[thirdparty/glibc.git] / string / memcmp.c

/* Copyright (C) 1991-2014 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Torbjorn Granlund (tege@sics.se).

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#ifdef HAVE_CONFIG_H
# include "config.h"
#endif

#undef	__ptr_t
#define __ptr_t	void *

#if defined HAVE_STRING_H || defined _LIBC
# include <string.h>
#endif

#undef memcmp

#ifndef MEMCMP
# define MEMCMP memcmp
#endif

#ifdef _LIBC

# include <memcopy.h>
# include <endian.h>

# if __BYTE_ORDER == __BIG_ENDIAN
#  define WORDS_BIGENDIAN
# endif

#else	/* Not in the GNU C library.  */

# include <sys/types.h>

/* Type to use for aligned memory operations.
   This should normally be the biggest type supported by a single load
   and store.  Must be an unsigned type.  */
# define op_t	unsigned long int
# define OPSIZ	(sizeof(op_t))

/* Threshold value for when to enter the unrolled loops.  */
# define OP_T_THRES	16

/* Type to use for unaligned operations.  */
typedef unsigned char byte;

# ifndef WORDS_BIGENDIAN
#  define MERGE(w0, sh_1, w1, sh_2) (((w0) >> (sh_1)) | ((w1) << (sh_2)))
# else
#  define MERGE(w0, sh_1, w1, sh_2) (((w0) << (sh_1)) | ((w1) >> (sh_2)))
# endif

#endif	/* In the GNU C library.  */

#ifdef WORDS_BIGENDIAN
# define CMP_LT_OR_GT(a, b) ((a) > (b) ? 1 : -1)
#else
# define CMP_LT_OR_GT(a, b) memcmp_bytes ((a), (b))
#endif

/* BE VERY CAREFUL IF YOU CHANGE THIS CODE!  */

/* The strategy of this memcmp is:

   1. Compare bytes until one of the block pointers is aligned.

   2. Compare using memcmp_common_alignment or
      memcmp_not_common_alignment, regarding the alignment of the other
      block after the initial byte operations.  The maximum number of
      full words (of type op_t) are compared in this way.

   3. Compare the few remaining bytes.  */

#ifndef WORDS_BIGENDIAN
/* memcmp_bytes -- Compare A and B bytewise in the byte order of the machine.
   A and B are known to be different.
   This is needed only on little-endian machines.  */

static int memcmp_bytes (op_t, op_t) __THROW;

static int
memcmp_bytes (a, b)
     op_t a, b;
{
  long int srcp1 = (long int) &a;
  long int srcp2 = (long int) &b;
  op_t a0, b0;

  do
    {
      a0 = ((byte *) srcp1)[0];
      b0 = ((byte *) srcp2)[0];
      srcp1 += 1;
      srcp2 += 1;
    }
  while (a0 == b0);
  return a0 - b0;
}
#endif

static int memcmp_common_alignment (long, long, size_t) __THROW;

/* memcmp_common_alignment -- Compare blocks at SRCP1 and SRCP2 with LEN `op_t'
   objects (not LEN bytes!).  Both SRCP1 and SRCP2 should be aligned for
   memory operations on `op_t's.  */
static int
memcmp_common_alignment (srcp1, srcp2, len)
     long int srcp1;
     long int srcp2;
     size_t len;
{
  op_t a0, a1;
  op_t b0, b1;

  switch (len % 4)
    {
    default: /* Avoid warning about uninitialized local variables.  */
    case 2:
      a0 = ((op_t *) srcp1)[0];
      b0 = ((op_t *) srcp2)[0];
      srcp1 -= 2 * OPSIZ;
      srcp2 -= 2 * OPSIZ;
      len += 2;
      goto do1;
    case 3:
      a1 = ((op_t *) srcp1)[0];
      b1 = ((op_t *) srcp2)[0];
      srcp1 -= OPSIZ;
      srcp2 -= OPSIZ;
      len += 1;
      goto do2;
    case 0:
      if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	return 0;
      a0 = ((op_t *) srcp1)[0];
      b0 = ((op_t *) srcp2)[0];
      goto do3;
    case 1:
      a1 = ((op_t *) srcp1)[0];
      b1 = ((op_t *) srcp2)[0];
      srcp1 += OPSIZ;
      srcp2 += OPSIZ;
      len -= 1;
      if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	goto do0;
      /* Fall through.  */
    }

  do
    {
      a0 = ((op_t *) srcp1)[0];
      b0 = ((op_t *) srcp2)[0];
      if (a1 != b1)
	return CMP_LT_OR_GT (a1, b1);

    do3:
      a1 = ((op_t *) srcp1)[1];
      b1 = ((op_t *) srcp2)[1];
      if (a0 != b0)
	return CMP_LT_OR_GT (a0, b0);

    do2:
      a0 = ((op_t *) srcp1)[2];
      b0 = ((op_t *) srcp2)[2];
      if (a1 != b1)
	return CMP_LT_OR_GT (a1, b1);

    do1:
      a1 = ((op_t *) srcp1)[3];
      b1 = ((op_t *) srcp2)[3];
      if (a0 != b0)
	return CMP_LT_OR_GT (a0, b0);

      srcp1 += 4 * OPSIZ;
      srcp2 += 4 * OPSIZ;
      len -= 4;
    }
  while (len != 0);

  /* This is the right position for do0.  Please don't move
     it into the loop.  */
 do0:
  if (a1 != b1)
    return CMP_LT_OR_GT (a1, b1);
  return 0;
}

static int memcmp_not_common_alignment (long, long, size_t) __THROW;

/* memcmp_not_common_alignment -- Compare blocks at SRCP1 and SRCP2 with LEN
   `op_t' objects (not LEN bytes!).  SRCP2 should be aligned for memory
   operations on `op_t', but SRCP1 *should be unaligned*.  */
static int
memcmp_not_common_alignment (srcp1, srcp2, len)
     long int srcp1;
     long int srcp2;
     size_t len;
{
  op_t a0, a1, a2, a3;
  op_t b0, b1, b2, b3;
  op_t x;
  int shl, shr;

  /* Calculate how to shift a word read at the memory operation
     aligned srcp1 to make it aligned for comparison.  */

  shl = 8 * (srcp1 % OPSIZ);
  shr = 8 * OPSIZ - shl;

  /* Make SRCP1 aligned by rounding it down to the beginning of the `op_t'
     it points in the middle of.  */
  srcp1 &= -OPSIZ;

  switch (len % 4)
    {
    default: /* Avoid warning about uninitialized local variables.  */
    case 2:
      a1 = ((op_t *) srcp1)[0];
      a2 = ((op_t *) srcp1)[1];
      b2 = ((op_t *) srcp2)[0];
      srcp1 -= 1 * OPSIZ;
      srcp2 -= 2 * OPSIZ;
      len += 2;
      goto do1;
    case 3:
      a0 = ((op_t *) srcp1)[0];
      a1 = ((op_t *) srcp1)[1];
      b1 = ((op_t *) srcp2)[0];
      srcp2 -= 1 * OPSIZ;
      len += 1;
      goto do2;
    case 0:
      if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	return 0;
      a3 = ((op_t *) srcp1)[0];
      a0 = ((op_t *) srcp1)[1];
      b0 = ((op_t *) srcp2)[0];
      srcp1 += 1 * OPSIZ;
      goto do3;
    case 1:
      a2 = ((op_t *) srcp1)[0];
      a3 = ((op_t *) srcp1)[1];
      b3 = ((op_t *) srcp2)[0];
      srcp1 += 2 * OPSIZ;
      srcp2 += 1 * OPSIZ;
      len -= 1;
      if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	goto do0;
      /* Fall through.  */
    }

  do
    {
      a0 = ((op_t *) srcp1)[0];
      b0 = ((op_t *) srcp2)[0];
      x = MERGE(a2, shl, a3, shr);
      if (x != b3)
	return CMP_LT_OR_GT (x, b3);

    do3:
      a1 = ((op_t *) srcp1)[1];
      b1 = ((op_t *) srcp2)[1];
      x = MERGE(a3, shl, a0, shr);
      if (x != b0)
	return CMP_LT_OR_GT (x, b0);

    do2:
      a2 = ((op_t *) srcp1)[2];
      b2 = ((op_t *) srcp2)[2];
      x = MERGE(a0, shl, a1, shr);
      if (x != b1)
	return CMP_LT_OR_GT (x, b1);

    do1:
      a3 = ((op_t *) srcp1)[3];
      b3 = ((op_t *) srcp2)[3];
      x = MERGE(a1, shl, a2, shr);
      if (x != b2)
	return CMP_LT_OR_GT (x, b2);

      srcp1 += 4 * OPSIZ;
      srcp2 += 4 * OPSIZ;
      len -= 4;
    }
  while (len != 0);

  /* This is the right position for do0.  Please don't move
     it into the loop.  */
 do0:
  x = MERGE(a2, shl, a3, shr);
  if (x != b3)
    return CMP_LT_OR_GT (x, b3);
  return 0;
}

int
MEMCMP (s1, s2, len)
     const __ptr_t s1;
     const __ptr_t s2;
     size_t len;
{
  op_t a0;
  op_t b0;
  long int srcp1 = (long int) s1;
  long int srcp2 = (long int) s2;
  op_t res;

  if (len >= OP_T_THRES)
    {
      /* There are at least some bytes to compare.  No need to test
	 for LEN == 0 in this alignment loop.  */
      while (srcp2 % OPSIZ != 0)
	{
	  a0 = ((byte *) srcp1)[0];
	  b0 = ((byte *) srcp2)[0];
	  srcp1 += 1;
	  srcp2 += 1;
	  res = a0 - b0;
	  if (res != 0)
	    return res;
	  len -= 1;
	}

      /* SRCP2 is now aligned for memory operations on `op_t'.
	 SRCP1 alignment determines if we can do a simple,
	 aligned compare or need to shuffle bits.  */

      if (srcp1 % OPSIZ == 0)
	res = memcmp_common_alignment (srcp1, srcp2, len / OPSIZ);
      else
	res = memcmp_not_common_alignment (srcp1, srcp2, len / OPSIZ);
      if (res != 0)
	return res;

      /* Number of bytes remaining in the interval [0..OPSIZ-1].  */
      srcp1 += len & -OPSIZ;
      srcp2 += len & -OPSIZ;
      len %= OPSIZ;
    }

  /* There are just a few bytes to compare.  Use byte memory operations.  */
  while (len != 0)
    {
      a0 = ((byte *) srcp1)[0];
      b0 = ((byte *) srcp2)[0];
      srcp1 += 1;
      srcp2 += 1;
      res = a0 - b0;
      if (res != 0)
	return res;
      len -= 1;
    }

  return 0;
}
libc_hidden_builtin_def(memcmp)
#ifdef weak_alias
# undef bcmp
weak_alias (memcmp, bcmp)
#endif
Commit	Line	Data
d4697bc9	1	/* Copyright (C) 1991-2014 Free Software Foundation, Inc.
478b92f0	2	This file is part of the GNU C Library.
28f540f4 RM	3	Contributed by Torbjorn Granlund (tege@sics.se).
28f540f4 RM	4
478b92f0	5	The GNU C Library is free software; you can redistribute it and/or
41bdb6e2 AJ	6	modify it under the terms of the GNU Lesser General Public
	7	License as published by the Free Software Foundation; either
	8	version 2.1 of the License, or (at your option) any later version.
28f540f4	9
478b92f0 UD	10	The GNU C Library is distributed in the hope that it will be useful,
	11	but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
41bdb6e2	13	Lesser General Public License for more details.
28f540f4	14
41bdb6e2	15	You should have received a copy of the GNU Lesser General Public
59ba27a6 PE	16	License along with the GNU C Library; if not, see
59ba27a6 PE	17	<http://www.gnu.org/licenses/>. */
28f540f4 RM	18
28f540f4 RM	19	#ifdef HAVE_CONFIG_H
af6f3906	20	# include "config.h"
28f540f4 RM	21	#endif
	22
	23	#undef __ptr_t
c8a89e7d	24	#define __ptr_t void *
28f540f4	25
af6f3906 UD	26	#if defined HAVE_STRING_H \|\| defined _LIBC
af6f3906 UD	27	# include <string.h>
28f540f4 RM	28	#endif
28f540f4 RM	29
9a0a462c UD	30	#undef memcmp
9a0a462c UD	31
07253fcf AZ	32	#ifndef MEMCMP
	33	# define MEMCMP memcmp
	34	#endif
	35
28f540f4 RM	36	#ifdef _LIBC
28f540f4 RM	37
af6f3906	38	# include <memcopy.h>
789b13c4 UD	39	# include <endian.h>
	40
	41	# if __BYTE_ORDER == __BIG_ENDIAN
	42	# define WORDS_BIGENDIAN
	43	# endif
28f540f4 RM	44
	45	#else /* Not in the GNU C library. */
	46
af6f3906	47	# include <sys/types.h>
28f540f4 RM	48
	49	/* Type to use for aligned memory operations.
	50	This should normally be the biggest type supported by a single load
	51	and store. Must be an unsigned type. */
af6f3906 UD	52	# define op_t unsigned long int
af6f3906 UD	53	# define OPSIZ (sizeof(op_t))
28f540f4 RM	54
28f540f4 RM	55	/* Threshold value for when to enter the unrolled loops. */
af6f3906	56	# define OP_T_THRES 16
28f540f4 RM	57
	58	/* Type to use for unaligned operations. */
	59	typedef unsigned char byte;
	60
af6f3906 UD	61	# ifndef WORDS_BIGENDIAN
	62	# define MERGE(w0, sh_1, w1, sh_2) (((w0) >> (sh_1)) \| ((w1) << (sh_2)))
	63	# else
	64	# define MERGE(w0, sh_1, w1, sh_2) (((w0) << (sh_1)) \| ((w1) >> (sh_2)))
	65	# endif
28f540f4 RM	66
	67	#endif /* In the GNU C library. */
	68
	69	#ifdef WORDS_BIGENDIAN
af6f3906	70	# define CMP_LT_OR_GT(a, b) ((a) > (b) ? 1 : -1)
28f540f4	71	#else
af6f3906	72	# define CMP_LT_OR_GT(a, b) memcmp_bytes ((a), (b))
28f540f4 RM	73	#endif
	74
	75	/* BE VERY CAREFUL IF YOU CHANGE THIS CODE! */
	76
	77	/* The strategy of this memcmp is:
	78
	79	1. Compare bytes until one of the block pointers is aligned.
	80
	81	2. Compare using memcmp_common_alignment or
	82	memcmp_not_common_alignment, regarding the alignment of the other
	83	block after the initial byte operations. The maximum number of
	84	full words (of type op_t) are compared in this way.
	85
	86	3. Compare the few remaining bytes. */
	87
	88	#ifndef WORDS_BIGENDIAN
	89	/* memcmp_bytes -- Compare A and B bytewise in the byte order of the machine.
	90	A and B are known to be different.
	91	This is needed only on little-endian machines. */
a1470b6f	92
79937577	93	static int memcmp_bytes (op_t, op_t) __THROW;
a1470b6f	94
28f540f4 RM	95	static int
	96	memcmp_bytes (a, b)
	97	op_t a, b;
	98	{
	99	long int srcp1 = (long int) &a;
	100	long int srcp2 = (long int) &b;
	101	op_t a0, b0;
	102
	103	do
	104	{
	105	a0 = ((byte *) srcp1)[0];
	106	b0 = ((byte *) srcp2)[0];
	107	srcp1 += 1;
	108	srcp2 += 1;
	109	}
	110	while (a0 == b0);
	111	return a0 - b0;
	112	}
	113	#endif
	114
79937577	115	static int memcmp_common_alignment (long, long, size_t) __THROW;
a1470b6f	116
28f540f4 RM	117	/* memcmp_common_alignment -- Compare blocks at SRCP1 and SRCP2 with LEN `op_t'
	118	objects (not LEN bytes!). Both SRCP1 and SRCP2 should be aligned for
	119	memory operations on `op_t's. */
28f540f4 RM	120	static int
	121	memcmp_common_alignment (srcp1, srcp2, len)
	122	long int srcp1;
	123	long int srcp2;
	124	size_t len;
	125	{
	126	op_t a0, a1;
	127	op_t b0, b1;
	128
	129	switch (len % 4)
	130	{
dfd2257a	131	default: /* Avoid warning about uninitialized local variables. */
28f540f4 RM	132	case 2:
	133	a0 = ((op_t *) srcp1)[0];
	134	b0 = ((op_t *) srcp2)[0];
	135	srcp1 -= 2 * OPSIZ;
	136	srcp2 -= 2 * OPSIZ;
	137	len += 2;
	138	goto do1;
	139	case 3:
	140	a1 = ((op_t *) srcp1)[0];
	141	b1 = ((op_t *) srcp2)[0];
	142	srcp1 -= OPSIZ;
	143	srcp2 -= OPSIZ;
	144	len += 1;
	145	goto do2;
	146	case 0:
	147	if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	148	return 0;
	149	a0 = ((op_t *) srcp1)[0];
	150	b0 = ((op_t *) srcp2)[0];
	151	goto do3;
	152	case 1:
	153	a1 = ((op_t *) srcp1)[0];
	154	b1 = ((op_t *) srcp2)[0];
	155	srcp1 += OPSIZ;
	156	srcp2 += OPSIZ;
	157	len -= 1;
	158	if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	159	goto do0;
	160	/* Fall through. */
	161	}
	162
	163	do
	164	{
	165	a0 = ((op_t *) srcp1)[0];
	166	b0 = ((op_t *) srcp2)[0];
	167	if (a1 != b1)
	168	return CMP_LT_OR_GT (a1, b1);
	169
	170	do3:
	171	a1 = ((op_t *) srcp1)[1];
	172	b1 = ((op_t *) srcp2)[1];
	173	if (a0 != b0)
	174	return CMP_LT_OR_GT (a0, b0);
	175
	176	do2:
	177	a0 = ((op_t *) srcp1)[2];
	178	b0 = ((op_t *) srcp2)[2];
	179	if (a1 != b1)
	180	return CMP_LT_OR_GT (a1, b1);
	181
	182	do1:
	183	a1 = ((op_t *) srcp1)[3];
	184	b1 = ((op_t *) srcp2)[3];
	185	if (a0 != b0)
	186	return CMP_LT_OR_GT (a0, b0);
	187
	188	srcp1 += 4 * OPSIZ;
	189	srcp2 += 4 * OPSIZ;
	190	len -= 4;
	191	}
	192	while (len != 0);
	193
	194	/* This is the right position for do0. Please don't move
	195	it into the loop. */
196	do0:
197	if (a1 != b1)
198	return CMP_LT_OR_GT (a1, b1);
199	return 0;
200	}
201
79937577	202	static int memcmp_not_common_alignment (long, long, size_t) __THROW;
a1470b6f	203
28f540f4 RM	204	/* memcmp_not_common_alignment -- Compare blocks at SRCP1 and SRCP2 with LEN
	205	`op_t' objects (not LEN bytes!). SRCP2 should be aligned for memory
	206	operations on `op_t', but SRCP1 should be unaligned. */
28f540f4 RM	207	static int
	208	memcmp_not_common_alignment (srcp1, srcp2, len)
	209	long int srcp1;
	210	long int srcp2;
	211	size_t len;
	212	{
	213	op_t a0, a1, a2, a3;
	214	op_t b0, b1, b2, b3;
	215	op_t x;
	216	int shl, shr;
	217
	218	/* Calculate how to shift a word read at the memory operation
	219	aligned srcp1 to make it aligned for comparison. */
	220
	221	shl = 8 * (srcp1 % OPSIZ);
	222	shr = 8 * OPSIZ - shl;
	223
	224	/* Make SRCP1 aligned by rounding it down to the beginning of the `op_t'
	225	it points in the middle of. */
	226	srcp1 &= -OPSIZ;
	227
	228	switch (len % 4)
	229	{
dfd2257a	230	default: /* Avoid warning about uninitialized local variables. */
28f540f4 RM	231	case 2:
	232	a1 = ((op_t *) srcp1)[0];
	233	a2 = ((op_t *) srcp1)[1];
	234	b2 = ((op_t *) srcp2)[0];
	235	srcp1 -= 1 * OPSIZ;
	236	srcp2 -= 2 * OPSIZ;
	237	len += 2;
	238	goto do1;
	239	case 3:
	240	a0 = ((op_t *) srcp1)[0];
	241	a1 = ((op_t *) srcp1)[1];
	242	b1 = ((op_t *) srcp2)[0];
	243	srcp2 -= 1 * OPSIZ;
	244	len += 1;
	245	goto do2;
	246	case 0:
	247	if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	248	return 0;
	249	a3 = ((op_t *) srcp1)[0];
	250	a0 = ((op_t *) srcp1)[1];
	251	b0 = ((op_t *) srcp2)[0];
	252	srcp1 += 1 * OPSIZ;
	253	goto do3;
	254	case 1:
	255	a2 = ((op_t *) srcp1)[0];
	256	a3 = ((op_t *) srcp1)[1];
	257	b3 = ((op_t *) srcp2)[0];
	258	srcp1 += 2 * OPSIZ;
	259	srcp2 += 1 * OPSIZ;
	260	len -= 1;
	261	if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	262	goto do0;
	263	/* Fall through. */
	264	}
	265
	266	do
	267	{
	268	a0 = ((op_t *) srcp1)[0];
	269	b0 = ((op_t *) srcp2)[0];
	270	x = MERGE(a2, shl, a3, shr);
	271	if (x != b3)
	272	return CMP_LT_OR_GT (x, b3);
	273
	274	do3:
	275	a1 = ((op_t *) srcp1)[1];
	276	b1 = ((op_t *) srcp2)[1];
	277	x = MERGE(a3, shl, a0, shr);
	278	if (x != b0)
	279	return CMP_LT_OR_GT (x, b0);
	280
	281	do2:
	282	a2 = ((op_t *) srcp1)[2];
	283	b2 = ((op_t *) srcp2)[2];
	284	x = MERGE(a0, shl, a1, shr);
	285	if (x != b1)
	286	return CMP_LT_OR_GT (x, b1);
	287
	288	do1:
	289	a3 = ((op_t *) srcp1)[3];
	290	b3 = ((op_t *) srcp2)[3];
	291	x = MERGE(a1, shl, a2, shr);
	292	if (x != b2)
	293	return CMP_LT_OR_GT (x, b2);
	294
295	srcp1 += 4 * OPSIZ;
296	srcp2 += 4 * OPSIZ;
297	len -= 4;
298	}
299	while (len != 0);
300
301	/* This is the right position for do0. Please don't move
302	it into the loop. */
303	do0:
304	x = MERGE(a2, shl, a3, shr);
305	if (x != b3)
306	return CMP_LT_OR_GT (x, b3);
307	return 0;
308	}
309
310	int
07253fcf	311	MEMCMP (s1, s2, len)
28f540f4 RM	312	const __ptr_t s1;
	313	const __ptr_t s2;
	314	size_t len;
	315	{
	316	op_t a0;
	317	op_t b0;
	318	long int srcp1 = (long int) s1;
	319	long int srcp2 = (long int) s2;
	320	op_t res;
	321
	322	if (len >= OP_T_THRES)
	323	{
	324	/* There are at least some bytes to compare. No need to test
	325	for LEN == 0 in this alignment loop. */
	326	while (srcp2 % OPSIZ != 0)
	327	{
	328	a0 = ((byte *) srcp1)[0];
	329	b0 = ((byte *) srcp2)[0];
	330	srcp1 += 1;
	331	srcp2 += 1;
	332	res = a0 - b0;
	333	if (res != 0)
	334	return res;
	335	len -= 1;
	336	}
	337
	338	/* SRCP2 is now aligned for memory operations on `op_t'.
	339	SRCP1 alignment determines if we can do a simple,
	340	aligned compare or need to shuffle bits. */
	341
	342	if (srcp1 % OPSIZ == 0)
	343	res = memcmp_common_alignment (srcp1, srcp2, len / OPSIZ);
	344	else
	345	res = memcmp_not_common_alignment (srcp1, srcp2, len / OPSIZ);
	346	if (res != 0)
	347	return res;
	348
	349	/* Number of bytes remaining in the interval [0..OPSIZ-1]. */
	350	srcp1 += len & -OPSIZ;
	351	srcp2 += len & -OPSIZ;
	352	len %= OPSIZ;
	353	}
	354
	355	/* There are just a few bytes to compare. Use byte memory operations. */
	356	while (len != 0)
	357	{
	358	a0 = ((byte *) srcp1)[0];
	359	b0 = ((byte *) srcp2)[0];
	360	srcp1 += 1;
	361	srcp2 += 1;
	362	res = a0 - b0;
	363	if (res != 0)
	364	return res;
	365	len -= 1;
	366	}
	367
	368	return 0;
	369	}
758b2153	370	libc_hidden_builtin_def(memcmp)
28f540f4	371	#ifdef weak_alias
af6f3906	372	# undef bcmp
28f540f4 RM	373	weak_alias (memcmp, bcmp)
28f540f4 RM	374	#endif