| Elliott Hughes | 76f8916 | 2015-01-26 13:34:58 -0800 | [diff] [blame] | 1 | /* $OpenBSD: memcpy.c,v 1.1 2014/11/30 19:43:56 deraadt Exp $ */ |
| 2 | /*- |
| 3 | * Copyright (c) 1990 The Regents of the University of California. |
| 4 | * All rights reserved. |
| 5 | * |
| 6 | * This code is derived from software contributed to Berkeley by |
| 7 | * Chris Torek. |
| 8 | * |
| 9 | * Redistribution and use in source and binary forms, with or without |
| 10 | * modification, are permitted provided that the following conditions |
| 11 | * are met: |
| 12 | * 1. Redistributions of source code must retain the above copyright |
| 13 | * notice, this list of conditions and the following disclaimer. |
| 14 | * 2. Redistributions in binary form must reproduce the above copyright |
| 15 | * notice, this list of conditions and the following disclaimer in the |
| 16 | * documentation and/or other materials provided with the distribution. |
| 17 | * 3. Neither the name of the University nor the names of its contributors |
| 18 | * may be used to endorse or promote products derived from this software |
| 19 | * without specific prior written permission. |
| 20 | * |
| 21 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| 22 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 23 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| 24 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| 25 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| 26 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| 27 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| 28 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| 29 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| 30 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| 31 | * SUCH DAMAGE. |
| 32 | */ |
| 33 | |
| 34 | #include <string.h> |
| 35 | #include <stdlib.h> |
| 36 | #include <syslog.h> |
| 37 | |
| 38 | /* |
| 39 | * sizeof(word) MUST BE A POWER OF TWO |
| 40 | * SO THAT wmask BELOW IS ALL ONES |
| 41 | */ |
| 42 | typedef long word; /* "word" used for optimal copy speed */ |
| 43 | |
| 44 | #define wsize sizeof(word) |
| 45 | #define wmask (wsize - 1) |
| 46 | |
| 47 | /* |
| 48 | * Copy a block of memory, not handling overlap. |
| 49 | */ |
| 50 | void * |
| 51 | memcpy(void *dst0, const void *src0, size_t length) |
| 52 | { |
| 53 | char *dst = dst0; |
| 54 | const char *src = src0; |
| 55 | size_t t; |
| 56 | |
| 57 | if (length == 0 || dst == src) /* nothing to do */ |
| 58 | goto done; |
| 59 | |
| Elliott Hughes | 76f8916 | 2015-01-26 13:34:58 -0800 | [diff] [blame] | 60 | /* |
| 61 | * Macros: loop-t-times; and loop-t-times, t>0 |
| 62 | */ |
| 63 | #define TLOOP(s) if (t) TLOOP1(s) |
| 64 | #define TLOOP1(s) do { s; } while (--t) |
| 65 | |
| 66 | /* |
| 67 | * Copy forward. |
| 68 | */ |
| 69 | t = (long)src; /* only need low bits */ |
| 70 | if ((t | (long)dst) & wmask) { |
| 71 | /* |
| 72 | * Try to align operands. This cannot be done |
| 73 | * unless the low bits match. |
| 74 | */ |
| 75 | if ((t ^ (long)dst) & wmask || length < wsize) |
| 76 | t = length; |
| 77 | else |
| 78 | t = wsize - (t & wmask); |
| 79 | length -= t; |
| 80 | TLOOP1(*dst++ = *src++); |
| 81 | } |
| 82 | /* |
| 83 | * Copy whole words, then mop up any trailing bytes. |
| 84 | */ |
| 85 | t = length / wsize; |
| 86 | TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize); |
| 87 | t = length & wmask; |
| 88 | TLOOP(*dst++ = *src++); |
| 89 | done: |
| 90 | return (dst0); |
| 91 | } |