Execute Brain****/ALGOL 68

From Rosetta Code
Execute Brain****/ALGOL 68 is an implementation of Brainf***. Other implementations of Brainf***.
Execute Brain****/ALGOL 68 is part of RCBF. You may find other members of RCBF at Category:RCBF.

An implementation of BF in ALGOL 68 for Rosetta Code.

MODE BYTE = SHORT SHORT SHORT INT;
 
MODE CADDR = BYTE; # code address #
MODE OPCODE = BYTE;
OPCODE nop = 0;
 
MODE DADDR = BYTE; # data address #
MODE DATA = BYTE;
DATA zero = 0;
 
PROC run = ([] OPCODE code list)VOID:(
[-255:255]DATA data list; # finite data space #
FOR i FROM LWB data list TO UPB data list DO data list[i] := zero OD;
 
DADDR data addr := ( UPB data list + LWB data list ) OVER 2;
CADDR code addr := LWB code list;
 
[0:127]OPCODE assembler; # 7 bit ascii only #
 
STRING op code list="><+-.,[]";
[]PROC VOID op list= []PROC VOID(
# ? # VOID: SKIP, # NOP #
# > # VOID: data addr +:= 1,
# < # VOID: data addr -:= 1,
# + # VOID: data list[data addr] +:= 1,
# - # VOID: data list[data addr] -:= 1,
# . # VOID: print(REPR data list[data addr]),
# , # VOID: data list[data addr]:=ABS read char,
# [ # VOID:
IF data list[data addr] = zero THEN
# skip to the end of the loop, allowing for nested loops #
INT br level := 0;
WHILE
IF code list[code addr] = ABS "["
THEN
br level +:= 1;
ELIF code list[code addr] = ABS "]"
THEN
br level -:= 1
FI;
IF br level > 0
THEN
code addr +:= 1;
TRUE
ELSE
FALSE
FI
DO SKIP OD
FI,
# ] # VOID:
IF data list[data addr] /= zero THEN
# skip to the start of the loop, allowing for nested loops #
INT br level := 0;
WHILE
IF code list[code addr] = ABS "["
THEN
br level +:= 1
ELIF code list[code addr] = ABS "]"
THEN
br level -:= 1
FI;
code addr -:= 1;
br level < 0
DO SKIP OD
FI
)[:@0];
 
FOR op TO UPB assembler DO assembler[op] := nop OD; # insert NOP #
FOR op TO UPB op code list DO assembler[ABS op code list[op]] := op OD;
 
WHILE code addr <= UPB code list DO
op list[ABS assembler[ABS code list[code addr]]];
code addr +:= 1
OD
);
 
STRING code list := "++++++[>+++++++++++<-]>-."; # print the ascii letter A #
 
[UPB code list]BYTE byte code list; # convert to bytes #
FOR i TO UPB code list DO byte code list[i] := ABS code list[i] OD;
 
run(byte code list)