| | 1 | /*- |
| | 2 | * Copyright (c) 1990, 1993 |
| | 3 | * The Regents of the University of California. All rights reserved. |
| | 4 | * |
| | 5 | * This code is derived from software contributed to Berkeley by |
| | 6 | * Chris Torek. |
| | 7 | * |
| | 8 | * Redistribution and use in source and binary forms, with or without |
| | 9 | * modification, are permitted provided that the following conditions |
| | 10 | * are met: |
| | 11 | * 1. Redistributions of source code must retain the above copyright |
| | 12 | * notice, this list of conditions and the following disclaimer. |
| | 13 | * 2. Redistributions in binary form must reproduce the above copyright |
| | 14 | * notice, this list of conditions and the following disclaimer in the |
| | 15 | * documentation and/or other materials provided with the distribution. |
| | 16 | * 4. Neither the name of the University nor the names of its contributors |
| | 17 | * may be used to endorse or promote products derived from this software |
| | 18 | * without specific prior written permission. |
| | 19 | * |
| | 20 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| | 21 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| | 22 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| | 23 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| | 24 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| | 25 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| | 26 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| | 27 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| | 28 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| | 29 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| | 30 | * SUCH DAMAGE. |
| | 31 | */ |
| | 32 | |
| | 33 | #include "string.h" |
| | 34 | |
| | 35 | /* |
| | 36 | * sizeof(word) MUST BE A POWER OF TWO |
| | 37 | * SO THAT wmask BELOW IS ALL ONES |
| | 38 | */ |
| | 39 | typedef int word; /* "word" used for optimal copy speed */ |
| | 40 | |
| | 41 | #define wsize sizeof(word) |
| | 42 | #define wmask (wsize - 1) |
| | 43 | |
| | 44 | /* |
| | 45 | * Copy a block of memory, handling overlap. |
| | 46 | * This is the routine that actually implements |
| | 47 | * (the portable versions of) bcopy, memcpy, and memmove. |
| | 48 | */ |
| | 49 | |
| | 50 | __attribute__((visibility("hidden"))) |
| | 51 | void * |
| | 52 | _libkernel_memmove(void *dst0, const void *src0, size_t length) |
| | 53 | { |
| | 54 | char *dst = dst0; |
| | 55 | const char *src = src0; |
| | 56 | size_t t; |
| | 57 | |
| | 58 | if (length == 0 || dst == src) { /* nothing to do */ |
| | 59 | goto done; |
| | 60 | } |
| | 61 | |
| | 62 | /* |
| | 63 | * Macros: loop-t-times; and loop-t-times, t>0 |
| | 64 | */ |
| | 65 | #define TLOOP(s) if (t) TLOOP1(s) |
| | 66 | #define TLOOP1(s) do { s; } while (--t) |
| | 67 | |
| | 68 | if ((unsigned long)dst < (unsigned long)src) { |
| | 69 | /* |
| | 70 | * Copy forward. |
| | 71 | */ |
| | 72 | t = (uintptr_t)src; /* only need low bits */ |
| | 73 | if ((t | (uintptr_t)dst) & wmask) { |
| | 74 | /* |
| | 75 | * Try to align operands. This cannot be done |
| | 76 | * unless the low bits match. |
| | 77 | */ |
| | 78 | if ((t ^ (uintptr_t)dst) & wmask || length < wsize) { |
| | 79 | t = length; |
| | 80 | } else { |
| | 81 | t = wsize - (t & wmask); |
| | 82 | } |
| | 83 | length -= t; |
| | 84 | TLOOP1(*dst++ = *src++); |
| | 85 | } |
| | 86 | /* |
| | 87 | * Copy whole words, then mop up any trailing bytes. |
| | 88 | */ |
| | 89 | t = length / wsize; |
| | 90 | TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize); |
| | 91 | t = length & wmask; |
| | 92 | TLOOP(*dst++ = *src++); |
| | 93 | } else { |
| | 94 | /* |
| | 95 | * Copy backwards. Otherwise essentially the same. |
| | 96 | * Alignment works as before, except that it takes |
| | 97 | * (t&wmask) bytes to align, not wsize-(t&wmask). |
| | 98 | */ |
| | 99 | src += length; |
| | 100 | dst += length; |
| | 101 | t = (uintptr_t)src; |
| | 102 | if ((t | (uintptr_t)dst) & wmask) { |
| | 103 | if ((t ^ (uintptr_t)dst) & wmask || length <= wsize) { |
| | 104 | t = length; |
| | 105 | } else { |
| | 106 | t &= wmask; |
| | 107 | } |
| | 108 | length -= t; |
| | 109 | TLOOP1(*--dst = *--src); |
| | 110 | } |
| | 111 | t = length / wsize; |
| | 112 | TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src); |
| | 113 | t = length & wmask; |
| | 114 | TLOOP(*--dst = *--src); |
| | 115 | } |
| | 116 | done: |
| | 117 | return dst0; |
| | 118 | } |
| | 119 | |
| | 120 | __attribute__((visibility("hidden"))) |
| | 121 | void |
| | 122 | bcopy(const void *s1, void *s2, size_t n) |
| | 123 | { |
| | 124 | memcpy(s2, s1, n); |
| | 125 | } |
projects / apple / xnu.git / blame_incremental