1/* Ppmd7.c -- PPMdH codec
22010-03-12 : Igor Pavlov : Public domain
3This code is based on PPMd var.H (2001): Dmitry Shkarin : Public domain */
4
5#include "Precomp.h"
6
7#include <memory.h>
8
9#include "Ppmd7.h"
10
11const Byte PPMD7_kExpEscape[16] = { 25, 14, 9, 7, 5, 5, 4, 4, 4, 3, 3, 3, 2, 2, 2, 2 };
12static const UInt16 kInitBinEsc[] = { 0x3CDD, 0x1F3F, 0x59BF, 0x48F3, 0x64A1, 0x5ABC, 0x6632, 0x6051};
13
14#define MAX_FREQ 124
15#define UNIT_SIZE 12
16
17#define U2B(nu) ((UInt32)(nu) * UNIT_SIZE)
18#define U2I(nu) (p->Units2Indx[(nu) - 1])
19#define I2U(indx) (p->Indx2Units[indx])
20
21#ifdef PPMD_32BIT
22  #define REF(ptr) (ptr)
23#else
24  #define REF(ptr) ((UInt32)((Byte *)(ptr) - (p)->Base))
25#endif
26
27#define STATS_REF(ptr) ((CPpmd_State_Ref)REF(ptr))
28
29#define CTX(ref) ((CPpmd7_Context *)Ppmd7_GetContext(p, ref))
30#define STATS(ctx) Ppmd7_GetStats(p, ctx)
31#define ONE_STATE(ctx) Ppmd7Context_OneState(ctx)
32#define SUFFIX(ctx) CTX((ctx)->Suffix)
33
34typedef CPpmd7_Context * CTX_PTR;
35
36struct CPpmd7_Node_;
37
38typedef
39  #ifdef PPMD_32BIT
40    struct CPpmd7_Node_ *
41  #else
42    UInt32
43  #endif
44  CPpmd7_Node_Ref;
45
46typedef struct CPpmd7_Node_
47{
48  UInt16 Stamp; /* must be at offset 0 as CPpmd7_Context::NumStats. Stamp=0 means free */
49  UInt16 NU;
50  CPpmd7_Node_Ref Next; /* must be at offset >= 4 */
51  CPpmd7_Node_Ref Prev;
52} CPpmd7_Node;
53
54#ifdef PPMD_32BIT
55  #define NODE(ptr) (ptr)
56#else
57  #define NODE(offs) ((CPpmd7_Node *)(p->Base + (offs)))
58#endif
59
60void Ppmd7_Construct(CPpmd7 *p)
61{
62  unsigned i, k, m;
63
64  p->Base = 0;
65
66  for (i = 0, k = 0; i < PPMD_NUM_INDEXES; i++)
67  {
68    unsigned step = (i >= 12 ? 4 : (i >> 2) + 1);
69    do { p->Units2Indx[k++] = (Byte)i; } while(--step);
70    p->Indx2Units[i] = (Byte)k;
71  }
72
73  p->NS2BSIndx[0] = (0 << 1);
74  p->NS2BSIndx[1] = (1 << 1);
75  memset(p->NS2BSIndx + 2, (2 << 1), 9);
76  memset(p->NS2BSIndx + 11, (3 << 1), 256 - 11);
77
78  for (i = 0; i < 3; i++)
79    p->NS2Indx[i] = (Byte)i;
80  for (m = i, k = 1; i < 256; i++)
81  {
82    p->NS2Indx[i] = (Byte)m;
83    if (--k == 0)
84      k = (++m) - 2;
85  }
86
87  memset(p->HB2Flag, 0, 0x40);
88  memset(p->HB2Flag + 0x40, 8, 0x100 - 0x40);
89}
90
91void Ppmd7_Free(CPpmd7 *p, ISzAlloc *alloc)
92{
93  alloc->Free(alloc, p->Base);
94  p->Size = 0;
95  p->Base = 0;
96}
97
98Bool Ppmd7_Alloc(CPpmd7 *p, UInt32 size, ISzAlloc *alloc)
99{
100  if (p->Base == 0 || p->Size != size)
101  {
102    Ppmd7_Free(p, alloc);
103    p->AlignOffset =
104      #ifdef PPMD_32BIT
105        (4 - size) & 3;
106      #else
107        4 - (size & 3);
108      #endif
109    if ((p->Base = (Byte *)alloc->Alloc(alloc, p->AlignOffset + size
110        #ifndef PPMD_32BIT
111        + UNIT_SIZE
112        #endif
113        )) == 0)
114      return False;
115    p->Size = size;
116  }
117  return True;
118}
119
120static void InsertNode(CPpmd7 *p, void *node, unsigned indx)
121{
122  *((CPpmd_Void_Ref *)node) = p->FreeList[indx];
123  p->FreeList[indx] = REF(node);
124}
125
126static void *RemoveNode(CPpmd7 *p, unsigned indx)
127{
128  CPpmd_Void_Ref *node = (CPpmd_Void_Ref *)Ppmd7_GetPtr(p, p->FreeList[indx]);
129  p->FreeList[indx] = *node;
130  return node;
131}
132
133static void SplitBlock(CPpmd7 *p, void *ptr, unsigned oldIndx, unsigned newIndx)
134{
135  unsigned i, nu = I2U(oldIndx) - I2U(newIndx);
136  ptr = (Byte *)ptr + U2B(I2U(newIndx));
137  if (I2U(i = U2I(nu)) != nu)
138  {
139    unsigned k = I2U(--i);
140    InsertNode(p, ((Byte *)ptr) + U2B(k), nu - k - 1);
141  }
142  InsertNode(p, ptr, i);
143}
144
145static void GlueFreeBlocks(CPpmd7 *p)
146{
147  #ifdef PPMD_32BIT
148  CPpmd7_Node headItem;
149  CPpmd7_Node_Ref head = &headItem;
150  #else
151  CPpmd7_Node_Ref head = p->AlignOffset + p->Size;
152  #endif
153
154  CPpmd7_Node_Ref n = head;
155  unsigned i;
156
157  p->GlueCount = 255;
158
159  /* create doubly-linked list of free blocks */
160  for (i = 0; i < PPMD_NUM_INDEXES; i++)
161  {
162    UInt16 nu = I2U(i);
163    CPpmd7_Node_Ref next = (CPpmd7_Node_Ref)p->FreeList[i];
164    p->FreeList[i] = 0;
165    while (next != 0)
166    {
167      CPpmd7_Node *node = NODE(next);
168      node->Next = n;
169      n = NODE(n)->Prev = next;
170      next = *(const CPpmd7_Node_Ref *)node;
171      node->Stamp = 0;
172      node->NU = (UInt16)nu;
173    }
174  }
175  NODE(head)->Stamp = 1;
176  NODE(head)->Next = n;
177  NODE(n)->Prev = head;
178  if (p->LoUnit != p->HiUnit)
179    ((CPpmd7_Node *)p->LoUnit)->Stamp = 1;
180
181  /* Glue free blocks */
182  while (n != head)
183  {
184    CPpmd7_Node *node = NODE(n);
185    UInt32 nu = (UInt32)node->NU;
186    for (;;)
187    {
188      CPpmd7_Node *node2 = NODE(n) + nu;
189      nu += node2->NU;
190      if (node2->Stamp != 0 || nu >= 0x10000)
191        break;
192      NODE(node2->Prev)->Next = node2->Next;
193      NODE(node2->Next)->Prev = node2->Prev;
194      node->NU = (UInt16)nu;
195    }
196    n = node->Next;
197  }
198
199  /* Fill lists of free blocks */
200  for (n = NODE(head)->Next; n != head;)
201  {
202    CPpmd7_Node *node = NODE(n);
203    unsigned nu;
204    CPpmd7_Node_Ref next = node->Next;
205    for (nu = node->NU; nu > 128; nu -= 128, node += 128)
206      InsertNode(p, node, PPMD_NUM_INDEXES - 1);
207    if (I2U(i = U2I(nu)) != nu)
208    {
209      unsigned k = I2U(--i);
210      InsertNode(p, node + k, nu - k - 1);
211    }
212    InsertNode(p, node, i);
213    n = next;
214  }
215}
216
217static void *AllocUnitsRare(CPpmd7 *p, unsigned indx)
218{
219  unsigned i;
220  void *retVal;
221  if (p->GlueCount == 0)
222  {
223    GlueFreeBlocks(p);
224    if (p->FreeList[indx] != 0)
225      return RemoveNode(p, indx);
226  }
227  i = indx;
228  do
229  {
230    if (++i == PPMD_NUM_INDEXES)
231    {
232      UInt32 numBytes = U2B(I2U(indx));
233      p->GlueCount--;
234      return ((UInt32)(p->UnitsStart - p->Text) > numBytes) ? (p->UnitsStart -= numBytes) : (NULL);
235    }
236  }
237  while (p->FreeList[i] == 0);
238  retVal = RemoveNode(p, i);
239  SplitBlock(p, retVal, i, indx);
240  return retVal;
241}
242
243static void *AllocUnits(CPpmd7 *p, unsigned indx)
244{
245  UInt32 numBytes;
246  if (p->FreeList[indx] != 0)
247    return RemoveNode(p, indx);
248  numBytes = U2B(I2U(indx));
249  if (numBytes <= (UInt32)(p->HiUnit - p->LoUnit))
250  {
251    void *retVal = p->LoUnit;
252    p->LoUnit += numBytes;
253    return retVal;
254  }
255  return AllocUnitsRare(p, indx);
256}
257
258#define MyMem12Cpy(dest, src, num) \
259  { UInt32 *d = (UInt32 *)dest; const UInt32 *s = (const UInt32 *)src; UInt32 n = num; \
260    do { d[0] = s[0]; d[1] = s[1]; d[2] = s[2]; s += 3; d += 3; } while(--n); }
261
262static void *ShrinkUnits(CPpmd7 *p, void *oldPtr, unsigned oldNU, unsigned newNU)
263{
264  unsigned i0 = U2I(oldNU);
265  unsigned i1 = U2I(newNU);
266  if (i0 == i1)
267    return oldPtr;
268  if (p->FreeList[i1] != 0)
269  {
270    void *ptr = RemoveNode(p, i1);
271    MyMem12Cpy(ptr, oldPtr, newNU);
272    InsertNode(p, oldPtr, i0);
273    return ptr;
274  }
275  SplitBlock(p, oldPtr, i0, i1);
276  return oldPtr;
277}
278
279#define SUCCESSOR(p) ((CPpmd_Void_Ref)((p)->SuccessorLow | ((UInt32)(p)->SuccessorHigh << 16)))
280
281static void SetSuccessor(CPpmd_State *p, CPpmd_Void_Ref v)
282{
283  (p)->SuccessorLow = (UInt16)((UInt32)(v) & 0xFFFF);
284  (p)->SuccessorHigh = (UInt16)(((UInt32)(v) >> 16) & 0xFFFF);
285}
286
287static void RestartModel(CPpmd7 *p)
288{
289  unsigned i, k, m;
290
291  memset(p->FreeList, 0, sizeof(p->FreeList));
292  p->Text = p->Base + p->AlignOffset;
293  p->HiUnit = p->Text + p->Size;
294  p->LoUnit = p->UnitsStart = p->HiUnit - p->Size / 8 / UNIT_SIZE * 7 * UNIT_SIZE;
295  p->GlueCount = 0;
296
297  p->OrderFall = p->MaxOrder;
298  p->RunLength = p->InitRL = -(Int32)((p->MaxOrder < 12) ? p->MaxOrder : 12) - 1;
299  p->PrevSuccess = 0;
300
301  p->MinContext = p->MaxContext = (CTX_PTR)(p->HiUnit -= UNIT_SIZE); /* AllocContext(p); */
302  p->MinContext->Suffix = 0;
303  p->MinContext->NumStats = 256;
304  p->MinContext->SummFreq = 256 + 1;
305  p->FoundState = (CPpmd_State *)p->LoUnit; /* AllocUnits(p, PPMD_NUM_INDEXES - 1); */
306  p->LoUnit += U2B(256 / 2);
307  p->MinContext->Stats = REF(p->FoundState);
308  for (i = 0; i < 256; i++)
309  {
310    CPpmd_State *s = &p->FoundState[i];
311    s->Symbol = (Byte)i;
312    s->Freq = 1;
313    SetSuccessor(s, 0);
314  }
315
316  for (i = 0; i < 128; i++)
317    for (k = 0; k < 8; k++)
318    {
319      UInt16 *dest = p->BinSumm[i] + k;
320      UInt16 val = (UInt16)(PPMD_BIN_SCALE - kInitBinEsc[k] / (i + 2));
321      for (m = 0; m < 64; m += 8)
322        dest[m] = val;
323    }
324
325  for (i = 0; i < 25; i++)
326    for (k = 0; k < 16; k++)
327    {
328      CPpmd_See *s = &p->See[i][k];
329      s->Summ = (UInt16)((5 * i + 10) << (s->Shift = PPMD_PERIOD_BITS - 4));
330      s->Count = 4;
331    }
332}
333
334void Ppmd7_Init(CPpmd7 *p, unsigned maxOrder)
335{
336  p->MaxOrder = maxOrder;
337  RestartModel(p);
338  p->DummySee.Shift = PPMD_PERIOD_BITS;
339  p->DummySee.Summ = 0; /* unused */
340  p->DummySee.Count = 64; /* unused */
341}
342
343static CTX_PTR CreateSuccessors(CPpmd7 *p, Bool skip)
344{
345  CPpmd_State upState;
346  CTX_PTR c = p->MinContext;
347  CPpmd_Byte_Ref upBranch = (CPpmd_Byte_Ref)SUCCESSOR(p->FoundState);
348  CPpmd_State *ps[PPMD7_MAX_ORDER];
349  unsigned numPs = 0;
350
351  if (!skip)
352    ps[numPs++] = p->FoundState;
353
354  while (c->Suffix)
355  {
356    CPpmd_Void_Ref successor;
357    CPpmd_State *s;
358    c = SUFFIX(c);
359    if (c->NumStats != 1)
360    {
361      for (s = STATS(c); s->Symbol != p->FoundState->Symbol; s++);
362    }
363    else
364      s = ONE_STATE(c);
365    successor = SUCCESSOR(s);
366    if (successor != upBranch)
367    {
368      c = CTX(successor);
369      if (numPs == 0)
370        return c;
371      break;
372    }
373    ps[numPs++] = s;
374  }
375
376  upState.Symbol = *(const Byte *)Ppmd7_GetPtr(p, upBranch);
377  SetSuccessor(&upState, upBranch + 1);
378
379  if (c->NumStats == 1)
380    upState.Freq = ONE_STATE(c)->Freq;
381  else
382  {
383    UInt32 cf, s0;
384    CPpmd_State *s;
385    for (s = STATS(c); s->Symbol != upState.Symbol; s++);
386    cf = s->Freq - 1;
387    s0 = c->SummFreq - c->NumStats - cf;
388    upState.Freq = (Byte)(1 + ((2 * cf <= s0) ? (5 * cf > s0) : ((2 * cf + 3 * s0 - 1) / (2 * s0))));
389  }
390
391  do
392  {
393    /* Create Child */
394    CTX_PTR c1; /* = AllocContext(p); */
395    if (p->HiUnit != p->LoUnit)
396      c1 = (CTX_PTR)(p->HiUnit -= UNIT_SIZE);
397    else if (p->FreeList[0] != 0)
398      c1 = (CTX_PTR)RemoveNode(p, 0);
399    else
400    {
401      c1 = (CTX_PTR)AllocUnitsRare(p, 0);
402      if (!c1)
403        return NULL;
404    }
405    c1->NumStats = 1;
406    *ONE_STATE(c1) = upState;
407    c1->Suffix = REF(c);
408    SetSuccessor(ps[--numPs], REF(c1));
409    c = c1;
410  }
411  while (numPs != 0);
412
413  return c;
414}
415
416static void SwapStates(CPpmd_State *t1, CPpmd_State *t2)
417{
418  CPpmd_State tmp = *t1;
419  *t1 = *t2;
420  *t2 = tmp;
421}
422
423static void UpdateModel(CPpmd7 *p)
424{
425  CPpmd_Void_Ref successor, fSuccessor = SUCCESSOR(p->FoundState);
426  CTX_PTR c;
427  unsigned s0, ns;
428
429  if (p->FoundState->Freq < MAX_FREQ / 4 && p->MinContext->Suffix != 0)
430  {
431    c = SUFFIX(p->MinContext);
432
433    if (c->NumStats == 1)
434    {
435      CPpmd_State *s = ONE_STATE(c);
436      if (s->Freq < 32)
437        s->Freq++;
438    }
439    else
440    {
441      CPpmd_State *s = STATS(c);
442      if (s->Symbol != p->FoundState->Symbol)
443      {
444        do { s++; } while (s->Symbol != p->FoundState->Symbol);
445        if (s[0].Freq >= s[-1].Freq)
446        {
447          SwapStates(&s[0], &s[-1]);
448          s--;
449        }
450      }
451      if (s->Freq < MAX_FREQ - 9)
452      {
453        s->Freq += 2;
454        c->SummFreq += 2;
455      }
456    }
457  }
458
459  if (p->OrderFall == 0)
460  {
461    p->MinContext = p->MaxContext = CreateSuccessors(p, True);
462    if (p->MinContext == 0)
463    {
464      RestartModel(p);
465      return;
466    }
467    SetSuccessor(p->FoundState, REF(p->MinContext));
468    return;
469  }
470
471  *p->Text++ = p->FoundState->Symbol;
472  successor = REF(p->Text);
473  if (p->Text >= p->UnitsStart)
474  {
475    RestartModel(p);
476    return;
477  }
478
479  if (fSuccessor)
480  {
481    if (fSuccessor <= successor)
482    {
483      CTX_PTR cs = CreateSuccessors(p, False);
484      if (cs == NULL)
485      {
486        RestartModel(p);
487        return;
488      }
489      fSuccessor = REF(cs);
490    }
491    if (--p->OrderFall == 0)
492    {
493      successor = fSuccessor;
494      p->Text -= (p->MaxContext != p->MinContext);
495    }
496  }
497  else
498  {
499    SetSuccessor(p->FoundState, successor);
500    fSuccessor = REF(p->MinContext);
501  }
502
503  s0 = p->MinContext->SummFreq - (ns = p->MinContext->NumStats) - (p->FoundState->Freq - 1);
504
505  for (c = p->MaxContext; c != p->MinContext; c = SUFFIX(c))
506  {
507    unsigned ns1;
508    UInt32 cf, sf;
509    if ((ns1 = c->NumStats) != 1)
510    {
511      if ((ns1 & 1) == 0)
512      {
513        /* Expand for one UNIT */
514        unsigned oldNU = ns1 >> 1;
515        unsigned i = U2I(oldNU);
516        if (i != U2I(oldNU + 1))
517        {
518          void *ptr = AllocUnits(p, i + 1);
519          void *oldPtr;
520          if (!ptr)
521          {
522            RestartModel(p);
523            return;
524          }
525          oldPtr = STATS(c);
526          MyMem12Cpy(ptr, oldPtr, oldNU);
527          InsertNode(p, oldPtr, i);
528          c->Stats = STATS_REF(ptr);
529        }
530      }
531      c->SummFreq = (UInt16)(c->SummFreq + (2 * ns1 < ns) + 2 * ((4 * ns1 <= ns) & (c->SummFreq <= 8 * ns1)));
532    }
533    else
534    {
535      CPpmd_State *s = (CPpmd_State*)AllocUnits(p, 0);
536      if (!s)
537      {
538        RestartModel(p);
539        return;
540      }
541      *s = *ONE_STATE(c);
542      c->Stats = REF(s);
543      if (s->Freq < MAX_FREQ / 4 - 1)
544        s->Freq <<= 1;
545      else
546        s->Freq = MAX_FREQ - 4;
547      c->SummFreq = (UInt16)(s->Freq + p->InitEsc + (ns > 3));
548    }
549    cf = 2 * (UInt32)p->FoundState->Freq * (c->SummFreq + 6);
550    sf = (UInt32)s0 + c->SummFreq;
551    if (cf < 6 * sf)
552    {
553      cf = 1 + (cf > sf) + (cf >= 4 * sf);
554      c->SummFreq += 3;
555    }
556    else
557    {
558      cf = 4 + (cf >= 9 * sf) + (cf >= 12 * sf) + (cf >= 15 * sf);
559      c->SummFreq = (UInt16)(c->SummFreq + cf);
560    }
561    {
562      CPpmd_State *s = STATS(c) + ns1;
563      SetSuccessor(s, successor);
564      s->Symbol = p->FoundState->Symbol;
565      s->Freq = (Byte)cf;
566      c->NumStats = (UInt16)(ns1 + 1);
567    }
568  }
569  p->MaxContext = p->MinContext = CTX(fSuccessor);
570}
571
572static void Rescale(CPpmd7 *p)
573{
574  unsigned i, adder, sumFreq, escFreq;
575  CPpmd_State *stats = STATS(p->MinContext);
576  CPpmd_State *s = p->FoundState;
577  {
578    CPpmd_State tmp = *s;
579    for (; s != stats; s--)
580      s[0] = s[-1];
581    *s = tmp;
582  }
583  escFreq = p->MinContext->SummFreq - s->Freq;
584  s->Freq += 4;
585  adder = (p->OrderFall != 0);
586  s->Freq = (Byte)((s->Freq + adder) >> 1);
587  sumFreq = s->Freq;
588
589  i = p->MinContext->NumStats - 1;
590  do
591  {
592    escFreq -= (++s)->Freq;
593    s->Freq = (Byte)((s->Freq + adder) >> 1);
594    sumFreq += s->Freq;
595    if (s[0].Freq > s[-1].Freq)
596    {
597      CPpmd_State *s1 = s;
598      CPpmd_State tmp = *s1;
599      do
600        s1[0] = s1[-1];
601      while (--s1 != stats && tmp.Freq > s1[-1].Freq);
602      *s1 = tmp;
603    }
604  }
605  while (--i);
606
607  if (s->Freq == 0)
608  {
609    unsigned numStats = p->MinContext->NumStats;
610    unsigned n0, n1;
611    do { i++; } while ((--s)->Freq == 0);
612    escFreq += i;
613    p->MinContext->NumStats = (UInt16)(p->MinContext->NumStats - i);
614    if (p->MinContext->NumStats == 1)
615    {
616      CPpmd_State tmp = *stats;
617      do
618      {
619        tmp.Freq = (Byte)(tmp.Freq - (tmp.Freq >> 1));
620        escFreq >>= 1;
621      }
622      while (escFreq > 1);
623      InsertNode(p, stats, U2I(((numStats + 1) >> 1)));
624      *(p->FoundState = ONE_STATE(p->MinContext)) = tmp;
625      return;
626    }
627    n0 = (numStats + 1) >> 1;
628    n1 = (p->MinContext->NumStats + 1) >> 1;
629    if (n0 != n1)
630      p->MinContext->Stats = STATS_REF(ShrinkUnits(p, stats, n0, n1));
631  }
632  p->MinContext->SummFreq = (UInt16)(sumFreq + escFreq - (escFreq >> 1));
633  p->FoundState = STATS(p->MinContext);
634}
635
636CPpmd_See *Ppmd7_MakeEscFreq(CPpmd7 *p, unsigned numMasked, UInt32 *escFreq)
637{
638  CPpmd_See *see;
639  unsigned nonMasked = p->MinContext->NumStats - numMasked;
640  if (p->MinContext->NumStats != 256)
641  {
642    see = p->See[p->NS2Indx[nonMasked - 1]] +
643        (nonMasked < (unsigned)SUFFIX(p->MinContext)->NumStats - p->MinContext->NumStats) +
644        2 * (p->MinContext->SummFreq < 11 * p->MinContext->NumStats) +
645        4 * (numMasked > nonMasked) +
646        p->HiBitsFlag;
647    {
648      unsigned r = (see->Summ >> see->Shift);
649      see->Summ = (UInt16)(see->Summ - r);
650      *escFreq = r + (r == 0);
651    }
652  }
653  else
654  {
655    see = &p->DummySee;
656    *escFreq = 1;
657  }
658  return see;
659}
660
661static void NextContext(CPpmd7 *p)
662{
663  CTX_PTR c = CTX(SUCCESSOR(p->FoundState));
664  if (p->OrderFall == 0 && (Byte *)c > p->Text)
665    p->MinContext = p->MaxContext = c;
666  else
667    UpdateModel(p);
668}
669
670void Ppmd7_Update1(CPpmd7 *p)
671{
672  CPpmd_State *s = p->FoundState;
673  s->Freq += 4;
674  p->MinContext->SummFreq += 4;
675  if (s[0].Freq > s[-1].Freq)
676  {
677    SwapStates(&s[0], &s[-1]);
678    p->FoundState = --s;
679    if (s->Freq > MAX_FREQ)
680      Rescale(p);
681  }
682  NextContext(p);
683}
684
685void Ppmd7_Update1_0(CPpmd7 *p)
686{
687  p->PrevSuccess = (2 * p->FoundState->Freq > p->MinContext->SummFreq);
688  p->RunLength += p->PrevSuccess;
689  p->MinContext->SummFreq += 4;
690  if ((p->FoundState->Freq += 4) > MAX_FREQ)
691    Rescale(p);
692  NextContext(p);
693}
694
695void Ppmd7_UpdateBin(CPpmd7 *p)
696{
697  p->FoundState->Freq = (Byte)(p->FoundState->Freq + (p->FoundState->Freq < 128 ? 1: 0));
698  p->PrevSuccess = 1;
699  p->RunLength++;
700  NextContext(p);
701}
702
703void Ppmd7_Update2(CPpmd7 *p)
704{
705  p->MinContext->SummFreq += 4;
706  if ((p->FoundState->Freq += 4) > MAX_FREQ)
707    Rescale(p);
708  p->RunLength = p->InitRL;
709  UpdateModel(p);
710}
711