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 = 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) do { \
246 UInt32 *d = (UInt32 *)dest; \
247 const UInt32 *z = (const UInt32 *)src; \
248 UInt32 n = num; \
249 do { \
250 d[0] = z[0]; d[1] = z[1]; d[2] = z[2]; z += 3; d += 3; \
251 } while (--n); \
252 } while (0)
253
ShrinkUnits(CPpmd8 * p,void * oldPtr,unsigned oldNU,unsigned newNU)254 static void *ShrinkUnits(CPpmd8 *p, void *oldPtr, unsigned oldNU, unsigned newNU)
255 {
256 unsigned i0 = U2I(oldNU);
257 unsigned i1 = U2I(newNU);
258 if (i0 == i1)
259 return oldPtr;
260 if (p->FreeList[i1] != 0)
261 {
262 void *ptr = RemoveNode(p, i1);
263 MyMem12Cpy(ptr, oldPtr, newNU);
264 InsertNode(p, oldPtr, i0);
265 return ptr;
266 }
267 SplitBlock(p, oldPtr, i0, i1);
268 return oldPtr;
269 }
270
FreeUnits(CPpmd8 * p,void * ptr,unsigned nu)271 static void FreeUnits(CPpmd8 *p, void *ptr, unsigned nu)
272 {
273 InsertNode(p, ptr, U2I(nu));
274 }
275
SpecialFreeUnit(CPpmd8 * p,void * ptr)276 static void SpecialFreeUnit(CPpmd8 *p, void *ptr)
277 {
278 if ((Byte *)ptr != p->UnitsStart)
279 InsertNode(p, ptr, 0);
280 else
281 {
282 #ifdef PPMD8_FREEZE_SUPPORT
283 *(UInt32 *)ptr = EMPTY_NODE; /* it's used for (Flags == 0xFF) check in RemoveBinContexts */
284 #endif
285 p->UnitsStart += UNIT_SIZE;
286 }
287 }
288
MoveUnitsUp(CPpmd8 * p,void * oldPtr,unsigned nu)289 static void *MoveUnitsUp(CPpmd8 *p, void *oldPtr, unsigned nu)
290 {
291 unsigned indx = U2I(nu);
292 void *ptr;
293 if ((Byte *)oldPtr > p->UnitsStart + 16 * 1024 || REF(oldPtr) > p->FreeList[indx])
294 return oldPtr;
295 ptr = RemoveNode(p, indx);
296 MyMem12Cpy(ptr, oldPtr, nu);
297 if ((Byte*)oldPtr != p->UnitsStart)
298 InsertNode(p, oldPtr, indx);
299 else
300 p->UnitsStart += U2B(I2U(indx));
301 return ptr;
302 }
303
ExpandTextArea(CPpmd8 * p)304 static void ExpandTextArea(CPpmd8 *p)
305 {
306 UInt32 count[PPMD_NUM_INDEXES];
307 unsigned i;
308 memset(count, 0, sizeof(count));
309 if (p->LoUnit != p->HiUnit)
310 ((CPpmd8_Node *)p->LoUnit)->Stamp = 0;
311
312 {
313 CPpmd8_Node *node = (CPpmd8_Node *)p->UnitsStart;
314 for (; node->Stamp == EMPTY_NODE; node += node->NU)
315 {
316 node->Stamp = 0;
317 count[U2I(node->NU)]++;
318 }
319 p->UnitsStart = (Byte *)node;
320 }
321
322 for (i = 0; i < PPMD_NUM_INDEXES; i++)
323 {
324 CPpmd8_Node_Ref *next = (CPpmd8_Node_Ref *)&p->FreeList[i];
325 while (count[i] != 0)
326 {
327 CPpmd8_Node *node = NODE(*next);
328 while (node->Stamp == 0)
329 {
330 *next = node->Next;
331 node = NODE(*next);
332 p->Stamps[i]--;
333 if (--count[i] == 0)
334 break;
335 }
336 next = &node->Next;
337 }
338 }
339 }
340
341 #define SUCCESSOR(p) ((CPpmd_Void_Ref)((p)->SuccessorLow | ((UInt32)(p)->SuccessorHigh << 16)))
342
SetSuccessor(CPpmd_State * p,CPpmd_Void_Ref v)343 static void SetSuccessor(CPpmd_State *p, CPpmd_Void_Ref v)
344 {
345 (p)->SuccessorLow = (UInt16)((UInt32)(v) & 0xFFFF);
346 (p)->SuccessorHigh = (UInt16)(((UInt32)(v) >> 16) & 0xFFFF);
347 }
348
349 #define RESET_TEXT(offs) do { \
350 p->Text = p->Base + p->AlignOffset + (offs); \
351 } while (0)
352
RestartModel(CPpmd8 * p)353 static void RestartModel(CPpmd8 *p)
354 {
355 unsigned i, k, m, r;
356
357 memset(p->FreeList, 0, sizeof(p->FreeList));
358 memset(p->Stamps, 0, sizeof(p->Stamps));
359 RESET_TEXT(0);
360 p->HiUnit = p->Text + p->Size;
361 p->LoUnit = p->UnitsStart = p->HiUnit - p->Size / 8 / UNIT_SIZE * 7 * UNIT_SIZE;
362 p->GlueCount = 0;
363
364 p->OrderFall = p->MaxOrder;
365 p->RunLength = p->InitRL = -(Int32)((p->MaxOrder < 12) ? p->MaxOrder : 12) - 1;
366 p->PrevSuccess = 0;
367
368 p->MinContext = p->MaxContext = (CTX_PTR)(p->HiUnit -= UNIT_SIZE); /* AllocContext(p); */
369 p->MinContext->Suffix = 0;
370 p->MinContext->NumStats = 255;
371 p->MinContext->Flags = 0;
372 p->MinContext->SummFreq = 256 + 1;
373 p->FoundState = (CPpmd_State *)p->LoUnit; /* AllocUnits(p, PPMD_NUM_INDEXES - 1); */
374 p->LoUnit += U2B(256 / 2);
375 p->MinContext->Stats = REF(p->FoundState);
376 for (i = 0; i < 256; i++)
377 {
378 CPpmd_State *s = &p->FoundState[i];
379 s->Symbol = (Byte)i;
380 s->Freq = 1;
381 SetSuccessor(s, 0);
382 }
383
384 for (i = m = 0; m < 25; m++)
385 {
386 while (p->NS2Indx[i] == m)
387 i++;
388 for (k = 0; k < 8; k++)
389 {
390 UInt16 val = (UInt16)(PPMD_BIN_SCALE - kInitBinEsc[k] / (i + 1));
391 UInt16 *dest = p->BinSumm[m] + k;
392 for (r = 0; r < 64; r += 8)
393 dest[r] = val;
394 }
395 }
396
397 for (i = m = 0; m < 24; m++)
398 {
399 while (p->NS2Indx[i + 3] == m + 3)
400 i++;
401 for (k = 0; k < 32; k++)
402 {
403 CPpmd_See *s = &p->See[m][k];
404 s->Summ = (UInt16)((2 * i + 5) << (s->Shift = PPMD_PERIOD_BITS - 4));
405 s->Count = 7;
406 }
407 }
408 }
409
Ppmd8_Init(CPpmd8 * p,unsigned maxOrder,unsigned restoreMethod)410 void Ppmd8_Init(CPpmd8 *p, unsigned maxOrder, unsigned restoreMethod)
411 {
412 p->MaxOrder = maxOrder;
413 p->RestoreMethod = restoreMethod;
414 RestartModel(p);
415 p->DummySee.Shift = PPMD_PERIOD_BITS;
416 p->DummySee.Summ = 0; /* unused */
417 p->DummySee.Count = 64; /* unused */
418 }
419
Refresh(CPpmd8 * p,CTX_PTR ctx,unsigned oldNU,unsigned scale)420 static void Refresh(CPpmd8 *p, CTX_PTR ctx, unsigned oldNU, unsigned scale)
421 {
422 unsigned i = ctx->NumStats, escFreq, sumFreq, flags;
423 CPpmd_State *s = (CPpmd_State *)ShrinkUnits(p, STATS(ctx), oldNU, (i + 2) >> 1);
424 ctx->Stats = REF(s);
425 #ifdef PPMD8_FREEZE_SUPPORT
426 /* fixed over Shkarin's code. Fixed code is not compatible with original code for some files in FREEZE mode. */
427 scale |= (ctx->SummFreq >= ((UInt32)1 << 15));
428 #endif
429 flags = (ctx->Flags & (0x10 + 0x04 * scale)) + 0x08 * (s->Symbol >= 0x40);
430 escFreq = ctx->SummFreq - s->Freq;
431 sumFreq = (s->Freq = (Byte)((s->Freq + scale) >> scale));
432 do
433 {
434 escFreq -= (++s)->Freq;
435 sumFreq += (s->Freq = (Byte)((s->Freq + scale) >> scale));
436 flags |= 0x08 * (s->Symbol >= 0x40);
437 }
438 while (--i);
439 ctx->SummFreq = (UInt16)(sumFreq + ((escFreq + scale) >> scale));
440 ctx->Flags = (Byte)flags;
441 }
442
SwapStates(CPpmd_State * t1,CPpmd_State * t2)443 static void SwapStates(CPpmd_State *t1, CPpmd_State *t2)
444 {
445 CPpmd_State tmp = *t1;
446 *t1 = *t2;
447 *t2 = tmp;
448 }
449
CutOff(CPpmd8 * p,CTX_PTR ctx,unsigned order)450 static CPpmd_Void_Ref CutOff(CPpmd8 *p, CTX_PTR ctx, unsigned order)
451 {
452 int i;
453 unsigned tmp;
454 CPpmd_State *s;
455
456 if (!ctx->NumStats)
457 {
458 s = ONE_STATE(ctx);
459 if ((Byte *)Ppmd8_GetPtr(p, SUCCESSOR(s)) >= p->UnitsStart)
460 {
461 if (order < p->MaxOrder)
462 SetSuccessor(s, CutOff(p, CTX(SUCCESSOR(s)), order + 1));
463 else
464 SetSuccessor(s, 0);
465 if (SUCCESSOR(s) || order <= 9) /* O_BOUND */
466 return REF(ctx);
467 }
468 SpecialFreeUnit(p, ctx);
469 return 0;
470 }
471
472 ctx->Stats = STATS_REF(MoveUnitsUp(p, STATS(ctx), tmp = ((unsigned)ctx->NumStats + 2) >> 1));
473
474 for (s = STATS(ctx) + (i = ctx->NumStats); s >= STATS(ctx); s--)
475 if ((Byte *)Ppmd8_GetPtr(p, SUCCESSOR(s)) < p->UnitsStart)
476 {
477 CPpmd_State *s2 = STATS(ctx) + (i--);
478 SetSuccessor(s, 0);
479 SwapStates(s, s2);
480 }
481 else if (order < p->MaxOrder)
482 SetSuccessor(s, CutOff(p, CTX(SUCCESSOR(s)), order + 1));
483 else
484 SetSuccessor(s, 0);
485
486 if (i != ctx->NumStats && order)
487 {
488 ctx->NumStats = (Byte)i;
489 s = STATS(ctx);
490 if (i < 0)
491 {
492 FreeUnits(p, s, tmp);
493 SpecialFreeUnit(p, ctx);
494 return 0;
495 }
496 if (i == 0)
497 {
498 ctx->Flags = (Byte)((ctx->Flags & 0x10) + 0x08 * (s->Symbol >= 0x40));
499 *ONE_STATE(ctx) = *s;
500 FreeUnits(p, s, tmp);
501 /* 9.31: the code was fixed. It's was not BUG, if Freq <= MAX_FREQ = 124 */
502 ONE_STATE(ctx)->Freq = (Byte)(((unsigned)ONE_STATE(ctx)->Freq + 11) >> 3);
503 }
504 else
505 Refresh(p, ctx, tmp, ctx->SummFreq > 16 * i);
506 }
507 return REF(ctx);
508 }
509
510 #ifdef PPMD8_FREEZE_SUPPORT
RemoveBinContexts(CPpmd8 * p,CTX_PTR ctx,unsigned order)511 static CPpmd_Void_Ref RemoveBinContexts(CPpmd8 *p, CTX_PTR ctx, unsigned order)
512 {
513 CPpmd_State *s;
514 if (!ctx->NumStats)
515 {
516 s = ONE_STATE(ctx);
517 if ((Byte *)Ppmd8_GetPtr(p, SUCCESSOR(s)) >= p->UnitsStart && order < p->MaxOrder)
518 SetSuccessor(s, RemoveBinContexts(p, CTX(SUCCESSOR(s)), order + 1));
519 else
520 SetSuccessor(s, 0);
521 /* Suffix context can be removed already, since different (high-order)
522 Successors may refer to same context. So we check Flags == 0xFF (Stamp == EMPTY_NODE) */
523 if (!SUCCESSOR(s) && (!SUFFIX(ctx)->NumStats || SUFFIX(ctx)->Flags == 0xFF))
524 {
525 FreeUnits(p, ctx, 1);
526 return 0;
527 }
528 else
529 return REF(ctx);
530 }
531
532 for (s = STATS(ctx) + ctx->NumStats; s >= STATS(ctx); s--)
533 if ((Byte *)Ppmd8_GetPtr(p, SUCCESSOR(s)) >= p->UnitsStart && order < p->MaxOrder)
534 SetSuccessor(s, RemoveBinContexts(p, CTX(SUCCESSOR(s)), order + 1));
535 else
536 SetSuccessor(s, 0);
537
538 return REF(ctx);
539 }
540 #endif
541
GetUsedMemory(const CPpmd8 * p)542 static UInt32 GetUsedMemory(const CPpmd8 *p)
543 {
544 UInt32 v = 0;
545 unsigned i;
546 for (i = 0; i < PPMD_NUM_INDEXES; i++)
547 v += p->Stamps[i] * I2U(i);
548 return p->Size - (UInt32)(p->HiUnit - p->LoUnit) - (UInt32)(p->UnitsStart - p->Text) - U2B(v);
549 }
550
551 #ifdef PPMD8_FREEZE_SUPPORT
552 #define RESTORE_MODEL(c1, fSuccessor) RestoreModel(p, c1, fSuccessor)
553 #else
554 #define RESTORE_MODEL(c1, fSuccessor) RestoreModel(p, c1)
555 #endif
556
RestoreModel(CPpmd8 * p,CTX_PTR c1,CTX_PTR fSuccessor)557 static void RestoreModel(CPpmd8 *p, CTX_PTR c1
558 #ifdef PPMD8_FREEZE_SUPPORT
559 , CTX_PTR fSuccessor
560 #endif
561 )
562 {
563 CTX_PTR c;
564 CPpmd_State *s;
565 RESET_TEXT(0);
566 for (c = p->MaxContext; c != c1; c = SUFFIX(c))
567 if (--(c->NumStats) == 0)
568 {
569 s = STATS(c);
570 c->Flags = (Byte)((c->Flags & 0x10) + 0x08 * (s->Symbol >= 0x40));
571 *ONE_STATE(c) = *s;
572 SpecialFreeUnit(p, s);
573 ONE_STATE(c)->Freq = (Byte)(((unsigned)ONE_STATE(c)->Freq + 11) >> 3);
574 }
575 else
576 Refresh(p, c, (c->NumStats+3) >> 1, 0);
577
578 for (; c != p->MinContext; c = SUFFIX(c))
579 if (!c->NumStats)
580 ONE_STATE(c)->Freq = (Byte)(ONE_STATE(c)->Freq - (ONE_STATE(c)->Freq >> 1));
581 else if ((c->SummFreq += 4) > 128 + 4 * c->NumStats)
582 Refresh(p, c, (c->NumStats + 2) >> 1, 1);
583
584 #ifdef PPMD8_FREEZE_SUPPORT
585 if (p->RestoreMethod > PPMD8_RESTORE_METHOD_FREEZE)
586 {
587 p->MaxContext = fSuccessor;
588 p->GlueCount += !(p->Stamps[1] & 1);
589 }
590 else if (p->RestoreMethod == PPMD8_RESTORE_METHOD_FREEZE)
591 {
592 while (p->MaxContext->Suffix)
593 p->MaxContext = SUFFIX(p->MaxContext);
594 RemoveBinContexts(p, p->MaxContext, 0);
595 p->RestoreMethod++;
596 p->GlueCount = 0;
597 p->OrderFall = p->MaxOrder;
598 }
599 else
600 #endif
601 if (p->RestoreMethod == PPMD8_RESTORE_METHOD_RESTART || GetUsedMemory(p) < (p->Size >> 1))
602 RestartModel(p);
603 else
604 {
605 while (p->MaxContext->Suffix)
606 p->MaxContext = SUFFIX(p->MaxContext);
607 do
608 {
609 CutOff(p, p->MaxContext, 0);
610 ExpandTextArea(p);
611 }
612 while (GetUsedMemory(p) > 3 * (p->Size >> 2));
613 p->GlueCount = 0;
614 p->OrderFall = p->MaxOrder;
615 }
616 }
617
CreateSuccessors(CPpmd8 * p,Bool skip,CPpmd_State * s1,CTX_PTR c)618 static CTX_PTR CreateSuccessors(CPpmd8 *p, Bool skip, CPpmd_State *s1, CTX_PTR c)
619 {
620 CPpmd_State upState;
621 Byte flags;
622 CPpmd_Byte_Ref upBranch = (CPpmd_Byte_Ref)SUCCESSOR(p->FoundState);
623 /* fixed over Shkarin's code. Maybe it could work without + 1 too. */
624 CPpmd_State *ps[PPMD8_MAX_ORDER + 1];
625 unsigned numPs = 0;
626
627 if (!skip)
628 ps[numPs++] = p->FoundState;
629
630 while (c->Suffix)
631 {
632 CPpmd_Void_Ref successor;
633 CPpmd_State *s;
634 c = SUFFIX(c);
635 if (s1)
636 {
637 s = s1;
638 s1 = NULL;
639 }
640 else if (c->NumStats != 0)
641 {
642 for (s = STATS(c); s->Symbol != p->FoundState->Symbol; s++);
643 if (s->Freq < MAX_FREQ - 9)
644 {
645 s->Freq++;
646 c->SummFreq++;
647 }
648 }
649 else
650 {
651 s = ONE_STATE(c);
652 s->Freq = (Byte)(s->Freq + (!SUFFIX(c)->NumStats & (s->Freq < 24)));
653 }
654 successor = SUCCESSOR(s);
655 if (successor != upBranch)
656 {
657 c = CTX(successor);
658 if (numPs == 0)
659 return c;
660 break;
661 }
662 ps[numPs++] = s;
663 }
664
665 upState.Symbol = *(const Byte *)Ppmd8_GetPtr(p, upBranch);
666 SetSuccessor(&upState, upBranch + 1);
667 flags = (Byte)(0x10 * (p->FoundState->Symbol >= 0x40) + 0x08 * (upState.Symbol >= 0x40));
668
669 if (c->NumStats == 0)
670 upState.Freq = ONE_STATE(c)->Freq;
671 else
672 {
673 UInt32 cf, s0;
674 CPpmd_State *s;
675 for (s = STATS(c); s->Symbol != upState.Symbol; s++);
676 cf = s->Freq - 1;
677 s0 = c->SummFreq - c->NumStats - cf;
678 upState.Freq = (Byte)(1 + ((2 * cf <= s0) ? (5 * cf > s0) : ((cf + 2 * s0 - 3) / s0)));
679 }
680
681 while (numPs != 0)
682 {
683 /* Create Child */
684 CTX_PTR c1; /* = AllocContext(p); */
685 if (p->HiUnit != p->LoUnit)
686 c1 = (CTX_PTR)(p->HiUnit -= UNIT_SIZE);
687 else if (p->FreeList[0] != 0)
688 c1 = (CTX_PTR)RemoveNode(p, 0);
689 else
690 {
691 c1 = (CTX_PTR)AllocUnitsRare(p, 0);
692 if (!c1)
693 return NULL;
694 }
695 c1->NumStats = 0;
696 c1->Flags = flags;
697 *ONE_STATE(c1) = upState;
698 c1->Suffix = REF(c);
699 SetSuccessor(ps[--numPs], REF(c1));
700 c = c1;
701 }
702
703 return c;
704 }
705
ReduceOrder(CPpmd8 * p,CPpmd_State * s1,CTX_PTR c)706 static CTX_PTR ReduceOrder(CPpmd8 *p, CPpmd_State *s1, CTX_PTR c)
707 {
708 CPpmd_State *s = NULL;
709 CTX_PTR c1 = c;
710 CPpmd_Void_Ref upBranch = REF(p->Text);
711
712 #ifdef PPMD8_FREEZE_SUPPORT
713 /* The BUG in Shkarin's code was fixed: ps could overflow in CUT_OFF mode. */
714 CPpmd_State *ps[PPMD8_MAX_ORDER + 1];
715 unsigned numPs = 0;
716 ps[numPs++] = p->FoundState;
717 #endif
718
719 SetSuccessor(p->FoundState, upBranch);
720 p->OrderFall++;
721
722 for (;;)
723 {
724 if (s1)
725 {
726 c = SUFFIX(c);
727 s = s1;
728 s1 = NULL;
729 }
730 else
731 {
732 if (!c->Suffix)
733 {
734 #ifdef PPMD8_FREEZE_SUPPORT
735 if (p->RestoreMethod > PPMD8_RESTORE_METHOD_FREEZE)
736 {
737 do { SetSuccessor(ps[--numPs], REF(c)); } while (numPs);
738 RESET_TEXT(1);
739 p->OrderFall = 1;
740 }
741 #endif
742 return c;
743 }
744 c = SUFFIX(c);
745 if (c->NumStats)
746 {
747 if ((s = STATS(c))->Symbol != p->FoundState->Symbol)
748 do { s++; } while (s->Symbol != p->FoundState->Symbol);
749 if (s->Freq < MAX_FREQ - 9)
750 {
751 s->Freq += 2;
752 c->SummFreq += 2;
753 }
754 }
755 else
756 {
757 s = ONE_STATE(c);
758 s->Freq = (Byte)(s->Freq + (s->Freq < 32));
759 }
760 }
761 if (SUCCESSOR(s))
762 break;
763 #ifdef PPMD8_FREEZE_SUPPORT
764 ps[numPs++] = s;
765 #endif
766 SetSuccessor(s, upBranch);
767 p->OrderFall++;
768 }
769
770 #ifdef PPMD8_FREEZE_SUPPORT
771 if (p->RestoreMethod > PPMD8_RESTORE_METHOD_FREEZE)
772 {
773 c = CTX(SUCCESSOR(s));
774 do { SetSuccessor(ps[--numPs], REF(c)); } while (numPs);
775 RESET_TEXT(1);
776 p->OrderFall = 1;
777 return c;
778 }
779 else
780 #endif
781 if (SUCCESSOR(s) <= upBranch)
782 {
783 CTX_PTR successor;
784 CPpmd_State *s2 = p->FoundState;
785 p->FoundState = s;
786
787 successor = CreateSuccessors(p, False, NULL, c);
788 if (successor == NULL)
789 SetSuccessor(s, 0);
790 else
791 SetSuccessor(s, REF(successor));
792 p->FoundState = s2;
793 }
794
795 if (p->OrderFall == 1 && c1 == p->MaxContext)
796 {
797 SetSuccessor(p->FoundState, SUCCESSOR(s));
798 p->Text--;
799 }
800 if (SUCCESSOR(s) == 0)
801 return NULL;
802 return CTX(SUCCESSOR(s));
803 }
804
UpdateModel(CPpmd8 * p)805 static void UpdateModel(CPpmd8 *p)
806 {
807 CPpmd_Void_Ref successor, fSuccessor = SUCCESSOR(p->FoundState);
808 CTX_PTR c;
809 unsigned s0, ns, fFreq = p->FoundState->Freq;
810 Byte flag, fSymbol = p->FoundState->Symbol;
811 CPpmd_State *s = NULL;
812
813 if (p->FoundState->Freq < MAX_FREQ / 4 && p->MinContext->Suffix != 0)
814 {
815 c = SUFFIX(p->MinContext);
816
817 if (c->NumStats == 0)
818 {
819 s = ONE_STATE(c);
820 if (s->Freq < 32)
821 s->Freq++;
822 }
823 else
824 {
825 s = STATS(c);
826 if (s->Symbol != p->FoundState->Symbol)
827 {
828 do { s++; } while (s->Symbol != p->FoundState->Symbol);
829 if (s[0].Freq >= s[-1].Freq)
830 {
831 SwapStates(&s[0], &s[-1]);
832 s--;
833 }
834 }
835 if (s->Freq < MAX_FREQ - 9)
836 {
837 s->Freq += 2;
838 c->SummFreq += 2;
839 }
840 }
841 }
842
843 c = p->MaxContext;
844 if (p->OrderFall == 0 && fSuccessor)
845 {
846 CTX_PTR cs = CreateSuccessors(p, True, s, p->MinContext);
847 if (cs == 0)
848 {
849 SetSuccessor(p->FoundState, 0);
850 RESTORE_MODEL(c, CTX(fSuccessor));
851 }
852 else
853 {
854 SetSuccessor(p->FoundState, REF(cs));
855 p->MaxContext = cs;
856 }
857 return;
858 }
859
860 *p->Text++ = p->FoundState->Symbol;
861 successor = REF(p->Text);
862 if (p->Text >= p->UnitsStart)
863 {
864 RESTORE_MODEL(c, CTX(fSuccessor)); /* check it */
865 return;
866 }
867
868 if (!fSuccessor)
869 {
870 CTX_PTR cs = ReduceOrder(p, s, p->MinContext);
871 if (cs == NULL)
872 {
873 RESTORE_MODEL(c, 0);
874 return;
875 }
876 fSuccessor = REF(cs);
877 }
878 else if ((Byte *)Ppmd8_GetPtr(p, fSuccessor) < p->UnitsStart)
879 {
880 CTX_PTR cs = CreateSuccessors(p, False, s, p->MinContext);
881 if (cs == NULL)
882 {
883 RESTORE_MODEL(c, 0);
884 return;
885 }
886 fSuccessor = REF(cs);
887 }
888
889 if (--p->OrderFall == 0)
890 {
891 successor = fSuccessor;
892 p->Text -= (p->MaxContext != p->MinContext);
893 }
894 #ifdef PPMD8_FREEZE_SUPPORT
895 else if (p->RestoreMethod > PPMD8_RESTORE_METHOD_FREEZE)
896 {
897 successor = fSuccessor;
898 RESET_TEXT(0);
899 p->OrderFall = 0;
900 }
901 #endif
902
903 s0 = p->MinContext->SummFreq - (ns = p->MinContext->NumStats) - fFreq;
904 flag = (Byte)(0x08 * (fSymbol >= 0x40));
905
906 for (; c != p->MinContext; c = SUFFIX(c))
907 {
908 unsigned ns1;
909 UInt32 cf, sf;
910 if ((ns1 = c->NumStats) != 0)
911 {
912 if ((ns1 & 1) != 0)
913 {
914 /* Expand for one UNIT */
915 unsigned oldNU = (ns1 + 1) >> 1;
916 unsigned i = U2I(oldNU);
917 if (i != U2I(oldNU + 1))
918 {
919 void *ptr = AllocUnits(p, i + 1);
920 void *oldPtr;
921 if (!ptr)
922 {
923 RESTORE_MODEL(c, CTX(fSuccessor));
924 return;
925 }
926 oldPtr = STATS(c);
927 MyMem12Cpy(ptr, oldPtr, oldNU);
928 InsertNode(p, oldPtr, i);
929 c->Stats = STATS_REF(ptr);
930 }
931 }
932 c->SummFreq = (UInt16)(c->SummFreq + (3 * ns1 + 1 < ns));
933 }
934 else
935 {
936 CPpmd_State *s2 = (CPpmd_State*)AllocUnits(p, 0);
937 if (!s2)
938 {
939 RESTORE_MODEL(c, CTX(fSuccessor));
940 return;
941 }
942 *s2 = *ONE_STATE(c);
943 c->Stats = REF(s2);
944 if (s2->Freq < MAX_FREQ / 4 - 1)
945 s2->Freq <<= 1;
946 else
947 s2->Freq = MAX_FREQ - 4;
948 c->SummFreq = (UInt16)(s2->Freq + p->InitEsc + (ns > 2));
949 }
950 cf = 2 * fFreq * (c->SummFreq + 6);
951 sf = (UInt32)s0 + c->SummFreq;
952 if (cf < 6 * sf)
953 {
954 cf = 1 + (cf > sf) + (cf >= 4 * sf);
955 c->SummFreq += 4;
956 }
957 else
958 {
959 cf = 4 + (cf > 9 * sf) + (cf > 12 * sf) + (cf > 15 * sf);
960 c->SummFreq = (UInt16)(c->SummFreq + cf);
961 }
962 {
963 CPpmd_State *s2 = STATS(c) + ns1 + 1;
964 SetSuccessor(s2, successor);
965 s2->Symbol = fSymbol;
966 s2->Freq = (Byte)cf;
967 c->Flags |= flag;
968 c->NumStats = (Byte)(ns1 + 1);
969 }
970 }
971 p->MaxContext = p->MinContext = CTX(fSuccessor);
972 }
973
Rescale(CPpmd8 * p)974 static void Rescale(CPpmd8 *p)
975 {
976 unsigned i, adder, sumFreq, escFreq;
977 CPpmd_State *stats = STATS(p->MinContext);
978 CPpmd_State *s = p->FoundState;
979 {
980 CPpmd_State tmp = *s;
981 for (; s != stats; s--)
982 s[0] = s[-1];
983 *s = tmp;
984 }
985 escFreq = p->MinContext->SummFreq - s->Freq;
986 s->Freq += 4;
987 adder = (p->OrderFall != 0
988 #ifdef PPMD8_FREEZE_SUPPORT
989 || p->RestoreMethod > PPMD8_RESTORE_METHOD_FREEZE
990 #endif
991 );
992 s->Freq = (Byte)((s->Freq + adder) >> 1);
993 sumFreq = s->Freq;
994
995 i = p->MinContext->NumStats;
996 do
997 {
998 escFreq -= (++s)->Freq;
999 s->Freq = (Byte)((s->Freq + adder) >> 1);
1000 sumFreq += s->Freq;
1001 if (s[0].Freq > s[-1].Freq)
1002 {
1003 CPpmd_State *s1 = s;
1004 CPpmd_State tmp = *s1;
1005 do
1006 s1[0] = s1[-1];
1007 while (--s1 != stats && tmp.Freq > s1[-1].Freq);
1008 *s1 = tmp;
1009 }
1010 }
1011 while (--i);
1012
1013 if (s->Freq == 0)
1014 {
1015 unsigned numStats = p->MinContext->NumStats;
1016 unsigned n0, n1;
1017 do { i++; } while ((--s)->Freq == 0);
1018 escFreq += i;
1019 p->MinContext->NumStats = (Byte)(p->MinContext->NumStats - i);
1020 if (p->MinContext->NumStats == 0)
1021 {
1022 CPpmd_State tmp = *stats;
1023 tmp.Freq = (Byte)((2 * tmp.Freq + escFreq - 1) / escFreq);
1024 if (tmp.Freq > MAX_FREQ / 3)
1025 tmp.Freq = MAX_FREQ / 3;
1026 InsertNode(p, stats, U2I((numStats + 2) >> 1));
1027 p->MinContext->Flags = (Byte)((p->MinContext->Flags & 0x10) + 0x08 * (tmp.Symbol >= 0x40));
1028 *(p->FoundState = ONE_STATE(p->MinContext)) = tmp;
1029 return;
1030 }
1031 n0 = (numStats + 2) >> 1;
1032 n1 = (p->MinContext->NumStats + 2) >> 1;
1033 if (n0 != n1)
1034 p->MinContext->Stats = STATS_REF(ShrinkUnits(p, stats, n0, n1));
1035 p->MinContext->Flags &= ~0x08;
1036 p->MinContext->Flags |= 0x08 * ((s = STATS(p->MinContext))->Symbol >= 0x40);
1037 i = p->MinContext->NumStats;
1038 do { p->MinContext->Flags |= 0x08*((++s)->Symbol >= 0x40); } while (--i);
1039 }
1040 p->MinContext->SummFreq = (UInt16)(sumFreq + escFreq - (escFreq >> 1));
1041 p->MinContext->Flags |= 0x4;
1042 p->FoundState = STATS(p->MinContext);
1043 }
1044
Ppmd8_MakeEscFreq(CPpmd8 * p,unsigned numMasked1,UInt32 * escFreq)1045 CPpmd_See *Ppmd8_MakeEscFreq(CPpmd8 *p, unsigned numMasked1, UInt32 *escFreq)
1046 {
1047 CPpmd_See *see;
1048 if (p->MinContext->NumStats != 0xFF)
1049 {
1050 see = p->See[(unsigned)p->NS2Indx[(unsigned)p->MinContext->NumStats + 2] - 3] +
1051 (p->MinContext->SummFreq > 11 * ((unsigned)p->MinContext->NumStats + 1)) +
1052 2 * (unsigned)(2 * (unsigned)p->MinContext->NumStats <
1053 ((unsigned)SUFFIX(p->MinContext)->NumStats + numMasked1)) +
1054 p->MinContext->Flags;
1055 {
1056 unsigned r = (see->Summ >> see->Shift);
1057 see->Summ = (UInt16)(see->Summ - r);
1058 *escFreq = r + (r == 0);
1059 }
1060 }
1061 else
1062 {
1063 see = &p->DummySee;
1064 *escFreq = 1;
1065 }
1066 return see;
1067 }
1068
NextContext(CPpmd8 * p)1069 static void NextContext(CPpmd8 *p)
1070 {
1071 CTX_PTR c = CTX(SUCCESSOR(p->FoundState));
1072 if (p->OrderFall == 0 && (Byte *)c >= p->UnitsStart)
1073 p->MinContext = p->MaxContext = c;
1074 else
1075 {
1076 UpdateModel(p);
1077 p->MinContext = p->MaxContext;
1078 }
1079 }
1080
Ppmd8_Update1(CPpmd8 * p)1081 void Ppmd8_Update1(CPpmd8 *p)
1082 {
1083 CPpmd_State *s = p->FoundState;
1084 s->Freq += 4;
1085 p->MinContext->SummFreq += 4;
1086 if (s[0].Freq > s[-1].Freq)
1087 {
1088 SwapStates(&s[0], &s[-1]);
1089 p->FoundState = --s;
1090 if (s->Freq > MAX_FREQ)
1091 Rescale(p);
1092 }
1093 NextContext(p);
1094 }
1095
Ppmd8_Update1_0(CPpmd8 * p)1096 void Ppmd8_Update1_0(CPpmd8 *p)
1097 {
1098 p->PrevSuccess = (2 * p->FoundState->Freq >= p->MinContext->SummFreq);
1099 p->RunLength += p->PrevSuccess;
1100 p->MinContext->SummFreq += 4;
1101 if ((p->FoundState->Freq += 4) > MAX_FREQ)
1102 Rescale(p);
1103 NextContext(p);
1104 }
1105
Ppmd8_UpdateBin(CPpmd8 * p)1106 void Ppmd8_UpdateBin(CPpmd8 *p)
1107 {
1108 p->FoundState->Freq = (Byte)(p->FoundState->Freq + (p->FoundState->Freq < 196));
1109 p->PrevSuccess = 1;
1110 p->RunLength++;
1111 NextContext(p);
1112 }
1113
Ppmd8_Update2(CPpmd8 * p)1114 void Ppmd8_Update2(CPpmd8 *p)
1115 {
1116 p->MinContext->SummFreq += 4;
1117 if ((p->FoundState->Freq += 4) > MAX_FREQ)
1118 Rescale(p);
1119 p->RunLength = p->InitRL;
1120 UpdateModel(p);
1121 p->MinContext = p->MaxContext;
1122 }
1123
1124 /* Ppmd8Dec.c -- PPMdI Decoder
1125 2010-04-16 : Igor Pavlov : Public domain
1126 This code is based on:
1127 PPMd var.I (2002): Dmitry Shkarin : Public domain
1128 Carryless rangecoder (1999): Dmitry Subbotin : Public domain */
1129
Ppmd8_RangeDec_Init(CPpmd8 * p)1130 Bool Ppmd8_RangeDec_Init(CPpmd8 *p)
1131 {
1132 unsigned i;
1133 p->Low = 0;
1134 p->Range = 0xFFFFFFFF;
1135 p->Code = 0;
1136 for (i = 0; i < 4; i++)
1137 p->Code = (p->Code << 8) | p->Stream.In->Read(p->Stream.In);
1138 return (p->Code < 0xFFFFFFFF);
1139 }
1140
RangeDec_GetThreshold(CPpmd8 * p,UInt32 total)1141 static UInt32 RangeDec_GetThreshold(CPpmd8 *p, UInt32 total)
1142 {
1143 return p->Code / (p->Range /= total);
1144 }
1145
RangeDec_Decode(CPpmd8 * p,UInt32 start,UInt32 size)1146 static void RangeDec_Decode(CPpmd8 *p, UInt32 start, UInt32 size)
1147 {
1148 start *= p->Range;
1149 p->Low += start;
1150 p->Code -= start;
1151 p->Range *= size;
1152
1153 while ((p->Low ^ (p->Low + p->Range)) < kTop ||
1154 (p->Range < kBot && ((p->Range = (0 - p->Low) & (kBot - 1)), 1)))
1155 {
1156 p->Code = (p->Code << 8) | p->Stream.In->Read(p->Stream.In);
1157 p->Range <<= 8;
1158 p->Low <<= 8;
1159 }
1160 }
1161
1162 #define MASK(sym) ((signed char *)charMask)[sym]
1163
Ppmd8_DecodeSymbol(CPpmd8 * p)1164 int Ppmd8_DecodeSymbol(CPpmd8 *p)
1165 {
1166 size_t charMask[256 / sizeof(size_t)];
1167 if (p->MinContext->NumStats != 0)
1168 {
1169 CPpmd_State *s = Ppmd8_GetStats(p, p->MinContext);
1170 unsigned i;
1171 UInt32 count, hiCnt;
1172 if ((count = RangeDec_GetThreshold(p, p->MinContext->SummFreq)) < (hiCnt = s->Freq))
1173 {
1174 Byte symbol;
1175 RangeDec_Decode(p, 0, s->Freq);
1176 p->FoundState = s;
1177 symbol = s->Symbol;
1178 Ppmd8_Update1_0(p);
1179 return symbol;
1180 }
1181 p->PrevSuccess = 0;
1182 i = p->MinContext->NumStats;
1183 do
1184 {
1185 if ((hiCnt += (++s)->Freq) > count)
1186 {
1187 Byte symbol;
1188 RangeDec_Decode(p, hiCnt - s->Freq, s->Freq);
1189 p->FoundState = s;
1190 symbol = s->Symbol;
1191 Ppmd8_Update1(p);
1192 return symbol;
1193 }
1194 }
1195 while (--i);
1196 if (count >= p->MinContext->SummFreq)
1197 return -2;
1198 RangeDec_Decode(p, hiCnt, p->MinContext->SummFreq - hiCnt);
1199 PPMD_SetAllBitsIn256Bytes(charMask);
1200 MASK(s->Symbol) = 0;
1201 i = p->MinContext->NumStats;
1202 do { MASK((--s)->Symbol) = 0; } while (--i);
1203 }
1204 else
1205 {
1206 UInt16 *prob = Ppmd8_GetBinSumm(p);
1207 if (((p->Code / (p->Range >>= 14)) < *prob))
1208 {
1209 Byte symbol;
1210 RangeDec_Decode(p, 0, *prob);
1211 *prob = (UInt16)PPMD_UPDATE_PROB_0(*prob);
1212 symbol = (p->FoundState = Ppmd8Context_OneState(p->MinContext))->Symbol;
1213 Ppmd8_UpdateBin(p);
1214 return symbol;
1215 }
1216 RangeDec_Decode(p, *prob, (1 << 14) - *prob);
1217 *prob = (UInt16)PPMD_UPDATE_PROB_1(*prob);
1218 p->InitEsc = PPMD8_kExpEscape[*prob >> 10];
1219 PPMD_SetAllBitsIn256Bytes(charMask);
1220 MASK(Ppmd8Context_OneState(p->MinContext)->Symbol) = 0;
1221 p->PrevSuccess = 0;
1222 }
1223 for (;;)
1224 {
1225 CPpmd_State *ps[256], *s;
1226 UInt32 freqSum, count, hiCnt;
1227 CPpmd_See *see;
1228 unsigned i, num, numMasked = p->MinContext->NumStats;
1229 do
1230 {
1231 p->OrderFall++;
1232 if (!p->MinContext->Suffix)
1233 return -1;
1234 p->MinContext = Ppmd8_GetContext(p, p->MinContext->Suffix);
1235 }
1236 while (p->MinContext->NumStats == numMasked);
1237 hiCnt = 0;
1238 s = Ppmd8_GetStats(p, p->MinContext);
1239 i = 0;
1240 num = p->MinContext->NumStats - numMasked;
1241 do
1242 {
1243 int k = (int)(MASK(s->Symbol));
1244 hiCnt += (s->Freq & k);
1245 ps[i] = s++;
1246 i -= k;
1247 }
1248 while (i != num);
1249
1250 see = Ppmd8_MakeEscFreq(p, numMasked, &freqSum);
1251 freqSum += hiCnt;
1252 count = RangeDec_GetThreshold(p, freqSum);
1253
1254 if (count < hiCnt)
1255 {
1256 Byte symbol;
1257 CPpmd_State **pps = ps;
1258 for (hiCnt = 0; (hiCnt += (*pps)->Freq) <= count; pps++);
1259 s = *pps;
1260 RangeDec_Decode(p, hiCnt - s->Freq, s->Freq);
1261 Ppmd_See_Update(see);
1262 p->FoundState = s;
1263 symbol = s->Symbol;
1264 Ppmd8_Update2(p);
1265 return symbol;
1266 }
1267 if (count >= freqSum)
1268 return -2;
1269 RangeDec_Decode(p, hiCnt, freqSum - hiCnt);
1270 see->Summ = (UInt16)(see->Summ + freqSum);
1271 do { MASK(ps[--i]->Symbol) = 0; } while (i != 0);
1272 }
1273 }
1274
1275 /* H->I changes:
1276 NS2Indx
1277 GlewCount, and Glue method
1278 BinSum
1279 See / EscFreq
1280 CreateSuccessors updates more suffix contexts
1281 UpdateModel consts.
1282 PrevSuccess Update
1283 */
1284
1285 const IPpmd8 __archive_ppmd8_functions =
1286 {
1287 &Ppmd8_Construct,
1288 &Ppmd8_Alloc,
1289 &Ppmd8_Free,
1290 &Ppmd8_Init,
1291 &Ppmd8_RangeDec_Init,
1292 &Ppmd8_DecodeSymbol,
1293 };
1294