1 /* Ppmd7.c -- PPMdH codec
2 2017-04-03 : 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 <string.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[(size_t)(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,ISzAllocPtr alloc)91 void Ppmd7_Free(CPpmd7 *p, ISzAllocPtr alloc)
92 {
93   ISzAlloc_Free(alloc, p->Base);
94   p->Size = 0;
95   p->Base = 0;
96 }
97 
Ppmd7_Alloc(CPpmd7 * p,UInt32 size,ISzAllocPtr alloc)98 Bool Ppmd7_Alloc(CPpmd7 *p, UInt32 size, ISzAllocPtr alloc)
99 {
100   if (!p->Base || p->Size != size)
101   {
102     size_t size2;
103     Ppmd7_Free(p, alloc);
104     size2 = 0
105       #ifndef PPMD_32BIT
106       + UNIT_SIZE
107       #endif
108       ;
109     p->AlignOffset =
110       #ifdef PPMD_32BIT
111         (4 - size) & 3;
112       #else
113         4 - (size & 3);
114       #endif
115     if ((p->Base = (Byte *)ISzAlloc_Alloc(alloc, p->AlignOffset + size + size2)) == 0)
116       return False;
117     p->Size = size;
118   }
119   return True;
120 }
121 
InsertNode(CPpmd7 * p,void * node,unsigned indx)122 static void InsertNode(CPpmd7 *p, void *node, unsigned indx)
123 {
124   *((CPpmd_Void_Ref *)node) = p->FreeList[indx];
125   p->FreeList[indx] = REF(node);
126 }
127 
RemoveNode(CPpmd7 * p,unsigned indx)128 static void *RemoveNode(CPpmd7 *p, unsigned indx)
129 {
130   CPpmd_Void_Ref *node = (CPpmd_Void_Ref *)Ppmd7_GetPtr(p, p->FreeList[indx]);
131   p->FreeList[indx] = *node;
132   return node;
133 }
134 
SplitBlock(CPpmd7 * p,void * ptr,unsigned oldIndx,unsigned newIndx)135 static void SplitBlock(CPpmd7 *p, void *ptr, unsigned oldIndx, unsigned newIndx)
136 {
137   unsigned i, nu = I2U(oldIndx) - I2U(newIndx);
138   ptr = (Byte *)ptr + U2B(I2U(newIndx));
139   if (I2U(i = U2I(nu)) != nu)
140   {
141     unsigned k = I2U(--i);
142     InsertNode(p, ((Byte *)ptr) + U2B(k), nu - k - 1);
143   }
144   InsertNode(p, ptr, i);
145 }
146 
GlueFreeBlocks(CPpmd7 * p)147 static void GlueFreeBlocks(CPpmd7 *p)
148 {
149   #ifdef PPMD_32BIT
150   CPpmd7_Node headItem;
151   CPpmd7_Node_Ref head = &headItem;
152   #else
153   CPpmd7_Node_Ref head = p->AlignOffset + p->Size;
154   #endif
155 
156   CPpmd7_Node_Ref n = head;
157   unsigned i;
158 
159   p->GlueCount = 255;
160 
161   /* create doubly-linked list of free blocks */
162   for (i = 0; i < PPMD_NUM_INDEXES; i++)
163   {
164     UInt16 nu = I2U(i);
165     CPpmd7_Node_Ref next = (CPpmd7_Node_Ref)p->FreeList[i];
166     p->FreeList[i] = 0;
167     while (next != 0)
168     {
169       CPpmd7_Node *node = NODE(next);
170       node->Next = n;
171       n = NODE(n)->Prev = next;
172       next = *(const CPpmd7_Node_Ref *)node;
173       node->Stamp = 0;
174       node->NU = (UInt16)nu;
175     }
176   }
177   NODE(head)->Stamp = 1;
178   NODE(head)->Next = n;
179   NODE(n)->Prev = head;
180   if (p->LoUnit != p->HiUnit)
181     ((CPpmd7_Node *)p->LoUnit)->Stamp = 1;
182 
183   /* Glue free blocks */
184   while (n != head)
185   {
186     CPpmd7_Node *node = NODE(n);
187     UInt32 nu = (UInt32)node->NU;
188     for (;;)
189     {
190       CPpmd7_Node *node2 = NODE(n) + nu;
191       nu += node2->NU;
192       if (node2->Stamp != 0 || nu >= 0x10000)
193         break;
194       NODE(node2->Prev)->Next = node2->Next;
195       NODE(node2->Next)->Prev = node2->Prev;
196       node->NU = (UInt16)nu;
197     }
198     n = node->Next;
199   }
200 
201   /* Fill lists of free blocks */
202   for (n = NODE(head)->Next; n != head;)
203   {
204     CPpmd7_Node *node = NODE(n);
205     unsigned nu;
206     CPpmd7_Node_Ref next = node->Next;
207     for (nu = node->NU; nu > 128; nu -= 128, node += 128)
208       InsertNode(p, node, PPMD_NUM_INDEXES - 1);
209     if (I2U(i = U2I(nu)) != nu)
210     {
211       unsigned k = I2U(--i);
212       InsertNode(p, node + k, nu - k - 1);
213     }
214     InsertNode(p, node, i);
215     n = next;
216   }
217 }
218 
AllocUnitsRare(CPpmd7 * p,unsigned indx)219 static void *AllocUnitsRare(CPpmd7 *p, unsigned indx)
220 {
221   unsigned i;
222   void *retVal;
223   if (p->GlueCount == 0)
224   {
225     GlueFreeBlocks(p);
226     if (p->FreeList[indx] != 0)
227       return RemoveNode(p, indx);
228   }
229   i = indx;
230   do
231   {
232     if (++i == PPMD_NUM_INDEXES)
233     {
234       UInt32 numBytes = U2B(I2U(indx));
235       p->GlueCount--;
236       return ((UInt32)(p->UnitsStart - p->Text) > numBytes) ? (p->UnitsStart -= numBytes) : (NULL);
237     }
238   }
239   while (p->FreeList[i] == 0);
240   retVal = RemoveNode(p, i);
241   SplitBlock(p, retVal, i, indx);
242   return retVal;
243 }
244 
AllocUnits(CPpmd7 * p,unsigned indx)245 static void *AllocUnits(CPpmd7 *p, unsigned indx)
246 {
247   UInt32 numBytes;
248   if (p->FreeList[indx] != 0)
249     return RemoveNode(p, indx);
250   numBytes = U2B(I2U(indx));
251   if (numBytes <= (UInt32)(p->HiUnit - p->LoUnit))
252   {
253     void *retVal = p->LoUnit;
254     p->LoUnit += numBytes;
255     return retVal;
256   }
257   return AllocUnitsRare(p, indx);
258 }
259 
260 #define MyMem12Cpy(dest, src, num) \
261   { UInt32 *d = (UInt32 *)dest; const UInt32 *s = (const UInt32 *)src; UInt32 n = num; \
262     do { d[0] = s[0]; d[1] = s[1]; d[2] = s[2]; s += 3; d += 3; } while (--n); }
263 
ShrinkUnits(CPpmd7 * p,void * oldPtr,unsigned oldNU,unsigned newNU)264 static void *ShrinkUnits(CPpmd7 *p, void *oldPtr, unsigned oldNU, unsigned newNU)
265 {
266   unsigned i0 = U2I(oldNU);
267   unsigned i1 = U2I(newNU);
268   if (i0 == i1)
269     return oldPtr;
270   if (p->FreeList[i1] != 0)
271   {
272     void *ptr = RemoveNode(p, i1);
273     MyMem12Cpy(ptr, oldPtr, newNU);
274     InsertNode(p, oldPtr, i0);
275     return ptr;
276   }
277   SplitBlock(p, oldPtr, i0, i1);
278   return oldPtr;
279 }
280 
281 #define SUCCESSOR(p) ((CPpmd_Void_Ref)((p)->SuccessorLow | ((UInt32)(p)->SuccessorHigh << 16)))
282 
SetSuccessor(CPpmd_State * p,CPpmd_Void_Ref v)283 static void SetSuccessor(CPpmd_State *p, CPpmd_Void_Ref v)
284 {
285   (p)->SuccessorLow = (UInt16)((UInt32)(v) & 0xFFFF);
286   (p)->SuccessorHigh = (UInt16)(((UInt32)(v) >> 16) & 0xFFFF);
287 }
288 
RestartModel(CPpmd7 * p)289 static void RestartModel(CPpmd7 *p)
290 {
291   unsigned i, k, m;
292 
293   memset(p->FreeList, 0, sizeof(p->FreeList));
294   p->Text = p->Base + p->AlignOffset;
295   p->HiUnit = p->Text + p->Size;
296   p->LoUnit = p->UnitsStart = p->HiUnit - p->Size / 8 / UNIT_SIZE * 7 * UNIT_SIZE;
297   p->GlueCount = 0;
298 
299   p->OrderFall = p->MaxOrder;
300   p->RunLength = p->InitRL = -(Int32)((p->MaxOrder < 12) ? p->MaxOrder : 12) - 1;
301   p->PrevSuccess = 0;
302 
303   p->MinContext = p->MaxContext = (CTX_PTR)(p->HiUnit -= UNIT_SIZE); /* AllocContext(p); */
304   p->MinContext->Suffix = 0;
305   p->MinContext->NumStats = 256;
306   p->MinContext->SummFreq = 256 + 1;
307   p->FoundState = (CPpmd_State *)p->LoUnit; /* AllocUnits(p, PPMD_NUM_INDEXES - 1); */
308   p->LoUnit += U2B(256 / 2);
309   p->MinContext->Stats = REF(p->FoundState);
310   for (i = 0; i < 256; i++)
311   {
312     CPpmd_State *s = &p->FoundState[i];
313     s->Symbol = (Byte)i;
314     s->Freq = 1;
315     SetSuccessor(s, 0);
316   }
317 
318   for (i = 0; i < 128; i++)
319     for (k = 0; k < 8; k++)
320     {
321       UInt16 *dest = p->BinSumm[i] + k;
322       UInt16 val = (UInt16)(PPMD_BIN_SCALE - kInitBinEsc[k] / (i + 2));
323       for (m = 0; m < 64; m += 8)
324         dest[m] = val;
325     }
326 
327   for (i = 0; i < 25; i++)
328     for (k = 0; k < 16; k++)
329     {
330       CPpmd_See *s = &p->See[i][k];
331       s->Summ = (UInt16)((5 * i + 10) << (s->Shift = PPMD_PERIOD_BITS - 4));
332       s->Count = 4;
333     }
334 }
335 
Ppmd7_Init(CPpmd7 * p,unsigned maxOrder)336 void Ppmd7_Init(CPpmd7 *p, unsigned maxOrder)
337 {
338   p->MaxOrder = maxOrder;
339   RestartModel(p);
340   p->DummySee.Shift = PPMD_PERIOD_BITS;
341   p->DummySee.Summ = 0; /* unused */
342   p->DummySee.Count = 64; /* unused */
343 }
344 
CreateSuccessors(CPpmd7 * p,Bool skip)345 static CTX_PTR CreateSuccessors(CPpmd7 *p, Bool skip)
346 {
347   CPpmd_State upState;
348   CTX_PTR c = p->MinContext;
349   CPpmd_Byte_Ref upBranch = (CPpmd_Byte_Ref)SUCCESSOR(p->FoundState);
350   CPpmd_State *ps[PPMD7_MAX_ORDER];
351   unsigned numPs = 0;
352 
353   if (!skip)
354     ps[numPs++] = p->FoundState;
355 
356   while (c->Suffix)
357   {
358     CPpmd_Void_Ref successor;
359     CPpmd_State *s;
360     c = SUFFIX(c);
361     if (c->NumStats != 1)
362     {
363       for (s = STATS(c); s->Symbol != p->FoundState->Symbol; s++);
364     }
365     else
366       s = ONE_STATE(c);
367     successor = SUCCESSOR(s);
368     if (successor != upBranch)
369     {
370       c = CTX(successor);
371       if (numPs == 0)
372         return c;
373       break;
374     }
375     ps[numPs++] = s;
376   }
377 
378   upState.Symbol = *(const Byte *)Ppmd7_GetPtr(p, upBranch);
379   SetSuccessor(&upState, upBranch + 1);
380 
381   if (c->NumStats == 1)
382     upState.Freq = ONE_STATE(c)->Freq;
383   else
384   {
385     UInt32 cf, s0;
386     CPpmd_State *s;
387     for (s = STATS(c); s->Symbol != upState.Symbol; s++);
388     cf = s->Freq - 1;
389     s0 = c->SummFreq - c->NumStats - cf;
390     upState.Freq = (Byte)(1 + ((2 * cf <= s0) ? (5 * cf > s0) : ((2 * cf + 3 * s0 - 1) / (2 * s0))));
391   }
392 
393   do
394   {
395     /* Create Child */
396     CTX_PTR c1; /* = AllocContext(p); */
397     if (p->HiUnit != p->LoUnit)
398       c1 = (CTX_PTR)(p->HiUnit -= UNIT_SIZE);
399     else if (p->FreeList[0] != 0)
400       c1 = (CTX_PTR)RemoveNode(p, 0);
401     else
402     {
403       c1 = (CTX_PTR)AllocUnitsRare(p, 0);
404       if (!c1)
405         return NULL;
406     }
407     c1->NumStats = 1;
408     *ONE_STATE(c1) = upState;
409     c1->Suffix = REF(c);
410     SetSuccessor(ps[--numPs], REF(c1));
411     c = c1;
412   }
413   while (numPs != 0);
414 
415   return c;
416 }
417 
SwapStates(CPpmd_State * t1,CPpmd_State * t2)418 static void SwapStates(CPpmd_State *t1, CPpmd_State *t2)
419 {
420   CPpmd_State tmp = *t1;
421   *t1 = *t2;
422   *t2 = tmp;
423 }
424 
UpdateModel(CPpmd7 * p)425 static void UpdateModel(CPpmd7 *p)
426 {
427   CPpmd_Void_Ref successor, fSuccessor = SUCCESSOR(p->FoundState);
428   CTX_PTR c;
429   unsigned s0, ns;
430 
431   if (p->FoundState->Freq < MAX_FREQ / 4 && p->MinContext->Suffix != 0)
432   {
433     c = SUFFIX(p->MinContext);
434 
435     if (c->NumStats == 1)
436     {
437       CPpmd_State *s = ONE_STATE(c);
438       if (s->Freq < 32)
439         s->Freq++;
440     }
441     else
442     {
443       CPpmd_State *s = STATS(c);
444       if (s->Symbol != p->FoundState->Symbol)
445       {
446         do { s++; } while (s->Symbol != p->FoundState->Symbol);
447         if (s[0].Freq >= s[-1].Freq)
448         {
449           SwapStates(&s[0], &s[-1]);
450           s--;
451         }
452       }
453       if (s->Freq < MAX_FREQ - 9)
454       {
455         s->Freq += 2;
456         c->SummFreq += 2;
457       }
458     }
459   }
460 
461   if (p->OrderFall == 0)
462   {
463     p->MinContext = p->MaxContext = CreateSuccessors(p, True);
464     if (p->MinContext == 0)
465     {
466       RestartModel(p);
467       return;
468     }
469     SetSuccessor(p->FoundState, REF(p->MinContext));
470     return;
471   }
472 
473   *p->Text++ = p->FoundState->Symbol;
474   successor = REF(p->Text);
475   if (p->Text >= p->UnitsStart)
476   {
477     RestartModel(p);
478     return;
479   }
480 
481   if (fSuccessor)
482   {
483     if (fSuccessor <= successor)
484     {
485       CTX_PTR cs = CreateSuccessors(p, False);
486       if (cs == NULL)
487       {
488         RestartModel(p);
489         return;
490       }
491       fSuccessor = REF(cs);
492     }
493     if (--p->OrderFall == 0)
494     {
495       successor = fSuccessor;
496       p->Text -= (p->MaxContext != p->MinContext);
497     }
498   }
499   else
500   {
501     SetSuccessor(p->FoundState, successor);
502     fSuccessor = REF(p->MinContext);
503   }
504 
505   s0 = p->MinContext->SummFreq - (ns = p->MinContext->NumStats) - (p->FoundState->Freq - 1);
506 
507   for (c = p->MaxContext; c != p->MinContext; c = SUFFIX(c))
508   {
509     unsigned ns1;
510     UInt32 cf, sf;
511     if ((ns1 = c->NumStats) != 1)
512     {
513       if ((ns1 & 1) == 0)
514       {
515         /* Expand for one UNIT */
516         unsigned oldNU = ns1 >> 1;
517         unsigned i = U2I(oldNU);
518         if (i != U2I((size_t)oldNU + 1))
519         {
520           void *ptr = AllocUnits(p, i + 1);
521           void *oldPtr;
522           if (!ptr)
523           {
524             RestartModel(p);
525             return;
526           }
527           oldPtr = STATS(c);
528           MyMem12Cpy(ptr, oldPtr, oldNU);
529           InsertNode(p, oldPtr, i);
530           c->Stats = STATS_REF(ptr);
531         }
532       }
533       c->SummFreq = (UInt16)(c->SummFreq + (2 * ns1 < ns) + 2 * ((4 * ns1 <= ns) & (c->SummFreq <= 8 * ns1)));
534     }
535     else
536     {
537       CPpmd_State *s = (CPpmd_State*)AllocUnits(p, 0);
538       if (!s)
539       {
540         RestartModel(p);
541         return;
542       }
543       *s = *ONE_STATE(c);
544       c->Stats = REF(s);
545       if (s->Freq < MAX_FREQ / 4 - 1)
546         s->Freq <<= 1;
547       else
548         s->Freq = MAX_FREQ - 4;
549       c->SummFreq = (UInt16)(s->Freq + p->InitEsc + (ns > 3));
550     }
551     cf = 2 * (UInt32)p->FoundState->Freq * (c->SummFreq + 6);
552     sf = (UInt32)s0 + c->SummFreq;
553     if (cf < 6 * sf)
554     {
555       cf = 1 + (cf > sf) + (cf >= 4 * sf);
556       c->SummFreq += 3;
557     }
558     else
559     {
560       cf = 4 + (cf >= 9 * sf) + (cf >= 12 * sf) + (cf >= 15 * sf);
561       c->SummFreq = (UInt16)(c->SummFreq + cf);
562     }
563     {
564       CPpmd_State *s = STATS(c) + ns1;
565       SetSuccessor(s, successor);
566       s->Symbol = p->FoundState->Symbol;
567       s->Freq = (Byte)cf;
568       c->NumStats = (UInt16)(ns1 + 1);
569     }
570   }
571   p->MaxContext = p->MinContext = CTX(fSuccessor);
572 }
573 
Rescale(CPpmd7 * p)574 static void Rescale(CPpmd7 *p)
575 {
576   unsigned i, adder, sumFreq, escFreq;
577   CPpmd_State *stats = STATS(p->MinContext);
578   CPpmd_State *s = p->FoundState;
579   {
580     CPpmd_State tmp = *s;
581     for (; s != stats; s--)
582       s[0] = s[-1];
583     *s = tmp;
584   }
585   escFreq = p->MinContext->SummFreq - s->Freq;
586   s->Freq += 4;
587   adder = (p->OrderFall != 0);
588   s->Freq = (Byte)((s->Freq + adder) >> 1);
589   sumFreq = s->Freq;
590 
591   i = p->MinContext->NumStats - 1;
592   do
593   {
594     escFreq -= (++s)->Freq;
595     s->Freq = (Byte)((s->Freq + adder) >> 1);
596     sumFreq += s->Freq;
597     if (s[0].Freq > s[-1].Freq)
598     {
599       CPpmd_State *s1 = s;
600       CPpmd_State tmp = *s1;
601       do
602         s1[0] = s1[-1];
603       while (--s1 != stats && tmp.Freq > s1[-1].Freq);
604       *s1 = tmp;
605     }
606   }
607   while (--i);
608 
609   if (s->Freq == 0)
610   {
611     unsigned numStats = p->MinContext->NumStats;
612     unsigned n0, n1;
613     do { i++; } while ((--s)->Freq == 0);
614     escFreq += i;
615     p->MinContext->NumStats = (UInt16)(p->MinContext->NumStats - i);
616     if (p->MinContext->NumStats == 1)
617     {
618       CPpmd_State tmp = *stats;
619       do
620       {
621         tmp.Freq = (Byte)(tmp.Freq - (tmp.Freq >> 1));
622         escFreq >>= 1;
623       }
624       while (escFreq > 1);
625       InsertNode(p, stats, U2I(((numStats + 1) >> 1)));
626       *(p->FoundState = ONE_STATE(p->MinContext)) = tmp;
627       return;
628     }
629     n0 = (numStats + 1) >> 1;
630     n1 = (p->MinContext->NumStats + 1) >> 1;
631     if (n0 != n1)
632       p->MinContext->Stats = STATS_REF(ShrinkUnits(p, stats, n0, n1));
633   }
634   p->MinContext->SummFreq = (UInt16)(sumFreq + escFreq - (escFreq >> 1));
635   p->FoundState = STATS(p->MinContext);
636 }
637 
Ppmd7_MakeEscFreq(CPpmd7 * p,unsigned numMasked,UInt32 * escFreq)638 CPpmd_See *Ppmd7_MakeEscFreq(CPpmd7 *p, unsigned numMasked, UInt32 *escFreq)
639 {
640   CPpmd_See *see;
641   unsigned nonMasked = p->MinContext->NumStats - numMasked;
642   if (p->MinContext->NumStats != 256)
643   {
644     see = p->See[(unsigned)p->NS2Indx[(size_t)nonMasked - 1]] +
645         (nonMasked < (unsigned)SUFFIX(p->MinContext)->NumStats - p->MinContext->NumStats) +
646         2 * (unsigned)(p->MinContext->SummFreq < 11 * p->MinContext->NumStats) +
647         4 * (unsigned)(numMasked > nonMasked) +
648         p->HiBitsFlag;
649     {
650       unsigned r = (see->Summ >> see->Shift);
651       see->Summ = (UInt16)(see->Summ - r);
652       *escFreq = r + (r == 0);
653     }
654   }
655   else
656   {
657     see = &p->DummySee;
658     *escFreq = 1;
659   }
660   return see;
661 }
662 
NextContext(CPpmd7 * p)663 static void NextContext(CPpmd7 *p)
664 {
665   CTX_PTR c = CTX(SUCCESSOR(p->FoundState));
666   if (p->OrderFall == 0 && (Byte *)c > p->Text)
667     p->MinContext = p->MaxContext = c;
668   else
669     UpdateModel(p);
670 }
671 
Ppmd7_Update1(CPpmd7 * p)672 void Ppmd7_Update1(CPpmd7 *p)
673 {
674   CPpmd_State *s = p->FoundState;
675   s->Freq += 4;
676   p->MinContext->SummFreq += 4;
677   if (s[0].Freq > s[-1].Freq)
678   {
679     SwapStates(&s[0], &s[-1]);
680     p->FoundState = --s;
681     if (s->Freq > MAX_FREQ)
682       Rescale(p);
683   }
684   NextContext(p);
685 }
686 
Ppmd7_Update1_0(CPpmd7 * p)687 void Ppmd7_Update1_0(CPpmd7 *p)
688 {
689   p->PrevSuccess = (2 * p->FoundState->Freq > p->MinContext->SummFreq);
690   p->RunLength += p->PrevSuccess;
691   p->MinContext->SummFreq += 4;
692   if ((p->FoundState->Freq += 4) > MAX_FREQ)
693     Rescale(p);
694   NextContext(p);
695 }
696 
Ppmd7_UpdateBin(CPpmd7 * p)697 void Ppmd7_UpdateBin(CPpmd7 *p)
698 {
699   p->FoundState->Freq = (Byte)(p->FoundState->Freq + (p->FoundState->Freq < 128 ? 1: 0));
700   p->PrevSuccess = 1;
701   p->RunLength++;
702   NextContext(p);
703 }
704 
Ppmd7_Update2(CPpmd7 * p)705 void Ppmd7_Update2(CPpmd7 *p)
706 {
707   p->MinContext->SummFreq += 4;
708   if ((p->FoundState->Freq += 4) > MAX_FREQ)
709     Rescale(p);
710   p->RunLength = p->InitRL;
711   UpdateModel(p);
712 }
713