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annotate contrib/python-zstandard/zstd/common/bitstream.h @ 30822:b54a2984cdd4

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zstd: vendor python-zstandard 0.6.0 Commit 63c68d6f5fc8de4afd9bde81b13b537beb4e47e8 from https://github.com/indygreg/python-zstandard is imported without modifications (other than removing unwanted files). This includes minor performance and feature improvements. It also changes the vendored zstd library from 1.1.1 to 1.1.2. # no-check-commit
author Gregory Szorc <gregory.szorc@gmail.com>
date Sat, 14 Jan 2017 19:41:43 -0800
parents 2e484bdea8c4
children b1fb341d8a61
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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1 /* ******************************************************************
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2 bitstream
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3 Part of FSE library
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4 header file (to include)
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5 Copyright (C) 2013-2016, Yann Collet.
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6
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7 BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
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8
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9 Redistribution and use in source and binary forms, with or without
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10 modification, are permitted provided that the following conditions are
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11 met:
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12
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13 * Redistributions of source code must retain the above copyright
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14 notice, this list of conditions and the following disclaimer.
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15 * Redistributions in binary form must reproduce the above
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16 copyright notice, this list of conditions and the following disclaimer
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17 in the documentation and/or other materials provided with the
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18 distribution.
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19
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20 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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21 "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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22 LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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23 A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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24 OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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25 SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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26 LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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27 DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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28 THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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29 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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30 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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31
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32 You can contact the author at :
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33 - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
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34 ****************************************************************** */
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35 #ifndef BITSTREAM_H_MODULE
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36 #define BITSTREAM_H_MODULE
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37
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38 #if defined (__cplusplus)
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39 extern "C" {
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40 #endif
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41
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42
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43 /*
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44 * This API consists of small unitary functions, which must be inlined for best performance.
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45 * Since link-time-optimization is not available for all compilers,
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46 * these functions are defined into a .h to be included.
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47 */
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48
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49 /*-****************************************
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50 * Dependencies
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51 ******************************************/
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52 #include "mem.h" /* unaligned access routines */
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53 #include "error_private.h" /* error codes and messages */
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54
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55
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56 /*=========================================
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57 * Target specific
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58 =========================================*/
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59 #if defined(__BMI__) && defined(__GNUC__)
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60 # include <immintrin.h> /* support for bextr (experimental) */
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61 #endif
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62
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63
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64 /*-******************************************
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65 * bitStream encoding API (write forward)
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66 ********************************************/
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67 /* bitStream can mix input from multiple sources.
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68 * A critical property of these streams is that they encode and decode in **reverse** direction.
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69 * So the first bit sequence you add will be the last to be read, like a LIFO stack.
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70 */
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71 typedef struct
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72 {
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73 size_t bitContainer;
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74 int bitPos;
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75 char* startPtr;
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76 char* ptr;
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77 char* endPtr;
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78 } BIT_CStream_t;
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79
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80 MEM_STATIC size_t BIT_initCStream(BIT_CStream_t* bitC, void* dstBuffer, size_t dstCapacity);
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81 MEM_STATIC void BIT_addBits(BIT_CStream_t* bitC, size_t value, unsigned nbBits);
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82 MEM_STATIC void BIT_flushBits(BIT_CStream_t* bitC);
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83 MEM_STATIC size_t BIT_closeCStream(BIT_CStream_t* bitC);
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84
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85 /* Start with initCStream, providing the size of buffer to write into.
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86 * bitStream will never write outside of this buffer.
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87 * `dstCapacity` must be >= sizeof(bitD->bitContainer), otherwise @return will be an error code.
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88 *
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89 * bits are first added to a local register.
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90 * Local register is size_t, hence 64-bits on 64-bits systems, or 32-bits on 32-bits systems.
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91 * Writing data into memory is an explicit operation, performed by the flushBits function.
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92 * Hence keep track how many bits are potentially stored into local register to avoid register overflow.
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93 * After a flushBits, a maximum of 7 bits might still be stored into local register.
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94 *
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95 * Avoid storing elements of more than 24 bits if you want compatibility with 32-bits bitstream readers.
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96 *
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97 * Last operation is to close the bitStream.
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98 * The function returns the final size of CStream in bytes.
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99 * If data couldn't fit into `dstBuffer`, it will return a 0 ( == not storable)
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100 */
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101
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102
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103 /*-********************************************
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104 * bitStream decoding API (read backward)
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105 **********************************************/
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106 typedef struct
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107 {
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108 size_t bitContainer;
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109 unsigned bitsConsumed;
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110 const char* ptr;
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111 const char* start;
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112 } BIT_DStream_t;
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113
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114 typedef enum { BIT_DStream_unfinished = 0,
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115 BIT_DStream_endOfBuffer = 1,
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116 BIT_DStream_completed = 2,
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117 BIT_DStream_overflow = 3 } BIT_DStream_status; /* result of BIT_reloadDStream() */
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118 /* 1,2,4,8 would be better for bitmap combinations, but slows down performance a bit ... :( */
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119
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120 MEM_STATIC size_t BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, size_t srcSize);
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121 MEM_STATIC size_t BIT_readBits(BIT_DStream_t* bitD, unsigned nbBits);
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122 MEM_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD);
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123 MEM_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t* bitD);
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124
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125
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126 /* Start by invoking BIT_initDStream().
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127 * A chunk of the bitStream is then stored into a local register.
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128 * Local register size is 64-bits on 64-bits systems, 32-bits on 32-bits systems (size_t).
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129 * You can then retrieve bitFields stored into the local register, **in reverse order**.
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130 * Local register is explicitly reloaded from memory by the BIT_reloadDStream() method.
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parents:
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131 * A reload guarantee a minimum of ((8*sizeof(bitD->bitContainer))-7) bits when its result is BIT_DStream_unfinished.
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
132 * Otherwise, it can be less than that, so proceed accordingly.
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
133 * Checking if DStream has reached its end can be performed with BIT_endOfDStream().
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
134 */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
135
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
136
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
137 /*-****************************************
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
138 * unsafe API
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
139 ******************************************/
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
140 MEM_STATIC void BIT_addBitsFast(BIT_CStream_t* bitC, size_t value, unsigned nbBits);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
141 /* faster, but works only if value is "clean", meaning all high bits above nbBits are 0 */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
142
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
143 MEM_STATIC void BIT_flushBitsFast(BIT_CStream_t* bitC);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
144 /* unsafe version; does not check buffer overflow */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
145
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
146 MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, unsigned nbBits);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
147 /* faster, but works only if nbBits >= 1 */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
148
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
149
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
150
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
151 /*-**************************************************************
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
152 * Internal functions
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
153 ****************************************************************/
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
154 MEM_STATIC unsigned BIT_highbit32 (register U32 val)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
155 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
156 # if defined(_MSC_VER) /* Visual */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
157 unsigned long r=0;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
158 _BitScanReverse ( &r, val );
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
159 return (unsigned) r;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
160 # elif defined(__GNUC__) && (__GNUC__ >= 3) /* Use GCC Intrinsic */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
161 return 31 - __builtin_clz (val);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
162 # else /* Software version */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
163 static const unsigned DeBruijnClz[32] = { 0, 9, 1, 10, 13, 21, 2, 29, 11, 14, 16, 18, 22, 25, 3, 30, 8, 12, 20, 28, 15, 17, 24, 7, 19, 27, 23, 6, 26, 5, 4, 31 };
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
164 U32 v = val;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
165 v |= v >> 1;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
166 v |= v >> 2;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
167 v |= v >> 4;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
168 v |= v >> 8;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
169 v |= v >> 16;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
170 return DeBruijnClz[ (U32) (v * 0x07C4ACDDU) >> 27];
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
171 # endif
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
172 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
173
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
174 /*===== Local Constants =====*/
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
175 static const unsigned BIT_mask[] = { 0, 1, 3, 7, 0xF, 0x1F, 0x3F, 0x7F, 0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF, 0x1FFFF, 0x3FFFF, 0x7FFFF, 0xFFFFF, 0x1FFFFF, 0x3FFFFF, 0x7FFFFF, 0xFFFFFF, 0x1FFFFFF, 0x3FFFFFF }; /* up to 26 bits */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
176
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
177
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
178 /*-**************************************************************
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
179 * bitStream encoding
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
180 ****************************************************************/
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
181 /*! BIT_initCStream() :
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
182 * `dstCapacity` must be > sizeof(void*)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
183 * @return : 0 if success,
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
184 otherwise an error code (can be tested using ERR_isError() ) */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
185 MEM_STATIC size_t BIT_initCStream(BIT_CStream_t* bitC, void* startPtr, size_t dstCapacity)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
186 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
187 bitC->bitContainer = 0;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
188 bitC->bitPos = 0;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
189 bitC->startPtr = (char*)startPtr;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
190 bitC->ptr = bitC->startPtr;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
191 bitC->endPtr = bitC->startPtr + dstCapacity - sizeof(bitC->ptr);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
192 if (dstCapacity <= sizeof(bitC->ptr)) return ERROR(dstSize_tooSmall);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
193 return 0;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
194 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
195
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
196 /*! BIT_addBits() :
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
197 can add up to 26 bits into `bitC`.
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
198 Does not check for register overflow ! */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
199 MEM_STATIC void BIT_addBits(BIT_CStream_t* bitC, size_t value, unsigned nbBits)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
200 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
201 bitC->bitContainer |= (value & BIT_mask[nbBits]) << bitC->bitPos;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
202 bitC->bitPos += nbBits;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
203 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
204
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
205 /*! BIT_addBitsFast() :
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
206 * works only if `value` is _clean_, meaning all high bits above nbBits are 0 */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
207 MEM_STATIC void BIT_addBitsFast(BIT_CStream_t* bitC, size_t value, unsigned nbBits)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
208 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
209 bitC->bitContainer |= value << bitC->bitPos;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
210 bitC->bitPos += nbBits;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
211 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
212
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
213 /*! BIT_flushBitsFast() :
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
214 * unsafe version; does not check buffer overflow */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
215 MEM_STATIC void BIT_flushBitsFast(BIT_CStream_t* bitC)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
216 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
217 size_t const nbBytes = bitC->bitPos >> 3;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
218 MEM_writeLEST(bitC->ptr, bitC->bitContainer);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
219 bitC->ptr += nbBytes;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
220 bitC->bitPos &= 7;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
221 bitC->bitContainer >>= nbBytes*8; /* if bitPos >= sizeof(bitContainer)*8 --> undefined behavior */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
222 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
223
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
224 /*! BIT_flushBits() :
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
225 * safe version; check for buffer overflow, and prevents it.
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
226 * note : does not signal buffer overflow. This will be revealed later on using BIT_closeCStream() */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
227 MEM_STATIC void BIT_flushBits(BIT_CStream_t* bitC)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
228 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
229 size_t const nbBytes = bitC->bitPos >> 3;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
230 MEM_writeLEST(bitC->ptr, bitC->bitContainer);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
231 bitC->ptr += nbBytes;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
232 if (bitC->ptr > bitC->endPtr) bitC->ptr = bitC->endPtr;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
233 bitC->bitPos &= 7;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
234 bitC->bitContainer >>= nbBytes*8; /* if bitPos >= sizeof(bitContainer)*8 --> undefined behavior */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
235 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
236
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
237 /*! BIT_closeCStream() :
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
238 * @return : size of CStream, in bytes,
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
239 or 0 if it could not fit into dstBuffer */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
240 MEM_STATIC size_t BIT_closeCStream(BIT_CStream_t* bitC)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
241 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
242 BIT_addBitsFast(bitC, 1, 1); /* endMark */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
243 BIT_flushBits(bitC);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
244
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
245 if (bitC->ptr >= bitC->endPtr) return 0; /* doesn't fit within authorized budget : cancel */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
246
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
247 return (bitC->ptr - bitC->startPtr) + (bitC->bitPos > 0);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
248 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
249
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
250
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
251 /*-********************************************************
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
252 * bitStream decoding
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
253 **********************************************************/
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
254 /*! BIT_initDStream() :
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
255 * Initialize a BIT_DStream_t.
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
256 * `bitD` : a pointer to an already allocated BIT_DStream_t structure.
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
257 * `srcSize` must be the *exact* size of the bitStream, in bytes.
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
258 * @return : size of stream (== srcSize) or an errorCode if a problem is detected
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
259 */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
260 MEM_STATIC size_t BIT_initDStream(BIT_DStream_t* bitD, const void* srcBuffer, size_t srcSize)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
261 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
262 if (srcSize < 1) { memset(bitD, 0, sizeof(*bitD)); return ERROR(srcSize_wrong); }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
263
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
264 if (srcSize >= sizeof(bitD->bitContainer)) { /* normal case */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
265 bitD->start = (const char*)srcBuffer;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
266 bitD->ptr = (const char*)srcBuffer + srcSize - sizeof(bitD->bitContainer);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
267 bitD->bitContainer = MEM_readLEST(bitD->ptr);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
268 { BYTE const lastByte = ((const BYTE*)srcBuffer)[srcSize-1];
30822
b54a2984cdd4 zstd: vendor python-zstandard 0.6.0
Gregory Szorc <gregory.szorc@gmail.com>
parents: 30443
diff changeset
269 bitD->bitsConsumed = lastByte ? 8 - BIT_highbit32(lastByte) : 0; /* ensures bitsConsumed is always set */
30443
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
270 if (lastByte == 0) return ERROR(GENERIC); /* endMark not present */ }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
271 } else {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
272 bitD->start = (const char*)srcBuffer;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
273 bitD->ptr = bitD->start;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
274 bitD->bitContainer = *(const BYTE*)(bitD->start);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
275 switch(srcSize)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
276 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
277 case 7: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[6]) << (sizeof(bitD->bitContainer)*8 - 16);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
278 case 6: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[5]) << (sizeof(bitD->bitContainer)*8 - 24);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
279 case 5: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[4]) << (sizeof(bitD->bitContainer)*8 - 32);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
280 case 4: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[3]) << 24;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
281 case 3: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[2]) << 16;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
282 case 2: bitD->bitContainer += (size_t)(((const BYTE*)(srcBuffer))[1]) << 8;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
283 default:;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
284 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
285 { BYTE const lastByte = ((const BYTE*)srcBuffer)[srcSize-1];
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
286 bitD->bitsConsumed = lastByte ? 8 - BIT_highbit32(lastByte) : 0;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
287 if (lastByte == 0) return ERROR(GENERIC); /* endMark not present */ }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
288 bitD->bitsConsumed += (U32)(sizeof(bitD->bitContainer) - srcSize)*8;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
289 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
290
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
291 return srcSize;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
292 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
293
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
294 MEM_STATIC size_t BIT_getUpperBits(size_t bitContainer, U32 const start)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
295 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
296 return bitContainer >> start;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
297 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
298
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
299 MEM_STATIC size_t BIT_getMiddleBits(size_t bitContainer, U32 const start, U32 const nbBits)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
300 {
30822
b54a2984cdd4 zstd: vendor python-zstandard 0.6.0
Gregory Szorc <gregory.szorc@gmail.com>
parents: 30443
diff changeset
301 #if defined(__BMI__) && defined(__GNUC__) && __GNUC__*1000+__GNUC_MINOR__ >= 4008 /* experimental */
30443
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
302 # if defined(__x86_64__)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
303 if (sizeof(bitContainer)==8)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
304 return _bextr_u64(bitContainer, start, nbBits);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
305 else
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
306 # endif
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
307 return _bextr_u32(bitContainer, start, nbBits);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
308 #else
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
309 return (bitContainer >> start) & BIT_mask[nbBits];
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
310 #endif
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
311 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
312
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
313 MEM_STATIC size_t BIT_getLowerBits(size_t bitContainer, U32 const nbBits)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
314 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
315 return bitContainer & BIT_mask[nbBits];
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
316 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
317
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
318 /*! BIT_lookBits() :
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
319 * Provides next n bits from local register.
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
320 * local register is not modified.
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
321 * On 32-bits, maxNbBits==24.
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
322 * On 64-bits, maxNbBits==56.
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
323 * @return : value extracted
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
324 */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
325 MEM_STATIC size_t BIT_lookBits(const BIT_DStream_t* bitD, U32 nbBits)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
326 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
327 #if defined(__BMI__) && defined(__GNUC__) /* experimental; fails if bitD->bitsConsumed + nbBits > sizeof(bitD->bitContainer)*8 */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
328 return BIT_getMiddleBits(bitD->bitContainer, (sizeof(bitD->bitContainer)*8) - bitD->bitsConsumed - nbBits, nbBits);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
329 #else
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
330 U32 const bitMask = sizeof(bitD->bitContainer)*8 - 1;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
331 return ((bitD->bitContainer << (bitD->bitsConsumed & bitMask)) >> 1) >> ((bitMask-nbBits) & bitMask);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
332 #endif
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
333 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
334
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
335 /*! BIT_lookBitsFast() :
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
336 * unsafe version; only works only if nbBits >= 1 */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
337 MEM_STATIC size_t BIT_lookBitsFast(const BIT_DStream_t* bitD, U32 nbBits)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
338 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
339 U32 const bitMask = sizeof(bitD->bitContainer)*8 - 1;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
340 return (bitD->bitContainer << (bitD->bitsConsumed & bitMask)) >> (((bitMask+1)-nbBits) & bitMask);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
341 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
342
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
343 MEM_STATIC void BIT_skipBits(BIT_DStream_t* bitD, U32 nbBits)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
344 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
345 bitD->bitsConsumed += nbBits;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
346 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
347
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
348 /*! BIT_readBits() :
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
349 * Read (consume) next n bits from local register and update.
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
350 * Pay attention to not read more than nbBits contained into local register.
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
351 * @return : extracted value.
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
352 */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
353 MEM_STATIC size_t BIT_readBits(BIT_DStream_t* bitD, U32 nbBits)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
354 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
355 size_t const value = BIT_lookBits(bitD, nbBits);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
356 BIT_skipBits(bitD, nbBits);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
357 return value;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
358 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
359
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
360 /*! BIT_readBitsFast() :
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
361 * unsafe version; only works only if nbBits >= 1 */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
362 MEM_STATIC size_t BIT_readBitsFast(BIT_DStream_t* bitD, U32 nbBits)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
363 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
364 size_t const value = BIT_lookBitsFast(bitD, nbBits);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
365 BIT_skipBits(bitD, nbBits);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
366 return value;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
367 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
368
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
369 /*! BIT_reloadDStream() :
30822
b54a2984cdd4 zstd: vendor python-zstandard 0.6.0
Gregory Szorc <gregory.szorc@gmail.com>
parents: 30443
diff changeset
370 * Refill `bitD` from buffer previously set in BIT_initDStream() .
30443
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
371 * This function is safe, it guarantees it will not read beyond src buffer.
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
372 * @return : status of `BIT_DStream_t` internal register.
30822
b54a2984cdd4 zstd: vendor python-zstandard 0.6.0
Gregory Szorc <gregory.szorc@gmail.com>
parents: 30443
diff changeset
373 if status == BIT_DStream_unfinished, internal register is filled with >= (sizeof(bitD->bitContainer)*8 - 7) bits */
30443
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
374 MEM_STATIC BIT_DStream_status BIT_reloadDStream(BIT_DStream_t* bitD)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
375 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
376 if (bitD->bitsConsumed > (sizeof(bitD->bitContainer)*8)) /* should not happen => corruption detected */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
377 return BIT_DStream_overflow;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
378
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
379 if (bitD->ptr >= bitD->start + sizeof(bitD->bitContainer)) {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
380 bitD->ptr -= bitD->bitsConsumed >> 3;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
381 bitD->bitsConsumed &= 7;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
382 bitD->bitContainer = MEM_readLEST(bitD->ptr);
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
383 return BIT_DStream_unfinished;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
384 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
385 if (bitD->ptr == bitD->start) {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
386 if (bitD->bitsConsumed < sizeof(bitD->bitContainer)*8) return BIT_DStream_endOfBuffer;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
387 return BIT_DStream_completed;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
388 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
389 { U32 nbBytes = bitD->bitsConsumed >> 3;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
390 BIT_DStream_status result = BIT_DStream_unfinished;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
391 if (bitD->ptr - nbBytes < bitD->start) {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
392 nbBytes = (U32)(bitD->ptr - bitD->start); /* ptr > start */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
393 result = BIT_DStream_endOfBuffer;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
394 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
395 bitD->ptr -= nbBytes;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
396 bitD->bitsConsumed -= nbBytes*8;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
397 bitD->bitContainer = MEM_readLEST(bitD->ptr); /* reminder : srcSize > sizeof(bitD) */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
398 return result;
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
399 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
400 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
401
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
402 /*! BIT_endOfDStream() :
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
403 * @return Tells if DStream has exactly reached its end (all bits consumed).
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
404 */
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
405 MEM_STATIC unsigned BIT_endOfDStream(const BIT_DStream_t* DStream)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
406 {
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
407 return ((DStream->ptr == DStream->start) && (DStream->bitsConsumed == sizeof(DStream->bitContainer)*8));
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
408 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
409
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
410 #if defined (__cplusplus)
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
411 }
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
412 #endif
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
413
2e484bdea8c4 zstd: vendor zstd 1.1.1
Gregory Szorc <gregory.szorc@gmail.com>
parents:
diff changeset
414 #endif /* BITSTREAM_H_MODULE */