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1 /* |
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2 |
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3 Copyright (C) 2000,2004 Silicon Graphics, Inc. All Rights Reserved. |
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4 |
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5 This program is free software; you can redistribute it and/or modify it |
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6 under the terms of version 2.1 of the GNU Lesser General Public License |
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7 as published by the Free Software Foundation. |
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8 |
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9 This program is distributed in the hope that it would be useful, but |
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10 WITHOUT ANY WARRANTY; without even the implied warranty of |
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11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. |
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12 |
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13 Further, this software is distributed without any warranty that it is |
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14 free of the rightful claim of any third person regarding infringement |
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15 or the like. Any license provided herein, whether implied or |
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16 otherwise, applies only to this software file. Patent licenses, if |
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17 any, provided herein do not apply to combinations of this program with |
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18 other software, or any other product whatsoever. |
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19 |
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20 You should have received a copy of the GNU Lesser General Public |
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21 License along with this program; if not, write the Free Software |
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22 Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston MA 02110-1301, |
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23 USA. |
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24 |
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25 Contact information: Silicon Graphics, Inc., 1500 Crittenden Lane, |
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26 Mountain View, CA 94043, or: |
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27 |
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28 http://www.sgi.com |
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29 |
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30 For further information regarding this notice, see: |
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31 |
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32 http://oss.sgi.com/projects/GenInfo/NoticeExplan |
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33 |
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34 */ |
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35 |
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36 |
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37 |
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38 #include "config.h" |
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39 #include "dwarf_incl.h" |
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40 #include <stdio.h> |
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41 |
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42 |
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43 /* |
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44 decode ULEB |
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45 */ |
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46 Dwarf_Unsigned |
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47 _dwarf_decode_u_leb128(Dwarf_Small * leb128, Dwarf_Word * leb128_length) |
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48 { |
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49 unsigned char byte; |
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50 Dwarf_Word word_number; |
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51 Dwarf_Unsigned number; |
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52 Dwarf_Sword shift; |
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53 Dwarf_Sword byte_length; |
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54 |
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55 /* The following unrolls-the-loop for the first few bytes and |
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56 unpacks into 32 bits to make this as fast as possible. |
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57 word_number is assumed big enough that the shift has a defined |
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58 result. */ |
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59 if ((*leb128 & 0x80) == 0) { |
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60 if (leb128_length != NULL) |
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61 *leb128_length = 1; |
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62 return (*leb128); |
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63 } else if ((*(leb128 + 1) & 0x80) == 0) { |
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64 if (leb128_length != NULL) |
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65 *leb128_length = 2; |
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66 |
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67 word_number = *leb128 & 0x7f; |
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68 word_number |= (*(leb128 + 1) & 0x7f) << 7; |
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69 return (word_number); |
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70 } else if ((*(leb128 + 2) & 0x80) == 0) { |
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71 if (leb128_length != NULL) |
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72 *leb128_length = 3; |
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73 |
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74 word_number = *leb128 & 0x7f; |
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75 word_number |= (*(leb128 + 1) & 0x7f) << 7; |
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76 word_number |= (*(leb128 + 2) & 0x7f) << 14; |
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77 return (word_number); |
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78 } else if ((*(leb128 + 3) & 0x80) == 0) { |
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79 if (leb128_length != NULL) |
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80 *leb128_length = 4; |
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81 |
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82 word_number = *leb128 & 0x7f; |
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83 word_number |= (*(leb128 + 1) & 0x7f) << 7; |
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84 word_number |= (*(leb128 + 2) & 0x7f) << 14; |
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85 word_number |= (*(leb128 + 3) & 0x7f) << 21; |
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86 return (word_number); |
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87 } |
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88 |
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89 /* The rest handles long numbers Because the 'number' may be larger |
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90 than the default int/unsigned, we must cast the 'byte' before |
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91 the shift for the shift to have a defined result. */ |
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92 number = 0; |
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93 shift = 0; |
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94 byte_length = 1; |
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95 byte = *(leb128); |
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96 for (;;) { |
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97 number |= ((Dwarf_Unsigned) (byte & 0x7f)) << shift; |
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98 |
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99 if ((byte & 0x80) == 0) { |
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100 if (leb128_length != NULL) |
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101 *leb128_length = byte_length; |
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102 return (number); |
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103 } |
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104 shift += 7; |
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105 |
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106 byte_length++; |
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107 ++leb128; |
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108 byte = *leb128; |
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109 } |
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110 } |
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111 |
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112 #define BITSINBYTE 8 |
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113 |
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114 /* |
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115 decode SLEB |
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116 */ |
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117 Dwarf_Signed |
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118 _dwarf_decode_s_leb128(Dwarf_Small * leb128, Dwarf_Word * leb128_length) |
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119 { |
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120 Dwarf_Signed number = 0; |
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121 Dwarf_Bool sign = 0; |
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122 Dwarf_Sword shift = 0; |
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123 unsigned char byte = *leb128; |
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124 Dwarf_Sword byte_length = 1; |
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125 |
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126 /* byte_length being the number of bytes of data absorbed so far in |
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127 turning the leb into a Dwarf_Signed. */ |
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128 |
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129 for (;;) { |
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130 sign = byte & 0x40; |
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131 number |= ((Dwarf_Signed) ((byte & 0x7f))) << shift; |
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132 shift += 7; |
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133 |
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134 if ((byte & 0x80) == 0) { |
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135 break; |
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136 } |
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137 ++leb128; |
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138 byte = *leb128; |
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139 byte_length++; |
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140 } |
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141 |
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142 if ((shift < sizeof(Dwarf_Signed) * BITSINBYTE) && sign) { |
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143 number |= -((Dwarf_Signed) 1 << shift); |
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144 } |
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145 |
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146 if (leb128_length != NULL) |
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147 *leb128_length = byte_length; |
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148 return (number); |
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149 } |