toolchain/gcc/newlib/libc/machine/xscale/strchr.c

   1 #if defined __thumb__
   2
   3 #include "../../string/strchr.c"
   4
   5 #else
   6
   7 #include <string.h>
   8 #include "xscale.h"
   9
  10 char *
  11 strchr (const char *s, int c)
  12 {
  13   unsigned int c2;
  14   asm (PRELOADSTR ("%0") : : "r" (s));
  15
  16   c &= 0xff;
  17
  18 #ifndef __OPTIMIZE_SIZE__
  19   /* Skip unaligned part.  */
  20   if ((long)s & 3)
  21     {
  22       s--;
  23       do
  24         {
  25           int c2 = *++s;
  26           if (c2 == c)
  27             return (char *)s;
  28           if (c2 == '\0')
  29             return 0;
  30         }
  31       while (((long)s & 3) != 0);
  32     }
  33
  34   c2 = c + (c << 8);
  35   c2 += c2 << 16;
  36
  37   /* Load two constants:
  38      R6 = 0xfefefeff [ == ~(0x80808080 << 1) ]
  39      R5 = 0x80808080  */
  40
  41   asm (PRELOADSTR ("%0") "\n\
  42         mov     r5, #0x80\n\
  43         add     r5, r5, #0x8000\n\
  44         add     r5, r5, r5, lsl #16\n\
  45         mvn     r6, r5, lsl #1\n\
  46 \n\
  47         sub     %0, %0, #4\n\
  48 0:\n\
  49         ldr     r1, [%0, #4]!\n\
  50 "       PRELOADSTR ("%0") "\n\
  51         add     r3, r1, r6\n\
  52         bic     r3, r3, r1\n\
  53         ands    r2, r3, r5\n\
  54         bne     1f\n\
  55         eor     r2, r1, %1\n\
  56         add     r3, r2, r6\n\
  57         bic     r3, r3, r2\n\
  58         ands    r1, r3, r5\n\
  59         beq     0b\n\
  60 1:"
  61        : "=&r" (s)
  62        : "r" (c2), "0" (s)
  63        : "r1", "r2", "r3", "r5", "r6", "cc");
  64 #endif
  65
  66   while (*s && *s != c)
  67     s++;
  68   if (*s == c)
  69     return (char *)s;
  70   return NULL;
  71 }
  72
  73 #endif