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[/] [openrisc/] [tags/] [gnu-src/] [newlib-1.18.0/] [newlib-1.18.0-or32-1.0rc2/] [newlib/] [libc/] [string/] [mempcpy.c] - Rev 520
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/* FUNCTION <<mempcpy>>---copy memory regions and return end pointer ANSI_SYNOPSIS #include <string.h> void* mempcpy(void *<[out]>, const void *<[in]>, size_t <[n]>); TRAD_SYNOPSIS void *mempcpy(<[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 <<mempcpy>> returns a pointer to the byte following the last byte copied to the <[out]> region. PORTABILITY <<mempcpy>> is a GNU extension. <<mempcpy>> requires no supporting OS subroutines. */ #include <_ansi.h> #include <stddef.h> #include <limits.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 (mempcpy, (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; while (len0--) { *dst++ = *src++; } return dst; #else char *dst = dst0; _CONST char *src = src0; long *aligned_dst; _CONST long *aligned_src; int len = len0; /* 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(len) && !UNALIGNED (src, dst)) { aligned_dst = (long*)dst; aligned_src = (long*)src; /* Copy 4X long words at a time if possible. */ while (len >= BIGBLOCKSIZE) { *aligned_dst++ = *aligned_src++; *aligned_dst++ = *aligned_src++; *aligned_dst++ = *aligned_src++; *aligned_dst++ = *aligned_src++; len -= BIGBLOCKSIZE; } /* Copy one long word at a time if possible. */ while (len >= LITTLEBLOCKSIZE) { *aligned_dst++ = *aligned_src++; len -= LITTLEBLOCKSIZE; } /* Pick up any residual with a byte copier. */ dst = (char*)aligned_dst; src = (char*)aligned_src; } while (len--) *dst++ = *src++; return dst; #endif /* not PREFER_SIZE_OVER_SPEED */ }