source: trunk/libs/newlib/src/newlib/libc/machine/xscale/strlen.c @ 444

#if defined __thumb__ || defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__)

#include "../../string/strlen.c"

#else

#include <string.h>
#include "xscale.h"

size_t
strlen (const char *str)
{
  const char *start = str;

  /* Skip unaligned part.  */
  if ((long)str & 3)
    {
      str--;
      do
        {
          if (*++str == '\0')
            goto out;
        }
      while ((long)str & 3);
    }

  /* Load two constants:
     R4 = 0xfefefeff [ == ~(0x80808080 << 1) ]
     R5 = 0x80808080  */

  asm ("mov     r5, #0x80\n\
        add     r5, r5, #0x8000\n\
        add     r5, r5, r5, lsl #16\n\
        mvn     r4, r5, lsl #1\n\
"

#if defined __ARM_ARCH_5__ || defined __ARM_ARCH_5T__ || defined __ARM_ARCH_5E__ || defined __ARM_ARCH_5TE__

"       tst     %0, #0x7\n\
        ldreqd  r6, [%0]\n\
        beq     1f\n\
        ldr     r2, [%0]\n\
        add     r3, r2, r4\n\
        bic     r3, r3, r2\n\
        ands    r2, r3, r5\n\
        bne     2f\n\
        sub     %0, %0, #4\n\
\n\
0:\n\
        ldrd    r6, [%0, #8]!\n\
"
        PRELOADSTR ("%0")
"\n\
1:\n\
        add     r3, r6, r4\n\
        add     r2, r7, r4\n\
        bic     r3, r3, r6\n\
        bic     r2, r2, r7\n\
        and     r3, r3, r5\n\
        and     r2, r2, r5\n\
        orrs    r3, r2, r3\n\
        beq     0b\n\
"
#else

"       sub     %0, %0, #4\n\
\n\
0:\n\
        ldr     r6, [%0, #4]!\n\
"
        PRELOADSTR ("%0")
"\n\
        add     r3, r6, r4\n\
        bic     r3, r3, r6\n\
        ands    r3, r3, r5\n\
        beq     0b\n\
"
#endif /* __ARM_ARCH_5[T][E]__ */
"\n\
2:\n\
        ldrb    r3, [%0]\n\
        cmp     r3, #0x0\n\
        beq     1f\n\
\n\
0:\n\
        ldrb    r3, [%0, #1]!\n\
"
        PRELOADSTR ("%0")
"\n\
        cmp     r3, #0x0\n\
        bne     0b\n\
1:\n\
"
       : "=r" (str) : "0" (str) : "r2", "r3", "r4", "r5", "r6", "r7");

  out:
  return str - start;
}

#endif