mirror of
https://github.com/autc04/Retro68.git
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108 lines
1.9 KiB
C
108 lines
1.9 KiB
C
#if defined __thumb__
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#include "../../string/strcmp.c"
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#else
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#include <string.h>
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#include "xscale.h"
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int
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strcmp (const char *s1, const char *s2)
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{
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asm (PRELOADSTR ("%0") : : "r" (s1));
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asm (PRELOADSTR ("%0") : : "r" (s2));
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#ifndef __OPTIMIZE_SIZE__
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if (((long)s1 & 3) == ((long)s2 & 3))
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{
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int result;
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/* Skip unaligned part. */
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while ((long)s1 & 3)
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{
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if (*s1 == '\0' || *s1 != *s2)
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goto out;
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s1++;
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s2++;
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}
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/* Load two constants:
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lr = 0xfefefeff [ == ~(0x80808080 << 1) ]
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ip = 0x80808080 */
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asm (
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"ldr r2, [%1, #0]\n\
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ldr r3, [%2, #0]\n\
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cmp r2, r3\n\
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bne 2f\n\
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\n\
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mov ip, #0x80\n\
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add ip, ip, #0x8000\n\
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add ip, ip, ip, lsl #16\n\
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mvn lr, ip, lsl #1\n\
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\n\
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0:\n\
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ldr r2, [%1, #0]\n\
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add r3, r2, lr\n\
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bic r3, r3, r2\n\
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tst r3, ip\n\
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beq 1f\n\
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mov %0, #0x0\n\
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b 3f\n\
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1:\n\
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ldr r2, [%1, #4]!\n\
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ldr r3, [%2, #4]!\n\
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" PRELOADSTR("%1") "\n\
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" PRELOADSTR("%2") "\n\
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cmp r2, r3\n\
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beq 0b"
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/* The following part could be done in a C loop as well, but it needs
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to be assembler to save some cycles in the case where the optimized
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loop above finds the strings to be equal. */
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"\n\
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2:\n\
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ldrb r2, [%1, #0]\n\
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" PRELOADSTR("%1") "\n\
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" PRELOADSTR("%2") "\n\
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cmp r2, #0x0\n\
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beq 1f\n\
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ldrb r3, [%2, #0]\n\
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cmp r2, r3\n\
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bne 1f\n\
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0:\n\
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ldrb r3, [%1, #1]!\n\
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add %2, %2, #1\n\
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ands ip, r3, #0xff\n\
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beq 1f\n\
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ldrb r3, [%2]\n\
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cmp ip, r3\n\
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beq 0b\n\
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1:\n\
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ldrb lr, [%1, #0]\n\
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ldrb ip, [%2, #0]\n\
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rsb %0, ip, lr\n\
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3:\n\
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"
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: "=r" (result), "=&r" (s1), "=&r" (s2)
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: "1" (s1), "2" (s2)
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: "lr", "ip", "r2", "r3", "cc");
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return result;
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}
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#endif
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while (*s1 != '\0' && *s1 == *s2)
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{
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asm (PRELOADSTR("%0") : : "r" (s1));
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asm (PRELOADSTR("%0") : : "r" (s2));
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s1++;
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s2++;
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}
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out:
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return (*(unsigned char *) s1) - (*(unsigned char *) s2);
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}
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#endif
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