SYS_EXIT  equ 0x2000001 ;code
SYS_FORK  equ 0x2000002 ;--
SYS_READ  equ 0x2000003 ;fd, buf, len
SYS_WRITE equ 0x2000004 ;fd, buf, len
SYS_MMAP  equ 0x20000C5 ;addr, len, prot, flags, fd, offset

global start, putc, putint, getc, _builtin_malloc
default rel

extern main

section .text
start:
	call main
	mov rdi, rax
	mov eax, SYS_EXIT
	syscall
	jmp $

putc:
	push rax
	push rdi
	push rsi
	push rdx
	push rcx
	push r11
	mov eax, SYS_WRITE
	mov edi, 1
	lea rsi, [rsp+56]
	mov edx, edi
	syscall
	pop r11
	pop rcx
	pop rdx
	pop rsi
	pop rdi
	pop rax
	ret

putint:
	push rdi
	push rsi
	push rax
	push rbx
	push rcx
	push rdx
	push r11
	mov rax, [rsp+64]
	mov ebx, 18
	test rax, rax
	jz .numzero

	mov ecx, 10

.strlp:
	xor edx, edx
	div rcx
	add dl, '0'
	dec rbx
	mov [rsp+rbx], dl
	test rax, rax
	jnz .strlp
	jmp .strdone

.numzero:
	dec rbx
	mov byte [rsp+rbx], '0'
	jmp .strdone

.strdone:
	mov eax, SYS_WRITE
	mov edi, 1
	lea rsi, [rsp+rbx]
	mov edx, 18
	sub rdx, rbx
	syscall

	pop r11
	pop rdx
	pop rcx
	pop rbx
	pop rax
	pop rsi
	pop rdi
	ret

getc:
	push rdi
	push rsi
	push rdx
	push rcx
	push r11
	mov eax, SYS_READ
	xor edi, edi
	mov rsi, rsp
	mov edx, 1
	syscall
	cmp rax, 1
	jne .fail
	mov rax, [rsp]
.finish:
	pop r11
	pop rcx
	pop rdx
	pop rsi
	pop rdi
	ret
.fail:
	mov rax, -1
	jmp .finish

_builtin_malloc:
	push rdi
	push rsi
	push rdx
	push r8
	push r9
	push r10
	push r11
	push rcx
	xor edi, edi
	mov rsi, [rsp+72]
	mov edx, 0x03
	mov r10d, 0x1001
	mov r8d, -1
	xor r9d, r9d
	mov eax, SYS_MMAP
	syscall
	pop rcx
	pop r11
	pop r10
	pop r9
	pop r8
	pop rdx
	pop rsi
	pop rdi
	ret


section .data
db 0  ; for dyld