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[/] [openrisc/] [trunk/] [gnu-old/] [newlib-1.17.0/] [newlib/] [libc/] [machine/] [xscale/] [memset.c] - Rev 855
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#if defined __thumb__ #include "../../string/memset.c" #else #include <string.h> #include "xscale.h" void * memset (void *dst, int c, size_t len) { int dummy; asm volatile ("tst %0, #0x3" #ifndef __OPTIMIZE_SIZE__ "\n\ beq 1f\n\ b 2f\n\ 0:\n\ strb %1, [%0], #1\n\ tst %0, #0x3\n\ beq 1f\n\ 2:\n\ movs r3, %2\n\ sub %2, %2, #1\n\ bne 0b\n\ # At this point we know that %2 == len == -1 (since the SUB has already taken\n\ # place). If we fall through to the 1: label (as the code used to do), the\n\ # CMP will detect this negative value and branch to the 2: label. This will\n\ # test %2 again, but this time against 0. The test will fail and the loop\n\ # at 2: will go on for (almost) ever. Hence the explicit branch to the end\n\ # of the hand written assembly code.\n\ b 4f\n\ 1:\n\ cmp %2, #0x3\n\ bls 2f\n\ and %1, %1, #0xff\n\ orr lr, %1, %1, asl #8\n\ cmp %2, #0xf\n\ orr lr, lr, lr, asl #16\n\ bls 1f\n\ mov r3, lr\n\ mov r4, lr\n\ mov r5, lr\n\ 0:\n\ sub %2, %2, #16\n\ stmia %0!, { r3, r4, r5, lr }\n\ cmp %2, #0xf\n\ bhi 0b\n\ 1:\n\ cmp %2, #0x7\n\ bls 1f\n\ mov r3, lr\n\ 0:\n\ sub %2, %2, #8\n\ stmia %0!, { r3, lr }\n\ cmp %2, #0x7\n\ bhi 0b\n\ 1:\n\ cmp %2, #0x3\n\ bls 2f\n\ 0:\n\ sub %2, %2, #4\n\ str lr, [%0], #4\n\ cmp %2, #0x3\n\ bhi 0b\n\ " #endif /* !__OPTIMIZE_SIZE__ */ "\n\ 2:\n\ movs r3, %2\n\ sub %2, %2, #1\n\ beq 4f\n\ 0:\n\ movs r3, %2\n\ sub %2, %2, #1\n\ strb %1, [%0], #1\n\ bne 0b\n\ 4:" : "=&r" (dummy), "=&r" (c), "=&r" (len) : "0" (dst), "1" (c), "2" (len) : "memory", "r3", "r4", "r5", "lr"); return dst; } #endif
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