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