asm_util.s

;
; Low-level utility functions
;

; prototypes declared in 'util.h'
	.globl _outb
	.globl _inb
	.globl _jump

;----------------------------------------------------
;  void outb( BYTE port, BYTE byte );
;
;  outputs <byte> to i/o port <port>
;----------------------------------------------------
_outb::
	push	bc
	ld	hl, #0x0004
	add	hl, sp
	ld	c, (hl)
	inc	hl
	ld	b, (hl)
	out	(c), b
	pop	bc
	ret

;----------------------------------------------------
; BYTE inb( BYTE port );
;
; returns byte on i/o port <port>
;----------------------------------------------------
_inb::
	push	bc
	ld	hl, #0x0004
	add	hl, sp
	ld	c,(hl)
	in	l,(c)
	ld	h, #0x00
	pop	bc
	ret

;----------------------------------------------------
; void jump( addr_t addr );
;
; unconditionally jump to <addr>
;----------------------------------------------------
_jump::
	ld	hl, #0x0004
	add	hl, sp
	jp	(hl)