huf.h

  1/* SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause */
  2/* ******************************************************************
  3 * huff0 huffman codec,
  4 * part of Finite State Entropy library
  5 * Copyright (c) Meta Platforms, Inc. and affiliates.
  6 *
  7 * You can contact the author at :
  8 * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
  9 *
 10 * This source code is licensed under both the BSD-style license (found in the
 11 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
 12 * in the COPYING file in the root directory of this source tree).
 13 * You may select, at your option, one of the above-listed licenses.
 14****************************************************************** */
 15
 16#ifndef HUF_H_298734234
 17#define HUF_H_298734234
 18
 19/* *** Dependencies *** */
 20#include "zstd_deps.h"    /* size_t */
 21#include "mem.h"          /* U32 */
 22#define FSE_STATIC_LINKING_ONLY
 23#include "fse.h"
 24
 25/* ***   Tool functions *** */
 26#define HUF_BLOCKSIZE_MAX (128 * 1024)   /*< maximum input size for a single block compressed with HUF_compress */
 27size_t HUF_compressBound(size_t size);   /*< maximum compressed size (worst case) */
 28
 29/* Error Management */
 30unsigned    HUF_isError(size_t code);       /*< tells if a return value is an error code */
 31const char* HUF_getErrorName(size_t code);  /*< provides error code string (useful for debugging) */
 32
 33
 34#define HUF_WORKSPACE_SIZE ((8 << 10) + 512 /* sorting scratch space */)
 35#define HUF_WORKSPACE_SIZE_U64 (HUF_WORKSPACE_SIZE / sizeof(U64))
 36
 37/* *** Constants *** */
 38#define HUF_TABLELOG_MAX      12      /* max runtime value of tableLog (due to static allocation); can be modified up to HUF_TABLELOG_ABSOLUTEMAX */
 39#define HUF_TABLELOG_DEFAULT  11      /* default tableLog value when none specified */
 40#define HUF_SYMBOLVALUE_MAX  255
 41
 42#define HUF_TABLELOG_ABSOLUTEMAX  12  /* absolute limit of HUF_MAX_TABLELOG. Beyond that value, code does not work */
 43#if (HUF_TABLELOG_MAX > HUF_TABLELOG_ABSOLUTEMAX)
 44#  error "HUF_TABLELOG_MAX is too large !"
 45#endif
 46
 47
 48/* ****************************************
 49*  Static allocation
 50******************************************/
 51/* HUF buffer bounds */
 52#define HUF_CTABLEBOUND 129
 53#define HUF_BLOCKBOUND(size) (size + (size>>8) + 8)   /* only true when incompressible is pre-filtered with fast heuristic */
 54#define HUF_COMPRESSBOUND(size) (HUF_CTABLEBOUND + HUF_BLOCKBOUND(size))   /* Macro version, useful for static allocation */
 55
 56/* static allocation of HUF's Compression Table */
 57/* this is a private definition, just exposed for allocation and strict aliasing purpose. never EVER access its members directly */
 58typedef size_t HUF_CElt;   /* consider it an incomplete type */
 59#define HUF_CTABLE_SIZE_ST(maxSymbolValue)   ((maxSymbolValue)+2)   /* Use tables of size_t, for proper alignment */
 60#define HUF_CTABLE_SIZE(maxSymbolValue)       (HUF_CTABLE_SIZE_ST(maxSymbolValue) * sizeof(size_t))
 61#define HUF_CREATE_STATIC_CTABLE(name, maxSymbolValue) \
 62    HUF_CElt name[HUF_CTABLE_SIZE_ST(maxSymbolValue)] /* no final ; */
 63
 64/* static allocation of HUF's DTable */
 65typedef U32 HUF_DTable;
 66#define HUF_DTABLE_SIZE(maxTableLog)   (1 + (1<<(maxTableLog)))
 67#define HUF_CREATE_STATIC_DTABLEX1(DTable, maxTableLog) \
 68        HUF_DTable DTable[HUF_DTABLE_SIZE((maxTableLog)-1)] = { ((U32)((maxTableLog)-1) * 0x01000001) }
 69#define HUF_CREATE_STATIC_DTABLEX2(DTable, maxTableLog) \
 70        HUF_DTable DTable[HUF_DTABLE_SIZE(maxTableLog)] = { ((U32)(maxTableLog) * 0x01000001) }
 71
 72
 73/* ****************************************
 74*  Advanced decompression functions
 75******************************************/
 76
 77/*
 78 * Huffman flags bitset.
 79 * For all flags, 0 is the default value.
 80 */
 81typedef enum {
 82    /*
 83     * If compiled with DYNAMIC_BMI2: Set flag only if the CPU supports BMI2 at runtime.
 84     * Otherwise: Ignored.
 85     */
 86    HUF_flags_bmi2 = (1 << 0),
 87    /*
 88     * If set: Test possible table depths to find the one that produces the smallest header + encoded size.
 89     * If unset: Use heuristic to find the table depth.
 90     */
 91    HUF_flags_optimalDepth = (1 << 1),
 92    /*
 93     * If set: If the previous table can encode the input, always reuse the previous table.
 94     * If unset: If the previous table can encode the input, reuse the previous table if it results in a smaller output.
 95     */
 96    HUF_flags_preferRepeat = (1 << 2),
 97    /*
 98     * If set: Sample the input and check if the sample is uncompressible, if it is then don't attempt to compress.
 99     * If unset: Always histogram the entire input.
100     */
101    HUF_flags_suspectUncompressible = (1 << 3),
102    /*
103     * If set: Don't use assembly implementations
104     * If unset: Allow using assembly implementations
105     */
106    HUF_flags_disableAsm = (1 << 4),
107    /*
108     * If set: Don't use the fast decoding loop, always use the fallback decoding loop.
109     * If unset: Use the fast decoding loop when possible.
110     */
111    HUF_flags_disableFast = (1 << 5)
112} HUF_flags_e;
113
114
115/* ****************************************
116 *  HUF detailed API
117 * ****************************************/
118#define HUF_OPTIMAL_DEPTH_THRESHOLD ZSTD_btultra
119
120/*! HUF_compress() does the following:
121 *  1. count symbol occurrence from source[] into table count[] using FSE_count() (exposed within "fse.h")
122 *  2. (optional) refine tableLog using HUF_optimalTableLog()
123 *  3. build Huffman table from count using HUF_buildCTable()
124 *  4. save Huffman table to memory buffer using HUF_writeCTable()
125 *  5. encode the data stream using HUF_compress4X_usingCTable()
126 *
127 *  The following API allows targeting specific sub-functions for advanced tasks.
128 *  For example, it's possible to compress several blocks using the same 'CTable',
129 *  or to save and regenerate 'CTable' using external methods.
130 */
131unsigned HUF_minTableLog(unsigned symbolCardinality);
132unsigned HUF_cardinality(const unsigned* count, unsigned maxSymbolValue);
133unsigned HUF_optimalTableLog(unsigned maxTableLog, size_t srcSize, unsigned maxSymbolValue, void* workSpace,
134 size_t wkspSize, HUF_CElt* table, const unsigned* count, int flags); /* table is used as scratch space for building and testing tables, not a return value */
135size_t HUF_writeCTable_wksp(void* dst, size_t maxDstSize, const HUF_CElt* CTable, unsigned maxSymbolValue, unsigned huffLog, void* workspace, size_t workspaceSize);
136size_t HUF_compress4X_usingCTable(void* dst, size_t dstSize, const void* src, size_t srcSize, const HUF_CElt* CTable, int flags);
137size_t HUF_estimateCompressedSize(const HUF_CElt* CTable, const unsigned* count, unsigned maxSymbolValue);
138int HUF_validateCTable(const HUF_CElt* CTable, const unsigned* count, unsigned maxSymbolValue);
139
140typedef enum {
141   HUF_repeat_none,  /*< Cannot use the previous table */
142   HUF_repeat_check, /*< Can use the previous table but it must be checked. Note : The previous table must have been constructed by HUF_compress{1, 4}X_repeat */
143   HUF_repeat_valid  /*< Can use the previous table and it is assumed to be valid */
144 } HUF_repeat;
145
146/* HUF_compress4X_repeat() :
147 *  Same as HUF_compress4X_wksp(), but considers using hufTable if *repeat != HUF_repeat_none.
148 *  If it uses hufTable it does not modify hufTable or repeat.
149 *  If it doesn't, it sets *repeat = HUF_repeat_none, and it sets hufTable to the table used.
150 *  If preferRepeat then the old table will always be used if valid.
151 *  If suspectUncompressible then some sampling checks will be run to potentially skip huffman coding */
152size_t HUF_compress4X_repeat(void* dst, size_t dstSize,
153                       const void* src, size_t srcSize,
154                       unsigned maxSymbolValue, unsigned tableLog,
155                       void* workSpace, size_t wkspSize,    /*< `workSpace` must be aligned on 4-bytes boundaries, `wkspSize` must be >= HUF_WORKSPACE_SIZE */
156                       HUF_CElt* hufTable, HUF_repeat* repeat, int flags);
157
158/* HUF_buildCTable_wksp() :
159 *  Same as HUF_buildCTable(), but using externally allocated scratch buffer.
160 * `workSpace` must be aligned on 4-bytes boundaries, and its size must be >= HUF_CTABLE_WORKSPACE_SIZE.
161 */
162#define HUF_CTABLE_WORKSPACE_SIZE_U32 ((4 * (HUF_SYMBOLVALUE_MAX + 1)) + 192)
163#define HUF_CTABLE_WORKSPACE_SIZE (HUF_CTABLE_WORKSPACE_SIZE_U32 * sizeof(unsigned))
164size_t HUF_buildCTable_wksp (HUF_CElt* tree,
165                       const unsigned* count, U32 maxSymbolValue, U32 maxNbBits,
166                             void* workSpace, size_t wkspSize);
167
168/*! HUF_readStats() :
169 *  Read compact Huffman tree, saved by HUF_writeCTable().
170 * `huffWeight` is destination buffer.
171 * @return : size read from `src` , or an error Code .
172 *  Note : Needed by HUF_readCTable() and HUF_readDTableXn() . */
173size_t HUF_readStats(BYTE* huffWeight, size_t hwSize,
174                     U32* rankStats, U32* nbSymbolsPtr, U32* tableLogPtr,
175                     const void* src, size_t srcSize);
176
177/*! HUF_readStats_wksp() :
178 * Same as HUF_readStats() but takes an external workspace which must be
179 * 4-byte aligned and its size must be >= HUF_READ_STATS_WORKSPACE_SIZE.
180 * If the CPU has BMI2 support, pass bmi2=1, otherwise pass bmi2=0.
181 */
182#define HUF_READ_STATS_WORKSPACE_SIZE_U32 FSE_DECOMPRESS_WKSP_SIZE_U32(6, HUF_TABLELOG_MAX-1)
183#define HUF_READ_STATS_WORKSPACE_SIZE (HUF_READ_STATS_WORKSPACE_SIZE_U32 * sizeof(unsigned))
184size_t HUF_readStats_wksp(BYTE* huffWeight, size_t hwSize,
185                          U32* rankStats, U32* nbSymbolsPtr, U32* tableLogPtr,
186                          const void* src, size_t srcSize,
187                          void* workspace, size_t wkspSize,
188                          int flags);
189
190/* HUF_readCTable() :
191 *  Loading a CTable saved with HUF_writeCTable() */
192size_t HUF_readCTable (HUF_CElt* CTable, unsigned* maxSymbolValuePtr, const void* src, size_t srcSize, unsigned *hasZeroWeights);
193
194/* HUF_getNbBitsFromCTable() :
195 *  Read nbBits from CTable symbolTable, for symbol `symbolValue` presumed <= HUF_SYMBOLVALUE_MAX
196 *  Note 1 : If symbolValue > HUF_readCTableHeader(symbolTable).maxSymbolValue, returns 0
197 *  Note 2 : is not inlined, as HUF_CElt definition is private
198 */
199U32 HUF_getNbBitsFromCTable(const HUF_CElt* symbolTable, U32 symbolValue);
200
201typedef struct {
202    BYTE tableLog;
203    BYTE maxSymbolValue;
204    BYTE unused[sizeof(size_t) - 2];
205} HUF_CTableHeader;
206
207/* HUF_readCTableHeader() :
208 *  @returns The header from the CTable specifying the tableLog and the maxSymbolValue.
209 */
210HUF_CTableHeader HUF_readCTableHeader(HUF_CElt const* ctable);
211
212/*
213 * HUF_decompress() does the following:
214 * 1. select the decompression algorithm (X1, X2) based on pre-computed heuristics
215 * 2. build Huffman table from save, using HUF_readDTableX?()
216 * 3. decode 1 or 4 segments in parallel using HUF_decompress?X?_usingDTable()
217 */
218
219/* HUF_selectDecoder() :
220 *  Tells which decoder is likely to decode faster,
221 *  based on a set of pre-computed metrics.
222 * @return : 0==HUF_decompress4X1, 1==HUF_decompress4X2 .
223 *  Assumption : 0 < dstSize <= 128 KB */
224U32 HUF_selectDecoder (size_t dstSize, size_t cSrcSize);
225
226/*
227 *  The minimum workspace size for the `workSpace` used in
228 *  HUF_readDTableX1_wksp() and HUF_readDTableX2_wksp().
229 *
230 *  The space used depends on HUF_TABLELOG_MAX, ranging from ~1500 bytes when
231 *  HUF_TABLE_LOG_MAX=12 to ~1850 bytes when HUF_TABLE_LOG_MAX=15.
232 *  Buffer overflow errors may potentially occur if code modifications result in
233 *  a required workspace size greater than that specified in the following
234 *  macro.
235 */
236#define HUF_DECOMPRESS_WORKSPACE_SIZE ((2 << 10) + (1 << 9))
237#define HUF_DECOMPRESS_WORKSPACE_SIZE_U32 (HUF_DECOMPRESS_WORKSPACE_SIZE / sizeof(U32))
238
239
240/* ====================== */
241/* single stream variants */
242/* ====================== */
243
244size_t HUF_compress1X_usingCTable(void* dst, size_t dstSize, const void* src, size_t srcSize, const HUF_CElt* CTable, int flags);
245/* HUF_compress1X_repeat() :
246 *  Same as HUF_compress1X_wksp(), but considers using hufTable if *repeat != HUF_repeat_none.
247 *  If it uses hufTable it does not modify hufTable or repeat.
248 *  If it doesn't, it sets *repeat = HUF_repeat_none, and it sets hufTable to the table used.
249 *  If preferRepeat then the old table will always be used if valid.
250 *  If suspectUncompressible then some sampling checks will be run to potentially skip huffman coding */
251size_t HUF_compress1X_repeat(void* dst, size_t dstSize,
252                       const void* src, size_t srcSize,
253                       unsigned maxSymbolValue, unsigned tableLog,
254                       void* workSpace, size_t wkspSize,   /*< `workSpace` must be aligned on 4-bytes boundaries, `wkspSize` must be >= HUF_WORKSPACE_SIZE */
255                       HUF_CElt* hufTable, HUF_repeat* repeat, int flags);
256
257size_t HUF_decompress1X_DCtx_wksp(HUF_DTable* dctx, void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize, void* workSpace, size_t wkspSize, int flags);
258#ifndef HUF_FORCE_DECOMPRESS_X1
259size_t HUF_decompress1X2_DCtx_wksp(HUF_DTable* dctx, void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize, void* workSpace, size_t wkspSize, int flags);   /*< double-symbols decoder */
260#endif
261
262/* BMI2 variants.
263 * If the CPU has BMI2 support, pass bmi2=1, otherwise pass bmi2=0.
264 */
265size_t HUF_decompress1X_usingDTable(void* dst, size_t maxDstSize, const void* cSrc, size_t cSrcSize, const HUF_DTable* DTable, int flags);
266#ifndef HUF_FORCE_DECOMPRESS_X2
267size_t HUF_decompress1X1_DCtx_wksp(HUF_DTable* dctx, void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize, void* workSpace, size_t wkspSize, int flags);
268#endif
269size_t HUF_decompress4X_usingDTable(void* dst, size_t maxDstSize, const void* cSrc, size_t cSrcSize, const HUF_DTable* DTable, int flags);
270size_t HUF_decompress4X_hufOnly_wksp(HUF_DTable* dctx, void* dst, size_t dstSize, const void* cSrc, size_t cSrcSize, void* workSpace, size_t wkspSize, int flags);
271#ifndef HUF_FORCE_DECOMPRESS_X2
272size_t HUF_readDTableX1_wksp(HUF_DTable* DTable, const void* src, size_t srcSize, void* workSpace, size_t wkspSize, int flags);
273#endif
274#ifndef HUF_FORCE_DECOMPRESS_X1
275size_t HUF_readDTableX2_wksp(HUF_DTable* DTable, const void* src, size_t srcSize, void* workSpace, size_t wkspSize, int flags);
276#endif
277
278#endif   /* HUF_H_298734234 */