view release on metacpan or  search on metacpan

ext/zstd/lib/common/huf.h  view on Meta::CPAN

/* ******************************************************************
 * huff0 huffman codec,
 * part of Finite State Entropy library
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * You can contact the author at :
 * - Source repository : https://github.com/Cyan4973/FiniteStateEntropy
 *
 * This source code is licensed under both the BSD-style license (found in the
 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
 * in the COPYING file in the root directory of this source tree).
 * You may select, at your option, one of the above-listed licenses.
****************************************************************** */

#if defined (__cplusplus)
extern "C" {
#endif

#ifndef HUF_H_298734234
#define HUF_H_298734234

/* *** Dependencies *** */
#include "zstd_deps.h"    /* size_t */
#include "mem.h"          /* U32 */
#define FSE_STATIC_LINKING_ONLY
#include "fse.h"


/* ***   Tool functions *** */
#define HUF_BLOCKSIZE_MAX (128 * 1024)   /**< maximum input size for a single block compressed with HUF_compress */
size_t HUF_compressBound(size_t size);   /**< maximum compressed size (worst case) */

/* Error Management */
unsigned    HUF_isError(size_t code);       /**< tells if a return value is an error code */
const char* HUF_getErrorName(size_t code);  /**< provides error code string (useful for debugging) */


#define HUF_WORKSPACE_SIZE ((8 << 10) + 512 /* sorting scratch space */)
#define HUF_WORKSPACE_SIZE_U64 (HUF_WORKSPACE_SIZE / sizeof(U64))

/* *** Constants *** */
#define HUF_TABLELOG_MAX      12      /* max runtime value of tableLog (due to static allocation); can be modified up to HUF_TABLELOG_ABSOLUTEMAX */
#define HUF_TABLELOG_DEFAULT  11      /* default tableLog value when none specified */
#define HUF_SYMBOLVALUE_MAX  255

#define HUF_TABLELOG_ABSOLUTEMAX  12  /* absolute limit of HUF_MAX_TABLELOG. Beyond that value, code does not work */
#if (HUF_TABLELOG_MAX > HUF_TABLELOG_ABSOLUTEMAX)
#  error "HUF_TABLELOG_MAX is too large !"
#endif


/* ****************************************
*  Static allocation
******************************************/
/* HUF buffer bounds */
#define HUF_CTABLEBOUND 129
#define HUF_BLOCKBOUND(size) (size + (size>>8) + 8)   /* only true when incompressible is pre-filtered with fast heuristic */
#define HUF_COMPRESSBOUND(size) (HUF_CTABLEBOUND + HUF_BLOCKBOUND(size))   /* Macro version, useful for static allocation */

/* static allocation of HUF's Compression Table */
/* this is a private definition, just exposed for allocation and strict aliasing purpose. never EVER access its members directly */
typedef size_t HUF_CElt;   /* consider it an incomplete type */
#define HUF_CTABLE_SIZE_ST(maxSymbolValue)   ((maxSymbolValue)+2)   /* Use tables of size_t, for proper alignment */
#define HUF_CTABLE_SIZE(maxSymbolValue)       (HUF_CTABLE_SIZE_ST(maxSymbolValue) * sizeof(size_t))
#define HUF_CREATE_STATIC_CTABLE(name, maxSymbolValue) \
    HUF_CElt name[HUF_CTABLE_SIZE_ST(maxSymbolValue)] /* no final ; */

/* static allocation of HUF's DTable */
typedef U32 HUF_DTable;
#define HUF_DTABLE_SIZE(maxTableLog)   (1 + (1<<(maxTableLog)))
#define HUF_CREATE_STATIC_DTABLEX1(DTable, maxTableLog) \
        HUF_DTable DTable[HUF_DTABLE_SIZE((maxTableLog)-1)] = { ((U32)((maxTableLog)-1) * 0x01000001) }
#define HUF_CREATE_STATIC_DTABLEX2(DTable, maxTableLog) \
        HUF_DTable DTable[HUF_DTABLE_SIZE(maxTableLog)] = { ((U32)(maxTableLog) * 0x01000001) }


/* ****************************************
*  Advanced decompression functions
******************************************/

/**
 * Huffman flags bitset.
 * For all flags, 0 is the default value.
 */
typedef enum {
    /**
     * If compiled with DYNAMIC_BMI2: Set flag only if the CPU supports BMI2 at runtime.
     * Otherwise: Ignored.
     */
    HUF_flags_bmi2 = (1 << 0),
    /**
     * If set: Test possible table depths to find the one that produces the smallest header + encoded size.
     * If unset: Use heuristic to find the table depth.
     */
    HUF_flags_optimalDepth = (1 << 1),
    /**
     * If set: If the previous table can encode the input, always reuse the previous table.
     * If unset: If the previous table can encode the input, reuse the previous table if it results in a smaller output.
     */
    HUF_flags_preferRepeat = (1 << 2),
    /**
     * If set: Sample the input and check if the sample is uncompressible, if it is then don't attempt to compress.
     * If unset: Always histogram the entire input.
     */
    HUF_flags_suspectUncompressible = (1 << 3),
    /**
     * If set: Don't use assembly implementations
     * If unset: Allow using assembly implementations
     */
    HUF_flags_disableAsm = (1 << 4),
    /**
     * If set: Don't use the fast decoding loop, always use the fallback decoding loop.
     * If unset: Use the fast decoding loop when possible.
     */
    HUF_flags_disableFast = (1 << 5)
} HUF_flags_e;