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

   1 #if defined __thumb__
   2
   3 #include "../../string/strcmp.c"
   4
   5 #else
   6
   7 #include <string.h>
   8 #include "xscale.h"
   9
  10 int
  11 strcmp (const char *s1, const char *s2)
  12 {
  13   asm (PRELOADSTR ("%0") : : "r" (s1));
  14   asm (PRELOADSTR ("%0") : : "r" (s2));
  15
  16 #ifndef __OPTIMIZE_SIZE__
  17   if (((long)s1 & 3) == ((long)s2 & 3))
  18     {
  19       int result;
  20
  21       /* Skip unaligned part.  */
  22       while ((long)s1 & 3)
  23         {
  24           if (*s1 == '\0' || *s1 != *s2)
  25             goto out;
  26           s1++;
  27           s2++;
  28         }
  29
  30   /* Load two constants:
  31      lr = 0xfefefeff [ == ~(0x80808080 << 1) ]
  32      ip = 0x80808080  */
  33
  34       asm (
  35        "ldr     r2, [%1, #0]\n\
  36         ldr     r3, [%2, #0]\n\
  37         cmp     r2, r3\n\
  38         bne     2f\n\
  39 \n\
  40         mov     ip, #0x80\n\
  41         add     ip, ip, #0x8000\n\
  42         add     ip, ip, ip, lsl #16\n\
  43         mvn     lr, ip, lsl #1\n\
  44 \n\
  45 0:\n\
  46         ldr     r2, [%1, #0]\n\
  47         add     r3, r2, lr\n\
  48         bic     r3, r3, r2\n\
  49         tst     r3, ip\n\
  50         beq     1f\n\
  51         mov     %0, #0x0\n\
  52         b       3f\n\
  53 1:\n\
  54         ldr     r2, [%1, #4]!\n\
  55         ldr     r3, [%2, #4]!\n\
  56 "       PRELOADSTR("%1") "\n\
  57 "       PRELOADSTR("%2") "\n\
  58         cmp     r2, r3\n\
  59         beq     0b"
  60
  61        /* The following part could be done in a C loop as well, but it needs
  62           to be assembler to save some cycles in the case where the optimized
  63           loop above finds the strings to be equal.  */
  64 "\n\
  65 2:\n\
  66         ldrb    r2, [%1, #0]\n\
  67 "       PRELOADSTR("%1") "\n\
  68 "       PRELOADSTR("%2") "\n\
  69         cmp     r2, #0x0\n\
  70         beq     1f\n\
  71         ldrb    r3, [%2, #0]\n\
  72         cmp     r2, r3\n\
  73         bne     1f\n\
  74 0:\n\
  75         ldrb    r3, [%1, #1]!\n\
  76         add     %2, %2, #1\n\
  77         ands    ip, r3, #0xff\n\
  78         beq     1f\n\
  79         ldrb    r3, [%2]\n\
  80         cmp     ip, r3\n\
  81         beq     0b\n\
  82 1:\n\
  83         ldrb    lr, [%1, #0]\n\
  84         ldrb    ip, [%2, #0]\n\
  85         rsb     %0, ip, lr\n\
  86 3:\n\
  87 "
  88
  89        : "=r" (result), "=&r" (s1), "=&r" (s2)
  90        : "1" (s1), "2" (s2)
  91        : "lr", "ip", "r2", "r3", "cc");
  92       return result;
  93     }
  94 #endif
  95
  96   while (*s1 != '\0' && *s1 == *s2)
  97     {
  98       asm (PRELOADSTR("%0") : : "r" (s1));
  99       asm (PRELOADSTR("%0") : : "r" (s2));
 100       s1++;
 101       s2++;
 102     }
 103  out:
 104   return (*(unsigned char *) s1) - (*(unsigned char *) s2);
 105 }
 106
 107 #endif