1 | /* |
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2 | * JFFS2 -- Journalling Flash File System, Version 2. |
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3 | * |
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4 | * Copyright © 2001-2007 Red Hat, Inc. |
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5 | * Copyright © 2004-2010 David Woodhouse <dwmw2@infradead.org> |
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6 | * |
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7 | * Created by Arjan van de Ven <arjanv@redhat.com> |
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8 | * |
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9 | * For licensing information, see the file 'LICENCE' in this directory. |
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10 | * |
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11 | */ |
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12 | |
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13 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
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14 | |
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15 | #include <linux/string.h> |
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16 | #include <linux/types.h> |
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17 | #include <linux/jffs2.h> |
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18 | #include <linux/errno.h> |
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19 | #include "compr.h" |
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20 | |
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21 | |
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22 | #define RUBIN_REG_SIZE 16 |
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23 | #define UPPER_BIT_RUBIN (((long) 1)<<(RUBIN_REG_SIZE-1)) |
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24 | #define LOWER_BITS_RUBIN ((((long) 1)<<(RUBIN_REG_SIZE-1))-1) |
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25 | |
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26 | |
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27 | #define BIT_DIVIDER_MIPS 1043 |
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28 | static int bits_mips[8] = { 277, 249, 290, 267, 229, 341, 212, 241}; |
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29 | |
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30 | struct pushpull { |
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31 | unsigned char *buf; |
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32 | unsigned int buflen; |
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33 | unsigned int ofs; |
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34 | unsigned int reserve; |
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35 | }; |
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36 | |
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37 | struct rubin_state { |
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38 | unsigned long p; |
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39 | unsigned long q; |
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40 | unsigned long rec_q; |
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41 | long bit_number; |
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42 | struct pushpull pp; |
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43 | int bit_divider; |
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44 | int bits[8]; |
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45 | }; |
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46 | |
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47 | static inline void init_pushpull(struct pushpull *pp, char *buf, |
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48 | unsigned buflen, unsigned ofs, |
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49 | unsigned reserve) |
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50 | { |
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51 | pp->buf = buf; |
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52 | pp->buflen = buflen; |
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53 | pp->ofs = ofs; |
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54 | pp->reserve = reserve; |
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55 | } |
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56 | |
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57 | static inline int pushbit(struct pushpull *pp, int bit, int use_reserved) |
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58 | { |
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59 | if (pp->ofs >= pp->buflen - (use_reserved?0:pp->reserve)) |
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60 | return -ENOSPC; |
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61 | |
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62 | if (bit) |
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63 | pp->buf[pp->ofs >> 3] |= (1<<(7-(pp->ofs & 7))); |
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64 | else |
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65 | pp->buf[pp->ofs >> 3] &= ~(1<<(7-(pp->ofs & 7))); |
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66 | |
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67 | pp->ofs++; |
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68 | |
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69 | return 0; |
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70 | } |
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71 | |
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72 | static inline int pushedbits(struct pushpull *pp) |
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73 | { |
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74 | return pp->ofs; |
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75 | } |
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76 | |
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77 | static inline int pullbit(struct pushpull *pp) |
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78 | { |
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79 | int bit; |
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80 | |
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81 | bit = (pp->buf[pp->ofs >> 3] >> (7-(pp->ofs & 7))) & 1; |
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82 | |
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83 | pp->ofs++; |
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84 | return bit; |
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85 | } |
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86 | |
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87 | static inline int pulledbits(struct pushpull *pp) |
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88 | { |
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89 | return pp->ofs; |
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90 | } |
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91 | |
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92 | |
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93 | static void init_rubin(struct rubin_state *rs, int div, int *bits) |
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94 | { |
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95 | int c; |
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96 | |
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97 | rs->q = 0; |
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98 | rs->p = (long) (2 * UPPER_BIT_RUBIN); |
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99 | rs->bit_number = (long) 0; |
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100 | rs->bit_divider = div; |
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101 | |
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102 | for (c=0; c<8; c++) |
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103 | rs->bits[c] = bits[c]; |
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104 | } |
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105 | |
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106 | |
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107 | static int encode(struct rubin_state *rs, long A, long B, int symbol) |
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108 | { |
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109 | |
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110 | long i0, i1; |
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111 | int ret; |
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112 | |
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113 | while ((rs->q >= UPPER_BIT_RUBIN) || |
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114 | ((rs->p + rs->q) <= UPPER_BIT_RUBIN)) { |
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115 | rs->bit_number++; |
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116 | |
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117 | ret = pushbit(&rs->pp, (rs->q & UPPER_BIT_RUBIN) ? 1 : 0, 0); |
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118 | if (ret) |
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119 | return ret; |
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120 | rs->q &= LOWER_BITS_RUBIN; |
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121 | rs->q <<= 1; |
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122 | rs->p <<= 1; |
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123 | } |
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124 | i0 = A * rs->p / (A + B); |
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125 | if (i0 <= 0) |
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126 | i0 = 1; |
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127 | |
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128 | if (i0 >= rs->p) |
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129 | i0 = rs->p - 1; |
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130 | |
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131 | i1 = rs->p - i0; |
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132 | |
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133 | if (symbol == 0) |
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134 | rs->p = i0; |
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135 | else { |
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136 | rs->p = i1; |
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137 | rs->q += i0; |
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138 | } |
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139 | return 0; |
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140 | } |
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141 | |
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142 | |
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143 | static void end_rubin(struct rubin_state *rs) |
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144 | { |
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145 | |
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146 | int i; |
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147 | |
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148 | for (i = 0; i < RUBIN_REG_SIZE; i++) { |
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149 | pushbit(&rs->pp, (UPPER_BIT_RUBIN & rs->q) ? 1 : 0, 1); |
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150 | rs->q &= LOWER_BITS_RUBIN; |
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151 | rs->q <<= 1; |
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152 | } |
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153 | } |
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154 | |
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155 | |
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156 | static void init_decode(struct rubin_state *rs, int div, int *bits) |
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157 | { |
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158 | init_rubin(rs, div, bits); |
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159 | |
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160 | /* behalve lower */ |
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161 | rs->rec_q = 0; |
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162 | |
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163 | for (rs->bit_number = 0; rs->bit_number++ < RUBIN_REG_SIZE; |
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164 | rs->rec_q = rs->rec_q * 2 + (long) (pullbit(&rs->pp))) |
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165 | ; |
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166 | } |
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167 | |
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168 | static void __do_decode(struct rubin_state *rs, unsigned long p, |
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169 | unsigned long q) |
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170 | { |
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171 | register unsigned long lower_bits_rubin = LOWER_BITS_RUBIN; |
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172 | unsigned long rec_q; |
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173 | int c, bits = 0; |
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174 | |
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175 | /* |
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176 | * First, work out how many bits we need from the input stream. |
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177 | * Note that we have already done the initial check on this |
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178 | * loop prior to calling this function. |
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179 | */ |
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180 | do { |
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181 | bits++; |
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182 | q &= lower_bits_rubin; |
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183 | q <<= 1; |
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184 | p <<= 1; |
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185 | } while ((q >= UPPER_BIT_RUBIN) || ((p + q) <= UPPER_BIT_RUBIN)); |
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186 | |
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187 | rs->p = p; |
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188 | rs->q = q; |
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189 | |
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190 | rs->bit_number += bits; |
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191 | |
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192 | /* |
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193 | * Now get the bits. We really want this to be "get n bits". |
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194 | */ |
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195 | rec_q = rs->rec_q; |
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196 | do { |
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197 | c = pullbit(&rs->pp); |
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198 | rec_q &= lower_bits_rubin; |
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199 | rec_q <<= 1; |
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200 | rec_q += c; |
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201 | } while (--bits); |
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202 | rs->rec_q = rec_q; |
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203 | } |
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204 | |
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205 | static int decode(struct rubin_state *rs, long A, long B) |
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206 | { |
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207 | unsigned long p = rs->p, q = rs->q; |
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208 | long i0, threshold; |
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209 | int symbol; |
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210 | |
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211 | if (q >= UPPER_BIT_RUBIN || ((p + q) <= UPPER_BIT_RUBIN)) |
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212 | __do_decode(rs, p, q); |
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213 | |
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214 | i0 = A * rs->p / (A + B); |
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215 | if (i0 <= 0) |
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216 | i0 = 1; |
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217 | |
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218 | if (i0 >= rs->p) |
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219 | i0 = rs->p - 1; |
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220 | |
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221 | threshold = rs->q + i0; |
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222 | symbol = rs->rec_q >= threshold; |
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223 | if (rs->rec_q >= threshold) { |
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224 | rs->q += i0; |
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225 | i0 = rs->p - i0; |
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226 | } |
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227 | |
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228 | rs->p = i0; |
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229 | |
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230 | return symbol; |
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231 | } |
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232 | |
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233 | |
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234 | |
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235 | static int out_byte(struct rubin_state *rs, unsigned char byte) |
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236 | { |
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237 | int i, ret; |
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238 | struct rubin_state rs_copy; |
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239 | rs_copy = *rs; |
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240 | |
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241 | for (i=0; i<8; i++) { |
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242 | ret = encode(rs, rs->bit_divider-rs->bits[i], |
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243 | rs->bits[i], byte & 1); |
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244 | if (ret) { |
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245 | /* Failed. Restore old state */ |
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246 | *rs = rs_copy; |
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247 | return ret; |
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248 | } |
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249 | byte >>= 1 ; |
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250 | } |
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251 | return 0; |
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252 | } |
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253 | |
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254 | static int in_byte(struct rubin_state *rs) |
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255 | { |
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256 | int i, result = 0, bit_divider = rs->bit_divider; |
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257 | |
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258 | for (i = 0; i < 8; i++) |
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259 | result |= decode(rs, bit_divider - rs->bits[i], |
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260 | rs->bits[i]) << i; |
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261 | |
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262 | return result; |
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263 | } |
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264 | |
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265 | |
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266 | |
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267 | static int rubin_do_compress(int bit_divider, int *bits, unsigned char *data_in, |
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268 | unsigned char *cpage_out, uint32_t *sourcelen, |
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269 | uint32_t *dstlen) |
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270 | { |
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271 | int outpos = 0; |
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272 | int pos=0; |
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273 | struct rubin_state rs; |
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274 | |
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275 | init_pushpull(&rs.pp, cpage_out, *dstlen * 8, 0, 32); |
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276 | |
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277 | init_rubin(&rs, bit_divider, bits); |
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278 | |
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279 | while (pos < (*sourcelen) && !out_byte(&rs, data_in[pos])) |
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280 | pos++; |
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281 | |
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282 | end_rubin(&rs); |
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283 | |
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284 | if (outpos > pos) { |
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285 | /* We failed */ |
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286 | return -1; |
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287 | } |
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288 | |
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289 | /* Tell the caller how much we managed to compress, |
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290 | * and how much space it took */ |
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291 | |
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292 | outpos = (pushedbits(&rs.pp)+7)/8; |
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293 | |
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294 | if (outpos >= pos) |
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295 | return -1; /* We didn't actually compress */ |
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296 | *sourcelen = pos; |
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297 | *dstlen = outpos; |
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298 | return 0; |
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299 | } |
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300 | #if 0 |
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301 | /* _compress returns the compressed size, -1 if bigger */ |
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302 | int jffs2_rubinmips_compress(unsigned char *data_in, unsigned char *cpage_out, |
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303 | uint32_t *sourcelen, uint32_t *dstlen) |
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304 | { |
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305 | return rubin_do_compress(BIT_DIVIDER_MIPS, bits_mips, data_in, |
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306 | cpage_out, sourcelen, dstlen); |
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307 | } |
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308 | #endif |
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309 | static int jffs2_dynrubin_compress(unsigned char *data_in, |
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310 | unsigned char *cpage_out, |
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311 | uint32_t *sourcelen, uint32_t *dstlen) |
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312 | { |
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313 | int bits[8]; |
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314 | unsigned char histo[256]; |
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315 | int i; |
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316 | int ret; |
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317 | uint32_t mysrclen, mydstlen; |
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318 | |
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319 | mysrclen = *sourcelen; |
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320 | mydstlen = *dstlen - 8; |
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321 | |
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322 | if (*dstlen <= 12) |
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323 | return -1; |
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324 | |
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325 | memset(histo, 0, 256); |
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326 | for (i=0; i<mysrclen; i++) |
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327 | histo[data_in[i]]++; |
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328 | memset(bits, 0, sizeof(int)*8); |
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329 | for (i=0; i<256; i++) { |
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330 | if (i&128) |
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331 | bits[7] += histo[i]; |
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332 | if (i&64) |
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333 | bits[6] += histo[i]; |
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334 | if (i&32) |
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335 | bits[5] += histo[i]; |
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336 | if (i&16) |
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337 | bits[4] += histo[i]; |
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338 | if (i&8) |
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339 | bits[3] += histo[i]; |
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340 | if (i&4) |
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341 | bits[2] += histo[i]; |
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342 | if (i&2) |
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343 | bits[1] += histo[i]; |
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344 | if (i&1) |
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345 | bits[0] += histo[i]; |
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346 | } |
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347 | |
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348 | for (i=0; i<8; i++) { |
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349 | bits[i] = (bits[i] * 256) / mysrclen; |
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350 | if (!bits[i]) bits[i] = 1; |
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351 | if (bits[i] > 255) bits[i] = 255; |
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352 | cpage_out[i] = bits[i]; |
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353 | } |
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354 | |
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355 | ret = rubin_do_compress(256, bits, data_in, cpage_out+8, &mysrclen, |
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356 | &mydstlen); |
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357 | if (ret) |
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358 | return ret; |
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359 | |
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360 | /* Add back the 8 bytes we took for the probabilities */ |
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361 | mydstlen += 8; |
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362 | |
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363 | if (mysrclen <= mydstlen) { |
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364 | /* We compressed */ |
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365 | return -1; |
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366 | } |
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367 | |
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368 | *sourcelen = mysrclen; |
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369 | *dstlen = mydstlen; |
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370 | return 0; |
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371 | } |
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372 | |
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373 | static void rubin_do_decompress(int bit_divider, int *bits, |
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374 | unsigned char *cdata_in, |
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375 | unsigned char *page_out, uint32_t srclen, |
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376 | uint32_t destlen) |
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377 | { |
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378 | int outpos = 0; |
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379 | struct rubin_state rs; |
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380 | |
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381 | init_pushpull(&rs.pp, cdata_in, srclen, 0, 0); |
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382 | init_decode(&rs, bit_divider, bits); |
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383 | |
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384 | while (outpos < destlen) |
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385 | page_out[outpos++] = in_byte(&rs); |
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386 | } |
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387 | |
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388 | |
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389 | static int jffs2_rubinmips_decompress(unsigned char *data_in, |
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390 | unsigned char *cpage_out, |
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391 | uint32_t sourcelen, uint32_t dstlen) |
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392 | { |
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393 | rubin_do_decompress(BIT_DIVIDER_MIPS, bits_mips, data_in, |
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394 | cpage_out, sourcelen, dstlen); |
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395 | return 0; |
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396 | } |
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397 | |
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398 | static int jffs2_dynrubin_decompress(unsigned char *data_in, |
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399 | unsigned char *cpage_out, |
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400 | uint32_t sourcelen, uint32_t dstlen) |
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401 | { |
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402 | int bits[8]; |
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403 | int c; |
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404 | |
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405 | for (c=0; c<8; c++) |
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406 | bits[c] = data_in[c]; |
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407 | |
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408 | rubin_do_decompress(256, bits, data_in+8, cpage_out, sourcelen-8, |
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409 | dstlen); |
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410 | return 0; |
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411 | } |
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412 | |
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413 | static struct jffs2_compressor jffs2_rubinmips_comp = { |
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414 | .priority = JFFS2_RUBINMIPS_PRIORITY, |
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415 | .name = "rubinmips", |
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416 | .compr = JFFS2_COMPR_DYNRUBIN, |
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417 | .compress = NULL, /*&jffs2_rubinmips_compress,*/ |
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418 | .decompress = &jffs2_rubinmips_decompress, |
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419 | #ifdef JFFS2_RUBINMIPS_DISABLED |
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420 | .disabled = 1, |
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421 | #else |
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422 | .disabled = 0, |
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423 | #endif |
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424 | }; |
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425 | |
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426 | int jffs2_rubinmips_init(void) |
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427 | { |
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428 | return jffs2_register_compressor(&jffs2_rubinmips_comp); |
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429 | } |
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430 | |
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431 | void jffs2_rubinmips_exit(void) |
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432 | { |
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433 | jffs2_unregister_compressor(&jffs2_rubinmips_comp); |
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434 | } |
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435 | |
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436 | static struct jffs2_compressor jffs2_dynrubin_comp = { |
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437 | .priority = JFFS2_DYNRUBIN_PRIORITY, |
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438 | .name = "dynrubin", |
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439 | .compr = JFFS2_COMPR_RUBINMIPS, |
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440 | .compress = jffs2_dynrubin_compress, |
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441 | .decompress = &jffs2_dynrubin_decompress, |
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442 | #ifdef JFFS2_DYNRUBIN_DISABLED |
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443 | .disabled = 1, |
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444 | #else |
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445 | .disabled = 0, |
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446 | #endif |
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447 | }; |
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448 | |
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449 | int jffs2_dynrubin_init(void) |
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450 | { |
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451 | return jffs2_register_compressor(&jffs2_dynrubin_comp); |
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452 | } |
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453 | |
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454 | void jffs2_dynrubin_exit(void) |
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455 | { |
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456 | jffs2_unregister_compressor(&jffs2_dynrubin_comp); |
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457 | } |
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