inb.s

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#include "mem.h"

#define	BDNZ	BC	16,0,
#define	BDNE	BC	0,2,

TEXT	inb(SB), $0
	OR	$IOMEM, R3
	MOVBZ	(R3), R3
	RETURN

TEXT	insb(SB), $0
	MOVW	v+4(FP), R4
	MOVW	n+8(FP), R5
	MOVW	R5, CTR
	OR	$IOMEM, R3
	SUB	$1, R4
insb1:
	MOVBZ	(R3), R7
	MOVBU	R7, 1(R4)
	BDNZ	insb1
	RETURN

TEXT	outb(SB), $0
	MOVW	v+4(FP), R4
	OR	$IOMEM, R3
	EIEIO
	MOVB	R4, (R3)
	RETURN

TEXT	outsb(SB), $0
	MOVW	v+4(FP), R4
	MOVW	n+8(FP), R5
	MOVW	R5, CTR
	OR	$IOMEM, R3
	SUB	$1, R4
outsb1:
	EIEIO
	MOVBZU	1(R4), R7
	MOVB	R7, (R3)
	BDNZ	outsb1
	RETURN

TEXT	ins(SB), $0
	OR	$IOMEM, R3
	EIEIO
	MOVHBR	(R3), R3
	RETURN

TEXT	inss(SB), $0
	MOVW	v+4(FP), R4
	MOVW	n+8(FP), R5
	MOVW	R5, CTR
	OR	$IOMEM, R3
	SUB	$2, R4
inss1:
	EIEIO
	MOVHZ	(R3), R7
	MOVHU	R7, 2(R4)
	BDNZ	inss1
	RETURN

TEXT	outs(SB), $0
	MOVW	v+4(FP), R4
	OR	$IOMEM, R3
	EIEIO
	MOVHBR	R4, (R3)
	RETURN

TEXT	outss(SB), $0
	MOVW	v+4(FP), R4
	MOVW	n+8(FP), R5
	MOVW	R5, CTR
	OR	$IOMEM, R3
	SUB	$2, R4
outss1:
	EIEIO
	MOVHZU	2(R4), R7
	MOVH	R7, (R3)
	BDNZ	outss1
	RETURN

TEXT	inl(SB), $0
	OR	$IOMEM, R3
	EIEIO
	MOVWBR	(R3), R3
	RETURN

TEXT	insl(SB), $0
	MOVW	v+4(FP), R4
	MOVW	n+8(FP), R5
	MOVW	R5, CTR
	OR	$IOMEM, R3
	SUB	$4, R4
insl1:
	EIEIO
	MOVW	(R3), R7
	MOVWU	R7, 4(R4)
	BDNZ	insl1
	RETURN

TEXT	outl(SB), $0
	MOVW	v+4(FP), R4
	OR	$IOMEM, R3
	EIEIO
	MOVWBR	R4, (R3)
	RETURN

TEXT	outsl(SB), $0
	MOVW	v+4(FP), R4
	MOVW	n+8(FP), R5
	MOVW	R5, CTR
	OR	$IOMEM, R3
	SUB	$4, R4
outsl1:
	EIEIO
	MOVWU	4(R4), R7
	MOVW	R7, (R3)
	BDNZ	outsl1
	RETURN