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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.18.0/] [newlib/] [libc/] [string/] [memmove.c] - Rev 307
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/* FUNCTION <<memmove>>---move possibly overlapping memory INDEX memmove ANSI_SYNOPSIS #include <string.h> void *memmove(void *<[dst]>, const void *<[src]>, size_t <[length]>); TRAD_SYNOPSIS #include <string.h> void *memmove(<[dst]>, <[src]>, <[length]>) void *<[dst]>; void *<[src]>; size_t <[length]>; DESCRIPTION This function moves <[length]> characters from the block of memory starting at <<*<[src]>>> to the memory starting at <<*<[dst]>>>. <<memmove>> reproduces the characters correctly at <<*<[dst]>>> even if the two areas overlap. RETURNS The function returns <[dst]> as passed. PORTABILITY <<memmove>> is ANSI C. <<memmove>> requires no supporting OS subroutines. QUICKREF memmove ansi pure */ #include <string.h> #include <_ansi.h> #include <stddef.h> #include <limits.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) /*SUPPRESS 20*/ _PTR _DEFUN (memmove, (dst_void, src_void, length), _PTR dst_void _AND _CONST _PTR src_void _AND size_t length) { #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__) char *dst = dst_void; _CONST char *src = src_void; if (src < dst && dst < src + length) { /* Have to copy backwards */ src += length; dst += length; while (length--) { *--dst = *--src; } } else { while (length--) { *dst++ = *src++; } } return dst_void; #else char *dst = dst_void; _CONST char *src = src_void; long *aligned_dst; _CONST long *aligned_src; int len = length; if (src < dst && dst < src + len) { /* Destructive overlap...have to copy backwards */ src += len; dst += len; while (len--) { *--dst = *--src; } } else { /* Use optimizing algorithm for a non-destructive copy to closely match memcpy. 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_void; #endif /* not PREFER_SIZE_OVER_SPEED */ }
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