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annotate Resources/ThirdParty/base64/base64.cpp @ 3645:8aab20dde416

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Support of MPEG4 transfer syntaxes in C-Store SCP
author Sebastien Jodogne <s.jodogne@gmail.com>
date Tue, 04 Feb 2020 08:32:38 +0100
parents 79178122842c
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
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1 /*
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2 base64.cpp and base64.h
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3
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4 Copyright (C) 2004-2008 René Nyffenegger
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5
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6 This source code is provided 'as-is', without any express or implied
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7 warranty. In no event will the author be held liable for any damages
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8 arising from the use of this software.
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9
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10 Permission is granted to anyone to use this software for any purpose,
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11 including commercial applications, and to alter it and redistribute it
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12 freely, subject to the following restrictions:
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13
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14 1. The origin of this source code must not be misrepresented; you must not
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15 claim that you wrote the original source code. If you use this source code
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16 in a product, an acknowledgment in the product documentation would be
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17 appreciated but is not required.
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18
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19 2. Altered source versions must be plainly marked as such, and must not be
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20 misrepresented as being the original source code.
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21
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22 3. This notice may not be removed or altered from any source distribution.
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23
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24 René Nyffenegger rene.nyffenegger@adp-gmbh.ch
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25
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26 ------------------------------
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27 This version has been modified (changed the interface + use another decoding algorithm
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28 inspired from https://stackoverflow.com/a/34571089 which was faster)
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29 */
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30
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31 #include "base64.h"
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32 #include <string.h>
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33 #include <vector>
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34
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35 static const std::string base64_chars =
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36 "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
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37 "abcdefghijklmnopqrstuvwxyz"
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38 "0123456789+/";
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39
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40 static inline bool is_base64(unsigned char c) {
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41 return (isalnum(c) || (c == '+') || (c == '/'));
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42 }
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43
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44 void base64_encode(std::string& result, const std::string& stringToEncode)
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45 {
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46 const unsigned char* bytes_to_encode = reinterpret_cast<const unsigned char*>
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47 (stringToEncode.size() > 0 ? &stringToEncode[0] : NULL);
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48 size_t in_len = stringToEncode.size();
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49
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50 result.reserve(result.size() + in_len * 4 / 3 + 10);
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51
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52 int i = 0;
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53 int j = 0;
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54 unsigned char char_array_3[3];
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55 unsigned char char_array_4[4];
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56
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57 while (in_len--) {
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58 char_array_3[i++] = *(bytes_to_encode++);
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59 if (i == 3) {
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60 char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
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61 char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
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62 char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
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63 char_array_4[3] = char_array_3[2] & 0x3f;
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64
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65 for(i = 0; (i <4) ; i++)
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66 result += base64_chars[char_array_4[i]];
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67 i = 0;
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68 }
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69 }
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70
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71 if (i)
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72 {
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73 for(j = i; j < 3; j++)
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74 char_array_3[j] = '\0';
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75
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76 char_array_4[0] = (char_array_3[0] & 0xfc) >> 2;
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77 char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + ((char_array_3[1] & 0xf0) >> 4);
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78 char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + ((char_array_3[2] & 0xc0) >> 6);
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79 char_array_4[3] = char_array_3[2] & 0x3f;
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80
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81 for (j = 0; (j < i + 1); j++)
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82 result += base64_chars[char_array_4[j]];
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83
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84 while((i++ < 3))
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85 result += '=';
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86
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87 }
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88 }
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89
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90 // old code from René Nyffenegger. This code is slower
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91 void base64_decode_old(std::string& result, const std::string& encoded_string) {
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92 size_t in_len = encoded_string.size();
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93 int i = 0;
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94 int j = 0;
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95 int in_ = 0;
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96 unsigned char char_array_4[4], char_array_3[3];
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98 result.reserve(result.size() + in_len * 3 / 4 + 10);
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99
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100 while (in_len-- && ( encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {
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101 char_array_4[i++] = encoded_string[in_]; in_++;
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102 if (i ==4) {
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103 for (i = 0; i <4; i++)
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104 char_array_4[i] = base64_chars.find(char_array_4[i]);
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105
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106 char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
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107 char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
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108 char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
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109
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110 for (i = 0; (i < 3); i++)
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111 result += char_array_3[i];
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112 i = 0;
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113 }
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114 }
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115
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116 if (i) {
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117 for (j = i; j <4; j++)
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118 char_array_4[j] = 0;
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119
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120 for (j = 0; j <4; j++)
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121 char_array_4[j] = base64_chars.find(char_array_4[j]);
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122
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123 char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
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124 char_array_3[1] = ((char_array_4[1] & 0xf) << 4) + ((char_array_4[2] & 0x3c) >> 2);
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125 char_array_3[2] = ((char_array_4[2] & 0x3) << 6) + char_array_4[3];
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126
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127 for (j = 0; (j < i - 1); j++)
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128 result += char_array_3[j];
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129 }
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130 }
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131
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132
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133 // new code from https://stackoverflow.com/a/34571089
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134 // note that the encoding algorithm from this page was slower (and bugged !)
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135 // this code is not using std::vector::find
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136
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137 // static init equivalent to:
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138 // decode_indexes.assign(256, -1);
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139 // for (int i=0; i<64; ++i)
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140 // decode_indexes[base64_chars[i]] = i;
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141
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142 static const int decode_indexes[] = {
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143 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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144 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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145 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
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146 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
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147 -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
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148 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
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149 -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
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150 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
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151 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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152 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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153 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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154 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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155 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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156 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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157 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
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158 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
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159 };
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160
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161
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162 void base64_decode(std::string& result, const std::string &stringToDecode) {
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163
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164 result.reserve(result.size() + stringToDecode.size() * 3 / 4 + 10);
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165
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166 int val=0, valb=-8;
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167 for (std::string::const_iterator c = stringToDecode.begin(); c != stringToDecode.end(); ++c)
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168 {
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169 size_t index = static_cast<size_t>(*c);
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170 if (decode_indexes[index] == -1)
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171 break;
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172 val = (val<<6) + decode_indexes[index];
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173 valb += 6;
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174 if (valb>=0) {
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175 result.push_back(char((val>>valb)&0xFF));
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176 valb-=8;
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177 }
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178 }
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179 }