124 lines
2.6 KiB
C
124 lines
2.6 KiB
C
#include <string.h>
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#include <stdint.h>
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#include <endian.h>
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void *memcpy(void *restrict dest, const void *restrict src, size_t n)
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{
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unsigned char *d = dest;
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const unsigned char *s = src;
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#ifdef __GNUC__
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#if __BYTE_ORDER == __LITTLE_ENDIAN
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#define LS >>
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#define RS <<
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#else
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#define LS <<
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#define RS >>
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#endif
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typedef uint32_t __attribute__((__may_alias__)) u32;
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uint32_t w, x;
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for (; (uintptr_t)s % 4 && n; n--) *d++ = *s++;
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if ((uintptr_t)d % 4 == 0) {
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for (; n>=16; s+=16, d+=16, n-=16) {
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*(u32 *)(d+0) = *(u32 *)(s+0);
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*(u32 *)(d+4) = *(u32 *)(s+4);
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*(u32 *)(d+8) = *(u32 *)(s+8);
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*(u32 *)(d+12) = *(u32 *)(s+12);
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}
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if (n&8) {
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*(u32 *)(d+0) = *(u32 *)(s+0);
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*(u32 *)(d+4) = *(u32 *)(s+4);
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d += 8; s += 8;
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}
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if (n&4) {
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*(u32 *)(d+0) = *(u32 *)(s+0);
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d += 4; s += 4;
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}
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if (n&2) {
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*d++ = *s++; *d++ = *s++;
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}
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if (n&1) {
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*d = *s;
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}
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return dest;
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}
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if (n >= 32) switch ((uintptr_t)d % 4) {
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case 1:
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w = *(u32 *)s;
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*d++ = *s++;
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*d++ = *s++;
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*d++ = *s++;
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n -= 3;
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for (; n>=17; s+=16, d+=16, n-=16) {
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x = *(u32 *)(s+1);
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*(u32 *)(d+0) = (w LS 24) | (x RS 8);
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w = *(u32 *)(s+5);
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*(u32 *)(d+4) = (x LS 24) | (w RS 8);
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x = *(u32 *)(s+9);
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*(u32 *)(d+8) = (w LS 24) | (x RS 8);
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w = *(u32 *)(s+13);
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*(u32 *)(d+12) = (x LS 24) | (w RS 8);
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}
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break;
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case 2:
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w = *(u32 *)s;
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*d++ = *s++;
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*d++ = *s++;
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n -= 2;
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for (; n>=18; s+=16, d+=16, n-=16) {
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x = *(u32 *)(s+2);
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*(u32 *)(d+0) = (w LS 16) | (x RS 16);
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w = *(u32 *)(s+6);
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*(u32 *)(d+4) = (x LS 16) | (w RS 16);
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x = *(u32 *)(s+10);
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*(u32 *)(d+8) = (w LS 16) | (x RS 16);
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w = *(u32 *)(s+14);
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*(u32 *)(d+12) = (x LS 16) | (w RS 16);
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}
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break;
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case 3:
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w = *(u32 *)s;
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*d++ = *s++;
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n -= 1;
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for (; n>=19; s+=16, d+=16, n-=16) {
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x = *(u32 *)(s+3);
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*(u32 *)(d+0) = (w LS 8) | (x RS 24);
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w = *(u32 *)(s+7);
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*(u32 *)(d+4) = (x LS 8) | (w RS 24);
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x = *(u32 *)(s+11);
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*(u32 *)(d+8) = (w LS 8) | (x RS 24);
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w = *(u32 *)(s+15);
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*(u32 *)(d+12) = (x LS 8) | (w RS 24);
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}
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break;
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}
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if (n&16) {
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*d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
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*d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
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*d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
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*d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
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}
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if (n&8) {
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*d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
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*d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
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}
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if (n&4) {
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*d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
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}
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if (n&2) {
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*d++ = *s++; *d++ = *s++;
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}
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if (n&1) {
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*d = *s;
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}
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return dest;
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#endif
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for (; n; n--) *d++ = *s++;
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return dest;
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}
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