newlib/libc/machine/microblaze/strcmp.c

   1 /* Copyright (c) 2009 Xilinx, Inc.  All rights reserved.
   2
   3    Redistribution and use in source and binary forms, with or without
   4    modification, are permitted provided that the following conditions are
   5    met:
   6
   7    1.  Redistributions source code must retain the above copyright notice,
   8    this list of conditions and the following disclaimer.
   9
  10    2.  Redistributions in binary form must reproduce the above copyright
  11    notice, this list of conditions and the following disclaimer in the
  12    documentation and/or other materials provided with the distribution.
  13
  14    3.  Neither the name of Xilinx nor the names of its contributors may be
  15    used to endorse or promote products derived from this software without
  16    specific prior written permission.
  17
  18    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER AND CONTRIBUTORS "AS
  19    IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  20    TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  21    PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  22    HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  23    SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
  24    TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  25    PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  26    LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  27    NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  28    SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29
  30
  31 FUNCTION
  32         <<strcmp>>---character string compare
  33
  34 INDEX
  35         strcmp
  36
  37 SYNOPSIS
  38         #include <string.h>
  39         int strcmp(const char *<[a]>, const char *<[b]>);
  40
  41 DESCRIPTION
  42         <<strcmp>> compares the string at <[a]> to
  43         the string at <[b]>.
  44
  45 RETURNS
  46         If <<*<[a]>>> sorts lexicographically after <<*<[b]>>>,
  47         <<strcmp>> returns a number greater than zero.  If the two
  48         strings match, <<strcmp>> returns zero.  If <<*<[a]>>>
  49         sorts lexicographically before <<*<[b]>>>, <<strcmp>> returns a
  50         number less than zero.
  51
  52 PORTABILITY
  53 <<strcmp>> is ANSI C.
  54
  55 <<strcmp>> requires no supporting OS subroutines.
  56
  57 QUICKREF
  58         strcmp ansi pure
  59 */
  60
  61 #include <string.h>
  62 #include <limits.h>
  63
  64 /* Nonzero if either X or Y is not aligned on a "long" boundary.  */
  65 #define UNALIGNED(X, Y) \
  66   (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
  67
  68 /* DETECTNULL returns nonzero if (long)X contains a NULL byte. */
  69 #if LONG_MAX == 2147483647L
  70 #define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
  71 #else
  72 #if LONG_MAX == 9223372036854775807L
  73 #define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
  74 #else
  75 #error long int is not a 32bit or 64bit type.
  76 #endif
  77 #endif
  78
  79 #ifndef DETECTNULL
  80 #error long int is not a 32bit or 64bit byte
  81 #endif
  82
  83 int
  84 strcmp (const char *s1,
  85         const char *s2)
  86 {
  87
  88 #ifndef HAVE_HW_PCMP
  89
  90 #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
  91   while (*s1 != '\0' && *s1 == *s2)
  92     {
  93       s1++;
  94       s2++;
  95     }
  96
  97   return (*(unsigned char *) s1) - (*(unsigned char *) s2);
  98 #else
  99   unsigned long *a1;
 100   unsigned long *a2;
 101
 102   /* If s1 or s2 are unaligned, then compare bytes. */
 103   if (!UNALIGNED (s1, s2))
 104     {
 105       /* If s1 and s2 are word-aligned, compare them a word at a time. */
 106       a1 = (unsigned long*)s1;
 107       a2 = (unsigned long*)s2;
 108       while (*a1 == *a2)
 109         {
 110           /* To get here, *a1 == *a2, thus if we find a null in *a1,
 111              then the strings must be equal, so return zero.  */
 112           if (DETECTNULL (*a1))
 113             return 0;
 114
 115           a1++;
 116           a2++;
 117         }
 118
 119       /* A difference was detected in last few bytes of s1, so search bytewise */
 120       s1 = (char*)a1;
 121       s2 = (char*)a2;
 122     }
 123
 124   while (*s1 != '\0' && *s1 == *s2)
 125     {
 126       s1++;
 127       s2++;
 128     }
 129   return (*(unsigned char *) s1) - (*(unsigned char *) s2);
 130 #endif /* not PREFER_SIZE_OVER_SPEED */
 131
 132 #else
 133
 134 #include "mb_endian.h"
 135
 136     asm volatile ("                                          \n\
 137         or      r9, r0, r0               /* Index register */\n\
 138 check_alignment:                                             \n\
 139         andi    r3, r5, 3                                    \n\
 140         andi    r4, r6, 3                                    \n\
 141         bnei    r3, try_align_args                           \n\
 142         bnei    r4, regular_strcmp     /* At this point we don't have a choice */ \n\
 143 cmp_loop:                                                                       \n"
 144         LOAD4BYTES("r3", "r5", "r9")
 145         LOAD4BYTES("r4", "r6", "r9")
 146 "                                                                                      \n\
 147         pcmpbf  r7, r3, r0              /* See if there is Null byte */                         \n\
 148         bnei    r7, end_cmp_loop        /* IF yes (r7 > 0) use byte compares in end_cmp_loop */ \n\
 149         cmpu    r7, r4, r3              /* ELSE compare whole word */                   \n\
 150         bnei    r7, end_cmp                                                             \n\
 151         brid    cmp_loop                                                                \n\
 152         addik   r9, r9, 4               /* delay slot */                                \n\
 153 end_cmp_loop:                                                                           \n\
 154         lbu     r3, r5, r9              /* byte compare loop */                         \n\
 155         lbu     r4, r6, r9                                                              \n\
 156         cmpu    r7, r4, r3              /* Compare bytes */                             \n\
 157         bnei    r7, end_cmp_early                                                       \n\
 158         bneid   r3, end_cmp_loop        /* If reached null on one string, terminate */  \n\
 159         addik   r9, r9, 1               /* delay slot */                        \n\
 160 end_cmp_early:                                                                  \n\
 161         rtsd    r15, 8                                                          \n\
 162         or      r3, r0, r7                                                      \n\
 163 try_align_args:                                                                 \n\
 164         xor     r7, r4, r3                                                      \n\
 165         bnei    r7, regular_strcmp      /* cannot align args */                 \n\
 166         rsubik  r10, r3, 4              /* Number of initial bytes to align */  \n\
 167 align_loop:                                                                     \n\
 168         lbu     r3, r5, r9                                                      \n\
 169         lbu     r4, r6, r9                                                      \n\
 170         cmpu    r7, r4, r3                                                      \n\
 171         bnei    r7, end_cmp                                                     \n\
 172         beqi    r3, end_cmp                                                     \n\
 173         addik   r10, r10, -1                                                    \n\
 174         beqid   r10, cmp_loop                                                   \n\
 175         addik   r9, r9, 1                                                       \n\
 176         bri     align_loop                                                      \n\
 177 regular_strcmp:                                                                 \n\
 178         lbu     r3, r5, r9                                                      \n\
 179         lbu     r4, r6, r9                                                      \n\
 180         cmpu    r7, r4, r3                                                      \n\
 181         bnei    r7, end_cmp                                                     \n\
 182         beqi    r3, end_cmp                                                     \n\
 183         brid    regular_strcmp                                                  \n\
 184         addik   r9, r9, 1                                                       \n\
 185 end_cmp:                                                                        \n\
 186         rtsd    r15, 8                                                          \n\
 187         or      r3, r0, r7              /* Return strcmp result */");
 188
 189 #endif /* ! HAVE_HW_PCMP */
 190 }
 191