103 lines
1.6 KiB
C
103 lines
1.6 KiB
C
#if defined __thumb__
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#include "../../string/memchr.c"
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#else
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#include <string.h>
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#include "xscale.h"
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void *
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memchr (const void *start, int c, size_t len)
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{
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const char *str = start;
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if (len == 0)
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return 0;
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asm (PRELOADSTR ("%0") : : "r" (start));
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c &= 0xff;
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#ifndef __OPTIMIZE_SIZE__
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/* Skip unaligned part. */
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if ((long)str & 3)
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{
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str--;
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do
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{
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if (*++str == c)
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return (void *)str;
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}
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while (((long)str & 3) != 0 && --len > 0);
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}
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if (len > 3)
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{
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unsigned int c2 = c + (c << 8);
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c2 += c2 << 16;
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/* Load two constants:
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R7 = 0xfefefeff [ == ~(0x80808080 << 1) ]
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R6 = 0x80808080 */
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asm (
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"mov r6, #0x80\n\
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add r6, r6, #0x8000\n\
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add r6, r6, r6, lsl #16\n\
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mvn r7, r6, lsl #1\n\
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\n\
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0:\n\
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cmp %1, #0x7\n\
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bls 1f\n\
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\n\
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ldmia %0!, { r3, r9 }\n\
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" PRELOADSTR ("%0") "\n\
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sub %1, %1, #8\n\
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eor r3, r3, %2\n\
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eor r9, r9, %2\n\
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add r2, r3, r7\n\
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add r8, r9, r7\n\
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bic r2, r2, r3\n\
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bic r8, r8, r9\n\
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and r1, r2, r6\n\
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and r9, r8, r6\n\
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orrs r1, r1, r9\n\
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beq 0b\n\
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\n\
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add %1, %1, #8\n\
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sub %0, %0, #8\n\
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1:\n\
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cmp %1, #0x3\n\
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bls 2f\n\
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\n\
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ldr r3, [%0], #4\n\
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" PRELOADSTR ("%0") "\n\
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sub %1, %1, #4\n\
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eor r3, r3, %2\n\
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add r2, r3, r7\n\
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bic r2, r2, r3\n\
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ands r1, r2, r6\n\
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beq 1b\n\
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\n\
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sub %0, %0, #4\n\
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add %1, %1, #4\n\
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2:\n\
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"
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: "=&r" (str), "=&r" (len)
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: "r" (c2), "0" (str), "1" (len)
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: "r1", "r2", "r3", "r6", "r7", "r8", "r9", "cc");
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}
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#endif
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while (len-- > 0)
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{
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if (*str == c)
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return (void *)str;
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str++;
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}
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return 0;
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}
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#endif
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