[GitHub/mt8127/android_kernel_alcatel_ttab.git] / arch / tile / lib / strchr_64.c

/*
 * Copyright 2011 Tilera Corporation. All Rights Reserved.
 *
 *   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, version 2.
 *
 *   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, GOOD TITLE or
 *   NON INFRINGEMENT.  See the GNU General Public License for
 *   more details.
 */

#include <linux/types.h>
#include <linux/string.h>
#include <linux/module.h>
#include "string-endian.h"

char *strchr(const char *s, int c)
{
	int z, g;

	/* Get an aligned pointer. */
	const uintptr_t s_int = (uintptr_t) s;
	const uint64_t *p = (const uint64_t *)(s_int & -8);

	/* Create eight copies of the byte for which we are looking. */
	const uint64_t goal = 0x0101010101010101ULL * (uint8_t) c;

	/* Read the first aligned word, but force bytes before the string to
	 * match neither zero nor goal (we make sure the high bit of each
	 * byte is 1, and the low 7 bits are all the opposite of the goal
	 * byte).
	 */
	const uint64_t before_mask = MASK(s_int);
	uint64_t v = (*p | before_mask) ^ (goal & __insn_v1shrui(before_mask, 1));

	uint64_t zero_matches, goal_matches;
	while (1) {
		/* Look for a terminating '\0'. */
		zero_matches = __insn_v1cmpeqi(v, 0);

		/* Look for the goal byte. */
		goal_matches = __insn_v1cmpeq(v, goal);

		if (__builtin_expect((zero_matches | goal_matches) != 0, 0))
			break;

		v = *++p;
	}

	z = CFZ(zero_matches);
	g = CFZ(goal_matches);

	/* If we found c before '\0' we got a match. Note that if c == '\0'
	 * then g == z, and we correctly return the address of the '\0'
	 * rather than NULL.
	 */
	return (g <= z) ? ((char *)p) + (g >> 3) : NULL;
}
EXPORT_SYMBOL(strchr);
Commit	Line	Data
18aecc2b CM	1	/*
	2	* Copyright 2011 Tilera Corporation. All Rights Reserved.
	3	*
	4	* This program is free software; you can redistribute it and/or
	5	* modify it under the terms of the GNU General Public License
	6	* as published by the Free Software Foundation, version 2.
	7	*
	8	* This program is distributed in the hope that it will be useful, but
	9	* WITHOUT ANY WARRANTY; without even the implied warranty of
	10	* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
	11	* NON INFRINGEMENT. See the GNU General Public License for
	12	* more details.
	13	*/
	14
	15	#include <linux/types.h>
	16	#include <linux/string.h>
	17	#include <linux/module.h>
1efea40d	18	#include "string-endian.h"
18aecc2b CM	19
	20	char strchr(const char s, int c)
	21	{
	22	int z, g;
	23
	24	/* Get an aligned pointer. */
	25	const uintptr_t s_int = (uintptr_t) s;
	26	const uint64_t p = (const uint64_t )(s_int & -8);
	27
	28	/* Create eight copies of the byte for which we are looking. */
	29	const uint64_t goal = 0x0101010101010101ULL * (uint8_t) c;
	30
	31	/* Read the first aligned word, but force bytes before the string to
	32	* match neither zero nor goal (we make sure the high bit of each
	33	* byte is 1, and the low 7 bits are all the opposite of the goal
	34	* byte).
18aecc2b	35	*/
1efea40d CM	36	const uint64_t before_mask = MASK(s_int);
1efea40d CM	37	uint64_t v = (*p \| before_mask) ^ (goal & __insn_v1shrui(before_mask, 1));
18aecc2b CM	38
	39	uint64_t zero_matches, goal_matches;
	40	while (1) {
	41	/* Look for a terminating '\0'. */
	42	zero_matches = __insn_v1cmpeqi(v, 0);
	43
	44	/* Look for the goal byte. */
	45	goal_matches = __insn_v1cmpeq(v, goal);
	46
	47	if (__builtin_expect((zero_matches \| goal_matches) != 0, 0))
	48	break;
	49
	50	v = *++p;
	51	}
	52
1efea40d CM	53	z = CFZ(zero_matches);
1efea40d CM	54	g = CFZ(goal_matches);
18aecc2b CM	55
	56	/* If we found c before '\0' we got a match. Note that if c == '\0'
	57	* then g == z, and we correctly return the address of the '\0'
	58	* rather than NULL.
	59	*/
	60	return (g <= z) ? ((char *)p) + (g >> 3) : NULL;
	61	}
	62	EXPORT_SYMBOL(strchr);