| // SPDX-License-Identifier: BSD-3-Clause |
| /* |
| * Copyright (c) 1994-2009 Red Hat, Inc. |
| * All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions are met: |
| * |
| * 1. Redistributions of source code must retain the above copyright notice, |
| * this list of conditions and the following disclaimer. |
| * |
| * 2. Redistributions in binary form must reproduce the above copyright notice, |
| * this list of conditions and the following disclaimer in the documentation |
| * and/or other materials provided with the distribution. |
| * |
| * 3. Neither the name of the copyright holder nor the names of its |
| * contributors may be used to endorse or promote products derived from this |
| * software without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" |
| * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE |
| * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS |
| * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN |
| * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) |
| * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE |
| * POSSIBILITY OF SUCH DAMAGE. |
| */ |
| |
| /* |
| 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 */ |
| } |