/* Ppmd7.c -- PPMdH codec

2010-03-12 : Igor Pavlov : Public domain

This code is based on PPMd var.H (2001): Dmitry Shkarin : Public domain */

#include "archive_platform.h"

#include <stdlib.h>

#include "archive_ppmd7_private.h"

#ifdef PPMD_32BIT

  #define Ppmd7_GetPtr(p, ptr) (ptr)

  #define Ppmd7_GetContext(p, ptr) (ptr)

  #define Ppmd7_GetStats(p, ctx) ((ctx)->Stats)

#else

  #define Ppmd7_GetPtr(p, offs) ((void *)((p)->Base + (offs)))

  #define Ppmd7_GetContext(p, offs) ((CPpmd7_Context *)Ppmd7_GetPtr((p), (offs)))

  #define Ppmd7_GetStats(p, ctx) ((CPpmd_State *)Ppmd7_GetPtr((p), ((ctx)->Stats)))

#endif

#define Ppmd7_GetBinSumm(p) \

    &p->BinSumm[Ppmd7Context_OneState(p->MinContext)->Freq - 1][p->PrevSuccess + \

    p->NS2BSIndx[Ppmd7_GetContext(p, p->MinContext->Suffix)->NumStats - 1] + \

    (p->HiBitsFlag = p->HB2Flag[p->FoundState->Symbol]) + \

    2 * p->HB2Flag[Ppmd7Context_OneState(p->MinContext)->Symbol] + \

    ((p->RunLength >> 26) & 0x20)]

#define kTopValue (1 << 24)

#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) ((CPpmd7_Context *)Ppmd7_GetContext(p, ref))

#define STATS(ctx) Ppmd7_GetStats(p, ctx)

#define ONE_STATE(ctx) Ppmd7Context_OneState(ctx)

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

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

static const Byte PPMD7_kExpEscape[16] = { 25, 14, 9, 7, 5, 5, 4, 4, 4, 3, 3, 3, 2, 2, 2, 2 };

typedef CPpmd7_Context * CTX_PTR;

struct CPpmd7_Node_;

typedef

  #ifdef PPMD_32BIT

    struct CPpmd7_Node_ *

  #else

    UInt32

  #endif

  CPpmd7_Node_Ref;

typedef struct CPpmd7_Node_

{

  UInt16 Stamp; /* must be at offset 0 as CPpmd7_Context::NumStats. Stamp=0 means free */

  UInt16 NU;

  CPpmd7_Node_Ref Next; /* must be at offset >= 4 */

  CPpmd7_Node_Ref Prev;

} CPpmd7_Node;

#ifdef PPMD_32BIT

  #define NODE(ptr) (ptr)

#else

  #define NODE(offs) ((CPpmd7_Node *)(p->Base + (offs)))

#endif

static void Ppmd7_Update1(CPpmd7 *p);

static void Ppmd7_Update1_0(CPpmd7 *p);

static void Ppmd7_Update2(CPpmd7 *p);

static void Ppmd7_UpdateBin(CPpmd7 *p);

static CPpmd_See *Ppmd7_MakeEscFreq(CPpmd7 *p, unsigned numMasked,

                                    UInt32 *scale);

/* ----------- Base ----------- */

static void Ppmd7_Construct(CPpmd7 *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 < 3; i++)

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

  for (m = i, k = 1; i < 256; i++)

  {

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

    if (--k == 0)

      k = (++m) - 2;

  }

  memset(p->HB2Flag, 0, 0x40);

  memset(p->HB2Flag + 0x40, 8, 0x100 - 0x40);

}

static void Ppmd7_Free(CPpmd7 *p)

{

  free(p->Base);

  p->Size = 0;

  p->Base = 0;

}

static Bool Ppmd7_Alloc(CPpmd7 *p, UInt32 size)

{

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

  {

    /* RestartModel() below assumes that p->Size >= UNIT_SIZE

       (see the calculation of m->MinContext). */

    if (size < UNIT_SIZE) {

      return False;

    }

    Ppmd7_Free(p);

    p->AlignOffset =

      #ifdef PPMD_32BIT

        (4 - size) & 3;

      #else

        4 - (size & 3);

      #endif

    if ((p->Base = malloc(p->AlignOffset + size

        #ifndef PPMD_32BIT

        + UNIT_SIZE

        #endif

        )) == 0)

      return False;

    p->Size = size;

  }

  return True;

}

static void InsertNode(CPpmd7 *p, void *node, unsigned indx)

{

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

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

}

static void *RemoveNode(CPpmd7 *p, unsigned indx)

{

  CPpmd_Void_Ref *node = (CPpmd_Void_Ref *)Ppmd7_GetPtr(p, p->FreeList[indx]);

  p->FreeList[indx] = *node;

  return node;

}

static void SplitBlock(CPpmd7 *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(CPpmd7 *p)

{

  #ifdef PPMD_32BIT

  CPpmd7_Node headItem;

  CPpmd7_Node_Ref head = &headItem;

  #else

  CPpmd7_Node_Ref head = p->AlignOffset + p->Size;

  #endif

  CPpmd7_Node_Ref n = head;

  unsigned i;

  p->GlueCount = 255;

  /* create doubly-linked list of free blocks */

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

  {

    UInt16 nu = I2U(i);

    CPpmd7_Node_Ref next = (CPpmd7_Node_Ref)p->FreeList[i];

    p->FreeList[i] = 0;

    while (next != 0)

    {

      CPpmd7_Node *node = NODE(next);

      node->Next = n;

      n = NODE(n)->Prev = next;

      next = *(const CPpmd7_Node_Ref *)node;

      node->Stamp = 0;

      node->NU = (UInt16)nu;

    }

  }

  NODE(head)->Stamp = 1;

  NODE(head)->Next = n;

  NODE(n)->Prev = head;

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

    ((CPpmd7_Node *)p->LoUnit)->Stamp = 1;

  /* Glue free blocks */

  while (n != head)

  {

    CPpmd7_Node *node = NODE(n);

    UInt32 nu = (UInt32)node->NU;

    for (;;)

    {

      CPpmd7_Node *node2 = NODE(n) + nu;

      nu += node2->NU;

      if (node2->Stamp != 0 || nu >= 0x10000)

        break;

      NODE(node2->Prev)->Next = node2->Next;

      NODE(node2->Next)->Prev = node2->Prev;

      node->NU = (UInt16)nu;

    }

    n = node->Next;

  }

  /* Fill lists of free blocks */

  for (n = NODE(head)->Next; n != head;)

  {

    CPpmd7_Node *node = NODE(n);

    unsigned nu;

    CPpmd7_Node_Ref next = node->Next;

    for (nu = node->NU; 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);

    n = next;

  }

}

static void *AllocUnitsRare(CPpmd7 *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(CPpmd7 *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) do {         \

  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);              \

} while (0)

static void *ShrinkUnits(CPpmd7 *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;

}

#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);

}

static void RestartModel(CPpmd7 *p)

{

  unsigned i, k, m;

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

  p->Text = p->Base + p->AlignOffset;

  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 = 256;

  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 = 0; i < 128; i++)

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

    {

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

      UInt16 val = (UInt16)(PPMD_BIN_SCALE - kInitBinEsc[k] / (i + 2));

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

        dest[m] = val;

    }

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

    for (k = 0; k < 16; k++)

    {

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

      s->Summ = (UInt16)((5 * i + 10) << (s->Shift = PPMD_PERIOD_BITS - 4));

      s->Count = 4;

    }

}

static void Ppmd7_Init(CPpmd7 *p, unsigned maxOrder)

{

  p->MaxOrder = maxOrder;

  RestartModel(p);

  p->DummySee.Shift = PPMD_PERIOD_BITS;

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

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

}

static CTX_PTR CreateSuccessors(CPpmd7 *p, Bool skip)

{

  CPpmd_State upState;

  CTX_PTR c = p->MinContext;

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

  CPpmd_State *ps[PPMD7_MAX_ORDER];

  unsigned numPs = 0;

  if (!skip)

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

  while (c->Suffix)

  {

    CPpmd_Void_Ref successor;

    CPpmd_State *s;

    c = SUFFIX(c);

    if (c->NumStats != 1)

    {

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

    }

    else

      s = ONE_STATE(c);

    successor = SUCCESSOR(s);

    if (successor != upBranch)

    {

      c = CTX(successor);

      if (numPs == 0)

        return c;

      break;

    }

    ps[numPs++] = s;

  }

  upState.Symbol = *(const Byte *)Ppmd7_GetPtr(p, upBranch);

  SetSuccessor(&upState, upBranch + 1);

  if (c->NumStats == 1)

    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) : ((2 * cf + 3 * s0 - 1) / (2 * s0))));

  }

  while (numPs != 0)

  {

    /* 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 = 1;

    *ONE_STATE(c1) = upState;

    c1->Suffix = REF(c);

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

    c = c1;

  }

  return c;

}

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

{

  CPpmd_State tmp = *t1;

  *t1 = *t2;

  *t2 = tmp;

}

static void UpdateModel(CPpmd7 *p)

{

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

  CTX_PTR c;

  unsigned s0, ns;

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

  {

    c = SUFFIX(p->MinContext);

    if (c->NumStats == 1)

    {

      CPpmd_State *s = ONE_STATE(c);

      if (s->Freq < 32)

        s->Freq++;

    }

    else

    {

      CPpmd_State *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;

      }

    }

  }

  if (p->OrderFall == 0)

  {

    p->MinContext = p->MaxContext = CreateSuccessors(p, True);

    if (p->MinContext == 0)

    {

      RestartModel(p);

      return;

    }

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

    return;

  }

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

  successor = REF(p->Text);

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

  {

    RestartModel(p);

    return;

  }

  if (fSuccessor)

  {

    if (fSuccessor <= successor)

    {

      CTX_PTR cs = CreateSuccessors(p, False);

      if (cs == NULL)

      {

        RestartModel(p);

        return;

      }

      fSuccessor = REF(cs);

    }

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

    {

      successor = fSuccessor;

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

    }

  }

  else

  {

    SetSuccessor(p->FoundState, successor);

    fSuccessor = REF(p->MinContext);

  }

  s0 = p->MinContext->SummFreq - (ns = p->MinContext->NumStats) - (p->FoundState->Freq - 1);

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

  {

    unsigned ns1;

    UInt32 cf, sf;

    if ((ns1 = c->NumStats) != 1)

    {

      if ((ns1 & 1) == 0)

      {

        /* Expand for one UNIT */

        unsigned oldNU = ns1 >> 1;

        unsigned i = U2I(oldNU);

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

        {

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

          void *oldPtr;

          if (!ptr)

          {

            RestartModel(p);

            return;

          }

          oldPtr = STATS(c);

          MyMem12Cpy(ptr, oldPtr, oldNU);

          InsertNode(p, oldPtr, i);

          c->Stats = STATS_REF(ptr);

        }

      }

      c->SummFreq = (UInt16)(c->SummFreq + (2 * ns1 < ns) + 2 * ((4 * ns1 <= ns) & (c->SummFreq <= 8 * ns1)));

    }

    else

    {

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

      if (!s)

      {

        RestartModel(p);

        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 > 3));

    }

    cf = 2 * (UInt32)p->FoundState->Freq * (c->SummFreq + 6);

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

    if (cf < 6 * sf)

    {

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

      c->SummFreq += 3;

    }

    else

    {

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

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

    }

    {

      CPpmd_State *s = STATS(c) + ns1;

      SetSuccessor(s, successor);

      s->Symbol = p->FoundState->Symbol;

      s->Freq = (Byte)cf;

      c->NumStats = (UInt16)(ns1 + 1);

    }

  }

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

}

static void Rescale(CPpmd7 *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);

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

  sumFreq = s->Freq;

  i = p->MinContext->NumStats - 1;

  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 = (UInt16)(p->MinContext->NumStats - i);

    if (p->MinContext->NumStats == 1)

    {

      CPpmd_State tmp = *stats;

      do

      {

        tmp.Freq = (Byte)(tmp.Freq - (tmp.Freq >> 1));

        escFreq >>= 1;

      }

      while (escFreq > 1);

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

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

      return;

    }

    n0 = (numStats + 1) >> 1;

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

    if (n0 != n1)

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

  }

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

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

}

static CPpmd_See *Ppmd7_MakeEscFreq(CPpmd7 *p, unsigned numMasked, UInt32 *escFreq)

{

  CPpmd_See *see;

  unsigned nonMasked = p->MinContext->NumStats - numMasked;

  if (p->MinContext->NumStats != 256)

  {

    see = p->See[p->NS2Indx[nonMasked - 1]] +

        (nonMasked < (unsigned)SUFFIX(p->MinContext)->NumStats - p->MinContext->NumStats) +

        2 * (p->MinContext->SummFreq < 11 * p->MinContext->NumStats) +

        4 * (numMasked > nonMasked) +

        p->HiBitsFlag;

    {

      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(CPpmd7 *p)

{

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

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

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

  else

    UpdateModel(p);

}

static void Ppmd7_Update1(CPpmd7 *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);

}

static void Ppmd7_Update1_0(CPpmd7 *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);

}

static void Ppmd7_UpdateBin(CPpmd7 *p)

{

  p->FoundState->Freq = (Byte)(p->FoundState->Freq + (p->FoundState->Freq < 128 ? 1: 0));

  p->PrevSuccess = 1;

  p->RunLength++;

  NextContext(p);

}

static void Ppmd7_Update2(CPpmd7 *p)

{

  p->MinContext->SummFreq += 4;

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

    Rescale(p);

  p->RunLength = p->InitRL;

  UpdateModel(p);

}

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

static Bool Ppmd_RangeDec_Init(CPpmd7z_RangeDec *p)

{

  unsigned i;

  p->Low = p->Bottom = 0;

  p->Range = 0xFFFFFFFF;

  for (i = 0; i < 4; i++)

    p->Code = (p->Code << 8) | p->Stream->Read((void *)p->Stream);

  return (p->Code < 0xFFFFFFFF);

}

static Bool Ppmd7z_RangeDec_Init(CPpmd7z_RangeDec *p)

{

  if (p->Stream->Read((void *)p->Stream) != 0)

    return False;

  return Ppmd_RangeDec_Init(p);

}

static Bool PpmdRAR_RangeDec_Init(CPpmd7z_RangeDec *p)

{

  if (!Ppmd_RangeDec_Init(p))

    return False;

  p->Bottom = 0x8000;

  return True;

}

static UInt32 Range_GetThreshold(void *pp, UInt32 total)

{

  CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;

  return (p->Code - p->Low) / (p->Range /= total);

}

static void Range_Normalize(CPpmd7z_RangeDec *p)

{

  while (1)

  {

    if((p->Low ^ (p->Low + p->Range)) >= kTopValue)

    {

      if(p->Range >= p->Bottom)

        break;

      else

        p->Range = ((uint32_t)(-(int32_t)p->Low)) & (p->Bottom - 1);

    }

    p->Code = (p->Code << 8) | p->Stream->Read((void *)p->Stream);

    p->Range <<= 8;

    p->Low <<= 8;

  }

}

static void Range_Decode_7z(void *pp, UInt32 start, UInt32 size)

{

  CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;

  p->Code -= start * p->Range;

  p->Range *= size;

  Range_Normalize(p);

}

static void Range_Decode_RAR(void *pp, UInt32 start, UInt32 size)

{

  CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;

  p->Low += start * p->Range;

  p->Range *= size;

  Range_Normalize(p);

}

static UInt32 Range_DecodeBit_7z(void *pp, UInt32 size0)

{

  CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;

  UInt32 newBound = (p->Range >> 14) * size0;

  UInt32 symbol;

  if (p->Code < newBound)

  {

    symbol = 0;

    p->Range = newBound;

  }

  else

  {

    symbol = 1;

    p->Code -= newBound;

    p->Range -= newBound;

  }

  Range_Normalize(p);

  return symbol;

}

static UInt32 Range_DecodeBit_RAR(void *pp, UInt32 size0)

{

  CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;

  UInt32 bit, value = p->p.GetThreshold(p, PPMD_BIN_SCALE);

  if(value < size0)

  {

    bit = 0;

    p->p.Decode(p, 0, size0);

  }

  else

  {

    bit = 1;

    p->p.Decode(p, size0, PPMD_BIN_SCALE - size0);

  }

  return bit;

}

static void Ppmd7z_RangeDec_CreateVTable(CPpmd7z_RangeDec *p)

{

  p->p.GetThreshold = Range_GetThreshold;

  p->p.Decode = Range_Decode_7z;