1 /* Ppmd7.c -- PPMdH codec
2 2010-03-12 : Igor Pavlov : Public domain
3 This 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 
11 const Byte PPMD7_kExpEscape[16] = { 25, 14, 9, 7, 5, 5, 4, 4, 4, 3, 3, 3, 2, 2, 2, 2 };
12 static 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 
34 typedef CPpmd7_Context * CTX_PTR;
35 
36 struct CPpmd7_Node_;
37 
38 typedef
39   #ifdef PPMD_32BIT
40     struct CPpmd7_Node_ *
41   #else
42     UInt32
43   #endif
44   CPpmd7_Node_Ref;
45 
46 typedef 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 
Ppmd7_Construct(CPpmd7 * p)60 void 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 
Ppmd7_Free(CPpmd7 * p,ISzAlloc * alloc)91 void Ppmd7_Free(CPpmd7 *p, ISzAlloc *alloc)
92 {
93   alloc->Free(alloc, p->Base);
94   p->Size = 0;
95   p->Base = 0;
96 }
97 
Ppmd7_Alloc(CPpmd7 * p,UInt32 size,ISzAlloc * alloc)98 Bool 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 
InsertNode(CPpmd7 * p,void * node,unsigned indx)120 static 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 
RemoveNode(CPpmd7 * p,unsigned indx)126 static 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 
SplitBlock(CPpmd7 * p,void * ptr,unsigned oldIndx,unsigned newIndx)133 static 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 
GlueFreeBlocks(CPpmd7 * p)145 static 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 
AllocUnitsRare(CPpmd7 * p,unsigned indx)217 static 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 
AllocUnits(CPpmd7 * p,unsigned indx)243 static 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 
ShrinkUnits(CPpmd7 * p,void * oldPtr,unsigned oldNU,unsigned newNU)262 static 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 
SetSuccessor(CPpmd_State * p,CPpmd_Void_Ref v)281 static 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 
RestartModel(CPpmd7 * p)287 static 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 
Ppmd7_Init(CPpmd7 * p,unsigned maxOrder)334 void 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 
CreateSuccessors(CPpmd7 * p,Bool skip)343 static 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 
SwapStates(CPpmd_State * t1,CPpmd_State * t2)416 static void SwapStates(CPpmd_State *t1, CPpmd_State *t2)
417 {
418   CPpmd_State tmp = *t1;
419   *t1 = *t2;
420   *t2 = tmp;
421 }
422 
UpdateModel(CPpmd7 * p)423 static 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 
Rescale(CPpmd7 * p)572 static 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 
Ppmd7_MakeEscFreq(CPpmd7 * p,unsigned numMasked,UInt32 * escFreq)636 CPpmd_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 
NextContext(CPpmd7 * p)661 static 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 
Ppmd7_Update1(CPpmd7 * p)670 void 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 
Ppmd7_Update1_0(CPpmd7 * p)685 void 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 
Ppmd7_UpdateBin(CPpmd7 * p)695 void 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 
Ppmd7_Update2(CPpmd7 * p)703 void 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