newlib/libc/machine/mbtumbl/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 ANSI_SYNOPSIS
  38         #include <string.h>
  39         int strcmp(const char *<[a]>, const char *<[b]>);
  40
  41 TRAD_SYNOPSIS
  42         #include <string.h>
  43         int strcmp(<[a]>, <[b]>)
  44         char *<[a]>;
  45         char *<[b]>;
  46
  47 DESCRIPTION
  48         <<strcmp>> compares the string at <[a]> to
  49         the string at <[b]>.
  50
  51 RETURNS
  52         If <<*<[a]>>> sorts lexicographically after <<*<[b]>>>,
  53         <<strcmp>> returns a number greater than zero.  If the two
  54         strings match, <<strcmp>> returns zero.  If <<*<[a]>>>
  55         sorts lexicographically before <<*<[b]>>>, <<strcmp>> returns a
  56         number less than zero.
  57
  58 PORTABILITY
  59 <<strcmp>> is ANSI C.
  60
  61 <<strcmp>> requires no supporting OS subroutines.
  62
  63 QUICKREF
  64         strcmp ansi pure
  65 */
  66
  67 #include <string.h>
  68 #include <limits.h>
  69
  70 /* Nonzero if either X or Y is not aligned on a "long" boundary.  */
  71 #define UNALIGNED(X, Y) \
  72   (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1)))
  73
  74 /* DETECTNULL returns nonzero if (long)X contains a NULL byte. */
  75 #if LONG_MAX == 2147483647L
  76 #define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
  77 #else
  78 #if LONG_MAX == 9223372036854775807L
  79 #define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
  80 #else
  81 #error long int is not a 32bit or 64bit type.
  82 #endif
  83 #endif
  84
  85 #ifndef DETECTNULL
  86 #error long int is not a 32bit or 64bit byte
  87 #endif
  88
  89 int
  90 _DEFUN (strcmp, (s1, s2),
  91         _CONST char *s1 _AND
  92         _CONST char *s2)
  93 {
  94
  95 #ifndef HAVE_HW_PCMP
  96
  97 #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
  98   while (*s1 != '\0' && *s1 == *s2)
  99     {
 100       s1++;
 101       s2++;
 102     }
 103
 104   return (*(unsigned char *) s1) - (*(unsigned char *) s2);
 105 #else
 106   unsigned long *a1;
 107   unsigned long *a2;
 108
 109   /* If s1 or s2 are unaligned, then compare bytes. */
 110   if (!UNALIGNED (s1, s2))
 111     {
 112       /* If s1 and s2 are word-aligned, compare them a word at a time. */
 113       a1 = (unsigned long*)s1;
 114       a2 = (unsigned long*)s2;
 115       while (*a1 == *a2)
 116         {
 117           /* To get here, *a1 == *a2, thus if we find a null in *a1,
 118              then the strings must be equal, so return zero.  */
 119           if (DETECTNULL (*a1))
 120             return 0;
 121
 122           a1++;
 123           a2++;
 124         }
 125
 126       /* A difference was detected in last few bytes of s1, so search bytewise */
 127       s1 = (char*)a1;
 128       s2 = (char*)a2;
 129     }
 130
 131   while (*s1 != '\0' && *s1 == *s2)
 132     {
 133       s1++;
 134       s2++;
 135     }
 136   return (*(unsigned char *) s1) - (*(unsigned char *) s2);
 137 #endif /* not PREFER_SIZE_OVER_SPEED */
 138
 139 #else
 140
 141     asm volatile ("                                          \n\
 142        or      r9, r0, r0               /* Index register */ \n\
 143 check_alignment:                                             \n\
 144         andi    r3, r5, 3                                    \n\
 145         andi    r4, r6, 3                                    \n\
 146         bnei    r3, try_align_args                           \n\
 147         bnei    r4, regular_strcmp     /* At this point we don't have a choice */ \n\
 148 cmp_loop:                                                                       \n\
 149         lw      r3, r5, r9                                                      \n\
 150         lw      r4, r6, r9                                                      \n\
 151         pcmpbf  r7, r3, r0              /* See if there is Null byte */                         \n\
 152         bnei    r7, end_cmp_loop        /* IF yes (r7 > 0) use byte compares in end_cmp_loop */ \n\
 153         cmpu    r7, r4, r3              /* ELSE compare whole word */                   \n\
 154         bnei    r7, end_cmp                                                             \n\
 155         brid    cmp_loop                                                                \n\
 156         addik   r9, r9, 4               /* delay slot */                                \n\
 157 end_cmp_loop:                                                                           \n\
 158         lbu     r3, r5, r9              /* byte compare loop */                         \n\
 159         lbu     r4, r6, r9                                                              \n\
 160         cmpu    r7, r4, r3              /* Compare bytes */                             \n\
 161         bnei    r7, end_cmp_early                                                       \n\
 162         bneid   r3, end_cmp_loop        /* If reached null on one string, terminate */  \n\
 163         addik   r9, r9, 1               /* delay slot */                        \n\
 164 end_cmp_early:                                                                  \n\
 165         rtsd    r15, 8                                                          \n\
 166         or      r3, r0, r7                                                      \n\
 167 try_align_args:                                                                 \n\
 168         xor     r7, r4, r3                                                      \n\
 169         bnei    r7, regular_strcmp      /* cannot align args */                 \n\
 170         rsubik  r10, r3, 4              /* Number of initial bytes to align */  \n\
 171 align_loop:                                                                     \n\
 172         lbu     r3, r5, r9                                                      \n\
 173         lbu     r4, r6, r9                                                      \n\
 174         cmpu    r7, r4, r3                                                      \n\
 175         bnei    r7, end_cmp                                                     \n\
 176         beqi    r3, end_cmp                                                     \n\
 177         addik   r10, r10, -1                                                    \n\
 178         beqid   r10, cmp_loop                                                   \n\
 179         addik   r9, r9, 1                                                       \n\
 180         bri     align_loop                                                      \n\
 181 regular_strcmp:                                                                 \n\
 182         lbu     r3, r5, r9                                                      \n\
 183         lbu     r4, r6, r9                                                      \n\
 184         cmpu    r7, r4, r3                                                      \n\
 185         bnei    r7, end_cmp                                                     \n\
 186         beqi    r3, end_cmp                                                     \n\
 187         brid    regular_strcmp                                                  \n\
 188         addik   r9, r9, 1                                                       \n\
 189 end_cmp:                                                                        \n\
 190         rtsd    r15, 8                                                          \n\
 191         or      r3, r0, r7              /* Return strcmp result */");
 192
 193 #endif /* ! HAVE_HW_PCMP */
 194 }
 195