1 | /******************************************************************************* |
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2 | * |
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3 | * Copyright (c) 1993 Intel Corporation |
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4 | * |
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5 | * Intel hereby grants you permission to copy, modify, and distribute this |
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6 | * software and its documentation. Intel grants this permission provided |
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7 | * that the above copyright notice appears in all copies and that both the |
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8 | * copyright notice and this permission notice appear in supporting |
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9 | * documentation. In addition, Intel grants this permission provided that |
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10 | * you prominently mark as "not part of the original" any modifications |
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11 | * made to this software or documentation, and that the name of Intel |
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12 | * Corporation not be used in advertising or publicity pertaining to |
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13 | * distribution of the software or the documentation without specific, |
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14 | * written prior permission. |
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15 | * |
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16 | * Intel Corporation provides this AS IS, WITHOUT ANY WARRANTY, EXPRESS OR |
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17 | * IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY |
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18 | * OR FITNESS FOR A PARTICULAR PURPOSE. Intel makes no guarantee or |
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19 | * representations regarding the use of, or the results of the use of, |
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20 | * the software and documentation in terms of correctness, accuracy, |
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21 | * reliability, currentness, or otherwise; and you rely on the software, |
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22 | * documentation and results solely at your own risk. |
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23 | * |
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24 | * IN NO EVENT SHALL INTEL BE LIABLE FOR ANY LOSS OF USE, LOSS OF BUSINESS, |
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25 | * LOSS OF PROFITS, INDIRECT, INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES |
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26 | * OF ANY KIND. IN NO EVENT SHALL INTEL'S TOTAL LIABILITY EXCEED THE SUM |
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27 | * PAID TO INTEL FOR THE PRODUCT LICENSED HEREUNDER. |
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28 | * |
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29 | ******************************************************************************/ |
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30 | |
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31 | .file "strcpy.s" |
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32 | #ifdef __PIC |
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33 | .pic |
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34 | #endif |
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35 | #ifdef __PID |
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36 | .pid |
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37 | #endif |
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38 | /* |
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39 | * (c) copyright 1988,1993 Intel Corp., all rights reserved |
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40 | */ |
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41 | /* |
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42 | procedure strcpy (optimized assembler version for the 80960K series) |
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43 | procedure strcat (optimized assembler version for the 80960K series) |
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44 | |
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45 | dest_addr = strcpy (dest_addr, src_addr) |
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46 | |
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47 | copy the null terminated string pointed to by src_addr to |
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48 | the string space pointed to by dest_addr. Return the original |
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49 | dest_addr. |
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50 | |
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51 | This routine will fail if the source and destination string |
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52 | overlap (in particular, if the end of the source is overlapped |
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53 | by the beginning of the destination). The behavior is undefined. |
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54 | This is acceptable according to the draft C standard. |
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55 | |
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56 | Undefined behavior will also occur if the end of the source string |
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57 | (i.e. the terminating null byte) is in the last two words of the |
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58 | program's allocated memory space. This is so because strcpy fetches |
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59 | ahead. Disallowing the fetch ahead would impose a severe performance |
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60 | penalty. |
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61 | |
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62 | Strategy: |
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63 | |
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64 | Fetch the source string and store the destination string by words |
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65 | until the null byte is encountered. When the word with the null |
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66 | byte is reached, store it by bytes up through the null byte only. |
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67 | |
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68 | Tactics: |
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69 | |
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70 | 1) Do NOT try to fetch and store the words in a word aligned manner |
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71 | because, in my judgement, the performance degradation experienced due |
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72 | to non-aligned accesses does NOT outweigh the time and complexity added |
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73 | by the preamble and convoluted body that would be necessary to assure |
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74 | alignment. This is supported by the intuition that most source and |
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75 | destination strings will be word aligned to begin with. |
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76 | |
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77 | |
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78 | procedure strcat |
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79 | |
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80 | dest_addr = strcat (dest_addr, src_addr) |
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81 | |
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82 | Appends the string pointed to by src_addr to the string pointed |
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83 | to by dest_addr. The first character of the source string is |
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84 | copied to the location initially occupied by the trailing null |
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85 | byte of the destination string. Thereafter, characters are copied |
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86 | from the source to the destination up thru the null byte that |
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87 | trails the source string. |
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88 | |
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89 | See the strcpy routine, above, for its caveats, as they apply here too. |
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90 | |
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91 | Strategy: |
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92 | |
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93 | Skip to the end (null byte) of the destination string, and then drop |
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94 | into the strcpy code. |
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95 | |
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96 | Tactics: |
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97 | |
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98 | Skipping to the null byte is Ldone by reading the destination string |
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99 | in long-words and scanbyte'ing them, then examining the bytes of the |
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100 | word that contains the null byte, until the address of the null byte is |
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101 | known. Then we drop into the strcpy routine. It is probable (approx. |
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102 | three out of four times) that the destination string as strcpy sees |
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103 | it will NOT be word aligned (i.e. that the null byte won't be the |
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104 | last byte of a word). But it is not worth the complication to that |
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105 | routine to force word aligned memory accesses to be gaurenteed. |
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106 | */ |
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107 | .globl _strcpy, _strcat |
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108 | .globl __strcpy, __strcat |
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109 | .leafproc _strcpy,__strcpy |
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110 | .leafproc _strcat,__strcat |
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111 | .align 2 |
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112 | _strcat: |
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113 | #ifndef __PIC |
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114 | lda Lrett,g14 |
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115 | #else |
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116 | lda Lrett-(.+8)(ip),g14 |
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117 | #endif |
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118 | __strcat: |
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119 | mov g14,g13 # preserve return address |
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120 | ldl (g0),g4 # fetch first two words |
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121 | addo 8,g0,g2 # post-increment src word pointer |
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122 | lda 0xff,g3 # byte extraction mask |
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123 | |
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124 | Lsearch_for_word_with_null_byte: |
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125 | scanbyte 0,g4 # check for null byte |
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126 | mov g5,g7 # copy second word |
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127 | bo.f Lsearch_for_null # branch if null found |
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128 | scanbyte 0,g7 # check for null byte |
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129 | ldl (g2),g4 # fetch next pair of word of src |
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130 | addo 8,g2,g2 # post-increment src word pointer |
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131 | bno Lsearch_for_word_with_null_byte # branch if null not found yet |
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132 | |
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133 | subo 4,g2,g2 # back up the byte pointer |
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134 | mov g7,g4 # move word with null to search word |
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135 | Lsearch_for_null: |
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136 | subo 9,g2,g5 # back up the byte pointer |
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137 | Lsearch_for_null.a: |
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138 | and g4,g3,g6 # extract byte |
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139 | cmpo 0,g6 # is it null? |
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140 | addo 1,g5,g5 # bump src byte ptr |
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141 | shro 8,g4,g4 # shift word to position next byte |
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142 | bne Lsearch_for_null.a |
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143 | b Lend_of_dest_found |
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144 | |
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145 | _strcpy: |
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146 | #ifndef __PIC |
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147 | lda Lrett,g14 |
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148 | #else |
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149 | lda Lrett-(.+8)(ip),g14 |
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150 | #endif |
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151 | __strcpy: |
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152 | mov g0, g5 |
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153 | Lend_of_dest_found: |
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154 | ld (g1), g2 # fetch first word of source |
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155 | mov g14,g6 # preserve return address |
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156 | lda 0xff, g3 # byte extraction mask = 0xff; |
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157 | Lwloop: # word copying loop |
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158 | addo 4, g1, g1 # post-increment source ptr |
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159 | scanbyte 0, g2 # does source word contain null byte? |
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160 | mov g2, g4 # save a copy of the source word |
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161 | be Lcloop # branch if null present |
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162 | ld (g1), g2 # pre-fetch next word of source |
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163 | st g4, (g5) # store current word |
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164 | addo 4, g5, g5 # post-increment dest ptr |
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165 | b Lwloop |
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166 | |
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167 | Lcloop: # character copying loop |
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168 | and g3, g4, g14 # extract next char |
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169 | shro 8, g4, g4 # position word for next byte extraction |
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170 | cmpo 0, g14 # is it null? |
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171 | stob g14, (g5) # store the byte |
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172 | addo 1, g5, g5 # post-increment dest ptr |
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173 | bne Lcloop # quit if null encountered |
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174 | |
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175 | bx (g6) # g0 = dest string address; g14 = 0 |
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176 | Lrett: |
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177 | ret |
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