io-readsl.s

来自「Linux内核源代码 为压缩文件 是<<Linux内核>&gt」· S 代码 · 共 66 行

/*
 *  linux/arch/arm/lib/io-readsb.S
 *
 *  Copyright (C) 1995-2000 Russell King
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/hardware.h>

ENTRY(__arch_readsl)
		ands	ip, r1, #3
		bne	2f

1:		ldr	r3, [r0]
		str	r3, [r1], #4
		subs	r2, r2, #1
		bne	1b
		mov	pc, lr

2:		cmp	ip, #2
		ldr	ip, [r0]
		blt	4f
		bgt	6f

		strh	ip, [r1], #2
		mov	ip, ip, lsr #16
3:		subs	r2, r2, #1
		ldrne	r3, [r0]
		orrne	ip, ip, r3, lsl #16
		strne	ip, [r1], #4
		movne	ip, r3, lsr #16
		bne	3b
		strh	ip, [r1], #2
		mov	pc, lr

4:		strb	ip, [r1], #1
		mov	ip, ip, lsr #8
		strh	ip, [r1], #2
		mov	ip, ip, lsr #16
5:		subs	r2, r2, #1
		ldrne	r3, [r0]
		orrne	ip, ip, r3, lsl #8
		strne	ip, [r1], #4
		movne	ip, r3, lsr #24
		bne	5b
		strb	ip, [r1], #1
		mov	pc, lr

6:		strb	ip, [r1], #1
		mov	ip, ip, lsr #8
7:		subs	r2, r2, #1
		ldrne	r3, [r0]
		orrne	ip, ip, r3, lsl #24
		strne	ip, [r1], #4
		movne	ip, r3, lsr #8
		bne	7b
		strb	ip, [r1], #1
		mov	ip, ip, lsr #8
		strh	ip, [r1], #2
		mov	pc, lr