view target-utils/libc/bzero.S @ 964:a96cb97b66a2

ringtools/imy: fix duplicate definition of tdma_durations[] The bug was reported by Vadim Yanitskiy <fixeria@osmocom.org>, although the present fix is slightly different from the contributed patch: because main.c doesn't need this tdma_durations[] array at all, let's simply remove the reference to this array from main.c rather than turn it into an extern. I no longer remember my original thought flow that resulted (by mistake) in tdma_durations[] being multiply defined in main.c and durations.c. My intent might have been to define all globals in main.c and have the reference in durations.c be an extern - and I missed that extern - but without clear memory, I have no certainty. In any case, having this data array defined in the same module that fills it (durations.c) is sensible, so let's make it the new way.
author Mychaela Falconia <falcon@freecalypso.org>
date Thu, 31 Aug 2023 19:38:18 +0000
parents bfed7a5c21a6
children
line wrap: on
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/*
 * This ARM implementation of bzero() has been derived from:
 *
 *  linux/arch/arm/lib/memzero.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.
 */

	.text
	.code	32
	.globl	bzero

/*
 * Align the pointer in r0.  r3 contains the number of bytes that we are
 * mis-aligned by, and r1 is the number of bytes.  If r1 < 4, then we
 * don't bother; we use byte stores instead.
 */
1:	subs	r1, r1, #4		@ 1 do we have enough
	blt	5f			@ 1 bytes to align with?
	cmp	r3, #2			@ 1
	strltb	r2, [r0], #1		@ 1
	strleb	r2, [r0], #1		@ 1
	strb	r2, [r0], #1		@ 1
	add	r1, r1, r3		@ 1 (r1 = r1 - (4 - r3))
/*
 * The pointer is now aligned and the length is adjusted.  Try doing the
 * bzero again.
 */

bzero:
	mov	r2, #0			@ 1
	ands	r3, r0, #3		@ 1 unaligned?
	bne	1b			@ 1
/*
 * r3 = 0, and we know that the pointer in r0 is aligned to a word boundary.
 */
3:	subs	r1, r1, #4
	strcs	r2, [r0], #4
	bhi	3b			@ 1
	bxeq	lr			@ 1/2 quick exit
/*
 * No need to correct the count; we're only testing bits from now on
 *
 * When we get here, we've got less than 4 bytes to zero.  We
 * may have an unaligned pointer as well.
 */
5:	tst	r1, #2			@ 1 2 bytes or more?
	strneb	r2, [r0], #1		@ 1
	strneb	r2, [r0], #1		@ 1
	tst	r1, #1			@ 1 a byte left over
	strneb	r2, [r0], #1		@ 1
	bx	lr			@ 1