File indexing completed on 2025-03-09 04:13:31

 /* 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 "Precomp.h"
 
 #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
 */