56 lines
536 B
NASM
56 lines
536 B
NASM
extern libz_strlen
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global libz_atoi
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section .text
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libz_atoi:
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; mov r11, rdi ;saveing it for later
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push rdi
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call libz_strlen
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mov r9, rax
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pop rdi
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xor r10, r10
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mov rcx, 1
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add r9, rdi
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dec r9
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_loop:
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xor rax, rax
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mov al, [r9]
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cmp rax, 48
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jb _nan
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cmp rax, 57 ;if its not a number then return 0 then exit
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ja _nan
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; push rax
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sub rax, 48
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mul rcx
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add r10, rax
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; pop rax
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cmp r9, rdi
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je _end
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dec r9
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; push rax
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mov rax, 10
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mul rcx
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mov rcx, rax
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; pop rax
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jmp _loop
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_nan:
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xor r10 r10
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_end:
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mov rax, r10
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ret
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