Details | Last modification | View Log | RSS feed
| Rev | Author | Line No. | Line |
|---|---|---|---|
| 6557 | serge | 1 | /* |
| 2 | FUNCTION |
||
| 3 | < |
||
| 4 | |||
| 5 | ANSI_SYNOPSIS |
||
| 6 | #include |
||
| 7 | void* mempcpy(void *<[out]>, const void *<[in]>, size_t <[n]>); |
||
| 8 | |||
| 9 | TRAD_SYNOPSIS |
||
| 10 | void *mempcpy(<[out]>, <[in]>, <[n]> |
||
| 11 | void *<[out]>; |
||
| 12 | void *<[in]>; |
||
| 13 | size_t <[n]>; |
||
| 14 | |||
| 15 | DESCRIPTION |
||
| 16 | This function copies <[n]> bytes from the memory region |
||
| 17 | pointed to by <[in]> to the memory region pointed to by |
||
| 18 | <[out]>. |
||
| 19 | |||
| 20 | If the regions overlap, the behavior is undefined. |
||
| 21 | |||
| 22 | RETURNS |
||
| 23 | < |
||
| 24 | last byte copied to the <[out]> region. |
||
| 25 | |||
| 26 | PORTABILITY |
||
| 27 | < |
||
| 28 | |||
| 29 | < |
||
| 30 | |||
| 31 | */ |
||
| 32 | |||
| 33 | #include <_ansi.h> |
||
| 34 | #include |
||
| 35 | #include |
||
| 36 | #include |
||
| 37 | |||
| 38 | /* Nonzero if either X or Y is not aligned on a "long" boundary. */ |
||
| 39 | #define UNALIGNED(X, Y) \ |
||
| 40 | (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1))) |
||
| 41 | |||
| 42 | /* How many bytes are copied each iteration of the 4X unrolled loop. */ |
||
| 43 | #define BIGBLOCKSIZE (sizeof (long) << 2) |
||
| 44 | |||
| 45 | /* How many bytes are copied each iteration of the word copy loop. */ |
||
| 46 | #define LITTLEBLOCKSIZE (sizeof (long)) |
||
| 47 | |||
| 48 | /* Threshhold for punting to the byte copier. */ |
||
| 49 | #define TOO_SMALL(LEN) ((LEN) < BIGBLOCKSIZE) |
||
| 50 | |||
| 51 | _PTR |
||
| 52 | _DEFUN (mempcpy, (dst0, src0, len0), |
||
| 53 | _PTR dst0 _AND |
||
| 54 | _CONST _PTR src0 _AND |
||
| 55 | size_t len0) |
||
| 56 | { |
||
| 57 | #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__) |
||
| 58 | char *dst = (char *) dst0; |
||
| 59 | char *src = (char *) src0; |
||
| 60 | |||
| 61 | while (len0--) |
||
| 62 | { |
||
| 63 | *dst++ = *src++; |
||
| 64 | } |
||
| 65 | |||
| 66 | return dst; |
||
| 67 | #else |
||
| 68 | char *dst = dst0; |
||
| 69 | _CONST char *src = src0; |
||
| 70 | long *aligned_dst; |
||
| 71 | _CONST long *aligned_src; |
||
| 72 | |||
| 73 | /* If the size is small, or either SRC or DST is unaligned, |
||
| 74 | then punt into the byte copy loop. This should be rare. */ |
||
| 75 | if (!TOO_SMALL(len0) && !UNALIGNED (src, dst)) |
||
| 76 | { |
||
| 77 | aligned_dst = (long*)dst; |
||
| 78 | aligned_src = (long*)src; |
||
| 79 | |||
| 80 | /* Copy 4X long words at a time if possible. */ |
||
| 81 | while (len0 >= BIGBLOCKSIZE) |
||
| 82 | { |
||
| 83 | *aligned_dst++ = *aligned_src++; |
||
| 84 | *aligned_dst++ = *aligned_src++; |
||
| 85 | *aligned_dst++ = *aligned_src++; |
||
| 86 | *aligned_dst++ = *aligned_src++; |
||
| 87 | len0 -= BIGBLOCKSIZE; |
||
| 88 | } |
||
| 89 | |||
| 90 | /* Copy one long word at a time if possible. */ |
||
| 91 | while (len0 >= LITTLEBLOCKSIZE) |
||
| 92 | { |
||
| 93 | *aligned_dst++ = *aligned_src++; |
||
| 94 | len0 -= LITTLEBLOCKSIZE; |
||
| 95 | } |
||
| 96 | |||
| 97 | /* Pick up any residual with a byte copier. */ |
||
| 98 | dst = (char*)aligned_dst; |
||
| 99 | src = (char*)aligned_src; |
||
| 100 | } |
||
| 101 | |||
| 102 | while (len0--) |
||
| 103 | *dst++ = *src++; |
||
| 104 | |||
| 105 | return dst; |
||
| 106 | #endif /* not PREFER_SIZE_OVER_SPEED */ |
||
| 107 | } |