/External/7z/C/Ppmd8.c

/* Ppmd8.c -- PPMdI codec

2010-03-24 : Igor Pavlov : Public domain

This code is based on PPMd var.I (2002): Dmitry Shkarin : Public domain */



#include <memory.h>



#include "Ppmd8.h"



const Byte PPMD8_kExpEscape[16] = { 25, 14, 9, 7, 5, 5, 4, 4, 4, 3, 3, 3, 2, 2, 2, 2 };

static const UInt16 kInitBinEsc[] = { 0x3CDD, 0x1F3F, 0x59BF, 0x48F3, 0x64A1, 0x5ABC, 0x6632, 0x6051};



#define MAX_FREQ 124

#define UNIT_SIZE 12



#define U2B(nu) ((UInt32)(nu) * UNIT_SIZE)

#define U2I(nu) (p->Units2Indx[(nu) - 1])

#define I2U(indx) (p->Indx2Units[indx])



#ifdef PPMD_32BIT

  #define REF(ptr) (ptr)

#else

  #define REF(ptr) ((UInt32)((Byte *)(ptr) - (p)->Base))

#endif



#define STATS_REF(ptr) ((CPpmd_State_Ref)REF(ptr))



#define CTX(ref) ((CPpmd8_Context *)Ppmd8_GetContext(p, ref))

#define STATS(ctx) Ppmd8_GetStats(p, ctx)

#define ONE_STATE(ctx) Ppmd8Context_OneState(ctx)

#define SUFFIX(ctx) CTX((ctx)->Suffix)



typedef CPpmd8_Context * CTX_PTR;



struct CPpmd8_Node_;



typedef

  #ifdef PPMD_32BIT

    struct CPpmd8_Node_ *

  #else

    UInt32

  #endif

  CPpmd8_Node_Ref;



typedef struct CPpmd8_Node_

{

  UInt32 Stamp;

  CPpmd8_Node_Ref Next;

  UInt32 NU;

} CPpmd8_Node;



#ifdef PPMD_32BIT

  #define NODE(ptr) (ptr)

#else

  #define NODE(offs) ((CPpmd8_Node *)(p->Base + (offs)))

#endif



#define EMPTY_NODE 0xFFFFFFFF



void Ppmd8_Construct(CPpmd8 *p)

{

  unsigned i, k, m;



  p->Base = 0;



  for (i = 0, k = 0; i < PPMD_NUM_INDEXES; i++)

  {

    unsigned step = (i >= 12 ? 4 : (i >> 2) + 1);

    do { p->Units2Indx[k++] = (Byte)i; } while(--step);

    p->Indx2Units[i] = (Byte)k;

  }



  p->NS2BSIndx[0] = (0 << 1);

  p->NS2BSIndx[1] = (1 << 1);

  memset(p->NS2BSIndx + 2, (2 << 1), 9);

  memset(p->NS2BSIndx + 11, (3 << 1), 256 - 11);



  for (i = 0; i < 5; i++)

    p->NS2Indx[i] = (Byte)i;

  for (m = i, k = 1; i < 260; i++)

  {

    p->NS2Indx[i] = (Byte)m;

    if (--k == 0)

      k = (++m) - 4;

  }

}



void Ppmd8_Free(CPpmd8 *p, ISzAlloc *alloc)

{

  alloc->Free(alloc, p->Base);

  p->Size = 0;

  p->Base = 0;

}



Bool Ppmd8_Alloc(CPpmd8 *p, UInt32 size, ISzAlloc *alloc)

{

  if (p->Base == 0 || p->Size != size)

  {

    Ppmd8_Free(p, alloc);

    p->AlignOffset =

      #ifdef PPMD_32BIT

        (4 - size) & 3;

      #else

        4 - (size & 3);

      #endif

    if ((p->Base = (Byte *)alloc->Alloc(alloc, p->AlignOffset + size)) == 0)

      return False;

    p->Size = size;

  }

  return True;

}



static void InsertNode(CPpmd8 *p, void *node, unsigned indx)

{

  ((CPpmd8_Node *)node)->Stamp = EMPTY_NODE;

  ((CPpmd8_Node *)node)->Next = (CPpmd8_Node_Ref)p->FreeList[indx];

  ((CPpmd8_Node *)node)->NU = I2U(indx);

  p->FreeList[indx] = REF(node);

  p->Stamps[indx]++;

}



static void *RemoveNode(CPpmd8 *p, unsigned indx)

{

  CPpmd8_Node *node = NODE((CPpmd8_Node_Ref)p->FreeList[indx]);

  p->FreeList[indx] = node->Next;

  p->Stamps[indx]--;

  return node;

}



static void SplitBlock(CPpmd8 *p, void *ptr, unsigned oldIndx, unsigned newIndx)

{

  unsigned i, nu = I2U(oldIndx) - I2U(newIndx);

  ptr = (Byte *)ptr + U2B(I2U(newIndx));

  if (I2U(i = U2I(nu)) != nu)

  {

    unsigned k = I2U(--i);

    InsertNode(p, ((Byte *)ptr) + U2B(k), nu - k - 1);

  }

  InsertNode(p, ptr, i);

}



static void GlueFreeBlocks(CPpmd8 *p)

{

  CPpmd8_Node_Ref head = 0;

  CPpmd8_Node_Ref *prev = &head;

  unsigned i;



  p->GlueCount = 1 << 13;

  memset(p->Stamps, 0, sizeof(p->Stamps));

  

  /* Order-0 context is always at top UNIT, so we don't need guard NODE at the end.

     All blocks up to p->LoUnit can be free, so we need guard NODE at LoUnit. */

  if (p->LoUnit != p->HiUnit)

    ((CPpmd8_Node *)p->LoUnit)->Stamp = 0;



  /* Glue free blocks */

  for (i = 0; i < PPMD_NUM_INDEXES; i++)

  {

    CPpmd8_Node_Ref next = (CPpmd8_Node_Ref)p->FreeList[i];

    p->FreeList[i] = 0;

    while (next != 0)

    {

      CPpmd8_Node *node = NODE(next);

      if (node->NU != 0)

      {

        CPpmd8_Node *node2;

        *prev = next;

        prev = &(node->Next);

        while ((node2 = node + node->NU)->Stamp == EMPTY_NODE)

        {

          node->NU += node2->NU;

          node2->NU = 0;

        }

      }

      next = node->Next;

    }

  }

  *prev = 0;

  

  /* Fill lists of free blocks */

  while (head != 0)

  {

    CPpmd8_Node *node = NODE(head);

    unsigned nu;

    head = node->Next;

    nu = node->NU;

    if (nu == 0)

      continue;

    for (; nu > 128; nu -= 128, node += 128)

      InsertNode(p, node, PPMD_NUM_INDEXES - 1);

    if (I2U(i = U2I(nu)) != nu)

    {

      unsigned k = I2U(--i);

      InsertNode(p, node + k, nu - k - 1);

    }

    InsertNode(p, node, i);

  }

}



static void *AllocUnitsRare(CPpmd8 *p, unsigned indx)

{

  unsigned i;

  void *retVal;

  if (p->GlueCount == 0)

  {

    GlueFreeBlocks(p);

    if (p->FreeList[indx] != 0)

      return RemoveNode(p, indx);

  }

  i = indx;

  do

  {

    if (++i == PPMD_NUM_INDEXES)

    {

      UInt32 numBytes = U2B(I2U(indx));

      p->GlueCount--;

      return ((UInt32)(p->UnitsStart - p->Text) > numBytes) ? (p->UnitsStart -= numBytes) : (NULL);

    }

  }

  while (p->FreeList[i] == 0);

  retVal = RemoveNode(p, i);

  SplitBlock(p, retVal, i, indx);

  return retVal;

}



static void *AllocUnits(CPpmd8 *p, unsigned indx)

{

  UInt32 numBytes;

  if (p->FreeList[indx] != 0)

    return RemoveNode(p, indx);

  numBytes = U2B(I2U(indx));

  if (numBytes <= (UInt32)(p->HiUnit - p->LoUnit))

  {

    void *retVal = p->LoUnit;

    p->LoUnit += numBytes;

    return retVal;

  }

  return AllocUnitsRare(p, indx);

}



#define MyMem12Cpy(dest, src, num) \

  { UInt32 *d = (UInt32 *)dest; const UInt32 *s = (const UInt32 *)src; UInt32 n = num; \

    do { d[0] = s[0]; d[1] = s[1]; d[2] = s[2]; s += 3; d += 3; } while(--n); }



static void *ShrinkUnits(CPpmd8 *p, void *oldPtr, unsigned oldNU, unsigned newNU)

{

  unsigned i0 = U2I(oldNU);

  unsigned i1 = U2I(newNU);

  if (i0 == i1)

    return oldPtr;

  if (p->FreeList[i1] != 0)

  {

    void *ptr = RemoveNode(p, i1);

    MyMem12Cpy(ptr, oldPtr, newNU);

    InsertNode(p, oldPtr, i0);

    return ptr;

  }

  SplitBlock(p, oldPtr, i0, i1);

  return oldPtr;

}



static void FreeUnits(CPpmd8 *p, void *ptr, unsigned nu)

{

  InsertNode(p, ptr, U2I(nu));

}



static void SpecialFreeUnit(CPpmd8 *p, void *ptr)

{

  if ((Byte *)ptr != p->UnitsStart)

    InsertNode(p, ptr, 0);

  else

  {

    #ifdef PPMD8_FREEZE_SUPPORT

    *(UInt32 *)ptr = EMPTY_NODE; /* it's used for (Flags == 0xFF) check in RemoveBinContexts */

    #endif

    p->UnitsStart += UNIT_SIZE;

  }

}



static void *MoveUnitsUp(CPpmd8 *p, void *oldPtr, unsigned nu)

{

  unsigned indx = U2I(nu);

  void *ptr;

  if ((Byte *)oldPtr > p->UnitsStart + 16 * 1024 || REF(oldPtr) > p->FreeList[indx])

    return oldPtr;

  ptr = RemoveNode(p, indx);

  MyMem12Cpy(ptr, oldPtr, nu);

  if ((Byte*)oldPtr != p->UnitsStart)

    InsertNode(p, oldPtr, indx);

  else

    p->UnitsStart += U2B(I2U(indx));

  return ptr;

}



static void ExpandTextArea(CPpmd8 *p)

{

  UInt32 count[PPMD_NUM_INDEXES];

  unsigned i;

  memset(count, 0, sizeof(count));

  if (p->LoUnit != p->HiUnit)

    ((CPpmd8_Node *)p->LoUnit)->Stamp = 0;

  

  {

    CPpmd8_Node *node = (CPpmd8_Node *)p->UnitsStart;

    for (; node->Stamp == EMPTY_NODE; node += node->NU)

    {

      node->Stamp = 0;

      count[U2I(node->NU)]++;

    }

    p->UnitsStart = (Byte *)node;

  }

  

  for (i = 0; i < PPMD_NUM_INDEXES; i++)

  {

    CPpmd8_Node_Ref *next = (CPpmd8_Node_Ref *)&p->FreeList[i];

    while (count[i] != 0)

    {

      CPpmd8_Node *node = NODE(*next);

      while (node->Stamp == 0)

      {

        *next = node->Next;

        node = NODE(*next);

        p->Stamps[i]--;

        if (--count[i] == 0)

          break;

      }

      next = &node->Next;

    }

  }

}



#define SUCCESSOR(p) ((CPpmd_Void_Ref)((p)->SuccessorLow | ((UInt32)(p)->SuccessorHigh << 16)))



static void SetSuccessor(CPpmd_State *p, CPpmd_Void_Ref v)

{

  (p)->SuccessorLow = (UInt16)((UInt32)(v) & 0xFFFF);

  (p)->SuccessorHigh = (UInt16)(((UInt32)(v) >> 16) & 0xFFFF);

}



#define RESET_TEXT(offs) { p->Text = p->Base + p->AlignOffset + (offs); }



static void RestartModel(CPpmd8 *p)

{

  unsigned i, k, m, r;



  memset(p->FreeList, 0, sizeof(p->FreeList));

  memset(p->Stamps, 0, sizeof(p->Stamps));

  RESET_TEXT(0);

  p->HiUnit = p->Text + p->Size;

  p->LoUnit = p->UnitsStart = p->HiUnit - p->Size / 8 / UNIT_SIZE * 7 * UNIT_SIZE;

  p->GlueCount = 0;



  p->OrderFall = p->MaxOrder;

  p->RunLength = p->InitRL = -(Int32)((p->MaxOrder < 12) ? p->MaxOrder : 12) - 1;

  p->PrevSuccess = 0;



  p->MinContext = p->MaxContext = (CTX_PTR)(p->HiUnit -= UNIT_SIZE); /* AllocContext(p); */

  p->MinContext->Suffix = 0;

  p->MinContext->NumStats = 255;

  p->MinContext->Flags = 0;

  p->MinContext->SummFreq = 256 + 1;

  p->FoundState = (CPpmd_State *)p->LoUnit; /* AllocUnits(p, PPMD_NUM_INDEXES - 1); */

  p->LoUnit += U2B(256 / 2);

  p->MinContext->Stats = REF(p->FoundState);

  for (i = 0; i < 256; i++)

  {

    CPpmd_State *s = &p->FoundState[i];

    s->Symbol = (Byte)i;

    s->Freq = 1;

    SetSuccessor(s, 0);

  }



  for (i = m = 0; m < 25; m++)

  {

    while (p->NS2Indx[i] == m)

      i++;

    for (k = 0; k < 8; k++)

    {

      UInt16 val = (UInt16)(PPMD_BIN_SCALE - kInitBinEsc[k] / (i + 1));

      UInt16 *dest = p->BinSumm[m] + k;

      for (r = 0; r < 64; r += 8)

        dest[r] = val;

    }

  }



  for (i = m = 0; m < 24; m++)

  {

    while (p->NS2Indx[i + 3] == m + 3)

      i++;

    for (k = 0; k < 32; k++)

    {

      CPpmd_See *s = &p->See[m][k];

      s->Summ = (UInt16)((2 * i + 5) << (s->Shift = PPMD_PERIOD_BITS - 4));

      s->Count = 7;

    }

  }

}



void Ppmd8_Init(CPpmd8 *p, unsigned maxOrder, unsigned restoreMethod)

{

  p->MaxOrder = maxOrder;

  p->RestoreMethod = restoreMethod;

  RestartModel(p);

  p->DummySee.Shift = PPMD_PERIOD_BITS;

  p->DummySee.Summ = 0; /* unused */

  p->DummySee.Count = 64; /* unused */

}



static void Refresh(CPpmd8 *p, CTX_PTR ctx, unsigned oldNU, unsigned scale)

{

  unsigned i = ctx->NumStats, escFreq, sumFreq, flags;

  CPpmd_State *s = (CPpmd_State *)ShrinkUnits(p, STATS(ctx), oldNU, (i + 2) >> 1);

  ctx->Stats = REF(s);

  #ifdef PPMD8_FREEZE_SUPPORT

  /* fixed over Shkarin's code. Fixed code is not compatible with original code for some files in FREEZE mode. */

  scale |= (ctx->SummFreq >= ((UInt32)1 << 15));

  #endif

  flags = (ctx->Flags & (0x10 + 0x04 * scale)) + 0x08 * (s->Symbol >= 0x40);

  escFreq = ctx->SummFreq - s->Freq;

  sumFreq = (s->Freq = (Byte)((s->Freq + scale) >> scale));

  do

  {

    escFreq -= (++s)->Freq;

    sumFreq += (s->Freq = (Byte)((s->Freq + scale) >> scale));

    flags |= 0x08 * (s->Symbol >= 0x40);

  }

  while (--i);

  ctx->SummFreq = (UInt16)(sumFreq + ((escFreq + scale) >> scale));

  ctx->Flags = (Byte)flags;

}



static void SwapStates(CPpmd_State *t1, CPpmd_State *t2)

{

  CPpmd_State tmp = *t1;

  *t1 = *t2;

  *t2 = tmp;

}



static CPpmd_Void_Ref CutOff(CPpmd8 *p, CTX_PTR ctx, unsigned order)

{

  int i;

  unsigned tmp;

  CPpmd_State *s;

  

  if (!ctx->NumStats)

  {

    s = ONE_STATE(ctx);

    if ((Byte *)Ppmd8_GetPtr(p, SUCCESSOR(s)) >= p->UnitsStart)

    {

      if (order < p->MaxOrder)

        SetSuccessor(s, CutOff(p, CTX(SUCCESSOR(s)), order + 1));

      else

        SetSuccessor(s, 0);

      if (SUCCESSOR(s) || order <= 9) /* O_BOUND */

        return REF(ctx);

    }

    SpecialFreeUnit(p, ctx);

    return 0;

  }



  ctx->Stats = STATS_REF(MoveUnitsUp(p, STATS(ctx), tmp = ((unsigned)ctx->NumStats + 2) >> 1));



  for (s = STATS(ctx) + (i = ctx->NumStats); s >= STATS(ctx); s--)

    if ((Byte *)Ppmd8_GetPtr(p, SUCCESSOR(s)) < p->UnitsStart)

    {

      CPpmd_State *s2 = STATS(ctx) + (i--);

      SetSuccessor(s, 0);

      SwapStates(s, s2);

    }

    else if (order < p->MaxOrder)

      SetSuccessor(s, CutOff(p, CTX(SUCCESSOR(s)), order + 1));

    else

      SetSuccessor(s, 0);

    

  if (i != ctx->NumStats && order)

  {

    ctx->NumStats = (Byte)i;

    s = STATS(ctx);

    if (i < 0)

    {

      FreeUnits(p, s, tmp);

      SpecialFreeUnit(p, ctx);

      return 0;

    }

    if (i == 0)

    {

      ctx->Flags = (ctx->Flags & 0x10) + 0x08 * (s->Symbol >= 0x40);

      *ONE_STATE(ctx) = *s;

      FreeUnits(p, s, tmp);

      ONE_STATE(ctx)->Freq = (Byte)((unsigned)ONE_STATE(ctx)->Freq + 11) >> 3;

    }

    else

      Refresh(p, ctx, tmp, ctx->SummFreq > 16 * i);

  }

  return REF(ctx);

}



#ifdef PPMD8_FREEZE_SUPPORT

static CPpmd_Void_Ref RemoveBinContexts(CPpmd8 *p, CTX_PTR ctx, unsigned order)

{

  CPpmd_State *s;

  if (!ctx->NumStats)

  {

    s = ONE_STATE(ctx);

    if ((Byte *)Ppmd8_GetPtr(p, SUCCESSOR(s)) >= p->UnitsStart && order < p->MaxOrder)

      SetSuccessor(s, RemoveBinContexts(p, CTX(SUCCESSOR(s)), order + 1));

    else

      SetSuccessor(s, 0);

    /* Suffix context can be removed already, since different (high-order)

       Successors may refer to same context. So we check Flags == 0xFF (Stamp == EMPTY_NODE) */

    if (!SUCCESSOR(s) && (!SUFFIX(ctx)->NumStats || SUFFIX(ctx)->Flags == 0xFF))

    {

      FreeUnits(p, ctx, 1);

      return 0;

    }

    else

      return REF(ctx);

  }



  for (s = STATS(ctx) + ctx->NumStats; s >= STATS(ctx); s--)

    if ((Byte *)Ppmd8_GetPtr(p, SUCCESSOR(s)) >= p->UnitsStart && order < p->MaxOrder)

      SetSuccessor(s, RemoveBinContexts(p, CTX(SUCCESSOR(s)), order + 1));

    else

      SetSuccessor(s, 0);

  

  return REF(ctx);

}

#endif



static UInt32 GetUsedMemory(const CPpmd8 *p)

{

  UInt32 v = 0;

  unsigned i;

  for (i = 0; i < PPMD_NUM_INDEXES; i++)

    v += p->Stamps[i] * I2U(i);

  return p->Size - (UInt32)(p->HiUnit - p->LoUnit) - (UInt32)(p->UnitsStart - p->Text) - U2B(v);

}



#ifdef PPMD8_FREEZE_SUPPORT

  #define RESTORE_MODEL(c1, fSuccessor) RestoreModel(p, c1, fSuccessor)

#else

  #define RESTORE_MODEL(c1, fSuccessor) RestoreModel(p, c1)

#endif



static void RestoreModel(CPpmd8 *p, CTX_PTR c1

    #ifdef PPMD8_FREEZE_SUPPORT

    , CTX_PTR fSuccessor

    #endif

    )

{

  CTX_PTR c;

  CPpmd_State *s;

  RESET_TEXT(0);

  for (c = p->MaxContext; c != c1; c = SUFFIX(c))

    if (--(c->NumStats) == 0)

    {

      s = STATS(c);

      c->Flags = (c->Flags & 0x10) + 0x08 * (s->Symbol >= 0x40);

      *ONE_STATE(c) = *s;

      SpecialFreeUnit(p, s);

      ONE_STATE(c)->Freq = (ONE_STATE(c)->Freq + 11) >> 3;

    }

    else

      Refresh(p, c, (c->NumStats+3) >> 1, 0);

 

  for (; c != p->MinContext; c = SUFFIX(c))

    if (!c->NumStats)

      ONE_STATE(c)->Freq -= ONE_STATE(c)->Freq >> 1;

    else if ((c->SummFreq += 4) > 128 + 4 * c->NumStats)

      Refresh(p, c, (c->NumStats + 2) >> 1, 1);



  #ifdef PPMD8_FREEZE_SUPPORT

  if (p->RestoreMethod > PPMD8_RESTORE_METHOD_FREEZE)

  {

    p->MaxContext = fSuccessor;

    p->GlueCount += !(p->Stamps[1] & 1);

  }

  else if (p->RestoreMethod == PPMD8_RESTORE_METHOD_FREEZE)

  {

    while (p->MaxContext->Suffix)

      p->MaxContext = SUFFIX(p->MaxContext);

    RemoveBinContexts(p, p->MaxContext, 0);

    p->RestoreMethod++;

    p->GlueCount = 0;

    p->OrderFall = p->MaxOrder;

  }

  else

  #endif

  if (p->RestoreMethod == PPMD8_RESTORE_METHOD_RESTART || GetUsedMemory(p) < (p->Size >> 1))

    RestartModel(p);

  else

  {

    while (p->MaxContext->Suffix)

      p->MaxContext = SUFFIX(p->MaxContext);

    do

    {

      CutOff(p, p->MaxContext, 0);

      ExpandTextArea(p);

    }

    while (GetUsedMemory(p) > 3 * (p->Size >> 2));

    p->GlueCount = 0;

    p->OrderFall = p->MaxOrder;

  }

}



static CTX_PTR CreateSuccessors(CPpmd8 *p, Bool skip, CPpmd_State *s1, CTX_PTR c)

{

  CPpmd_State upState;

  Byte flags;

  CPpmd_Byte_Ref upBranch = (CPpmd_Byte_Ref)SUCCESSOR(p->FoundState);

  /* fixed over Shkarin's code. Maybe it could work without + 1 too. */

  CPpmd_State *ps[PPMD8_MAX_ORDER + 1];

  unsigned numPs = 0;

  

  if (!skip)

    ps[numPs++] = p->FoundState;

  

  while (c->Suffix)

  {

    CPpmd_Void_Ref successor;

    CPpmd_State *s;

    c = SUFFIX(c);

    if (s1)

    {

      s = s1;

      s1 = NULL;

    }

    else if (c->NumStats != 0)

    {

      for (s = STATS(c); s->Symbol != p->FoundState->Symbol; s++);

      if (s->Freq < MAX_FREQ - 9)

      {

        s->Freq++;

        c->SummFreq++;

      }

    }

    else

    {

      s = ONE_STATE(c);

      s->Freq += (!SUFFIX(c)->NumStats & (s->Freq < 24));

    }

    successor = SUCCESSOR(s);

    if (successor != upBranch)

    {

      c = CTX(successor);

      if (numPs == 0)

        return c;

      break;

    }

    ps[numPs++] = s;

  }

  

  upState.Symbol = *(const Byte *)Ppmd8_GetPtr(p, upBranch);

  SetSuccessor(&upState, upBranch + 1);

  flags = 0x10 * (p->FoundState->Symbol >= 0x40) + 0x08 * (upState.Symbol >= 0x40);



  if (c->NumStats == 0)

    upState.Freq = ONE_STATE(c)->Freq;

  else

  {

    UInt32 cf, s0;

    CPpmd_State *s;

    for (s = STATS(c); s->Symbol != upState.Symbol; s++);

    cf = s->Freq - 1;

    s0 = c->SummFreq - c->NumStats - cf;

    upState.Freq = (Byte)(1 + ((2 * cf <= s0) ? (5 * cf > s0) : ((cf + 2 * s0 - 3) / s0)));

  }



  do

  {

    /* Create Child */

    CTX_PTR c1; /* = AllocContext(p); */

    if (p->HiUnit != p->LoUnit)

      c1 = (CTX_PTR)(p->HiUnit -= UNIT_SIZE);

    else if (p->FreeList[0] != 0)

      c1 = (CTX_PTR)RemoveNode(p, 0);

    else

    {

      c1 = (CTX_PTR)AllocUnitsRare(p, 0);

      if (!c1)

        return NULL;

    }

    c1->NumStats = 0;

    c1->Flags = flags;

    *ONE_STATE(c1) = upState;

    c1->Suffix = REF(c);

    SetSuccessor(ps[--numPs], REF(c1));

    c = c1;

  }

  while (numPs != 0);

  

  return c;

}



static CTX_PTR ReduceOrder(CPpmd8 *p, CPpmd_State *s1, CTX_PTR c)

{

  CPpmd_State *s = NULL;

  CTX_PTR c1 = c;

  CPpmd_Void_Ref upBranch = REF(p->Text);

  

  #ifdef PPMD8_FREEZE_SUPPORT

  /* The BUG in Shkarin's code was fixed: ps could overflow in CUT_OFF mode. */

  CPpmd_State *ps[PPMD8_MAX_ORDER + 1];

  unsigned numPs = 0;

  ps[numPs++] = p->FoundState;

  #endif



  SetSuccessor(p->FoundState, upBranch);

  p->OrderFall++;



  for (;;)

  {

    if (s1)

    {

      c = SUFFIX(c);

      s = s1;

      s1 = NULL;

    }

    else

    {

      if (!c->Suffix)

      {

        #ifdef PPMD8_FREEZE_SUPPORT

        if (p->RestoreMethod > PPMD8_RESTORE_METHOD_FREEZE)

        {

          do { SetSuccessor(ps[--numPs], REF(c)); } while (numPs);

          RESET_TEXT(1);

          p->OrderFall = 1;

        }

        #endif

        return c;

      }

      c = SUFFIX(c);

      if (c->NumStats)

      {

        if ((s = STATS(c))->Symbol != p->FoundState->Symbol)

          do { s++; } while (s->Symbol != p->FoundState->Symbol);

        if (s->Freq < MAX_FREQ - 9)

        {

          s->Freq += 2;

          c->SummFreq += 2;

        }

      }

      else

      {

        s = ONE_STATE(c);

        s->Freq += (s->Freq < 32);

      }

    }

    if (SUCCESSOR(s))

      break;

    #ifdef PPMD8_FREEZE_SUPPORT

    ps[numPs++] = s;

    #endif

    SetSuccessor(s, upBranch);

    p->OrderFall++;

  }

  

  #ifdef PPMD8_FREEZE_SUPPORT

  if (p->RestoreMethod > PPMD8_RESTORE_METHOD_FREEZE)

  {

    c = CTX(SUCCESSOR(s));

    do { SetSuccessor(ps[--numPs], REF(c)); } while (numPs);

    RESET_TEXT(1);

    p->OrderFall = 1;

    return c;

  }

  else

  #endif

  if (SUCCESSOR(s) <= upBranch)

  {

    CTX_PTR successor;

    CPpmd_State *s1 = p->FoundState;

    p->FoundState = s;



    successor = CreateSuccessors(p, False, NULL, c);

    if (successor == NULL)

      SetSuccessor(s, 0);

    else

      SetSuccessor(s, REF(successor));

    p->FoundState = s1;

  }

  

  if (p->OrderFall == 1 && c1 == p->MaxContext)

  {

    SetSuccessor(p->FoundState, SUCCESSOR(s));

    p->Text--;

  }

  if (SUCCESSOR(s) == 0)

    return NULL;

  return CTX(SUCCESSOR(s));

}



static void UpdateModel(CPpmd8 *p)

{

  CPpmd_Void_Ref successor, fSuccessor = SUCCESSOR(p->FoundState);

  CTX_PTR c;

  unsigned s0, ns, fFreq = p->FoundState->Freq;

  Byte flag, fSymbol = p->FoundState->Symbol;

  CPpmd_State *s = NULL;

  

  if (p->FoundState->Freq < MAX_FREQ / 4 && p->MinContext->Suffix != 0)

  {

    c = SUFFIX(p->MinContext);

    

    if (c->NumStats == 0)

    {

      s = ONE_STATE(c);

      if (s->Freq < 32)

        s->Freq++;

    }

    else

    {

      s = STATS(c);

      if (s->Symbol != p->FoundState->Symbol)

      {

        do { s++; } while (s->Symbol != p->FoundState->Symbol);

        if (s[0].Freq >= s[-1].Freq)

        {

          SwapStates(&s[0], &s[-1]);

          s--;

        }

      }

      if (s->Freq < MAX_FREQ - 9)

      {

        s->Freq += 2;

        c->SummFreq += 2;

      }

    }

  }

  

  c = p->MaxContext;

  if (p->OrderFall == 0 && fSuccessor)

  {

    CTX_PTR cs = CreateSuccessors(p, True, s, p->MinContext);

    if (cs == 0)

    {

      SetSuccessor(p->FoundState, 0);

      RESTORE_MODEL(c, CTX(fSuccessor));

    }

    else

    {

      SetSuccessor(p->FoundState, REF(cs));

      p->MaxContext = cs;

    }

    return;

  }

  

  *p->Text++ = p->FoundState->Symbol;

  successor = REF(p->Text);

  if (p->Text >= p->UnitsStart)

  {

    RESTORE_MODEL(c, CTX(fSuccessor)); /* check it */

    return;

  }

  

  if (!fSuccessor)

  {

    CTX_PTR cs = ReduceOrder(p, s, p->MinContext);

    if (cs == NULL)

    {

      RESTORE_MODEL(c, 0);

      return;

    }

    fSuccessor = REF(cs);

  }

  else if ((Byte *)Ppmd8_GetPtr(p, fSuccessor) < p->UnitsStart)

  {

    CTX_PTR cs = CreateSuccessors(p, False, s, p->MinContext);

    if (cs == NULL)

    {

      RESTORE_MODEL(c, 0);

      return;

    }

    fSuccessor = REF(cs);

  }

  

  if (--p->OrderFall == 0)

  {

    successor = fSuccessor;

    p->Text -= (p->MaxContext != p->MinContext);

  }

  #ifdef PPMD8_FREEZE_SUPPORT

  else if (p->RestoreMethod > PPMD8_RESTORE_METHOD_FREEZE)

  {

    successor = fSuccessor;

    RESET_TEXT(0);

    p->OrderFall = 0;

  }

  #endif

  

  s0 = p->MinContext->SummFreq - (ns = p->MinContext->NumStats) - fFreq;

  flag = 0x08 * (fSymbol >= 0x40);

  

  for (; c != p->MinContext; c = SUFFIX(c))

  {

    unsigned ns1;

    UInt32 cf, sf;

    if ((ns1 = c->NumStats) != 0)

    {

      if ((ns1 & 1) != 0)

      {

        /* Expand for one UNIT */

        unsigned oldNU = (ns1 + 1) >> 1;

        unsigned i = U2I(oldNU);

        if (i != U2I(oldNU + 1))

        {

          void *ptr = AllocUnits(p, i + 1);

          void *oldPtr;

          if (!ptr)

          {

            RESTORE_MODEL(c, CTX(fSuccessor));

            return;

          }

          oldPtr = STATS(c);

          MyMem12Cpy(ptr, oldPtr, oldNU);

          InsertNode(p, oldPtr, i);

          c->Stats = STATS_REF(ptr);

        }

      }

      c->SummFreq = (UInt16)(c->SummFreq + (3 * ns1 + 1 < ns));

    }

    else

    {

      CPpmd_State *s = (CPpmd_State*)AllocUnits(p, 0);

      if (!s)

      {

        RESTORE_MODEL(c, CTX(fSuccessor));

        return;

      }

      *s = *ONE_STATE(c);

      c->Stats = REF(s);

      if (s->Freq < MAX_FREQ / 4 - 1)

        s->Freq <<= 1;

      else

        s->Freq = MAX_FREQ - 4;

      c->SummFreq = (UInt16)(s->Freq + p->InitEsc + (ns > 2));

    }

    cf = 2 * fFreq * (c->SummFreq + 6);

    sf = (UInt32)s0 + c->SummFreq;

    if (cf < 6 * sf)

    {

      cf = 1 + (cf > sf) + (cf >= 4 * sf);

      c->SummFreq += 4;

    }

    else

    {

      cf = 4 + (cf > 9 * sf) + (cf > 12 * sf) + (cf > 15 * sf);

      c->SummFreq = (UInt16)(c->SummFreq + cf);

    }

    {

      CPpmd_State *s = STATS(c) + ns1 + 1;

      SetSuccessor(s, successor);

      s->Symbol = fSymbol;

      s->Freq = (Byte)cf;

      c->Flags |= flag;

      c->NumStats = (Byte)(ns1 + 1);

    }

  }

  p->MaxContext = p->MinContext = CTX(fSuccessor);

}

  

static void Rescale(CPpmd8 *p)

{

  unsigned i, adder, sumFreq, escFreq;

  CPpmd_State *stats = STATS(p->MinContext);

  CPpmd_State *s = p->FoundState;

  {

    CPpmd_State tmp = *s;

    for (; s != stats; s--)

      s[0] = s[-1];

    *s = tmp;

  }

  escFreq = p->MinContext->SummFreq - s->Freq;

  s->Freq += 4;

  adder = (p->OrderFall != 0

      #ifdef PPMD8_FREEZE_SUPPORT

      || p->RestoreMethod > PPMD8_RESTORE_METHOD_FREEZE

      #endif

      );

  s->Freq = (Byte)((s->Freq + adder) >> 1);

  sumFreq = s->Freq;

  

  i = p->MinContext->NumStats;

  do

  {

    escFreq -= (++s)->Freq;

    s->Freq = (Byte)((s->Freq + adder) >> 1);

    sumFreq += s->Freq;

    if (s[0].Freq > s[-1].Freq)

    {

      CPpmd_State *s1 = s;

      CPpmd_State tmp = *s1;

      do

        s1[0] = s1[-1];

      while (--s1 != stats && tmp.Freq > s1[-1].Freq);

      *s1 = tmp;

    }

  }

  while (--i);

  

  if (s->Freq == 0)

  {

    unsigned numStats = p->MinContext->NumStats;

    unsigned n0, n1;

    do { i++; } while ((--s)->Freq == 0);

    escFreq += i;

    p->MinContext->NumStats = (Byte)(p->MinContext->NumStats - i);

    if (p->MinContext->NumStats == 0)

    {

      CPpmd_State tmp = *stats;

      tmp.Freq = (Byte)((2 * tmp.Freq + escFreq - 1) / escFreq);

      if (tmp.Freq > MAX_FREQ / 3)

        tmp.Freq = MAX_FREQ / 3;

      InsertNode(p, stats, U2I((numStats + 2) >> 1));

      p->MinContext->Flags = (p->MinContext->Flags & 0x10) + 0x08 * (tmp.Symbol >= 0x40);

      *(p->FoundState = ONE_STATE(p->MinContext)) = tmp;

      return;

    }

    n0 = (numStats + 2) >> 1;

    n1 = (p->MinContext->NumStats + 2) >> 1;

    if (n0 != n1)

      p->MinContext->Stats = STATS_REF(ShrinkUnits(p, stats, n0, n1));

    p->MinContext->Flags &= ~0x08;

    p->MinContext->Flags |= 0x08 * ((s = STATS(p->MinContext))->Symbol >= 0x40);

    i = p->MinContext->NumStats;

    do { p->MinContext->Flags |= 0x08*((++s)->Symbol >= 0x40); } while (--i);

  }

  p->MinContext->SummFreq = (UInt16)(sumFreq + escFreq - (escFreq >> 1));

  p->MinContext->Flags |= 0x4;

  p->FoundState = STATS(p->MinContext);

}



CPpmd_See *Ppmd8_MakeEscFreq(CPpmd8 *p, unsigned numMasked1, UInt32 *escFreq)

{

  CPpmd_See *see;

  if (p->MinContext->NumStats != 0xFF)

  {

    see = p->See[p->NS2Indx[p->MinContext->NumStats + 2] - 3] +

        (p->MinContext->SummFreq > 11 * ((unsigned)p->MinContext->NumStats + 1)) +

        2 * (2 * (unsigned)p->MinContext->NumStats <

        ((unsigned)SUFFIX(p->MinContext)->NumStats + numMasked1)) +

        p->MinContext->Flags;

    {

      unsigned r = (see->Summ >> see->Shift);

      see->Summ = (UInt16)(see->Summ - r);

      *escFreq = r + (r == 0);

    }

  }

  else

  {

    see = &p->DummySee;

    *escFreq = 1;

  }

  return see;

}



static void NextContext(CPpmd8 *p)

{

  CTX_PTR c = CTX(SUCCESSOR(p->FoundState));

  if (p->OrderFall == 0 && (Byte *)c >= p->UnitsStart)

    p->MinContext = p->MaxContext = c;

  else

  {

    UpdateModel(p);

    p->MinContext = p->MaxContext;

  }

}



void Ppmd8_Update1(CPpmd8 *p)

{

  CPpmd_State *s = p->FoundState;

  s->Freq += 4;

  p->MinContext->SummFreq += 4;

  if (s[0].Freq > s[-1].Freq)

  {

    SwapStates(&s[0], &s[-1]);

    p->FoundState = --s;

    if (s->Freq > MAX_FREQ)

      Rescale(p);

  }

  NextContext(p);

}



void Ppmd8_Update1_0(CPpmd8 *p)

{

  p->PrevSuccess = (2 * p->FoundState->Freq >= p->MinContext->SummFreq);

  p->RunLength += p->PrevSuccess;

  p->MinContext->SummFreq += 4;

  if ((p->FoundState->Freq += 4) > MAX_FREQ)

    Rescale(p);

  NextContext(p);

}



void Ppmd8_UpdateBin(CPpmd8 *p)

{

  p->FoundState->Freq = (Byte)(p->FoundState->Freq + (p->FoundState->Freq < 196));

  p->PrevSuccess = 1;

  p->RunLength++;

  NextContext(p);

}



void Ppmd8_Update2(CPpmd8 *p)

{

  p->MinContext->SummFreq += 4;

  if ((p->FoundState->Freq += 4) > MAX_FREQ)

    Rescale(p);

  p->RunLength = p->InitRL;

  UpdateModel(p);

  p->MinContext = p->MaxContext;

}



/* H->I changes:

  NS2Indx

  GlewCount, and Glue method

  BinSum

  See / EscFreq

  CreateSuccessors updates more suffix contexts

  UpdateModel consts.

  PrevSuccess Update

*/