utils.fasm

; My awesome standard library...
; exit                  - syscall to exit.
; print(msg,msg_size)   - print some message. 
; println(msg,msg_size) - print some message with newline.
; itoa(number,dst,base) - convert number to null terminated string using specified base.

; Network stuff
; ...

segment readable writeable executable

; Declare a string + length var
macro decl_str var, str
{
	var db str
	var#.len = $-var
}

; Print a declared string
macro print_str var { print var,var#.len }
macro println_str var { println var,var#.len }
macro print msg, msg_size
{
	push rdx
	push rsi
    mov rdx, msg_size
    mov rsi, msg
    call stdout
	pop rsi
	pop rdx
}

macro println msg, msg_size
{
	print msg, msg_size
	print lf, lf_size 
}

macro itoa num,base,dst
{
	push rax
	push rbx
	push rcx
	mov eax, num
	mov ebx, base
	mov rcx, dst
	call _itoa
	pop rcx
	pop rbx
	pop rax
}

; eax = number to convert
; ebx = base
; ecx = dst adress to save 
_itoa:
	mov r8b, 0 ; counter
	mov dx, 0
	mov qword [dst_adr], rcx
.loop:
	mov edx, 0
	; mov ebx, 10     ; base 10
	div ebx
	add dl, 48        ; ascii 0
	mov r9, itoa_buf  ; load our temp buffer
	add r9, r8        ; add offset
	mov byte [r9], dl
	inc r8b
	cmp eax, 0 ; if eax = 0
	jne .loop
	dec r8b
	; loop in reverse order and save to our specified dst adress
	mov r10,qword [dst_adr]
.save_result:
	mov r9,itoa_buf
	add r9,r8
	mov r12b,byte [r9]  ; copy a digit from itoa_buf
	mov byte [r10],r12b ; to dst_adr
	inc r10
	dec r8b
	cmp r8b,-1
	jne .save_result
	; inc r10 ; TODO: add NUL ?
	ret

stdout:
	push rax
	push rdi
	mov edi,1
	mov eax,1
	syscall
	pop rdi
	pop rax
	ret

exit:
    xor edi,edi ; exit code 0
    mov eax,60  ; sys_exit
    syscall

lf db 0xA
dst_adr db '           '
itoa_buf db '          '