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4921 | Serge | 1 | /* |
2 | FUNCTION |
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3 | < |
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4 | |||
5 | ANSI_SYNOPSIS |
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6 | #include |
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7 | void* memcpy(void *restrict <[out]>, const void *restrict <[in]>, |
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8 | size_t <[n]>); |
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9 | |||
10 | TRAD_SYNOPSIS |
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11 | #include |
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12 | void *memcpy(<[out]>, <[in]>, <[n]> |
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13 | void *<[out]>; |
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14 | void *<[in]>; |
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15 | size_t <[n]>; |
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16 | |||
17 | DESCRIPTION |
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18 | This function copies <[n]> bytes from the memory region |
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19 | pointed to by <[in]> to the memory region pointed to by |
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20 | <[out]>. |
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21 | |||
22 | If the regions overlap, the behavior is undefined. |
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23 | |||
24 | RETURNS |
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25 | < |
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26 | region. |
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27 | |||
28 | PORTABILITY |
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29 | < |
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30 | |||
31 | < |
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32 | |||
33 | QUICKREF |
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34 | memcpy ansi pure |
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35 | */ |
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36 | |||
37 | #include <_ansi.h> |
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38 | #include |
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39 | |||
40 | /* Nonzero if either X or Y is not aligned on a "long" boundary. */ |
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41 | #define UNALIGNED(X, Y) \ |
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42 | (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1))) |
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43 | |||
44 | /* How many bytes are copied each iteration of the 4X unrolled loop. */ |
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45 | #define BIGBLOCKSIZE (sizeof (long) << 2) |
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46 | |||
47 | /* How many bytes are copied each iteration of the word copy loop. */ |
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48 | #define LITTLEBLOCKSIZE (sizeof (long)) |
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49 | |||
50 | /* Threshhold for punting to the byte copier. */ |
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51 | #define TOO_SMALL(LEN) ((LEN) < BIGBLOCKSIZE) |
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52 | |||
53 | _PTR |
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54 | _DEFUN (memcpy, (dst0, src0, len0), |
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55 | _PTR __restrict dst0 _AND |
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56 | _CONST _PTR __restrict src0 _AND |
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57 | size_t len0) |
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58 | { |
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59 | #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__) |
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60 | char *dst = (char *) dst0; |
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61 | char *src = (char *) src0; |
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62 | |||
63 | _PTR save = dst0; |
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64 | |||
65 | while (len0--) |
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66 | { |
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67 | *dst++ = *src++; |
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68 | } |
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69 | |||
70 | return save; |
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71 | #else |
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72 | char *dst = dst0; |
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73 | _CONST char *src = src0; |
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74 | long *aligned_dst; |
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75 | _CONST long *aligned_src; |
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76 | |||
77 | /* If the size is small, or either SRC or DST is unaligned, |
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78 | then punt into the byte copy loop. This should be rare. */ |
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79 | if (!TOO_SMALL(len0) && !UNALIGNED (src, dst)) |
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80 | { |
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81 | aligned_dst = (long*)dst; |
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82 | aligned_src = (long*)src; |
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83 | |||
84 | /* Copy 4X long words at a time if possible. */ |
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85 | while (len0 >= BIGBLOCKSIZE) |
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86 | { |
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87 | *aligned_dst++ = *aligned_src++; |
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88 | *aligned_dst++ = *aligned_src++; |
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89 | *aligned_dst++ = *aligned_src++; |
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90 | *aligned_dst++ = *aligned_src++; |
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91 | len0 -= BIGBLOCKSIZE; |
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92 | } |
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93 | |||
94 | /* Copy one long word at a time if possible. */ |
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95 | while (len0 >= LITTLEBLOCKSIZE) |
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96 | { |
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97 | *aligned_dst++ = *aligned_src++; |
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98 | len0 -= LITTLEBLOCKSIZE; |
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99 | } |
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100 | |||
101 | /* Pick up any residual with a byte copier. */ |
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102 | dst = (char*)aligned_dst; |
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103 | src = (char*)aligned_src; |
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104 | } |
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105 | |||
106 | while (len0--) |
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107 | *dst++ = *src++; |
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108 | |||
109 | return dst0; |
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110 | #endif /* not PREFER_SIZE_OVER_SPEED */ |
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111 | }>><> |