memchr.s

来自「linux 内核源代码」· S 代码 · 共 71 行

/*
 * File:         arch/blackfin/lib/memchr.S
 * Based on:
 * Author:
 *
 * Created:
 * Description:
 *
 * Modified:
 *               Copyright 2004-2006 Analog Devices Inc.
 *
 * Bugs:         Enter bugs at http://blackfin.uclinux.org/
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see the file COPYING, or write
 * to the Free Software Foundation, Inc.,
 * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <linux/linkage.h>

/* void *memchr(const void *s, int c, size_t n);
 * R0 = address (s)
 * R1 = sought byte (c)
 * R2 = count (n)
 *
 * Returns pointer to located character.
 */

.text

.align 2

ENTRY(_memchr)
	P0 = R0;		/* P0 = address */
	P2 = R2;		/* P2 = count */
	R1 = R1.B(Z);
	CC = R2 == 0;
	IF CC JUMP .Lfailed;

.Lbytes:
	LSETUP (.Lbyte_loop_s, .Lbyte_loop_e) LC0=P2;

.Lbyte_loop_s:
	R3 = B[P0++](Z);
	CC = R3 == R1;
	IF CC JUMP .Lfound;
.Lbyte_loop_e:
	NOP;

.Lfailed:
	R0=0;
	RTS;

.Lfound:
	R0 = P0;
	R0 += -1;
	RTS;

ENDPROC(_memchr)