testclearbit.s

来自「Linux内核源代码 为压缩文件 是<<Linux内核>&gt」· S 代码 · 共 28 行

/*
 *  linux/arch/arm/lib/testclearbit.S
 *
 *  Copyright (C) 1995-1996 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>
                .text

ENTRY(test_and_clear_bit)
		add	r1, r1, r0, lsr #3	@ Get byte offset
		and	r3, r0, #7		@ Get bit offset
		mov	r0, #1
		save_and_disable_irqs ip, r2
		ldrb	r2, [r1]
		tst	r2, r0, lsl r3
		bic	r2, r2, r0, lsl r3
		strb	r2, [r1]
		restore_irqs ip
		moveq	r0, #0
		RETINSTR(mov,pc,lr)