mirror of https://gitee.com/openkylin/linux.git
x86, mem: Optimize memmove for small size and unaligned cases
movs instruction will combine data to accelerate moving data, however we need to concern two cases about it. 1. movs instruction need long lantency to startup, so here we use general mov instruction to copy data. 2. movs instruction is not good for unaligned case, even if src offset is 0x10, dest offset is 0x0, we avoid and handle the case by general mov instruction. Signed-off-by: Ma Ling <ling.ma@intel.com> LKML-Reference: <1284664360-6138-1-git-send-email-ling.ma@intel.com> Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
Ma Ling
H. Peter Anvin
parent
59daa706fb
commit
3b4b682bec
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@ -22,36 +22,187 @@ EXPORT_SYMBOL(memset);
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void *memmove(void *dest, const void *src, size_t n)
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{
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int d0, d1, d2;
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int d0,d1,d2,d3,d4,d5;
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char *ret = dest;
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if (dest < src) {
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if ((dest + n) < src)
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return memcpy(dest, src, n);
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else
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__asm__ __volatile__(
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"rep\n\t"
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"movsb\n\t"
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: "=&c" (d0), "=&S" (d1), "=&D" (d2)
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:"0" (n),
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"1" (src),
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"2" (dest)
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:"memory");
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} else {
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if((src + n) < dest)
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return memcpy(dest, src, n);
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else
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__asm__ __volatile__(
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"std\n\t"
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"rep\n\t"
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"movsb\n\t"
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"cld"
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: "=&c" (d0), "=&S" (d1), "=&D" (d2)
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:"0" (n),
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"1" (n-1+src),
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"2" (n-1+dest)
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:"memory");
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}
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__asm__ __volatile__(
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/* Handle more 16bytes in loop */
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"cmp $0x10, %0\n\t"
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"jb 1f\n\t"
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/* Decide forward/backward copy mode */
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"cmp %2, %1\n\t"
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"jb 2f\n\t"
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/*
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* movs instruction have many startup latency
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* so we handle small size by general register.
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*/
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"cmp $680, %0\n\t"
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"jb 3f\n\t"
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/*
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* movs instruction is only good for aligned case.
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*/
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"mov %1, %3\n\t"
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"xor %2, %3\n\t"
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"and $0xff, %3\n\t"
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"jz 4f\n\t"
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"3:\n\t"
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"sub $0x10, %0\n\t"
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/*
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* We gobble 16byts forward in each loop.
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*/
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"3:\n\t"
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"sub $0x10, %0\n\t"
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"mov 0*4(%1), %3\n\t"
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"mov 1*4(%1), %4\n\t"
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"mov %3, 0*4(%2)\n\t"
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"mov %4, 1*4(%2)\n\t"
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"mov 2*4(%1), %3\n\t"
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"mov 3*4(%1), %4\n\t"
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"mov %3, 2*4(%2)\n\t"
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"mov %4, 3*4(%2)\n\t"
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"lea 0x10(%1), %1\n\t"
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"lea 0x10(%2), %2\n\t"
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"jae 3b\n\t"
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"add $0x10, %0\n\t"
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"jmp 1f\n\t"
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/*
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* Handle data forward by movs.
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*/
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".p2align 4\n\t"
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"4:\n\t"
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"mov -4(%1, %0), %3\n\t"
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"lea -4(%2, %0), %4\n\t"
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"shr $2, %0\n\t"
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"rep movsl\n\t"
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"mov %3, (%4)\n\t"
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"jmp 11f\n\t"
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/*
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* Handle data backward by movs.
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*/
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".p2align 4\n\t"
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"6:\n\t"
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"mov (%1), %3\n\t"
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"mov %2, %4\n\t"
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"lea -4(%1, %0), %1\n\t"
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"lea -4(%2, %0), %2\n\t"
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"shr $2, %0\n\t"
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"std\n\t"
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"rep movsl\n\t"
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"mov %3,(%4)\n\t"
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"cld\n\t"
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"jmp 11f\n\t"
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/*
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* Start to prepare for backward copy.
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*/
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".p2align 4\n\t"
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"2:\n\t"
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"cmp $680, %0\n\t"
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"jb 5f\n\t"
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"mov %1, %3\n\t"
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"xor %2, %3\n\t"
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"and $0xff, %3\n\t"
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"jz 6b\n\t"
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/*
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* Calculate copy position to tail.
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*/
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"5:\n\t"
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"add %0, %1\n\t"
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"add %0, %2\n\t"
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"sub $0x10, %0\n\t"
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/*
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* We gobble 16byts backward in each loop.
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*/
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"7:\n\t"
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"sub $0x10, %0\n\t"
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"mov -1*4(%1), %3\n\t"
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"mov -2*4(%1), %4\n\t"
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"mov %3, -1*4(%2)\n\t"
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"mov %4, -2*4(%2)\n\t"
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"mov -3*4(%1), %3\n\t"
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"mov -4*4(%1), %4\n\t"
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"mov %3, -3*4(%2)\n\t"
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"mov %4, -4*4(%2)\n\t"
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"lea -0x10(%1), %1\n\t"
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"lea -0x10(%2), %2\n\t"
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"jae 7b\n\t"
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/*
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* Calculate copy position to head.
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*/
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"add $0x10, %0\n\t"
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"sub %0, %1\n\t"
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"sub %0, %2\n\t"
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/*
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* Move data from 8 bytes to 15 bytes.
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*/
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".p2align 4\n\t"
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"1:\n\t"
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"cmp $8, %0\n\t"
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"jb 8f\n\t"
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"mov 0*4(%1), %3\n\t"
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"mov 1*4(%1), %4\n\t"
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"mov -2*4(%1, %0), %5\n\t"
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"mov -1*4(%1, %0), %1\n\t"
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"mov %3, 0*4(%2)\n\t"
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"mov %4, 1*4(%2)\n\t"
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"mov %5, -2*4(%2, %0)\n\t"
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"mov %1, -1*4(%2, %0)\n\t"
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"jmp 11f\n\t"
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/*
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* Move data from 4 bytes to 7 bytes.
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*/
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".p2align 4\n\t"
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"8:\n\t"
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"cmp $4, %0\n\t"
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"jb 9f\n\t"
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"mov 0*4(%1), %3\n\t"
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"mov -1*4(%1, %0), %4\n\t"
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"mov %3, 0*4(%2)\n\t"
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"mov %4, -1*4(%2, %0)\n\t"
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"jmp 11f\n\t"
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/*
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* Move data from 2 bytes to 3 bytes.
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*/
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".p2align 4\n\t"
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"9:\n\t"
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"cmp $2, %0\n\t"
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"jb 10f\n\t"
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"movw 0*2(%1), %%dx\n\t"
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"movw -1*2(%1, %0), %%bx\n\t"
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"movw %%dx, 0*2(%2)\n\t"
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"movw %%bx, -1*2(%2, %0)\n\t"
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"jmp 11f\n\t"
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/*
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* Move data for 1 byte.
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*/
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".p2align 4\n\t"
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"10:\n\t"
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"cmp $1, %0\n\t"
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"jb 11f\n\t"
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"movb (%1), %%cl\n\t"
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"movb %%cl, (%2)\n\t"
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".p2align 4\n\t"
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"11:"
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: "=&c" (d0), "=&S" (d1), "=&D" (d2),
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"=r" (d3),"=r" (d4), "=r"(d5)
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:"0" (n),
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"1" (src),
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"2" (dest)
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:"memory");
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return ret;
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return dest;
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}
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EXPORT_SYMBOL(memmove);
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@ -8,50 +8,185 @@
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#undef memmove
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void *memmove(void *dest, const void *src, size_t count)
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{
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unsigned long d0, d1, d2, d3;
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if (dest < src) {
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if ((dest + count) < src)
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return memcpy(dest, src, count);
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else
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__asm__ __volatile__(
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"movq %0, %3\n\t"
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"shr $3, %0\n\t"
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"andq $7, %3\n\t"
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"rep\n\t"
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"movsq\n\t"
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"movq %3, %0\n\t"
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"rep\n\t"
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"movsb"
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: "=&c" (d0), "=&S" (d1), "=&D" (d2), "=r" (d3)
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:"0" (count),
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"1" (src),
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"2" (dest)
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:"memory");
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} else {
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if((src + count) < dest)
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return memcpy(dest, src, count);
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else
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__asm__ __volatile__(
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"movq %0, %3\n\t"
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"lea -8(%1, %0), %1\n\t"
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"lea -8(%2, %0), %2\n\t"
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"shr $3, %0\n\t"
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"andq $7, %3\n\t"
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"std\n\t"
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"rep\n\t"
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"movsq\n\t"
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"lea 7(%1), %1\n\t"
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"lea 7(%2), %2\n\t"
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"movq %3, %0\n\t"
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"rep\n\t"
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"movsb\n\t"
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"cld"
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: "=&c" (d0), "=&S" (d1), "=&D" (d2), "=r" (d3)
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:"0" (count),
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"1" (src),
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"2" (dest)
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:"memory");
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}
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return dest;
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unsigned long d0,d1,d2,d3,d4,d5,d6,d7;
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char *ret;
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__asm__ __volatile__(
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/* Handle more 32bytes in loop */
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"mov %2, %3\n\t"
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"cmp $0x20, %0\n\t"
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"jb 1f\n\t"
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/* Decide forward/backward copy mode */
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"cmp %2, %1\n\t"
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"jb 2f\n\t"
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/*
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* movsq instruction have many startup latency
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* so we handle small size by general register.
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*/
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"cmp $680, %0\n\t"
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"jb 3f\n\t"
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/*
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* movsq instruction is only good for aligned case.
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*/
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"cmpb %%dil, %%sil\n\t"
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"je 4f\n\t"
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"3:\n\t"
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"sub $0x20, %0\n\t"
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/*
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* We gobble 32byts forward in each loop.
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*/
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"5:\n\t"
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"sub $0x20, %0\n\t"
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"movq 0*8(%1), %4\n\t"
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"movq 1*8(%1), %5\n\t"
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"movq 2*8(%1), %6\n\t"
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"movq 3*8(%1), %7\n\t"
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"leaq 4*8(%1), %1\n\t"
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"movq %4, 0*8(%2)\n\t"
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"movq %5, 1*8(%2)\n\t"
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"movq %6, 2*8(%2)\n\t"
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"movq %7, 3*8(%2)\n\t"
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"leaq 4*8(%2), %2\n\t"
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"jae 5b\n\t"
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"addq $0x20, %0\n\t"
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"jmp 1f\n\t"
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/*
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* Handle data forward by movsq.
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*/
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".p2align 4\n\t"
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"4:\n\t"
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"movq %0, %8\n\t"
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"movq -8(%1, %0), %4\n\t"
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"lea -8(%2, %0), %5\n\t"
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"shrq $3, %8\n\t"
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"rep movsq\n\t"
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"movq %4, (%5)\n\t"
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"jmp 13f\n\t"
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/*
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* Handle data backward by movsq.
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*/
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".p2align 4\n\t"
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"7:\n\t"
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"movq %0, %8\n\t"
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"movq (%1), %4\n\t"
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"movq %2, %5\n\t"
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"leaq -8(%1, %0), %1\n\t"
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"leaq -8(%2, %0), %2\n\t"
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"shrq $3, %8\n\t"
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"std\n\t"
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"rep movsq\n\t"
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"cld\n\t"
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"movq %4, (%5)\n\t"
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"jmp 13f\n\t"
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/*
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* Start to prepare for backward copy.
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*/
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".p2align 4\n\t"
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"2:\n\t"
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"cmp $680, %0\n\t"
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"jb 6f \n\t"
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"cmp %%dil, %%sil\n\t"
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"je 7b \n\t"
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"6:\n\t"
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/*
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* Calculate copy position to tail.
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*/
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"addq %0, %1\n\t"
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"addq %0, %2\n\t"
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"subq $0x20, %0\n\t"
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/*
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* We gobble 32byts backward in each loop.
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*/
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"8:\n\t"
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"subq $0x20, %0\n\t"
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"movq -1*8(%1), %4\n\t"
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"movq -2*8(%1), %5\n\t"
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"movq -3*8(%1), %6\n\t"
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"movq -4*8(%1), %7\n\t"
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"leaq -4*8(%1), %1\n\t"
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"movq %4, -1*8(%2)\n\t"
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"movq %5, -2*8(%2)\n\t"
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"movq %6, -3*8(%2)\n\t"
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"movq %7, -4*8(%2)\n\t"
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"leaq -4*8(%2), %2\n\t"
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"jae 8b\n\t"
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/*
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* Calculate copy position to head.
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*/
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"addq $0x20, %0\n\t"
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"subq %0, %1\n\t"
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"subq %0, %2\n\t"
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"1:\n\t"
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"cmpq $16, %0\n\t"
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"jb 9f\n\t"
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/*
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* Move data from 16 bytes to 31 bytes.
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*/
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"movq 0*8(%1), %4\n\t"
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"movq 1*8(%1), %5\n\t"
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"movq -2*8(%1, %0), %6\n\t"
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"movq -1*8(%1, %0), %7\n\t"
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"movq %4, 0*8(%2)\n\t"
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"movq %5, 1*8(%2)\n\t"
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"movq %6, -2*8(%2, %0)\n\t"
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"movq %7, -1*8(%2, %0)\n\t"
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"jmp 13f\n\t"
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".p2align 4\n\t"
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"9:\n\t"
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"cmpq $8, %0\n\t"
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"jb 10f\n\t"
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/*
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* Move data from 8 bytes to 15 bytes.
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*/
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"movq 0*8(%1), %4\n\t"
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"movq -1*8(%1, %0), %5\n\t"
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"movq %4, 0*8(%2)\n\t"
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"movq %5, -1*8(%2, %0)\n\t"
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"jmp 13f\n\t"
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"10:\n\t"
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"cmpq $4, %0\n\t"
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"jb 11f\n\t"
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/*
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* Move data from 4 bytes to 7 bytes.
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*/
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"movl (%1), %4d\n\t"
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"movl -4(%1, %0), %5d\n\t"
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"movl %4d, (%2)\n\t"
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"movl %5d, -4(%2, %0)\n\t"
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"jmp 13f\n\t"
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"11:\n\t"
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"cmp $2, %0\n\t"
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"jb 12f\n\t"
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/*
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* Move data from 2 bytes to 3 bytes.
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*/
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"movw (%1), %4w\n\t"
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"movw -2(%1, %0), %5w\n\t"
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"movw %4w, (%2)\n\t"
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"movw %5w, -2(%2, %0)\n\t"
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"jmp 13f\n\t"
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"12:\n\t"
|
||||
"cmp $1, %0\n\t"
|
||||
"jb 13f\n\t"
|
||||
/*
|
||||
* Move data for 1 byte.
|
||||
*/
|
||||
"movb (%1), %4b\n\t"
|
||||
"movb %4b, (%2)\n\t"
|
||||
"13:\n\t"
|
||||
: "=&d" (d0), "=&S" (d1), "=&D" (d2), "=&a" (ret) ,
|
||||
"=r"(d3), "=r"(d4), "=r"(d5), "=r"(d6), "=&c" (d7)
|
||||
:"0" (count),
|
||||
"1" (src),
|
||||
"2" (dest)
|
||||
:"memory");
|
||||
|
||||
return ret;
|
||||
|
||||
}
|
||||
EXPORT_SYMBOL(memmove);
|
||||
|
|
|
|||
Loading…
Reference in New Issue