1 | /*- |
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2 | * Copyright (c) 1990, 1993 |
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3 | * The Regents of the University of California. All rights reserved. |
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4 | * |
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5 | * This code is derived from software contributed to Berkeley by |
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6 | * Chris Torek. |
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7 | * |
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8 | * Redistribution and use in source and binary forms, with or without |
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9 | * modification, are permitted provided that the following conditions |
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10 | * are met: |
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11 | * 1. Redistributions of source code must retain the above copyright |
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12 | * notice, this list of conditions and the following disclaimer. |
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13 | * 2. Redistributions in binary form must reproduce the above copyright |
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14 | * notice, this list of conditions and the following disclaimer in the |
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15 | * documentation and/or other materials provided with the distribution. |
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16 | * 3. Neither the name of the University nor the names of its contributors |
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17 | * may be used to endorse or promote products derived from this software |
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18 | * without specific prior written permission. |
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19 | * |
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20 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
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21 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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22 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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23 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
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24 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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25 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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26 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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27 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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28 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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29 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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30 | * SUCH DAMAGE. |
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31 | */ |
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32 | |
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33 | #if defined(LIBC_SCCS) && !defined(lint) |
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34 | static char sccsid[] = "@(#)bcopy.c 8.1 (Berkeley) 6/4/93"; |
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35 | #endif /* LIBC_SCCS and not lint */ |
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36 | #include <sys/cdefs.h> |
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37 | __FBSDID("$FreeBSD$"); |
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38 | |
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39 | #include <sys/types.h> |
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40 | |
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41 | /* |
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42 | * sizeof(word) MUST BE A POWER OF TWO |
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43 | * SO THAT wmask BELOW IS ALL ONES |
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44 | */ |
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45 | typedef int word; /* "word" used for optimal copy speed */ |
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46 | |
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47 | #define wsize sizeof(word) |
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48 | #define wmask (wsize - 1) |
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49 | |
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50 | /* |
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51 | * Copy a block of memory, handling overlap. |
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52 | * This is the routine that actually implements |
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53 | * (the portable versions of) bcopy, memcpy, and memmove. |
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54 | */ |
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55 | #if defined(MEMCOPY) || defined(MEMMOVE) |
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56 | #include <string.h> |
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57 | |
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58 | void * |
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59 | #ifdef MEMCOPY |
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60 | memcpy |
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61 | #else |
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62 | memmove |
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63 | #endif |
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64 | (void *dst0, const void *src0, size_t length) |
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65 | #else |
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66 | #include <strings.h> |
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67 | |
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68 | void |
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69 | bcopy(const void *src0, void *dst0, size_t length) |
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70 | #endif |
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71 | { |
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72 | char *dst = dst0; |
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73 | const char *src = src0; |
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74 | size_t t; |
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75 | |
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76 | if(length == 0 || dst == src) { /* nothing to do */ |
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77 | goto done; |
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78 | } |
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79 | |
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80 | /* |
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81 | * Macros: loop-t-times; and loop-t-times, t>0 |
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82 | */ |
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83 | #define TLOOP(s) if (t) TLOOP1(s) |
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84 | #define TLOOP1(s) do { s; } while (--t) |
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85 | |
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86 | if((unsigned long)dst < (unsigned long)src) { |
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87 | /* |
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88 | * Copy forward. |
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89 | */ |
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90 | t = (uintptr_t)src; /* only need low bits */ |
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91 | if((t | (uintptr_t)dst) & wmask) { |
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92 | /* |
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93 | * Try to align operands. This cannot be done |
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94 | * unless the low bits match. |
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95 | */ |
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96 | if((t ^ (uintptr_t)dst) & wmask || length < wsize) { |
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97 | t = length; |
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98 | } else { |
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99 | t = wsize - (t & wmask); |
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100 | } |
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101 | length -= t; |
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102 | TLOOP1(*dst++ = *src++); |
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103 | } |
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104 | /* |
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105 | * Copy whole words, then mop up any trailing bytes. |
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106 | */ |
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107 | t = length / wsize; |
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108 | TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize); |
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109 | t = length & wmask; |
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110 | TLOOP(*dst++ = *src++); |
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111 | } else { |
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112 | /* |
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113 | * Copy backwards. Otherwise essentially the same. |
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114 | * Alignment works as before, except that it takes |
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115 | * (t&wmask) bytes to align, not wsize-(t&wmask). |
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116 | */ |
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117 | src += length; |
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118 | dst += length; |
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119 | t = (uintptr_t)src; |
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120 | if((t | (uintptr_t)dst) & wmask) { |
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121 | if((t ^ (uintptr_t)dst) & wmask || length <= wsize) { |
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122 | t = length; |
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123 | } else { |
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124 | t &= wmask; |
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125 | } |
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126 | length -= t; |
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127 | TLOOP1(*--dst = *--src); |
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128 | } |
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129 | t = length / wsize; |
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130 | TLOOP(src -= wsize; dst -= wsize; *(word *)dst = *(word *)src); |
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131 | t = length & wmask; |
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132 | TLOOP(*--dst = *--src); |
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133 | } |
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134 | done: |
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135 | #if defined(MEMCOPY) || defined(MEMMOVE) |
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136 | return (dst0); |
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137 | #else |
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138 | return; |
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139 | #endif |
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140 | } |
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