feat(read): adding the read function in asm

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Raphael 2025-12-11 23:11:56 +01:00
parent e40d4748cd
commit d55c035b97
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20
src/ft_read.s Normal file
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segment .note.GNU-stack
extern __errno_location
section .text
global ft_read
ft_read:
mov rax, 0 ; syscall 0 is for read
syscall ; call the system call read
cmp rax, 0 ; check if the return value of syscall
jl .error ; jump if the syscall return less than 0
ret ; return the value of the syscall
.error:
mov rdi, rax ; stock errno value in rdi
neg rdi ; errno value in positive (index used by C function)
call __errno_location ; rax = &errno
mov [rax], edi ; stock the errno return in the address of rax
mov rax, -1 ; set the value of rax to -1
ret ; return with -1 (and errno value)