| 0,0 → 1,110 |
|---|
| /* |
| FUNCTION |
| <<memcpy>>---copy memory regions |
| |
| ANSI_SYNOPSIS |
| #include <string.h> |
| void* memcpy(void *<[out]>, const void *<[in]>, size_t <[n]>); |
| |
| TRAD_SYNOPSIS |
| #include <string.h> |
| void *memcpy(<[out]>, <[in]>, <[n]> |
| void *<[out]>; |
| void *<[in]>; |
| size_t <[n]>; |
| |
| DESCRIPTION |
| This function copies <[n]> bytes from the memory region |
| pointed to by <[in]> to the memory region pointed to by |
| <[out]>. |
| |
| If the regions overlap, the behavior is undefined. |
| |
| RETURNS |
| <<memcpy>> returns a pointer to the first byte of the <[out]> |
| region. |
| |
| PORTABILITY |
| <<memcpy>> is ANSI C. |
| |
| <<memcpy>> requires no supporting OS subroutines. |
| |
| QUICKREF |
| memcpy ansi pure |
| */ |
| |
| #include <_ansi.h> |
| #include <string.h> |
| |
| /* Nonzero if either X or Y is not aligned on a "long" boundary. */ |
| #define UNALIGNED(X, Y) \ |
| (((long)X & (sizeof (long) - 1)) | ((long)Y & (sizeof (long) - 1))) |
| |
| /* How many bytes are copied each iteration of the 4X unrolled loop. */ |
| #define BIGBLOCKSIZE (sizeof (long) << 2) |
| |
| /* How many bytes are copied each iteration of the word copy loop. */ |
| #define LITTLEBLOCKSIZE (sizeof (long)) |
| |
| /* Threshhold for punting to the byte copier. */ |
| #define TOO_SMALL(LEN) ((LEN) < BIGBLOCKSIZE) |
| |
| _PTR |
| _DEFUN (memcpy, (dst0, src0, len0), |
| _PTR dst0 _AND |
| _CONST _PTR src0 _AND |
| size_t len0) |
| { |
| #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__) |
| char *dst = (char *) dst0; |
| char *src = (char *) src0; |
| |
| _PTR save = dst0; |
| |
| while (len0--) |
| { |
| *dst++ = *src++; |
| } |
| |
| return save; |
| #else |
| char *dst = dst0; |
| _CONST char *src = src0; |
| long *aligned_dst; |
| _CONST long *aligned_src; |
| |
| /* If the size is small, or either SRC or DST is unaligned, |
| then punt into the byte copy loop. This should be rare. */ |
| if (!TOO_SMALL(len0) && !UNALIGNED (src, dst)) |
| { |
| aligned_dst = (long*)dst; |
| aligned_src = (long*)src; |
| |
| /* Copy 4X long words at a time if possible. */ |
| while (len0 >= BIGBLOCKSIZE) |
| { |
| *aligned_dst++ = *aligned_src++; |
| *aligned_dst++ = *aligned_src++; |
| *aligned_dst++ = *aligned_src++; |
| *aligned_dst++ = *aligned_src++; |
| len0 -= BIGBLOCKSIZE; |
| } |
| |
| /* Copy one long word at a time if possible. */ |
| while (len0 >= LITTLEBLOCKSIZE) |
| { |
| *aligned_dst++ = *aligned_src++; |
| len0 -= LITTLEBLOCKSIZE; |
| } |
| |
| /* Pick up any residual with a byte copier. */ |
| dst = (char*)aligned_dst; |
| src = (char*)aligned_src; |
| } |
| |
| while (len0--) |
| *dst++ = *src++; |
| |
| return dst0; |
| #endif /* not PREFER_SIZE_OVER_SPEED */ |
| } |