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1 //=========================================================================== |
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2 // |
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3 // memcmp.cxx |
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4 // |
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5 // ANSI standard memcmp() routine |
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6 // |
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7 //=========================================================================== |
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8 //####COPYRIGHTBEGIN#### |
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9 // |
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10 // ------------------------------------------- |
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11 // The contents of this file are subject to the Cygnus eCos Public License |
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12 // Version 1.0 (the "License"); you may not use this file except in |
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13 // compliance with the License. You may obtain a copy of the License at |
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14 // http://sourceware.cygnus.com/ecos |
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15 // |
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16 // Software distributed under the License is distributed on an "AS IS" |
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17 // basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See the |
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18 // License for the specific language governing rights and limitations under |
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19 // the License. |
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20 // |
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21 // The Original Code is eCos - Embedded Cygnus Operating System, released |
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22 // September 30, 1998. |
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23 // |
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24 // The Initial Developer of the Original Code is Cygnus. Portions created |
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25 // by Cygnus are Copyright (C) 1998,1999 Cygnus Solutions. All Rights Reserved. |
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26 // ------------------------------------------- |
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27 // |
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28 //####COPYRIGHTEND#### |
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29 //=========================================================================== |
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30 //#####DESCRIPTIONBEGIN#### |
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31 // |
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32 // Author(s): jlarmour |
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33 // Contributors: jlarmour |
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34 // Date: 1998-02-13 |
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35 // Purpose: |
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36 // Description: |
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37 // Usage: |
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38 // |
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39 //####DESCRIPTIONEND#### |
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40 // |
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41 //=========================================================================== |
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42 |
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43 // CONFIGURATION |
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44 |
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45 #include <pkgconf/libc.h> // Configuration header |
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46 |
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47 // Include the C library? |
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48 #ifdef CYGPKG_LIBC |
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49 |
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50 // INCLUDES |
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51 |
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52 #include <cyg/infra/cyg_type.h> // Common type definitions |
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53 #include <cyg/infra/cyg_trac.h> // Tracing support |
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54 #include <cyg/infra/cyg_ass.h> // Assertion support |
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55 #include <string.h> // Header for this file |
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56 #include <stddef.h> // Compiler definitions such as size_t, NULL etc. |
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57 #include "clibincl/stringsupp.hxx" // Useful string function support and |
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58 // prototypes |
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59 |
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60 |
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61 // EXPORTED SYMBOLS |
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62 |
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63 externC int |
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64 memcmp( const void *s1, const void *s2, size_t n ) \ |
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65 CYGPRI_LIBC_WEAK_ALIAS("_memcmp"); |
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66 |
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67 // FUNCTIONS |
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68 |
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69 int |
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70 _memcmp( const void *s1, const void *s2, size_t n ) |
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71 { |
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72 int retval; |
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73 |
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74 CYG_REPORT_FUNCNAMETYPE( "_memcmp", "returning %d" ); |
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75 CYG_REPORT_FUNCARG3( "s1=%08x, s2=%08x, n=%d", s1, s2, n ); |
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76 |
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77 CYG_CHECK_DATA_PTR( s1, "s1 is not a valid pointer!" ); |
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78 CYG_CHECK_DATA_PTR( s2, "s2 is not a valid pointer!" ); |
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79 |
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80 #if defined(CYGIMP_LIBC_STRING_PREFER_SMALL_TO_FAST) || defined(__OPTIMIZE_SIZE__) |
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81 const unsigned char *m1 = (const unsigned char *) s1; |
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82 const unsigned char *m2 = (const unsigned char *) s2; |
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83 |
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84 while (n--) |
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85 { |
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86 if (*m1 != *m2) |
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87 { |
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88 retval = *m1 - *m2; |
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89 CYG_REPORT_RETVAL( retval ); |
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90 return retval; |
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91 } |
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92 m1++; |
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93 m2++; |
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94 } |
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95 CYG_REPORT_RETVAL( 0 ); |
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96 return 0; |
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97 #else |
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98 const unsigned char *m1 = (const unsigned char *) s1; |
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99 const unsigned char *m2 = (const unsigned char *) s2; |
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100 const CYG_WORD *aligned_m1; |
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101 const CYG_WORD *aligned_m2; |
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102 |
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103 // If the size is too small, or either pointer is unaligned, |
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104 // then we punt to the byte compare loop. Hopefully this will |
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105 // not turn up in inner loops. |
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106 if (CYG_LIBC_STR_OPT_TOO_SMALL(n) || CYG_LIBC_STR_UNALIGNED2(m1,m2)) |
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107 { |
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108 while (n--) |
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109 { |
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110 if (*m1 != *m2) |
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111 { |
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112 retval = *m1 - *m2; |
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113 CYG_REPORT_RETVAL( retval ); |
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114 return retval; |
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115 } |
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116 m1++; |
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117 m2++; |
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118 } |
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119 CYG_REPORT_RETVAL( 0 ); |
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120 return 0; |
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121 } |
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122 |
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123 // Otherwise, load and compare the blocks of memory one |
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124 // word at a time. |
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125 aligned_m1 = (const CYG_WORD *) m1; |
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126 aligned_m2 = (const CYG_WORD *) m2; |
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127 while (n > CYG_LIBC_STR_OPT_LITTLEBLOCKSIZE) |
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128 { |
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129 if (*aligned_m1 != *aligned_m2) |
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130 { |
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131 // This block of characters has a mismatch, somewhere. |
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132 // xoring them together and then testing for null would |
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133 // be fastest, but this is clearer code. |
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134 m1 = (const unsigned char *)aligned_m1; |
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135 m2 = (const unsigned char *)aligned_m2; |
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136 while (n--) |
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137 { |
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138 if (*m1 != *m2) |
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139 { |
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140 retval = *m1 - *m2; |
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141 CYG_REPORT_RETVAL( retval ); |
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142 return retval; |
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143 } |
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144 m1++; |
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145 m2++; |
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146 } |
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147 // NOT REACHED |
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148 } |
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149 aligned_m1++; |
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150 aligned_m2++; |
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151 n -= CYG_LIBC_STR_OPT_LITTLEBLOCKSIZE; |
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152 } |
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153 |
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154 // checking the last few characters |
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155 |
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156 m1 = (const unsigned char *)aligned_m1; |
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157 m2 = (const unsigned char *)aligned_m2; |
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158 |
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159 while (n--) |
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160 { |
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161 if (*m1 != *m2) |
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162 { |
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163 retval = *m1 - *m2; |
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164 CYG_REPORT_RETVAL( retval ); |
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165 return retval; |
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166 } |
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167 m1++; |
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168 m2++; |
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169 } |
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170 |
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171 CYG_REPORT_RETVAL( 0 ); |
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172 return 0; |
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173 #endif // not defined(CYGIMP_LIBC_STRING_PREFER_SMALL_TO_FAST) || |
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174 // defined(__OPTIMIZE_SIZE__) |
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175 } // _memcmp() |
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176 |
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177 #endif // CYGPKG_LIBC |
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178 |
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179 // EOF memcmp.cxx |
