EQ,NE) { bop(stack,op) }
case(AND){ stack[-2] = stack[-2] and stack[-1]; stack.pop() }
case(OR) { stack[-2] = stack[-2] or stack[-1]; stack.pop() }
case(NEG){ stack[-1] = -stack[-1] }
case(NOT){ stack[-1] = not stack[-1] }
case(JMP){ pc+=code.toLittleEndian(pc,WORD_SIZE,False); } // signed
case(JZ) {
if(stack.pop()) pc+=WORD_SIZE;
else pc+=code.toLittleEndian(pc,WORD_SIZE,False);
}
case(PRTC){ } // not implemented
case(PRTS){ print(strings[stack.pop()]) }
case(PRTI){ print(stack.pop()) }
case(HALT){ break }
else{ throw(Exception.AssertionError(
"Bad op code (%d) @%d".fmt(op,pc-1))) }
}
}
}
 
code:=File(vm.nthArg(0)).read(); // binary code file
// the string table is prepended to the code:
// 66,1 byte len,text, no trailing '\0' needed
while(code[0]==66){ // read the string table
sz:=code[1];
strings.append(code[2,sz].text);
code.del(0,sz+2);
}
run_vm(code,1000);

The binary code file code.bin:

Output:
$ zkl hexDump code.bin 
   0: 42 0a 63 6f 75 6e 74 20 | 69 73 3a 20 42 01 0a 02   B.count is: B...
  16: 01 00 00 00 01 00 00 00 | 00 00 00 00 00 00 02 0a   ................
  32: 00 00 00 08 13 2b 00 00 | 00 02 00 00 00 00 15 00   .....+..........
  48: 00 00 00 00 16 02 01 00 | 00 00 15 00 00 00 00 00   ................
  64: 02 01 00 00 00 03 01 00 | 00 00 00 12 cd ff ff ff   ................
  80: 17
Output:
$ zkl rvm code.bin 
count is: 1
count is: 2
count is: 3
count is: 4
count is: 5
count is: 6
count is: 7
count is: 8
count is: 9