[337] | 1 | #include <string.h>
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| 2 | #include <stdint.h>
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| 3 | #include <endian.h>
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| 4 |
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| 5 | void *memcpy(void *restrict dest, const void *restrict src, size_t n)
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| 6 | {
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| 7 | unsigned char *d = dest;
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| 8 | const unsigned char *s = src;
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| 9 |
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| 10 | #ifdef __GNUC__
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| 11 |
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| 12 | #if __BYTE_ORDER == __LITTLE_ENDIAN
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| 13 | #define LS >>
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| 14 | #define RS <<
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| 15 | #else
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| 16 | #define LS <<
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| 17 | #define RS >>
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| 18 | #endif
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| 19 |
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| 20 | typedef uint32_t __attribute__((__may_alias__)) u32;
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| 21 | uint32_t w, x;
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| 22 |
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| 23 | for (; (uintptr_t)s % 4 && n; n--) *d++ = *s++;
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| 24 |
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| 25 | if ((uintptr_t)d % 4 == 0) {
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| 26 | for (; n>=16; s+=16, d+=16, n-=16) {
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| 27 | *(u32 *)(d+0) = *(u32 *)(s+0);
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| 28 | *(u32 *)(d+4) = *(u32 *)(s+4);
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| 29 | *(u32 *)(d+8) = *(u32 *)(s+8);
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| 30 | *(u32 *)(d+12) = *(u32 *)(s+12);
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| 31 | }
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| 32 | if (n&8) {
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| 33 | *(u32 *)(d+0) = *(u32 *)(s+0);
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| 34 | *(u32 *)(d+4) = *(u32 *)(s+4);
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| 35 | d += 8; s += 8;
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| 36 | }
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| 37 | if (n&4) {
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| 38 | *(u32 *)(d+0) = *(u32 *)(s+0);
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| 39 | d += 4; s += 4;
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| 40 | }
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| 41 | if (n&2) {
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| 42 | *d++ = *s++; *d++ = *s++;
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| 43 | }
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| 44 | if (n&1) {
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| 45 | *d = *s;
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| 46 | }
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| 47 | return dest;
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| 48 | }
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| 49 |
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| 50 | if (n >= 32) switch ((uintptr_t)d % 4) {
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| 51 | case 1:
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| 52 | w = *(u32 *)s;
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| 53 | *d++ = *s++;
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| 54 | *d++ = *s++;
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| 55 | *d++ = *s++;
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| 56 | n -= 3;
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| 57 | for (; n>=17; s+=16, d+=16, n-=16) {
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| 58 | x = *(u32 *)(s+1);
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| 59 | *(u32 *)(d+0) = (w LS 24) | (x RS 8);
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| 60 | w = *(u32 *)(s+5);
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| 61 | *(u32 *)(d+4) = (x LS 24) | (w RS 8);
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| 62 | x = *(u32 *)(s+9);
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| 63 | *(u32 *)(d+8) = (w LS 24) | (x RS 8);
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| 64 | w = *(u32 *)(s+13);
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| 65 | *(u32 *)(d+12) = (x LS 24) | (w RS 8);
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| 66 | }
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| 67 | break;
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| 68 | case 2:
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| 69 | w = *(u32 *)s;
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| 70 | *d++ = *s++;
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| 71 | *d++ = *s++;
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| 72 | n -= 2;
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| 73 | for (; n>=18; s+=16, d+=16, n-=16) {
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| 74 | x = *(u32 *)(s+2);
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| 75 | *(u32 *)(d+0) = (w LS 16) | (x RS 16);
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| 76 | w = *(u32 *)(s+6);
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| 77 | *(u32 *)(d+4) = (x LS 16) | (w RS 16);
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| 78 | x = *(u32 *)(s+10);
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| 79 | *(u32 *)(d+8) = (w LS 16) | (x RS 16);
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| 80 | w = *(u32 *)(s+14);
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| 81 | *(u32 *)(d+12) = (x LS 16) | (w RS 16);
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| 82 | }
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| 83 | break;
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| 84 | case 3:
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| 85 | w = *(u32 *)s;
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| 86 | *d++ = *s++;
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| 87 | n -= 1;
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| 88 | for (; n>=19; s+=16, d+=16, n-=16) {
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| 89 | x = *(u32 *)(s+3);
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| 90 | *(u32 *)(d+0) = (w LS 8) | (x RS 24);
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| 91 | w = *(u32 *)(s+7);
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| 92 | *(u32 *)(d+4) = (x LS 8) | (w RS 24);
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| 93 | x = *(u32 *)(s+11);
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| 94 | *(u32 *)(d+8) = (w LS 8) | (x RS 24);
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| 95 | w = *(u32 *)(s+15);
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| 96 | *(u32 *)(d+12) = (x LS 8) | (w RS 24);
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| 97 | }
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| 98 | break;
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| 99 | }
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| 100 | if (n&16) {
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| 101 | *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
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| 102 | *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
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| 103 | *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
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| 104 | *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
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| 105 | }
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| 106 | if (n&8) {
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| 107 | *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
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| 108 | *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
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| 109 | }
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| 110 | if (n&4) {
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| 111 | *d++ = *s++; *d++ = *s++; *d++ = *s++; *d++ = *s++;
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| 112 | }
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| 113 | if (n&2) {
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| 114 | *d++ = *s++; *d++ = *s++;
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| 115 | }
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| 116 | if (n&1) {
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| 117 | *d = *s;
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| 118 | }
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| 119 | return dest;
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| 120 | #endif
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| 121 |
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| 122 | for (; n; n--) *d++ = *s++;
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| 123 | return dest;
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| 124 | }
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