feat(read): adding the read function in asm
This commit is contained in:
parent
e40d4748cd
commit
d55c035b97
1 changed files with 20 additions and 0 deletions
20
src/ft_read.s
Normal file
20
src/ft_read.s
Normal file
|
|
@ -0,0 +1,20 @@
|
|||
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)
|
||||
Loading…
Add table
Add a link
Reference in a new issue