The aim of this project is to get familiar with assembly language.
Write the following functions in x64 assembly (in the Intel syntax):
int ft_strlen(char const *str);
int ft_strcmp(char const *s1, char const *s2);
char *ft_strcpy(char *dst, char const *src);
ssize_t ft_write(int fd, void const *buf, size_t nbyte);
ssize_t ft_read(int fd, void *buf, size_t nbyte);
char *ft_strdup(char const *s1);; 64-bit [QWORD]
R0 R1 R2 R3 R4 R5 R6 R7 R8 R9 R10 R11 R12 R13 R14 R15
RAX RCX RDX RBX RSP RBP RSI RDI
; 32-bit [DWORD]
R0D R1D R2D R3D R4D R5D R6D R7D R8D R9D R10D R11D R12D R13D R14D R15D
EAX ECX EDX EBX ESP EBP ESI EDI
; 16-bit [WORD]
R0W R1W R2W R3W R4W R5W R6W R7W R8W R9W R10W R11W R12W R13W R14W R15W
AX CX DX BX SP BP SI DI
; 8-bit [BYTE]
R0B R1B R2B R3B R4B R5B R6B R7B R8B R9B R10B R11B R12B R13B R14B R15B
AL CL DL BL SPL BPL SIL DIL
; 128-bit (used for floating point operations mostly)
XMM0 ... XMM15
; Save register
push REG
pop REG
; Set register value
mov REG, VALUE ; DEST = VALUE
; Common operations
add DEST, VALUE ; DEST = DEST + VALUE
sub - ; DEST = DEST - VALUE
inc REG ; REG++
dec - ; REG--
and DEST, REG ; DEST = DEST & REG
xor - ; DEST = DEST ^ REG
xor REG, REG ; = mov REG, 0
mul REG ; REG = REG * RAX
div REG ; REG = REG / RAX
; Dereferenced value
[REG] ; = *REG
; Compare
cmp REG, VALUE ; Set flags used by jmp variants
; Label
label:
jmp label ; next jumps depends on compare flags from cmp
je - ; is equal
jne - ; is not equal
jl - ; < VALUE
jle - ; <= VALUE
jz - ; = 0
jnz - ; != 0
jg - ; > VALUE
jge - ; >= VALUE
; Function call
call FUNCTION
; Parameters registers
RDI RSI RDX RCX R8 R9
; Register to preserve
RBP RBX R12 R13 R14 R15 ; You **MUST** push/pop them if you use them
; Return register
RAX
; syscall
mov rax, CODE ; Then RDI, RSI etc.. for params
; Add 0x2000000 to the syscall number, see table below
syscall