newlib/libc/machine/microblaze/strlen.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         <<strlen>>---character string length
  33
  34 INDEX
  35         strlen
  36
  37 SYNOPSIS
  38         #include <string.h>
  39         size_t strlen(const char *<[str]>);
  40
  41 DESCRIPTION
  42         The <<strlen>> function works out the length of the string
  43         starting at <<*<[str]>>> by counting chararacters until it
  44         reaches a <<NULL>> character.
  45
  46 RETURNS
  47         <<strlen>> returns the character count.
  48
  49 PORTABILITY
  50 <<strlen>> is ANSI C.
  51
  52 <<strlen>> requires no supporting OS subroutines.
  53
  54 QUICKREF
  55         strlen ansi pure
  56 */
  57
  58 #include <_ansi.h>
  59 #include <string.h>
  60 #include <limits.h>
  61
  62 #define LBLOCKSIZE   (sizeof (long))
  63 #define UNALIGNED(X) ((long)X & (LBLOCKSIZE - 1))
  64
  65 #if LONG_MAX == 2147483647L
  66 #define DETECTNULL(X) (((X) - 0x01010101) & ~(X) & 0x80808080)
  67 #else
  68 #if LONG_MAX == 9223372036854775807L
  69 /* Nonzero if X (a long int) contains a NULL byte. */
  70 #define DETECTNULL(X) (((X) - 0x0101010101010101) & ~(X) & 0x8080808080808080)
  71 #else
  72 #error long int is not a 32bit or 64bit type.
  73 #endif
  74 #endif
  75
  76 #ifndef DETECTNULL
  77 #error long int is not a 32bit or 64bit byte
  78 #endif
  79
  80 size_t
  81 strlen (const char *str)
  82 {
  83
  84 #ifndef HAVE_HW_PCMP
  85
  86 #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)
  87   const char *start = str;
  88
  89   while (*str)
  90     str++;
  91
  92   return str - start;
  93 #else
  94   const char *start = str;
  95   unsigned long *aligned_addr;
  96
  97   if (!UNALIGNED (str))
  98     {
  99       /* If the string is word-aligned, we can check for the presence of
 100          a null in each word-sized block.  */
 101       aligned_addr = (unsigned long*)str;
 102       while (!DETECTNULL (*aligned_addr))
 103         aligned_addr++;
 104
 105       /* Once a null is detected, we check each byte in that block for a
 106          precise position of the null.  */
 107       str = (char*)aligned_addr;
 108     }
 109
 110   while (*str)
 111     str++;
 112   return str - start;
 113 #endif /* not PREFER_SIZE_OVER_SPEED */
 114
 115 #else
 116
 117 #include "mb_endian.h"
 118
 119   asm volatile ("                                               \n\
 120         or      r9, r0, r0              /* Index register */    \n\
 121 check_alignment:                                                \n\
 122         andi    r3, r5, 3                                       \n\
 123         bnei    r3, align_arg                                   \n\
 124 len_loop:                                                       \n"
 125         LOAD4BYTES("r3", "r5", "r9")
 126 "                                                               \n\
 127         pcmpbf  r4, r3, r0                                      \n\
 128         bnei    r4, end_len                                     \n\
 129         brid    len_loop                                        \n\
 130         addik   r9, r9, 4                                       \n\
 131 end_len:                                                        \n\
 132         lbu     r3, r5, r9                                      \n\
 133         beqi    r3, done_len                                    \n\
 134         brid    end_len                                         \n\
 135         addik   r9, r9, 1                                       \n\
 136 done_len:                                                       \n\
 137         rtsd    r15, 8                                          \n\
 138         or      r3, r0, r9              /* Return len */        \n\
 139 align_arg:                                                      \n\
 140         rsubik  r10, r3, 4                                      \n\
 141 align_loop:                                                     \n\
 142         lbu     r3, r5, r9                                      \n\
 143         beqid   r3, done_len                                    \n\
 144         addik   r10, r10, -1                                    \n\
 145         bneid   r10, align_loop                                 \n\
 146         addik   r9, r9, 1                                       \n\
 147         bri     len_loop");
 148
 149 #endif  /* ! HAVE_HW_PCMP */
 150 }