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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