retroforth/vm/nga-c-no-libc/obsd64.s
crc ea8e12d32a finish reorg of main sources
FossilOrigin-Name: 6a7ee82ed6b024ee1d8f7a51a9b91a66a8041cde06b53cce649d6bd383ae9677
2019-11-22 18:30:02 +00:00

44 lines
884 B
ArmAsm

; This is the minimal startup + I/O functionality needed to run
; RETRO on an OpenBSD x86-64 system.
; =============================================================
bits 64
section .text
global putchar
global getchar
global _start
extern main
align 8
_start:
call main
jmp $
align 8
putchar:
mov rax, rdi
mov [buf], eax
mov rax, 4 ; sys_write
mov rdi, 1 ; stdout
mov rsi, buf ; address
mov rdx, 1 ; 1 byte
syscall
ret
align 8
getchar:
mov rax, 3 ; sys_read
mov rdi, 0 ; stdin
mov rsi, buf ; address
mov rdx, 1 ; 1 byte
syscall
mov rax, 0
mov eax, [buf]
ret
section .data
buf:
dd 0
dd 0
dd 0
dd 0