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99 Bottles of Beer/Assembly: Difference between revisions
→{{header|X86 Assembly}}
(+ OASYS) |
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mov eax, 1
int 0x80</lang>
===x86_64 (GAS)===
Could maybe have done it all with macros, but I wanted to write my own itoa function. Plus I feel like using the preprocessor for its looping directives takes the challenge out of the problem.
<lang>// Compiles with `gcc -nostdlib`
#define SYS_EXIT $60
#define SYS_WRITE $1
#define STDOUT $1
// Some numbers:
#define START_BOTTLES 99
#define NUM_LOCALS $8
#define WRL1_LEN $30
#define WRL2_LEN $53
#define WRL3_LEN $31
.global _start
.text
.macro WRITE
movq STDOUT, %rdi
movq SYS_WRITE, %rax
syscall
.endm
.macro WRITENUM
movq 8(%rsp), %rdx
movq (%rsp), %rsi
WRITE
.endm
/* void* itoa(long, char *)
0q 8q
- char * points to the *back* of the string. itoa writes from ls digit.
- clobbers rdi, rax, rdx
- returns pointer to beginning of string
*/
itoa:
pushq %rbp
movq %rsp, %rbp
movq 16(%rsp), %rdi
movq 24(%rsp), %rax
cycledigits:
xorq %rdx, %rdx
divq decimal
addq $48, %rdx // Add 48 to remainder, store digit
movb %dl, (%rdi) // Copy char
decq %rdi // Next digit
cmpq $0, %rax
jg cycledigits // No more digits?
leaq 1(%rdi), %rax // return value
popq %rbp
ret
_start:
// Set up stack
movq %rsp, %rbp
/*
bptr = itoa(counter, numstring)
do
{
write(stdout, bptr, bptr-numstring+1) // number
write(stdout, regstring, 30)
write(stdout, bptr, bptr-numstring+1) // number
write(stdout, regstring2, 52)
counter-=1
bptr = itoa(counter, numstring)
write(stdout, bptr, bptr-numstring+1) // number
write(stdout, regstring3, 30)
} while(counter>0)
*/
subq NUM_LOCALS, %rsp
pushq counter
pushq $numstring
precall:
call itoa
addq $16, %rsp // clean args
movq %rax, (%rsp) // bptr = itoa(counter, numstring)
subq $numstring, %rax
negq %rax
leaq 1(%rax), %rdx
movq %rdx, 8(%rsp) // Save the calculation
printloop:
WRITENUM // write(stdout, bptr, bptr-numstring+1)
writeline1:
movq WRL1_LEN, %rdx
movq $regstring, %rsi
WRITE // write(stdout, regstring, 30)
WRITENUM // write(stdout, bptr, bptr-numstring+1)
writeline2:
movq WRL2_LEN, %rdx
movq $regstring2, %rsi
WRITE // write(stdout, regstring2, 52)
decq counter // counter--
pluralcheck:
cmpq $1, counter
jg norm
cmpq $0, counter
je zeroconfirm
oneconfirm:
movq $regstring, %rdx
movb $0x20 , 7(%rdx)
movq $regstring2, %rdx
movb $0x20 , 7(%rdx)
movq $regstring3, %rdx
movb $0x20 , 7(%rdx)
jg norm
zeroconfirm:
movq $regstring, %rdx
movb $'s, 7(%rdx)
movq $regstring2, %rdx
movb $'s , 7(%rdx)
movq $regstring3, %rdx
movb $'s , 7(%rdx)
norm:
pushq counter
pushq $numstring
call itoa
addq $16, %rsp
movq %rax, (%rsp) // bptr = itoa(counter, numstring)
write3:
subq $numstring, %rax
negq %rax
leaq 1(%rax), %rdx
movq %rdx, 8(%rsp)
movq (%rsp), %rsi
WRITE // write(stdout, bptr, bptr-numstring+1)
writeline3:
movq WRL3_LEN, %rdx
movq $regstring3, %rsi
WRITE // write(stdout, regstring, 30)
cmpq $0, counter
jg printloop
exit:
movq SYS_EXIT, %rax
xorq %rdi, %rdi // The exit code.
syscall
.data
/* Begin Data Section: */
decimal: // base 10
.quad 10
counter:
.quad START_BOTTLES
numstring0:
.byte 'x /* Separated out because want back of string */
numstring:
.byte 'x
regstring:
.ascii " bottles of beer on the wall,\n"
regstring2:
.ascii " bottles of beer.\nTake one down, and pass it around:\n"
regstring3:
.ascii " bottles of beer on the wall.\n\n"
</lang>
=={{header|Z80 Assembly}}==
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