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

/* Copyright (C) 1991,1993,1995,1997,1998,2003,2004,2012
   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, write to the Free
   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
   02111-1307 USA.  */

#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

#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;

# ifdef  __GNUC__
__inline
# endif
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
c8a89e7d	1	/* Copyright (C) 1991,1993,1995,1997,1998,2003,2004,2012
758b2153	2	Free Software Foundation, Inc.
478b92f0	3	This file is part of the GNU C Library.
28f540f4 RM	4	Contributed by Torbjorn Granlund (tege@sics.se).
28f540f4 RM	5
478b92f0	6	The GNU C Library is free software; you can redistribute it and/or
41bdb6e2 AJ	7	modify it under the terms of the GNU Lesser General Public
	8	License as published by the Free Software Foundation; either
	9	version 2.1 of the License, or (at your option) any later version.
28f540f4	10
478b92f0 UD	11	The GNU C Library is distributed in the hope that it will be useful,
	12	but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
41bdb6e2	14	Lesser General Public License for more details.
28f540f4	15
41bdb6e2 AJ	16	You should have received a copy of the GNU Lesser General Public
	17	License along with the GNU C Library; if not, write to the Free
	18	Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
	19	02111-1307 USA. */
28f540f4 RM	20
28f540f4 RM	21	#ifdef HAVE_CONFIG_H
af6f3906	22	# include "config.h"
28f540f4 RM	23	#endif
	24
	25	#undef __ptr_t
c8a89e7d	26	#define __ptr_t void *
28f540f4	27
af6f3906 UD	28	#if defined HAVE_STRING_H \|\| defined _LIBC
af6f3906 UD	29	# include <string.h>
28f540f4 RM	30	#endif
28f540f4 RM	31
9a0a462c UD	32	#undef memcmp
9a0a462c UD	33
28f540f4 RM	34	#ifdef _LIBC
28f540f4 RM	35
af6f3906	36	# include <memcopy.h>
789b13c4 UD	37	# include <endian.h>
	38
	39	# if __BYTE_ORDER == __BIG_ENDIAN
	40	# define WORDS_BIGENDIAN
	41	# endif
28f540f4 RM	42
	43	#else /* Not in the GNU C library. */
	44
af6f3906	45	# include <sys/types.h>
28f540f4 RM	46
	47	/* Type to use for aligned memory operations.
	48	This should normally be the biggest type supported by a single load
	49	and store. Must be an unsigned type. */
af6f3906 UD	50	# define op_t unsigned long int
af6f3906 UD	51	# define OPSIZ (sizeof(op_t))
28f540f4 RM	52
28f540f4 RM	53	/* Threshold value for when to enter the unrolled loops. */
af6f3906	54	# define OP_T_THRES 16
28f540f4 RM	55
	56	/* Type to use for unaligned operations. */
	57	typedef unsigned char byte;
	58
af6f3906 UD	59	# ifndef WORDS_BIGENDIAN
	60	# define MERGE(w0, sh_1, w1, sh_2) (((w0) >> (sh_1)) \| ((w1) << (sh_2)))
	61	# else
	62	# define MERGE(w0, sh_1, w1, sh_2) (((w0) << (sh_1)) \| ((w1) >> (sh_2)))
	63	# endif
28f540f4 RM	64
	65	#endif /* In the GNU C library. */
	66
	67	#ifdef WORDS_BIGENDIAN
af6f3906	68	# define CMP_LT_OR_GT(a, b) ((a) > (b) ? 1 : -1)
28f540f4	69	#else
af6f3906	70	# define CMP_LT_OR_GT(a, b) memcmp_bytes ((a), (b))
28f540f4 RM	71	#endif
	72
	73	/* BE VERY CAREFUL IF YOU CHANGE THIS CODE! */
	74
	75	/* The strategy of this memcmp is:
	76
	77	1. Compare bytes until one of the block pointers is aligned.
	78
	79	2. Compare using memcmp_common_alignment or
	80	memcmp_not_common_alignment, regarding the alignment of the other
	81	block after the initial byte operations. The maximum number of
	82	full words (of type op_t) are compared in this way.
	83
	84	3. Compare the few remaining bytes. */
	85
	86	#ifndef WORDS_BIGENDIAN
	87	/* memcmp_bytes -- Compare A and B bytewise in the byte order of the machine.
	88	A and B are known to be different.
	89	This is needed only on little-endian machines. */
a1470b6f	90
79937577	91	static int memcmp_bytes (op_t, op_t) __THROW;
a1470b6f	92
af6f3906	93	# ifdef __GNUC__
28f540f4	94	__inline
af6f3906	95	# endif
28f540f4 RM	96	static int
	97	memcmp_bytes (a, b)
	98	op_t a, b;
	99	{
	100	long int srcp1 = (long int) &a;
	101	long int srcp2 = (long int) &b;
	102	op_t a0, b0;
	103
	104	do
	105	{
	106	a0 = ((byte *) srcp1)[0];
	107	b0 = ((byte *) srcp2)[0];
	108	srcp1 += 1;
	109	srcp2 += 1;
	110	}
	111	while (a0 == b0);
	112	return a0 - b0;
	113	}
	114	#endif
	115
79937577	116	static int memcmp_common_alignment (long, long, size_t) __THROW;
a1470b6f	117
28f540f4 RM	118	/* memcmp_common_alignment -- Compare blocks at SRCP1 and SRCP2 with LEN `op_t'
	119	objects (not LEN bytes!). Both SRCP1 and SRCP2 should be aligned for
	120	memory operations on `op_t's. */
28f540f4 RM	121	static int
	122	memcmp_common_alignment (srcp1, srcp2, len)
	123	long int srcp1;
	124	long int srcp2;
	125	size_t len;
	126	{
	127	op_t a0, a1;
	128	op_t b0, b1;
	129
	130	switch (len % 4)
	131	{
dfd2257a	132	default: /* Avoid warning about uninitialized local variables. */
28f540f4 RM	133	case 2:
	134	a0 = ((op_t *) srcp1)[0];
	135	b0 = ((op_t *) srcp2)[0];
	136	srcp1 -= 2 * OPSIZ;
	137	srcp2 -= 2 * OPSIZ;
	138	len += 2;
	139	goto do1;
	140	case 3:
	141	a1 = ((op_t *) srcp1)[0];
	142	b1 = ((op_t *) srcp2)[0];
	143	srcp1 -= OPSIZ;
	144	srcp2 -= OPSIZ;
	145	len += 1;
	146	goto do2;
	147	case 0:
	148	if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	149	return 0;
	150	a0 = ((op_t *) srcp1)[0];
	151	b0 = ((op_t *) srcp2)[0];
	152	goto do3;
	153	case 1:
	154	a1 = ((op_t *) srcp1)[0];
	155	b1 = ((op_t *) srcp2)[0];
	156	srcp1 += OPSIZ;
	157	srcp2 += OPSIZ;
	158	len -= 1;
	159	if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	160	goto do0;
	161	/* Fall through. */
	162	}
	163
	164	do
	165	{
	166	a0 = ((op_t *) srcp1)[0];
	167	b0 = ((op_t *) srcp2)[0];
	168	if (a1 != b1)
	169	return CMP_LT_OR_GT (a1, b1);
	170
	171	do3:
	172	a1 = ((op_t *) srcp1)[1];
	173	b1 = ((op_t *) srcp2)[1];
	174	if (a0 != b0)
	175	return CMP_LT_OR_GT (a0, b0);
	176
	177	do2:
	178	a0 = ((op_t *) srcp1)[2];
	179	b0 = ((op_t *) srcp2)[2];
	180	if (a1 != b1)
	181	return CMP_LT_OR_GT (a1, b1);
	182
	183	do1:
	184	a1 = ((op_t *) srcp1)[3];
	185	b1 = ((op_t *) srcp2)[3];
	186	if (a0 != b0)
	187	return CMP_LT_OR_GT (a0, b0);
	188
	189	srcp1 += 4 * OPSIZ;
	190	srcp2 += 4 * OPSIZ;
	191	len -= 4;
	192	}
	193	while (len != 0);
	194
	195	/* This is the right position for do0. Please don't move
	196	it into the loop. */
197	do0:
198	if (a1 != b1)
199	return CMP_LT_OR_GT (a1, b1);
200	return 0;
201	}
202
79937577	203	static int memcmp_not_common_alignment (long, long, size_t) __THROW;
a1470b6f	204
28f540f4 RM	205	/* memcmp_not_common_alignment -- Compare blocks at SRCP1 and SRCP2 with LEN
	206	`op_t' objects (not LEN bytes!). SRCP2 should be aligned for memory
	207	operations on `op_t', but SRCP1 should be unaligned. */
28f540f4 RM	208	static int
	209	memcmp_not_common_alignment (srcp1, srcp2, len)
	210	long int srcp1;
	211	long int srcp2;
	212	size_t len;
	213	{
	214	op_t a0, a1, a2, a3;
	215	op_t b0, b1, b2, b3;
	216	op_t x;
	217	int shl, shr;
	218
	219	/* Calculate how to shift a word read at the memory operation
	220	aligned srcp1 to make it aligned for comparison. */
	221
	222	shl = 8 * (srcp1 % OPSIZ);
	223	shr = 8 * OPSIZ - shl;
	224
	225	/* Make SRCP1 aligned by rounding it down to the beginning of the `op_t'
	226	it points in the middle of. */
	227	srcp1 &= -OPSIZ;
	228
	229	switch (len % 4)
	230	{
dfd2257a	231	default: /* Avoid warning about uninitialized local variables. */
28f540f4 RM	232	case 2:
	233	a1 = ((op_t *) srcp1)[0];
	234	a2 = ((op_t *) srcp1)[1];
	235	b2 = ((op_t *) srcp2)[0];
	236	srcp1 -= 1 * OPSIZ;
	237	srcp2 -= 2 * OPSIZ;
	238	len += 2;
	239	goto do1;
	240	case 3:
	241	a0 = ((op_t *) srcp1)[0];
	242	a1 = ((op_t *) srcp1)[1];
	243	b1 = ((op_t *) srcp2)[0];
	244	srcp2 -= 1 * OPSIZ;
	245	len += 1;
	246	goto do2;
	247	case 0:
	248	if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	249	return 0;
	250	a3 = ((op_t *) srcp1)[0];
	251	a0 = ((op_t *) srcp1)[1];
	252	b0 = ((op_t *) srcp2)[0];
	253	srcp1 += 1 * OPSIZ;
	254	goto do3;
	255	case 1:
	256	a2 = ((op_t *) srcp1)[0];
	257	a3 = ((op_t *) srcp1)[1];
	258	b3 = ((op_t *) srcp2)[0];
	259	srcp1 += 2 * OPSIZ;
	260	srcp2 += 1 * OPSIZ;
	261	len -= 1;
	262	if (OP_T_THRES <= 3 * OPSIZ && len == 0)
	263	goto do0;
	264	/* Fall through. */
	265	}
	266
	267	do
	268	{
	269	a0 = ((op_t *) srcp1)[0];
	270	b0 = ((op_t *) srcp2)[0];
	271	x = MERGE(a2, shl, a3, shr);
	272	if (x != b3)
	273	return CMP_LT_OR_GT (x, b3);
	274
	275	do3:
	276	a1 = ((op_t *) srcp1)[1];
	277	b1 = ((op_t *) srcp2)[1];
	278	x = MERGE(a3, shl, a0, shr);
	279	if (x != b0)
	280	return CMP_LT_OR_GT (x, b0);
	281
	282	do2:
	283	a2 = ((op_t *) srcp1)[2];
	284	b2 = ((op_t *) srcp2)[2];
	285	x = MERGE(a0, shl, a1, shr);
	286	if (x != b1)
	287	return CMP_LT_OR_GT (x, b1);
	288
	289	do1:
	290	a3 = ((op_t *) srcp1)[3];
	291	b3 = ((op_t *) srcp2)[3];
	292	x = MERGE(a1, shl, a2, shr);
	293	if (x != b2)
	294	return CMP_LT_OR_GT (x, b2);
	295
296	srcp1 += 4 * OPSIZ;
297	srcp2 += 4 * OPSIZ;
298	len -= 4;
299	}
300	while (len != 0);
301
302	/* This is the right position for do0. Please don't move
303	it into the loop. */
304	do0:
305	x = MERGE(a2, shl, a3, shr);
306	if (x != b3)
307	return CMP_LT_OR_GT (x, b3);
308	return 0;
309	}
310
311	int
312	memcmp (s1, s2, len)
313	const __ptr_t s1;
314	const __ptr_t s2;
315	size_t len;
316	{
317	op_t a0;
318	op_t b0;
319	long int srcp1 = (long int) s1;
320	long int srcp2 = (long int) s2;
321	op_t res;
322
323	if (len >= OP_T_THRES)
324	{
325	/* There are at least some bytes to compare. No need to test
326	for LEN == 0 in this alignment loop. */
327	while (srcp2 % OPSIZ != 0)
328	{
329	a0 = ((byte *) srcp1)[0];
330	b0 = ((byte *) srcp2)[0];
331	srcp1 += 1;
332	srcp2 += 1;
333	res = a0 - b0;
334	if (res != 0)
335	return res;
336	len -= 1;
337	}
338
339	/* SRCP2 is now aligned for memory operations on `op_t'.
340	SRCP1 alignment determines if we can do a simple,
341	aligned compare or need to shuffle bits. */
342
343	if (srcp1 % OPSIZ == 0)
344	res = memcmp_common_alignment (srcp1, srcp2, len / OPSIZ);
345	else
346	res = memcmp_not_common_alignment (srcp1, srcp2, len / OPSIZ);
347	if (res != 0)
348	return res;
349
350	/* Number of bytes remaining in the interval [0..OPSIZ-1]. */
351	srcp1 += len & -OPSIZ;
352	srcp2 += len & -OPSIZ;
353	len %= OPSIZ;
354	}
355
356	/* There are just a few bytes to compare. Use byte memory operations. */
357	while (len != 0)
358	{
359	a0 = ((byte *) srcp1)[0];
360	b0 = ((byte *) srcp2)[0];
361	srcp1 += 1;
362	srcp2 += 1;
363	res = a0 - b0;
364	if (res != 0)
365	return res;
366	len -= 1;
367	}
368
369	return 0;
370	}
758b2153	371	libc_hidden_builtin_def(memcmp)
28f540f4	372	#ifdef weak_alias
af6f3906	373	# undef bcmp
28f540f4 RM	374	weak_alias (memcmp, bcmp)
28f540f4 RM	375	#endif