xref: /aosp_15_r20/external/lzma/C/Ppmd8.h (revision f6dc9357d832569d4d1f5d24eacdb3935a1ae8e6)

/* Ppmd8.h -- Ppmd8 (PPMdI) compression codec
2023-04-02 : Igor Pavlov : Public domain
This code is based on:
  PPMd var.I (2002): Dmitry Shkarin : Public domain
  Carryless rangecoder (1999): Dmitry Subbotin : Public domain */

#ifndef ZIP7_INC_PPMD8_H
#define ZIP7_INC_PPMD8_H

#include "Ppmd.h"

EXTERN_C_BEGIN

#define PPMD8_MIN_ORDER 2
#define PPMD8_MAX_ORDER 16




struct CPpmd8_Context_;

typedef Ppmd_Ref_Type(struct CPpmd8_Context_) CPpmd8_Context_Ref;

// MY_CPU_pragma_pack_push_1

typedef struct CPpmd8_Context_
{
  Byte NumStats;
  Byte Flags;

  union
  {
    UInt16 SummFreq;
    CPpmd_State2 State2;
  } Union2;

  union
  {
    CPpmd_State_Ref Stats;
    CPpmd_State4 State4;
  } Union4;

  CPpmd8_Context_Ref Suffix;
} CPpmd8_Context;

// MY_CPU_pragma_pop

#define Ppmd8Context_OneState(p) ((CPpmd_State *)&(p)->Union2)

/* PPMdI code rev.2 contains the fix over PPMdI code rev.1.
   But the code PPMdI.2 is not compatible with PPMdI.1 for some files compressed
   in FREEZE mode. So we disable FREEZE mode support. */

// #define PPMD8_FREEZE_SUPPORT

enum
{
  PPMD8_RESTORE_METHOD_RESTART,
  PPMD8_RESTORE_METHOD_CUT_OFF
  #ifdef PPMD8_FREEZE_SUPPORT
  , PPMD8_RESTORE_METHOD_FREEZE
  #endif
  , PPMD8_RESTORE_METHOD_UNSUPPPORTED
};








typedef struct
{
  CPpmd8_Context *MinContext, *MaxContext;
  CPpmd_State *FoundState;
  unsigned OrderFall, InitEsc, PrevSuccess, MaxOrder, RestoreMethod;
  Int32 RunLength, InitRL; /* must be 32-bit at least */

  UInt32 Size;
  UInt32 GlueCount;
  UInt32 AlignOffset;
  Byte *Base, *LoUnit, *HiUnit, *Text, *UnitsStart;

  UInt32 Range;
  UInt32 Code;
  UInt32 Low;
  union
  {
    IByteInPtr In;
    IByteOutPtr Out;
  } Stream;

  Byte Indx2Units[PPMD_NUM_INDEXES + 2]; // +2 for alignment
  Byte Units2Indx[128];
  CPpmd_Void_Ref FreeList[PPMD_NUM_INDEXES];
  UInt32 Stamps[PPMD_NUM_INDEXES];
  Byte NS2BSIndx[256], NS2Indx[260];
  Byte ExpEscape[16];
  CPpmd_See DummySee, See[24][32];
  UInt16 BinSumm[25][64];

} CPpmd8;


void Ppmd8_Construct(CPpmd8 *p);
BoolInt Ppmd8_Alloc(CPpmd8 *p, UInt32 size, ISzAllocPtr alloc);
void Ppmd8_Free(CPpmd8 *p, ISzAllocPtr alloc);
void Ppmd8_Init(CPpmd8 *p, unsigned maxOrder, unsigned restoreMethod);
#define Ppmd8_WasAllocated(p) ((p)->Base != NULL)


/* ---------- Internal Functions ---------- */

#define Ppmd8_GetPtr(p, ptr)     Ppmd_GetPtr(p, ptr)
#define Ppmd8_GetContext(p, ptr) Ppmd_GetPtr_Type(p, ptr, CPpmd8_Context)
#define Ppmd8_GetStats(p, ctx)   Ppmd_GetPtr_Type(p, (ctx)->Union4.Stats, CPpmd_State)

void Ppmd8_Update1(CPpmd8 *p);
void Ppmd8_Update1_0(CPpmd8 *p);
void Ppmd8_Update2(CPpmd8 *p);






#define Ppmd8_GetBinSumm(p) \
    &p->BinSumm[p->NS2Indx[(size_t)Ppmd8Context_OneState(p->MinContext)->Freq - 1]] \
    [ p->PrevSuccess + ((p->RunLength >> 26) & 0x20) \
    + p->NS2BSIndx[Ppmd8_GetContext(p, p->MinContext->Suffix)->NumStats] + \
    + p->MinContext->Flags ]


CPpmd_See *Ppmd8_MakeEscFreq(CPpmd8 *p, unsigned numMasked, UInt32 *scale);


/* 20.01: the original PPMdI encoder and decoder probably could work incorrectly in some rare cases,
   where the original PPMdI code can give "Divide by Zero" operation.
   We use the following fix to allow correct working of encoder and decoder in any cases.
   We correct (Escape_Freq) and (_sum_), if (_sum_) is larger than p->Range) */
#define PPMD8_CORRECT_SUM_RANGE(p, _sum_) if (_sum_ > p->Range /* /1 */) _sum_ = p->Range;


/* ---------- Decode ---------- */

#define PPMD8_SYM_END    (-1)
#define PPMD8_SYM_ERROR  (-2)

/*
You must set (CPpmd8::Stream.In) before Ppmd8_RangeDec_Init()

Ppmd8_DecodeSymbol()
out:
  >= 0 : decoded byte
    -1 : PPMD8_SYM_END   : End of payload marker
    -2 : PPMD8_SYM_ERROR : Data error
*/


BoolInt Ppmd8_Init_RangeDec(CPpmd8 *p);
#define Ppmd8_RangeDec_IsFinishedOK(p) ((p)->Code == 0)
int Ppmd8_DecodeSymbol(CPpmd8 *p);








/* ---------- Encode ---------- */

#define Ppmd8_Init_RangeEnc(p) { (p)->Low = 0; (p)->Range = 0xFFFFFFFF; }
void Ppmd8_Flush_RangeEnc(CPpmd8 *p);
void Ppmd8_EncodeSymbol(CPpmd8 *p, int symbol);


EXTERN_C_END

#endif