1 | /* |
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2 | * Copyright (c) 1992, 1993, 1994, 1995, 1996 |
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3 | * The Regents of the University of California. All rights reserved. |
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4 | * |
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5 | * Redistribution and use in source and binary forms, with or without |
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6 | * modification, are permitted provided that: (1) source code distributions |
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7 | * retain the above copyright notice and this paragraph in its entirety, (2) |
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8 | * distributions including binary code include the above copyright notice and |
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9 | * this paragraph in its entirety in the documentation or other materials |
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10 | * provided with the distribution, and (3) all advertising materials mentioning |
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11 | * features or use of this software display the following acknowledgement: |
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12 | * ``This product includes software developed by the University of California, |
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13 | * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of |
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14 | * the University nor the names of its contributors may be used to endorse |
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15 | * or promote products derived from this software without specific prior |
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16 | * written permission. |
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17 | * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED |
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18 | * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF |
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19 | * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. |
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20 | */ |
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21 | |
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22 | #ifndef _WIN32 |
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23 | #include <arpa/inet.h> |
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24 | #endif |
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25 | |
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26 | /* |
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27 | * Macros to extract possibly-unaligned big-endian integral values. |
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28 | */ |
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29 | #ifdef LBL_ALIGN |
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30 | /* |
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31 | * The processor doesn't natively handle unaligned loads. |
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32 | */ |
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33 | #if defined(__GNUC__) && defined(HAVE___ATTRIBUTE__) && \ |
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34 | (defined(__alpha) || defined(__alpha__) || \ |
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35 | defined(__mips) || defined(__mips__)) |
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36 | |
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37 | /* |
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38 | * This is a GCC-compatible compiler and we have __attribute__, which |
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39 | * we assume that mean we have __attribute__((packed)), and this is |
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40 | * MIPS or Alpha, which has instructions that can help when doing |
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41 | * unaligned loads. |
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42 | * |
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43 | * Declare packed structures containing a uint16_t and a uint32_t, |
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44 | * cast the pointer to point to one of those, and fetch through it; |
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45 | * the GCC manual doesn't appear to explicitly say that |
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46 | * __attribute__((packed)) causes the compiler to generate unaligned-safe |
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47 | * code, but it apppears to do so. |
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48 | * |
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49 | * We do this in case the compiler can generate code using those |
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50 | * instructions to do an unaligned load and pass stuff to "ntohs()" or |
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51 | * "ntohl()", which might be better than than the code to fetch the |
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52 | * bytes one at a time and assemble them. (That might not be the |
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53 | * case on a little-endian platform, such as DEC's MIPS machines and |
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54 | * Alpha machines, where "ntohs()" and "ntohl()" might not be done |
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55 | * inline.) |
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56 | * |
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57 | * We do this only for specific architectures because, for example, |
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58 | * at least some versions of GCC, when compiling for 64-bit SPARC, |
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59 | * generate code that assumes alignment if we do this. |
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60 | * |
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61 | * XXX - add other architectures and compilers as possible and |
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62 | * appropriate. |
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63 | * |
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64 | * HP's C compiler, indicated by __HP_cc being defined, supports |
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65 | * "#pragma unaligned N" in version A.05.50 and later, where "N" |
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66 | * specifies a number of bytes at which the typedef on the next |
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67 | * line is aligned, e.g. |
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68 | * |
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69 | * #pragma unalign 1 |
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70 | * typedef uint16_t unaligned_uint16_t; |
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71 | * |
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72 | * to define unaligned_uint16_t as a 16-bit unaligned data type. |
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73 | * This could be presumably used, in sufficiently recent versions of |
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74 | * the compiler, with macros similar to those below. This would be |
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75 | * useful only if that compiler could generate better code for PA-RISC |
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76 | * or Itanium than would be generated by a bunch of shifts-and-ORs. |
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77 | * |
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78 | * DEC C, indicated by __DECC being defined, has, at least on Alpha, |
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79 | * an __unaligned qualifier that can be applied to pointers to get the |
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80 | * compiler to generate code that does unaligned loads and stores when |
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81 | * dereferencing the pointer in question. |
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82 | * |
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83 | * XXX - what if the native C compiler doesn't support |
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84 | * __attribute__((packed))? How can we get it to generate unaligned |
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85 | * accesses for *specific* items? |
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86 | */ |
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87 | typedef struct { |
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88 | uint16_t val; |
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89 | } __attribute__((packed)) unaligned_uint16_t; |
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90 | |
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91 | typedef struct { |
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92 | uint32_t val; |
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93 | } __attribute__((packed)) unaligned_uint32_t; |
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94 | |
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95 | static inline uint16_t |
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96 | EXTRACT_16BITS(const void *p) |
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97 | { |
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98 | return ((uint16_t)ntohs(((const unaligned_uint16_t *)(p))->val)); |
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99 | } |
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100 | |
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101 | static inline uint32_t |
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102 | EXTRACT_32BITS(const void *p) |
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103 | { |
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104 | return ((uint32_t)ntohl(((const unaligned_uint32_t *)(p))->val)); |
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105 | } |
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106 | |
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107 | static inline uint64_t |
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108 | EXTRACT_64BITS(const void *p) |
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109 | { |
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110 | return ((uint64_t)(((uint64_t)ntohl(((const unaligned_uint32_t *)(p) + 0)->val)) << 32 | \ |
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111 | ((uint64_t)ntohl(((const unaligned_uint32_t *)(p) + 1)->val)) << 0)); |
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112 | } |
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113 | |
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114 | #else /* have to do it a byte at a time */ |
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115 | /* |
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116 | * This isn't a GCC-compatible compiler, we don't have __attribute__, |
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117 | * or we do but we don't know of any better way with this instruction |
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118 | * set to do unaligned loads, so do unaligned loads of big-endian |
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119 | * quantities the hard way - fetch the bytes one at a time and |
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120 | * assemble them. |
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121 | */ |
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122 | #define EXTRACT_16BITS(p) \ |
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123 | ((uint16_t)(((uint16_t)(*((const uint8_t *)(p) + 0)) << 8) | \ |
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124 | ((uint16_t)(*((const uint8_t *)(p) + 1)) << 0))) |
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125 | #define EXTRACT_32BITS(p) \ |
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126 | ((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 0)) << 24) | \ |
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127 | ((uint32_t)(*((const uint8_t *)(p) + 1)) << 16) | \ |
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128 | ((uint32_t)(*((const uint8_t *)(p) + 2)) << 8) | \ |
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129 | ((uint32_t)(*((const uint8_t *)(p) + 3)) << 0))) |
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130 | #define EXTRACT_64BITS(p) \ |
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131 | ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 56) | \ |
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132 | ((uint64_t)(*((const uint8_t *)(p) + 1)) << 48) | \ |
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133 | ((uint64_t)(*((const uint8_t *)(p) + 2)) << 40) | \ |
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134 | ((uint64_t)(*((const uint8_t *)(p) + 3)) << 32) | \ |
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135 | ((uint64_t)(*((const uint8_t *)(p) + 4)) << 24) | \ |
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136 | ((uint64_t)(*((const uint8_t *)(p) + 5)) << 16) | \ |
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137 | ((uint64_t)(*((const uint8_t *)(p) + 6)) << 8) | \ |
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138 | ((uint64_t)(*((const uint8_t *)(p) + 7)) << 0))) |
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139 | #endif /* must special-case unaligned accesses */ |
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140 | #else /* LBL_ALIGN */ |
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141 | /* |
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142 | * The processor natively handles unaligned loads, so we can just |
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143 | * cast the pointer and fetch through it. |
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144 | */ |
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145 | static inline uint16_t |
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146 | EXTRACT_16BITS(const void *p) |
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147 | { |
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148 | return ((uint16_t)ntohs(*(const uint16_t *)(p))); |
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149 | } |
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150 | |
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151 | static inline uint32_t |
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152 | EXTRACT_32BITS(const void *p) |
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153 | { |
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154 | return ((uint32_t)ntohl(*(const uint32_t *)(p))); |
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155 | } |
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156 | |
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157 | static inline uint64_t |
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158 | EXTRACT_64BITS(const void *p) |
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159 | { |
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160 | return ((uint64_t)(((uint64_t)ntohl(*((const uint32_t *)(p) + 0))) << 32 | \ |
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161 | ((uint64_t)ntohl(*((const uint32_t *)(p) + 1))) << 0)); |
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162 | |
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163 | } |
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164 | |
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165 | #endif /* LBL_ALIGN */ |
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166 | |
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167 | #define EXTRACT_24BITS(p) \ |
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168 | ((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 0)) << 16) | \ |
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169 | ((uint32_t)(*((const uint8_t *)(p) + 1)) << 8) | \ |
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170 | ((uint32_t)(*((const uint8_t *)(p) + 2)) << 0))) |
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171 | |
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172 | #define EXTRACT_40BITS(p) \ |
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173 | ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 32) | \ |
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174 | ((uint64_t)(*((const uint8_t *)(p) + 1)) << 24) | \ |
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175 | ((uint64_t)(*((const uint8_t *)(p) + 2)) << 16) | \ |
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176 | ((uint64_t)(*((const uint8_t *)(p) + 3)) << 8) | \ |
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177 | ((uint64_t)(*((const uint8_t *)(p) + 4)) << 0))) |
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178 | |
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179 | #define EXTRACT_48BITS(p) \ |
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180 | ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 40) | \ |
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181 | ((uint64_t)(*((const uint8_t *)(p) + 1)) << 32) | \ |
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182 | ((uint64_t)(*((const uint8_t *)(p) + 2)) << 24) | \ |
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183 | ((uint64_t)(*((const uint8_t *)(p) + 3)) << 16) | \ |
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184 | ((uint64_t)(*((const uint8_t *)(p) + 4)) << 8) | \ |
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185 | ((uint64_t)(*((const uint8_t *)(p) + 5)) << 0))) |
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186 | |
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187 | #define EXTRACT_56BITS(p) \ |
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188 | ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 0)) << 48) | \ |
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189 | ((uint64_t)(*((const uint8_t *)(p) + 1)) << 40) | \ |
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190 | ((uint64_t)(*((const uint8_t *)(p) + 2)) << 32) | \ |
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191 | ((uint64_t)(*((const uint8_t *)(p) + 3)) << 24) | \ |
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192 | ((uint64_t)(*((const uint8_t *)(p) + 4)) << 16) | \ |
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193 | ((uint64_t)(*((const uint8_t *)(p) + 5)) << 8) | \ |
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194 | ((uint64_t)(*((const uint8_t *)(p) + 6)) << 0))) |
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195 | |
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196 | /* |
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197 | * Macros to extract possibly-unaligned little-endian integral values. |
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198 | * XXX - do loads on little-endian machines that support unaligned loads? |
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199 | */ |
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200 | #define EXTRACT_LE_8BITS(p) (*(p)) |
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201 | #define EXTRACT_LE_16BITS(p) \ |
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202 | ((uint16_t)(((uint16_t)(*((const uint8_t *)(p) + 1)) << 8) | \ |
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203 | ((uint16_t)(*((const uint8_t *)(p) + 0)) << 0))) |
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204 | #define EXTRACT_LE_32BITS(p) \ |
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205 | ((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 3)) << 24) | \ |
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206 | ((uint32_t)(*((const uint8_t *)(p) + 2)) << 16) | \ |
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207 | ((uint32_t)(*((const uint8_t *)(p) + 1)) << 8) | \ |
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208 | ((uint32_t)(*((const uint8_t *)(p) + 0)) << 0))) |
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209 | #define EXTRACT_LE_24BITS(p) \ |
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210 | ((uint32_t)(((uint32_t)(*((const uint8_t *)(p) + 2)) << 16) | \ |
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211 | ((uint32_t)(*((const uint8_t *)(p) + 1)) << 8) | \ |
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212 | ((uint32_t)(*((const uint8_t *)(p) + 0)) << 0))) |
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213 | #define EXTRACT_LE_64BITS(p) \ |
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214 | ((uint64_t)(((uint64_t)(*((const uint8_t *)(p) + 7)) << 56) | \ |
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215 | ((uint64_t)(*((const uint8_t *)(p) + 6)) << 48) | \ |
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216 | ((uint64_t)(*((const uint8_t *)(p) + 5)) << 40) | \ |
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217 | ((uint64_t)(*((const uint8_t *)(p) + 4)) << 32) | \ |
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218 | ((uint64_t)(*((const uint8_t *)(p) + 3)) << 24) | \ |
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219 | ((uint64_t)(*((const uint8_t *)(p) + 2)) << 16) | \ |
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220 | ((uint64_t)(*((const uint8_t *)(p) + 1)) << 8) | \ |
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221 | ((uint64_t)(*((const uint8_t *)(p) + 0)) << 0))) |
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