1 /* Ppmd8.c -- PPMdI codec
2 2016-05-21 : Igor Pavlov : Public domain
3 This code is based on PPMd var.I (2002): Dmitry Shkarin : Public domain */
4
5 #include "archive_platform.h"
6
7 #include <string.h>
8
9 #include "archive_ppmd8_private.h"
10
11 const Byte PPMD8_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) ((CPpmd8_Context *)Ppmd8_GetContext(p, ref))
30 #define STATS(ctx) Ppmd8_GetStats(p, ctx)
31 #define ONE_STATE(ctx) Ppmd8Context_OneState(ctx)
32 #define SUFFIX(ctx) CTX((ctx)->Suffix)
33
34 #define kTop (1 << 24)
35 #define kBot (1 << 15)
36
37 typedef CPpmd8_Context * CTX_PTR;
38
39 struct CPpmd8_Node_;
40
41 typedef
42 #ifdef PPMD_32BIT
43 struct CPpmd8_Node_ *
44 #else
45 UInt32
46 #endif
47 CPpmd8_Node_Ref;
48
49 typedef struct CPpmd8_Node_
50 {
51 UInt32 Stamp;
52 CPpmd8_Node_Ref Next;
53 UInt32 NU;
54 } CPpmd8_Node;
55
56 #ifdef PPMD_32BIT
57 #define NODE(ptr) (ptr)
58 #else
59 #define NODE(offs) ((CPpmd8_Node *)(p->Base + (offs)))
60 #endif
61
62 #define EMPTY_NODE 0xFFFFFFFF
63
Ppmd8_Construct(CPpmd8 * p)64 void Ppmd8_Construct(CPpmd8 *p)
65 {
66 unsigned i, k, m;
67
68 p->Base = 0;
69
70 for (i = 0, k = 0; i < PPMD_NUM_INDEXES; i++)
71 {
72 unsigned step = (i >= 12 ? 4 : (i >> 2) + 1);
73 do { p->Units2Indx[k++] = (Byte)i; } while (--step);
74 p->Indx2Units[i] = (Byte)k;
75 }
76
77 p->NS2BSIndx[0] = (0 << 1);
78 p->NS2BSIndx[1] = (1 << 1);
79 memset(p->NS2BSIndx + 2, (2 << 1), 9);
80 memset(p->NS2BSIndx + 11, (3 << 1), 256 - 11);
81
82 for (i = 0; i < 5; i++)
83 p->NS2Indx[i] = (Byte)i;
84 for (m = i, k = 1; i < 260; i++)
85 {
86 p->NS2Indx[i] = (Byte)m;
87 if (--k == 0)
88 k = (++m) - 4;
89 }
90 }
91
Ppmd8_Free(CPpmd8 * p)92 void Ppmd8_Free(CPpmd8 *p)
93 {
94 free(p->Base);
95 p->Size = 0;
96 p->Base = 0;
97 }
98
Ppmd8_Alloc(CPpmd8 * p,UInt32 size)99 Bool Ppmd8_Alloc(CPpmd8 *p, UInt32 size)
100 {
101 if (p->Base == 0 || p->Size != size)
102 {
103 Ppmd8_Free(p);
104 p->AlignOffset =
105 #ifdef PPMD_32BIT
106 (4 - size) & 3;
107 #else
108 4 - (size & 3);
109 #endif
110 if ((p->Base = (Byte *)malloc(p->AlignOffset + size)) == 0)
111 return False;
112 p->Size = size;
113 }
114 return True;
115 }
116
InsertNode(CPpmd8 * p,void * node,unsigned indx)117 static void InsertNode(CPpmd8 *p, void *node, unsigned indx)
118 {
119 ((CPpmd8_Node *)node)->Stamp = EMPTY_NODE;
120 ((CPpmd8_Node *)node)->Next = (CPpmd8_Node_Ref)p->FreeList[indx];
121 ((CPpmd8_Node *)node)->NU = I2U(indx);
122 p->FreeList[indx] = REF(node);
123 p->Stamps[indx]++;
124 }
125
RemoveNode(CPpmd8 * p,unsigned indx)126 static void *RemoveNode(CPpmd8 *p, unsigned indx)
127 {
128 CPpmd8_Node *node = NODE((CPpmd8_Node_Ref)p->FreeList[indx]);
129 p->FreeList[indx] = node->Next;
130 p->Stamps[indx]--;
131 return node;
132 }
133
SplitBlock(CPpmd8 * p,void * ptr,unsigned oldIndx,unsigned newIndx)134 static void SplitBlock(CPpmd8 *p, void *ptr, unsigned oldIndx, unsigned newIndx)
135 {
136 unsigned i, nu = I2U(oldIndx) - I2U(newIndx);
137 ptr = (Byte *)ptr + U2B(I2U(newIndx));
138 if (I2U(i = U2I(nu)) != nu)
139 {
140 unsigned k = I2U(--i);
141 InsertNode(p, ((Byte *)ptr) + U2B(k), nu - k - 1);
142 }
143 InsertNode(p, ptr, i);
144 }
145
GlueFreeBlocks(CPpmd8 * p)146 static void GlueFreeBlocks(CPpmd8 *p)
147 {
148 CPpmd8_Node_Ref head = 0;
149 CPpmd8_Node_Ref *prev = &head;
150 unsigned i;
151
152 p->GlueCount = 1 << 13;
153 memset(p->Stamps, 0, sizeof(p->Stamps));
154
155 /* Order-0 context is always at top UNIT, so we don't need guard NODE at the end.
156 All blocks up to p->LoUnit can be free, so we need guard NODE at LoUnit. */
157 if (p->LoUnit != p->HiUnit)
158 ((CPpmd8_Node *)p->LoUnit)->Stamp = 0;
159
160 /* Glue free blocks */
161 for (i = 0; i < PPMD_NUM_INDEXES; i++)
162 {
163 CPpmd8_Node_Ref next = (CPpmd8_Node_Ref)p->FreeList[i];
164 p->FreeList[i] = 0;
165 while (next != 0)
166 {
167 CPpmd8_Node *node = NODE(next);
168 if (node->NU != 0)
169 {
170 CPpmd8_Node *node2;
171 *prev = next;
172 prev = &(node->Next);
173 while ((node2 = node + node->NU)->Stamp == EMPTY_NODE)
174 {
175 node->NU += node2->NU;
176 node2->NU = 0;
177 }
178 }
179 next = node->Next;
180 }
181 }
182 *prev = 0;
183
184 /* Fill lists of free blocks */
185 while (head != 0)
186 {
187 CPpmd8_Node *node = NODE(head);
188 unsigned nu;
189 head = node->Next;
190 nu = node->NU;
191 if (nu == 0)
192 continue;
193 for (; nu > 128; nu -= 128, node += 128)
194 InsertNode(p, node, PPMD_NUM_INDEXES - 1);
195 if (I2U(i = U2I(nu)) != nu)
196 {
197 unsigned k = I2U(--i);
198 InsertNode(p, node + k, nu - k - 1);
199 }
200 InsertNode(p, node, i);
201 }
202 }
203
AllocUnitsRare(CPpmd8 * p,unsigned indx)204 static void *AllocUnitsRare(CPpmd8 *p, unsigned indx)
205 {
206 unsigned i;
207 void *retVal;
208 if (p->GlueCount == 0)
209 {
210 GlueFreeBlocks(p);
211 if (p->FreeList[indx] != 0)
212 return RemoveNode(p, indx);
213 }
214 i = indx;
215 do
216 {
217 if (++i == PPMD_NUM_INDEXES)
218 {
219 UInt32 numBytes = U2B(I2U(indx));
220 p->GlueCount--;
221 return ((UInt32)(p->UnitsStart - p->Text) > numBytes) ? (p->UnitsStart -= numBytes) : (NULL);
222 }
223 }
224 while (p->FreeList[i] == 0);
225 retVal = RemoveNode(p, i);
226 SplitBlock(p, retVal, i, indx);
227 return retVal;
228 }
229
AllocUnits(CPpmd8 * p,unsigned indx)230 static void *AllocUnits(CPpmd8 *p, unsigned indx)
231 {
232 UInt32 numBytes;
233 if (p->FreeList[indx] != 0)
234 return RemoveNode(p, indx);
235 numBytes = U2B(I2U(indx));
236 if (numBytes <= (UInt32)(p->HiUnit - p->LoUnit))
237 {
238 void *retVal = p->LoUnit;
239 p->LoUnit += numBytes;
240 return retVal;
241 }
242 return AllocUnitsRare(p, indx);
243 }
244
245 #define MyMem12Cpy(dest, src, num) \
246 { UInt32 *d = (UInt32 *)dest; const UInt32 *z = (const UInt32 *)src; UInt32 n = num; \
247 do { d[0] = z[0]; d[1] = z[1]; d[2] = z[2]; z += 3; d += 3; } while (--n); }
248
ShrinkUnits(CPpmd8 * p,void * oldPtr,unsigned oldNU,unsigned newNU)249 static void *ShrinkUnits(CPpmd8 *p, void *oldPtr, unsigned oldNU, unsigned newNU)
250 {
251 unsigned i0 = U2I(oldNU);
252 unsigned i1 = U2I(newNU);
253 if (i0 == i1)
254 return oldPtr;
255 if (p->FreeList[i1] != 0)
256 {
257 void *ptr = RemoveNode(p, i1);
258 MyMem12Cpy(ptr, oldPtr, newNU);
259 InsertNode(p, oldPtr, i0);
260 return ptr;
261 }
262 SplitBlock(p, oldPtr, i0, i1);
263 return oldPtr;
264 }
265
FreeUnits(CPpmd8 * p,void * ptr,unsigned nu)266 static void FreeUnits(CPpmd8 *p, void *ptr, unsigned nu)
267 {
268 InsertNode(p, ptr, U2I(nu));
269 }
270
SpecialFreeUnit(CPpmd8 * p,void * ptr)271 static void SpecialFreeUnit(CPpmd8 *p, void *ptr)
272 {
273 if ((Byte *)ptr != p->UnitsStart)
274 InsertNode(p, ptr, 0);
275 else
276 {
277 #ifdef PPMD8_FREEZE_SUPPORT
278 *(UInt32 *)ptr = EMPTY_NODE; /* it's used for (Flags == 0xFF) check in RemoveBinContexts */
279 #endif
280 p->UnitsStart += UNIT_SIZE;
281 }
282 }
283
MoveUnitsUp(CPpmd8 * p,void * oldPtr,unsigned nu)284 static void *MoveUnitsUp(CPpmd8 *p, void *oldPtr, unsigned nu)
285 {
286 unsigned indx = U2I(nu);
287 void *ptr;
288 if ((Byte *)oldPtr > p->UnitsStart + 16 * 1024 || REF(oldPtr) > p->FreeList[indx])
289 return oldPtr;
290 ptr = RemoveNode(p, indx);
291 MyMem12Cpy(ptr, oldPtr, nu);
292 if ((Byte*)oldPtr != p->UnitsStart)
293 InsertNode(p, oldPtr, indx);
294 else
295 p->UnitsStart += U2B(I2U(indx));
296 return ptr;
297 }
298
ExpandTextArea(CPpmd8 * p)299 static void ExpandTextArea(CPpmd8 *p)
300 {
301 UInt32 count[PPMD_NUM_INDEXES];
302 unsigned i;
303 memset(count, 0, sizeof(count));
304 if (p->LoUnit != p->HiUnit)
305 ((CPpmd8_Node *)p->LoUnit)->Stamp = 0;
306
307 {
308 CPpmd8_Node *node = (CPpmd8_Node *)p->UnitsStart;
309 for (; node->Stamp == EMPTY_NODE; node += node->NU)
310 {
311 node->Stamp = 0;
312 count[U2I(node->NU)]++;
313 }
314 p->UnitsStart = (Byte *)node;
315 }
316
317 for (i = 0; i < PPMD_NUM_INDEXES; i++)
318 {
319 CPpmd8_Node_Ref *next = (CPpmd8_Node_Ref *)&p->FreeList[i];
320 while (count[i] != 0)
321 {
322 CPpmd8_Node *node = NODE(*next);
323 while (node->Stamp == 0)
324 {
325 *next = node->Next;
326 node = NODE(*next);
327 p->Stamps[i]--;
328 if (--count[i] == 0)
329 break;
330 }
331 next = &node->Next;
332 }
333 }
334 }
335
336 #define SUCCESSOR(p) ((CPpmd_Void_Ref)((p)->SuccessorLow | ((UInt32)(p)->SuccessorHigh << 16)))
337
SetSuccessor(CPpmd_State * p,CPpmd_Void_Ref v)338 static void SetSuccessor(CPpmd_State *p, CPpmd_Void_Ref v)
339 {
340 (p)->SuccessorLow = (UInt16)((UInt32)(v) & 0xFFFF);
341 (p)->SuccessorHigh = (UInt16)(((UInt32)(v) >> 16) & 0xFFFF);
342 }
343
344 #define RESET_TEXT(offs) { p->Text = p->Base + p->AlignOffset + (offs); }
345
RestartModel(CPpmd8 * p)346 static void RestartModel(CPpmd8 *p)
347 {
348 unsigned i, k, m, r;
349
350 memset(p->FreeList, 0, sizeof(p->FreeList));
351 memset(p->Stamps, 0, sizeof(p->Stamps));
352 RESET_TEXT(0);
353 p->HiUnit = p->Text + p->Size;
354 p->LoUnit = p->UnitsStart = p->HiUnit - p->Size / 8 / UNIT_SIZE * 7 * UNIT_SIZE;
355 p->GlueCount = 0;
356
357 p->OrderFall = p->MaxOrder;
358 p->RunLength = p->InitRL = -(Int32)((p->MaxOrder < 12) ? p->MaxOrder : 12) - 1;
359 p->PrevSuccess = 0;
360
361 p->MinContext = p->MaxContext = (CTX_PTR)(p->HiUnit -= UNIT_SIZE); /* AllocContext(p); */
362 p->MinContext->Suffix = 0;
363 p->MinContext->NumStats = 255;
364 p->MinContext->Flags = 0;
365 p->MinContext->SummFreq = 256 + 1;
366 p->FoundState = (CPpmd_State *)p->LoUnit; /* AllocUnits(p, PPMD_NUM_INDEXES - 1); */
367 p->LoUnit += U2B(256 / 2);
368 p->MinContext->Stats = REF(p->FoundState);
369 for (i = 0; i < 256; i++)
370 {
371 CPpmd_State *s = &p->FoundState[i];
372 s->Symbol = (Byte)i;
373 s->Freq = 1;
374 SetSuccessor(s, 0);
375 }
376
377 for (i = m = 0; m < 25; m++)
378 {
379 while (p->NS2Indx[i] == m)
380 i++;
381 for (k = 0; k < 8; k++)
382 {
383 UInt16 val = (UInt16)(PPMD_BIN_SCALE - kInitBinEsc[k] / (i + 1));
384 UInt16 *dest = p->BinSumm[m] + k;
385 for (r = 0; r < 64; r += 8)
386 dest[r] = val;
387 }
388 }
389
390 for (i = m = 0; m < 24; m++)
391 {
392 while (p->NS2Indx[i + 3] == m + 3)
393 i++;
394 for (k = 0; k < 32; k++)
395 {
396 CPpmd_See *s = &p->See[m][k];
397 s->Summ = (UInt16)((2 * i + 5) << (s->Shift = PPMD_PERIOD_BITS - 4));
398 s->Count = 7;
399 }
400 }
401 }
402
Ppmd8_Init(CPpmd8 * p,unsigned maxOrder,unsigned restoreMethod)403 void Ppmd8_Init(CPpmd8 *p, unsigned maxOrder, unsigned restoreMethod)
404 {
405 p->MaxOrder = maxOrder;
406 p->RestoreMethod = restoreMethod;
407 RestartModel(p);
408 p->DummySee.Shift = PPMD_PERIOD_BITS;
409 p->DummySee.Summ = 0; /* unused */
410 p->DummySee.Count = 64; /* unused */
411 }
412
Refresh(CPpmd8 * p,CTX_PTR ctx,unsigned oldNU,unsigned scale)413 static void Refresh(CPpmd8 *p, CTX_PTR ctx, unsigned oldNU, unsigned scale)
414 {
415 unsigned i = ctx->NumStats, escFreq, sumFreq, flags;
416 CPpmd_State *s = (CPpmd_State *)ShrinkUnits(p, STATS(ctx), oldNU, (i + 2) >> 1);
417 ctx->Stats = REF(s);
418 #ifdef PPMD8_FREEZE_SUPPORT
419 /* fixed over Shkarin's code. Fixed code is not compatible with original code for some files in FREEZE mode. */
420 scale |= (ctx->SummFreq >= ((UInt32)1 << 15));
421 #endif
422 flags = (ctx->Flags & (0x10 + 0x04 * scale)) + 0x08 * (s->Symbol >= 0x40);
423 escFreq = ctx->SummFreq - s->Freq;
424 sumFreq = (s->Freq = (Byte)((s->Freq + scale) >> scale));
425 do
426 {
427 escFreq -= (++s)->Freq;
428 sumFreq += (s->Freq = (Byte)((s->Freq + scale) >> scale));
429 flags |= 0x08 * (s->Symbol >= 0x40);
430 }
431 while (--i);
432 ctx->SummFreq = (UInt16)(sumFreq + ((escFreq + scale) >> scale));
433 ctx->Flags = (Byte)flags;
434 }
435
SwapStates(CPpmd_State * t1,CPpmd_State * t2)436 static void SwapStates(CPpmd_State *t1, CPpmd_State *t2)
437 {
438 CPpmd_State tmp = *t1;
439 *t1 = *t2;
440 *t2 = tmp;
441 }
442
CutOff(CPpmd8 * p,CTX_PTR ctx,unsigned order)443 static CPpmd_Void_Ref CutOff(CPpmd8 *p, CTX_PTR ctx, unsigned order)
444 {
445 int i;
446 unsigned tmp;
447 CPpmd_State *s;
448
449 if (!ctx->NumStats)
450 {
451 s = ONE_STATE(ctx);
452 if ((Byte *)Ppmd8_GetPtr(p, SUCCESSOR(s)) >= p->UnitsStart)
453 {
454 if (order < p->MaxOrder)
455 SetSuccessor(s, CutOff(p, CTX(SUCCESSOR(s)), order + 1));
456 else
457 SetSuccessor(s, 0);
458 if (SUCCESSOR(s) || order <= 9) /* O_BOUND */
459 return REF(ctx);
460 }
461 SpecialFreeUnit(p, ctx);
462 return 0;
463 }
464
465 ctx->Stats = STATS_REF(MoveUnitsUp(p, STATS(ctx), tmp = ((unsigned)ctx->NumStats + 2) >> 1));
466
467 for (s = STATS(ctx) + (i = ctx->NumStats); s >= STATS(ctx); s--)
468 if ((Byte *)Ppmd8_GetPtr(p, SUCCESSOR(s)) < p->UnitsStart)
469 {
470 CPpmd_State *s2 = STATS(ctx) + (i--);
471 SetSuccessor(s, 0);
472 SwapStates(s, s2);
473 }
474 else if (order < p->MaxOrder)
475 SetSuccessor(s, CutOff(p, CTX(SUCCESSOR(s)), order + 1));
476 else
477 SetSuccessor(s, 0);
478
479 if (i != ctx->NumStats && order)
480 {
481 ctx->NumStats = (Byte)i;
482 s = STATS(ctx);
483 if (i < 0)
484 {
485 FreeUnits(p, s, tmp);
486 SpecialFreeUnit(p, ctx);
487 return 0;
488 }
489 if (i == 0)
490 {
491 ctx->Flags = (Byte)((ctx->Flags & 0x10) + 0x08 * (s->Symbol >= 0x40));
492 *ONE_STATE(ctx) = *s;
493 FreeUnits(p, s, tmp);
494 /* 9.31: the code was fixed. It's was not BUG, if Freq <= MAX_FREQ = 124 */
495 ONE_STATE(ctx)->Freq = (Byte)(((unsigned)ONE_STATE(ctx)->Freq + 11) >> 3);
496 }
497 else
498 Refresh(p, ctx, tmp, ctx->SummFreq > 16 * i);
499 }
500 return REF(ctx);
501 }
502
503 #ifdef PPMD8_FREEZE_SUPPORT
RemoveBinContexts(CPpmd8 * p,CTX_PTR ctx,unsigned order)504 static CPpmd_Void_Ref RemoveBinContexts(CPpmd8 *p, CTX_PTR ctx, unsigned order)
505 {
506 CPpmd_State *s;
507 if (!ctx->NumStats)
508 {
509 s = ONE_STATE(ctx);
510 if ((Byte *)Ppmd8_GetPtr(p, SUCCESSOR(s)) >= p->UnitsStart && order < p->MaxOrder)
511 SetSuccessor(s, RemoveBinContexts(p, CTX(SUCCESSOR(s)), order + 1));
512 else
513 SetSuccessor(s, 0);
514 /* Suffix context can be removed already, since different (high-order)
515 Successors may refer to same context. So we check Flags == 0xFF (Stamp == EMPTY_NODE) */
516 if (!SUCCESSOR(s) && (!SUFFIX(ctx)->NumStats || SUFFIX(ctx)->Flags == 0xFF))
517 {
518 FreeUnits(p, ctx, 1);
519 return 0;
520 }
521 else
522 return REF(ctx);
523 }
524
525 for (s = STATS(ctx) + ctx->NumStats; s >= STATS(ctx); s--)
526 if ((Byte *)Ppmd8_GetPtr(p, SUCCESSOR(s)) >= p->UnitsStart && order < p->MaxOrder)
527 SetSuccessor(s, RemoveBinContexts(p, CTX(SUCCESSOR(s)), order + 1));
528 else
529 SetSuccessor(s, 0);
530
531 return REF(ctx);
532 }
533 #endif
534
GetUsedMemory(const CPpmd8 * p)535 static UInt32 GetUsedMemory(const CPpmd8 *p)
536 {
537 UInt32 v = 0;
538 unsigned i;
539 for (i = 0; i < PPMD_NUM_INDEXES; i++)
540 v += p->Stamps[i] * I2U(i);
541 return p->Size - (UInt32)(p->HiUnit - p->LoUnit) - (UInt32)(p->UnitsStart - p->Text) - U2B(v);
542 }
543
544 #ifdef PPMD8_FREEZE_SUPPORT
545 #define RESTORE_MODEL(c1, fSuccessor) RestoreModel(p, c1, fSuccessor)
546 #else
547 #define RESTORE_MODEL(c1, fSuccessor) RestoreModel(p, c1)
548 #endif
549
RestoreModel(CPpmd8 * p,CTX_PTR c1,CTX_PTR fSuccessor)550 static void RestoreModel(CPpmd8 *p, CTX_PTR c1
551 #ifdef PPMD8_FREEZE_SUPPORT
552 , CTX_PTR fSuccessor
553 #endif
554 )
555 {
556 CTX_PTR c;
557 CPpmd_State *s;
558 RESET_TEXT(0);
559 for (c = p->MaxContext; c != c1; c = SUFFIX(c))
560 if (--(c->NumStats) == 0)
561 {
562 s = STATS(c);
563 c->Flags = (Byte)((c->Flags & 0x10) + 0x08 * (s->Symbol >= 0x40));
564 *ONE_STATE(c) = *s;
565 SpecialFreeUnit(p, s);
566 ONE_STATE(c)->Freq = (Byte)(((unsigned)ONE_STATE(c)->Freq + 11) >> 3);
567 }
568 else
569 Refresh(p, c, (c->NumStats+3) >> 1, 0);
570
571 for (; c != p->MinContext; c = SUFFIX(c))
572 if (!c->NumStats)
573 ONE_STATE(c)->Freq = (Byte)(ONE_STATE(c)->Freq - (ONE_STATE(c)->Freq >> 1));
574 else if ((c->SummFreq += 4) > 128 + 4 * c->NumStats)
575 Refresh(p, c, (c->NumStats + 2) >> 1, 1);
576
577 #ifdef PPMD8_FREEZE_SUPPORT
578 if (p->RestoreMethod > PPMD8_RESTORE_METHOD_FREEZE)
579 {
580 p->MaxContext = fSuccessor;
581 p->GlueCount += !(p->Stamps[1] & 1);
582 }
583 else if (p->RestoreMethod == PPMD8_RESTORE_METHOD_FREEZE)
584 {
585 while (p->MaxContext->Suffix)
586 p->MaxContext = SUFFIX(p->MaxContext);
587 RemoveBinContexts(p, p->MaxContext, 0);
588 p->RestoreMethod++;
589 p->GlueCount = 0;
590 p->OrderFall = p->MaxOrder;
591 }
592 else
593 #endif
594 if (p->RestoreMethod == PPMD8_RESTORE_METHOD_RESTART || GetUsedMemory(p) < (p->Size >> 1))
595 RestartModel(p);
596 else
597 {
598 while (p->MaxContext->Suffix)
599 p->MaxContext = SUFFIX(p->MaxContext);
600 do
601 {
602 CutOff(p, p->MaxContext, 0);
603 ExpandTextArea(p);
604 }
605 while (GetUsedMemory(p) > 3 * (p->Size >> 2));
606 p->GlueCount = 0;
607 p->OrderFall = p->MaxOrder;
608 }
609 }
610
CreateSuccessors(CPpmd8 * p,Bool skip,CPpmd_State * s1,CTX_PTR c)611 static CTX_PTR CreateSuccessors(CPpmd8 *p, Bool skip, CPpmd_State *s1, CTX_PTR c)
612 {
613 CPpmd_State upState;
614 Byte flags;
615 CPpmd_Byte_Ref upBranch = (CPpmd_Byte_Ref)SUCCESSOR(p->FoundState);
616 /* fixed over Shkarin's code. Maybe it could work without + 1 too. */
617 CPpmd_State *ps[PPMD8_MAX_ORDER + 1];
618 unsigned numPs = 0;
619
620 if (!skip)
621 ps[numPs++] = p->FoundState;
622
623 while (c->Suffix)
624 {
625 CPpmd_Void_Ref successor;
626 CPpmd_State *s;
627 c = SUFFIX(c);
628 if (s1)
629 {
630 s = s1;
631 s1 = NULL;
632 }
633 else if (c->NumStats != 0)
634 {
635 for (s = STATS(c); s->Symbol != p->FoundState->Symbol; s++);
636 if (s->Freq < MAX_FREQ - 9)
637 {
638 s->Freq++;
639 c->SummFreq++;
640 }
641 }
642 else
643 {
644 s = ONE_STATE(c);
645 s->Freq = (Byte)(s->Freq + (!SUFFIX(c)->NumStats & (s->Freq < 24)));
646 }
647 successor = SUCCESSOR(s);
648 if (successor != upBranch)
649 {
650 c = CTX(successor);
651 if (numPs == 0)
652 return c;
653 break;
654 }
655 ps[numPs++] = s;
656 }
657
658 upState.Symbol = *(const Byte *)Ppmd8_GetPtr(p, upBranch);
659 SetSuccessor(&upState, upBranch + 1);
660 flags = (Byte)(0x10 * (p->FoundState->Symbol >= 0x40) + 0x08 * (upState.Symbol >= 0x40));
661
662 if (c->NumStats == 0)
663 upState.Freq = ONE_STATE(c)->Freq;
664 else
665 {
666 UInt32 cf, s0;
667 CPpmd_State *s;
668 for (s = STATS(c); s->Symbol != upState.Symbol; s++);
669 cf = s->Freq - 1;
670 s0 = c->SummFreq - c->NumStats - cf;
671 upState.Freq = (Byte)(1 + ((2 * cf <= s0) ? (5 * cf > s0) : ((cf + 2 * s0 - 3) / s0)));
672 }
673
674 do
675 {
676 /* Create Child */
677 CTX_PTR c1; /* = AllocContext(p); */
678 if (p->HiUnit != p->LoUnit)
679 c1 = (CTX_PTR)(p->HiUnit -= UNIT_SIZE);
680 else if (p->FreeList[0] != 0)
681 c1 = (CTX_PTR)RemoveNode(p, 0);
682 else
683 {
684 c1 = (CTX_PTR)AllocUnitsRare(p, 0);
685 if (!c1)
686 return NULL;
687 }
688 c1->NumStats = 0;
689 c1->Flags = flags;
690 *ONE_STATE(c1) = upState;
691 c1->Suffix = REF(c);
692 SetSuccessor(ps[--numPs], REF(c1));
693 c = c1;
694 }
695 while (numPs != 0);
696
697 return c;
698 }
699
ReduceOrder(CPpmd8 * p,CPpmd_State * s1,CTX_PTR c)700 static CTX_PTR ReduceOrder(CPpmd8 *p, CPpmd_State *s1, CTX_PTR c)
701 {
702 CPpmd_State *s = NULL;
703 CTX_PTR c1 = c;
704 CPpmd_Void_Ref upBranch = REF(p->Text);
705
706 #ifdef PPMD8_FREEZE_SUPPORT
707 /* The BUG in Shkarin's code was fixed: ps could overflow in CUT_OFF mode. */
708 CPpmd_State *ps[PPMD8_MAX_ORDER + 1];
709 unsigned numPs = 0;
710 ps[numPs++] = p->FoundState;
711 #endif
712
713 SetSuccessor(p->FoundState, upBranch);
714 p->OrderFall++;
715
716 for (;;)
717 {
718 if (s1)
719 {
720 c = SUFFIX(c);
721 s = s1;
722 s1 = NULL;
723 }
724 else
725 {
726 if (!c->Suffix)
727 {
728 #ifdef PPMD8_FREEZE_SUPPORT
729 if (p->RestoreMethod > PPMD8_RESTORE_METHOD_FREEZE)
730 {
731 do { SetSuccessor(ps[--numPs], REF(c)); } while (numPs);
732 RESET_TEXT(1);
733 p->OrderFall = 1;
734 }
735 #endif
736 return c;
737 }
738 c = SUFFIX(c);
739 if (c->NumStats)
740 {
741 if ((s = STATS(c))->Symbol != p->FoundState->Symbol)
742 do { s++; } while (s->Symbol != p->FoundState->Symbol);
743 if (s->Freq < MAX_FREQ - 9)
744 {
745 s->Freq += 2;
746 c->SummFreq += 2;
747 }
748 }
749 else
750 {
751 s = ONE_STATE(c);
752 s->Freq = (Byte)(s->Freq + (s->Freq < 32));
753 }
754 }
755 if (SUCCESSOR(s))
756 break;
757 #ifdef PPMD8_FREEZE_SUPPORT
758 ps[numPs++] = s;
759 #endif
760 SetSuccessor(s, upBranch);
761 p->OrderFall++;
762 }
763
764 #ifdef PPMD8_FREEZE_SUPPORT
765 if (p->RestoreMethod > PPMD8_RESTORE_METHOD_FREEZE)
766 {
767 c = CTX(SUCCESSOR(s));
768 do { SetSuccessor(ps[--numPs], REF(c)); } while (numPs);
769 RESET_TEXT(1);
770 p->OrderFall = 1;
771 return c;
772 }
773 else
774 #endif
775 if (SUCCESSOR(s) <= upBranch)
776 {
777 CTX_PTR successor;
778 CPpmd_State *s2 = p->FoundState;
779 p->FoundState = s;
780
781 successor = CreateSuccessors(p, False, NULL, c);
782 if (successor == NULL)
783 SetSuccessor(s, 0);
784 else
785 SetSuccessor(s, REF(successor));
786 p->FoundState = s2;
787 }
788
789 if (p->OrderFall == 1 && c1 == p->MaxContext)
790 {
791 SetSuccessor(p->FoundState, SUCCESSOR(s));
792 p->Text--;
793 }
794 if (SUCCESSOR(s) == 0)
795 return NULL;
796 return CTX(SUCCESSOR(s));
797 }
798
UpdateModel(CPpmd8 * p)799 static void UpdateModel(CPpmd8 *p)
800 {
801 CPpmd_Void_Ref successor, fSuccessor = SUCCESSOR(p->FoundState);
802 CTX_PTR c;
803 unsigned s0, ns, fFreq = p->FoundState->Freq;
804 Byte flag, fSymbol = p->FoundState->Symbol;
805 CPpmd_State *s = NULL;
806
807 if (p->FoundState->Freq < MAX_FREQ / 4 && p->MinContext->Suffix != 0)
808 {
809 c = SUFFIX(p->MinContext);
810
811 if (c->NumStats == 0)
812 {
813 s = ONE_STATE(c);
814 if (s->Freq < 32)
815 s->Freq++;
816 }
817 else
818 {
819 s = STATS(c);
820 if (s->Symbol != p->FoundState->Symbol)
821 {
822 do { s++; } while (s->Symbol != p->FoundState->Symbol);
823 if (s[0].Freq >= s[-1].Freq)
824 {
825 SwapStates(&s[0], &s[-1]);
826 s--;
827 }
828 }
829 if (s->Freq < MAX_FREQ - 9)
830 {
831 s->Freq += 2;
832 c->SummFreq += 2;
833 }
834 }
835 }
836
837 c = p->MaxContext;
838 if (p->OrderFall == 0 && fSuccessor)
839 {
840 CTX_PTR cs = CreateSuccessors(p, True, s, p->MinContext);
841 if (cs == 0)
842 {
843 SetSuccessor(p->FoundState, 0);
844 RESTORE_MODEL(c, CTX(fSuccessor));
845 }
846 else
847 {
848 SetSuccessor(p->FoundState, REF(cs));
849 p->MaxContext = cs;
850 }
851 return;
852 }
853
854 *p->Text++ = p->FoundState->Symbol;
855 successor = REF(p->Text);
856 if (p->Text >= p->UnitsStart)
857 {
858 RESTORE_MODEL(c, CTX(fSuccessor)); /* check it */
859 return;
860 }
861
862 if (!fSuccessor)
863 {
864 CTX_PTR cs = ReduceOrder(p, s, p->MinContext);
865 if (cs == NULL)
866 {
867 RESTORE_MODEL(c, 0);
868 return;
869 }
870 fSuccessor = REF(cs);
871 }
872 else if ((Byte *)Ppmd8_GetPtr(p, fSuccessor) < p->UnitsStart)
873 {
874 CTX_PTR cs = CreateSuccessors(p, False, s, p->MinContext);
875 if (cs == NULL)
876 {
877 RESTORE_MODEL(c, 0);
878 return;
879 }
880 fSuccessor = REF(cs);
881 }
882
883 if (--p->OrderFall == 0)
884 {
885 successor = fSuccessor;
886 p->Text -= (p->MaxContext != p->MinContext);
887 }
888 #ifdef PPMD8_FREEZE_SUPPORT
889 else if (p->RestoreMethod > PPMD8_RESTORE_METHOD_FREEZE)
890 {
891 successor = fSuccessor;
892 RESET_TEXT(0);
893 p->OrderFall = 0;
894 }
895 #endif
896
897 s0 = p->MinContext->SummFreq - (ns = p->MinContext->NumStats) - fFreq;
898 flag = (Byte)(0x08 * (fSymbol >= 0x40));
899
900 for (; c != p->MinContext; c = SUFFIX(c))
901 {
902 unsigned ns1;
903 UInt32 cf, sf;
904 if ((ns1 = c->NumStats) != 0)
905 {
906 if ((ns1 & 1) != 0)
907 {
908 /* Expand for one UNIT */
909 unsigned oldNU = (ns1 + 1) >> 1;
910 unsigned i = U2I(oldNU);
911 if (i != U2I(oldNU + 1))
912 {
913 void *ptr = AllocUnits(p, i + 1);
914 void *oldPtr;
915 if (!ptr)
916 {
917 RESTORE_MODEL(c, CTX(fSuccessor));
918 return;
919 }
920 oldPtr = STATS(c);
921 MyMem12Cpy(ptr, oldPtr, oldNU);
922 InsertNode(p, oldPtr, i);
923 c->Stats = STATS_REF(ptr);
924 }
925 }
926 c->SummFreq = (UInt16)(c->SummFreq + (3 * ns1 + 1 < ns));
927 }
928 else
929 {
930 CPpmd_State *s2 = (CPpmd_State*)AllocUnits(p, 0);
931 if (!s2)
932 {
933 RESTORE_MODEL(c, CTX(fSuccessor));
934 return;
935 }
936 *s2 = *ONE_STATE(c);
937 c->Stats = REF(s2);
938 if (s2->Freq < MAX_FREQ / 4 - 1)
939 s2->Freq <<= 1;
940 else
941 s2->Freq = MAX_FREQ - 4;
942 c->SummFreq = (UInt16)(s2->Freq + p->InitEsc + (ns > 2));
943 }
944 cf = 2 * fFreq * (c->SummFreq + 6);
945 sf = (UInt32)s0 + c->SummFreq;
946 if (cf < 6 * sf)
947 {
948 cf = 1 + (cf > sf) + (cf >= 4 * sf);
949 c->SummFreq += 4;
950 }
951 else
952 {
953 cf = 4 + (cf > 9 * sf) + (cf > 12 * sf) + (cf > 15 * sf);
954 c->SummFreq = (UInt16)(c->SummFreq + cf);
955 }
956 {
957 CPpmd_State *s2 = STATS(c) + ns1 + 1;
958 SetSuccessor(s2, successor);
959 s2->Symbol = fSymbol;
960 s2->Freq = (Byte)cf;
961 c->Flags |= flag;
962 c->NumStats = (Byte)(ns1 + 1);
963 }
964 }
965 p->MaxContext = p->MinContext = CTX(fSuccessor);
966 }
967
Rescale(CPpmd8 * p)968 static void Rescale(CPpmd8 *p)
969 {
970 unsigned i, adder, sumFreq, escFreq;
971 CPpmd_State *stats = STATS(p->MinContext);
972 CPpmd_State *s = p->FoundState;
973 {
974 CPpmd_State tmp = *s;
975 for (; s != stats; s--)
976 s[0] = s[-1];
977 *s = tmp;
978 }
979 escFreq = p->MinContext->SummFreq - s->Freq;
980 s->Freq += 4;
981 adder = (p->OrderFall != 0
982 #ifdef PPMD8_FREEZE_SUPPORT
983 || p->RestoreMethod > PPMD8_RESTORE_METHOD_FREEZE
984 #endif
985 );
986 s->Freq = (Byte)((s->Freq + adder) >> 1);
987 sumFreq = s->Freq;
988
989 i = p->MinContext->NumStats;
990 do
991 {
992 escFreq -= (++s)->Freq;
993 s->Freq = (Byte)((s->Freq + adder) >> 1);
994 sumFreq += s->Freq;
995 if (s[0].Freq > s[-1].Freq)
996 {
997 CPpmd_State *s1 = s;
998 CPpmd_State tmp = *s1;
999 do
1000 s1[0] = s1[-1];
1001 while (--s1 != stats && tmp.Freq > s1[-1].Freq);
1002 *s1 = tmp;
1003 }
1004 }
1005 while (--i);
1006
1007 if (s->Freq == 0)
1008 {
1009 unsigned numStats = p->MinContext->NumStats;
1010 unsigned n0, n1;
1011 do { i++; } while ((--s)->Freq == 0);
1012 escFreq += i;
1013 p->MinContext->NumStats = (Byte)(p->MinContext->NumStats - i);
1014 if (p->MinContext->NumStats == 0)
1015 {
1016 CPpmd_State tmp = *stats;
1017 tmp.Freq = (Byte)((2 * tmp.Freq + escFreq - 1) / escFreq);
1018 if (tmp.Freq > MAX_FREQ / 3)
1019 tmp.Freq = MAX_FREQ / 3;
1020 InsertNode(p, stats, U2I((numStats + 2) >> 1));
1021 p->MinContext->Flags = (Byte)((p->MinContext->Flags & 0x10) + 0x08 * (tmp.Symbol >= 0x40));
1022 *(p->FoundState = ONE_STATE(p->MinContext)) = tmp;
1023 return;
1024 }
1025 n0 = (numStats + 2) >> 1;
1026 n1 = (p->MinContext->NumStats + 2) >> 1;
1027 if (n0 != n1)
1028 p->MinContext->Stats = STATS_REF(ShrinkUnits(p, stats, n0, n1));
1029 p->MinContext->Flags &= ~0x08;
1030 p->MinContext->Flags |= 0x08 * ((s = STATS(p->MinContext))->Symbol >= 0x40);
1031 i = p->MinContext->NumStats;
1032 do { p->MinContext->Flags |= 0x08*((++s)->Symbol >= 0x40); } while (--i);
1033 }
1034 p->MinContext->SummFreq = (UInt16)(sumFreq + escFreq - (escFreq >> 1));
1035 p->MinContext->Flags |= 0x4;
1036 p->FoundState = STATS(p->MinContext);
1037 }
1038
Ppmd8_MakeEscFreq(CPpmd8 * p,unsigned numMasked1,UInt32 * escFreq)1039 CPpmd_See *Ppmd8_MakeEscFreq(CPpmd8 *p, unsigned numMasked1, UInt32 *escFreq)
1040 {
1041 CPpmd_See *see;
1042 if (p->MinContext->NumStats != 0xFF)
1043 {
1044 see = p->See[(unsigned)p->NS2Indx[(unsigned)p->MinContext->NumStats + 2] - 3] +
1045 (p->MinContext->SummFreq > 11 * ((unsigned)p->MinContext->NumStats + 1)) +
1046 2 * (unsigned)(2 * (unsigned)p->MinContext->NumStats <
1047 ((unsigned)SUFFIX(p->MinContext)->NumStats + numMasked1)) +
1048 p->MinContext->Flags;
1049 {
1050 unsigned r = (see->Summ >> see->Shift);
1051 see->Summ = (UInt16)(see->Summ - r);
1052 *escFreq = r + (r == 0);
1053 }
1054 }
1055 else
1056 {
1057 see = &p->DummySee;
1058 *escFreq = 1;
1059 }
1060 return see;
1061 }
1062
NextContext(CPpmd8 * p)1063 static void NextContext(CPpmd8 *p)
1064 {
1065 CTX_PTR c = CTX(SUCCESSOR(p->FoundState));
1066 if (p->OrderFall == 0 && (Byte *)c >= p->UnitsStart)
1067 p->MinContext = p->MaxContext = c;
1068 else
1069 {
1070 UpdateModel(p);
1071 p->MinContext = p->MaxContext;
1072 }
1073 }
1074
Ppmd8_Update1(CPpmd8 * p)1075 void Ppmd8_Update1(CPpmd8 *p)
1076 {
1077 CPpmd_State *s = p->FoundState;
1078 s->Freq += 4;
1079 p->MinContext->SummFreq += 4;
1080 if (s[0].Freq > s[-1].Freq)
1081 {
1082 SwapStates(&s[0], &s[-1]);
1083 p->FoundState = --s;
1084 if (s->Freq > MAX_FREQ)
1085 Rescale(p);
1086 }
1087 NextContext(p);
1088 }
1089
Ppmd8_Update1_0(CPpmd8 * p)1090 void Ppmd8_Update1_0(CPpmd8 *p)
1091 {
1092 p->PrevSuccess = (2 * p->FoundState->Freq >= p->MinContext->SummFreq);
1093 p->RunLength += p->PrevSuccess;
1094 p->MinContext->SummFreq += 4;
1095 if ((p->FoundState->Freq += 4) > MAX_FREQ)
1096 Rescale(p);
1097 NextContext(p);
1098 }
1099
Ppmd8_UpdateBin(CPpmd8 * p)1100 void Ppmd8_UpdateBin(CPpmd8 *p)
1101 {
1102 p->FoundState->Freq = (Byte)(p->FoundState->Freq + (p->FoundState->Freq < 196));
1103 p->PrevSuccess = 1;
1104 p->RunLength++;
1105 NextContext(p);
1106 }
1107
Ppmd8_Update2(CPpmd8 * p)1108 void Ppmd8_Update2(CPpmd8 *p)
1109 {
1110 p->MinContext->SummFreq += 4;
1111 if ((p->FoundState->Freq += 4) > MAX_FREQ)
1112 Rescale(p);
1113 p->RunLength = p->InitRL;
1114 UpdateModel(p);
1115 p->MinContext = p->MaxContext;
1116 }
1117
1118 /* Ppmd8Dec.c -- PPMdI Decoder
1119 2010-04-16 : Igor Pavlov : Public domain
1120 This code is based on:
1121 PPMd var.I (2002): Dmitry Shkarin : Public domain
1122 Carryless rangecoder (1999): Dmitry Subbotin : Public domain */
1123
Ppmd8_RangeDec_Init(CPpmd8 * p)1124 Bool Ppmd8_RangeDec_Init(CPpmd8 *p)
1125 {
1126 unsigned i;
1127 p->Low = 0;
1128 p->Range = 0xFFFFFFFF;
1129 p->Code = 0;
1130 for (i = 0; i < 4; i++)
1131 p->Code = (p->Code << 8) | p->Stream.In->Read(p->Stream.In);
1132 return (p->Code < 0xFFFFFFFF);
1133 }
1134
RangeDec_GetThreshold(CPpmd8 * p,UInt32 total)1135 static UInt32 RangeDec_GetThreshold(CPpmd8 *p, UInt32 total)
1136 {
1137 return p->Code / (p->Range /= total);
1138 }
1139
RangeDec_Decode(CPpmd8 * p,UInt32 start,UInt32 size)1140 static void RangeDec_Decode(CPpmd8 *p, UInt32 start, UInt32 size)
1141 {
1142 start *= p->Range;
1143 p->Low += start;
1144 p->Code -= start;
1145 p->Range *= size;
1146
1147 while ((p->Low ^ (p->Low + p->Range)) < kTop ||
1148 (p->Range < kBot && ((p->Range = (0 - p->Low) & (kBot - 1)), 1)))
1149 {
1150 p->Code = (p->Code << 8) | p->Stream.In->Read(p->Stream.In);
1151 p->Range <<= 8;
1152 p->Low <<= 8;
1153 }
1154 }
1155
1156 #define MASK(sym) ((signed char *)charMask)[sym]
1157
Ppmd8_DecodeSymbol(CPpmd8 * p)1158 int Ppmd8_DecodeSymbol(CPpmd8 *p)
1159 {
1160 size_t charMask[256 / sizeof(size_t)];
1161 if (p->MinContext->NumStats != 0)
1162 {
1163 CPpmd_State *s = Ppmd8_GetStats(p, p->MinContext);
1164 unsigned i;
1165 UInt32 count, hiCnt;
1166 if ((count = RangeDec_GetThreshold(p, p->MinContext->SummFreq)) < (hiCnt = s->Freq))
1167 {
1168 Byte symbol;
1169 RangeDec_Decode(p, 0, s->Freq);
1170 p->FoundState = s;
1171 symbol = s->Symbol;
1172 Ppmd8_Update1_0(p);
1173 return symbol;
1174 }
1175 p->PrevSuccess = 0;
1176 i = p->MinContext->NumStats;
1177 do
1178 {
1179 if ((hiCnt += (++s)->Freq) > count)
1180 {
1181 Byte symbol;
1182 RangeDec_Decode(p, hiCnt - s->Freq, s->Freq);
1183 p->FoundState = s;
1184 symbol = s->Symbol;
1185 Ppmd8_Update1(p);
1186 return symbol;
1187 }
1188 }
1189 while (--i);
1190 if (count >= p->MinContext->SummFreq)
1191 return -2;
1192 RangeDec_Decode(p, hiCnt, p->MinContext->SummFreq - hiCnt);
1193 PPMD_SetAllBitsIn256Bytes(charMask);
1194 MASK(s->Symbol) = 0;
1195 i = p->MinContext->NumStats;
1196 do { MASK((--s)->Symbol) = 0; } while (--i);
1197 }
1198 else
1199 {
1200 UInt16 *prob = Ppmd8_GetBinSumm(p);
1201 if (((p->Code / (p->Range >>= 14)) < *prob))
1202 {
1203 Byte symbol;
1204 RangeDec_Decode(p, 0, *prob);
1205 *prob = (UInt16)PPMD_UPDATE_PROB_0(*prob);
1206 symbol = (p->FoundState = Ppmd8Context_OneState(p->MinContext))->Symbol;
1207 Ppmd8_UpdateBin(p);
1208 return symbol;
1209 }
1210 RangeDec_Decode(p, *prob, (1 << 14) - *prob);
1211 *prob = (UInt16)PPMD_UPDATE_PROB_1(*prob);
1212 p->InitEsc = PPMD8_kExpEscape[*prob >> 10];
1213 PPMD_SetAllBitsIn256Bytes(charMask);
1214 MASK(Ppmd8Context_OneState(p->MinContext)->Symbol) = 0;
1215 p->PrevSuccess = 0;
1216 }
1217 for (;;)
1218 {
1219 CPpmd_State *ps[256], *s;
1220 UInt32 freqSum, count, hiCnt;
1221 CPpmd_See *see;
1222 unsigned i, num, numMasked = p->MinContext->NumStats;
1223 do
1224 {
1225 p->OrderFall++;
1226 if (!p->MinContext->Suffix)
1227 return -1;
1228 p->MinContext = Ppmd8_GetContext(p, p->MinContext->Suffix);
1229 }
1230 while (p->MinContext->NumStats == numMasked);
1231 hiCnt = 0;
1232 s = Ppmd8_GetStats(p, p->MinContext);
1233 i = 0;
1234 num = p->MinContext->NumStats - numMasked;
1235 do
1236 {
1237 int k = (int)(MASK(s->Symbol));
1238 hiCnt += (s->Freq & k);
1239 ps[i] = s++;
1240 i -= k;
1241 }
1242 while (i != num);
1243
1244 see = Ppmd8_MakeEscFreq(p, numMasked, &freqSum);
1245 freqSum += hiCnt;
1246 count = RangeDec_GetThreshold(p, freqSum);
1247
1248 if (count < hiCnt)
1249 {
1250 Byte symbol;
1251 CPpmd_State **pps = ps;
1252 for (hiCnt = 0; (hiCnt += (*pps)->Freq) <= count; pps++);
1253 s = *pps;
1254 RangeDec_Decode(p, hiCnt - s->Freq, s->Freq);
1255 Ppmd_See_Update(see);
1256 p->FoundState = s;
1257 symbol = s->Symbol;
1258 Ppmd8_Update2(p);
1259 return symbol;
1260 }
1261 if (count >= freqSum)
1262 return -2;
1263 RangeDec_Decode(p, hiCnt, freqSum - hiCnt);
1264 see->Summ = (UInt16)(see->Summ + freqSum);
1265 do { MASK(ps[--i]->Symbol) = 0; } while (i != 0);
1266 }
1267 }
1268
1269 /* H->I changes:
1270 NS2Indx
1271 GlewCount, and Glue method
1272 BinSum
1273 See / EscFreq
1274 CreateSuccessors updates more suffix contexts
1275 UpdateModel consts.
1276 PrevSuccess Update
1277 */
1278
1279 const IPpmd8 __archive_ppmd8_functions =
1280 {
1281 &Ppmd8_Construct,
1282 &Ppmd8_Alloc,
1283 &Ppmd8_Free,
1284 &Ppmd8_Init,
1285 &Ppmd8_RangeDec_Init,
1286 &Ppmd8_DecodeSymbol,
1287 };
1288