contrib/libarchive/libarchive/archive_ppmd7.c

   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 "archive_platform.h"
   6
   7 #include <memory.h>
   8
   9 #include "archive_ppmd7_private.h"
  10
  11 #ifdef PPMD_32BIT
  12   #define Ppmd7_GetPtr(p, ptr) (ptr)
  13   #define Ppmd7_GetContext(p, ptr) (ptr)
  14   #define Ppmd7_GetStats(p, ctx) ((ctx)->Stats)
  15 #else
  16   #define Ppmd7_GetPtr(p, offs) ((void *)((p)->Base + (offs)))
  17   #define Ppmd7_GetContext(p, offs) ((CPpmd7_Context *)Ppmd7_GetPtr((p), (offs)))
  18   #define Ppmd7_GetStats(p, ctx) ((CPpmd_State *)Ppmd7_GetPtr((p), ((ctx)->Stats)))
  19 #endif
  20
  21 #define Ppmd7_GetBinSumm(p) \
  22     &p->BinSumm[Ppmd7Context_OneState(p->MinContext)->Freq - 1][p->PrevSuccess + \
  23     p->NS2BSIndx[Ppmd7_GetContext(p, p->MinContext->Suffix)->NumStats - 1] + \
  24     (p->HiBitsFlag = p->HB2Flag[p->FoundState->Symbol]) + \
  25     2 * p->HB2Flag[Ppmd7Context_OneState(p->MinContext)->Symbol] + \
  26     ((p->RunLength >> 26) & 0x20)]
  27
  28 #define kTopValue (1 << 24)
  29 #define MAX_FREQ 124
  30 #define UNIT_SIZE 12
  31
  32 #define U2B(nu) ((UInt32)(nu) * UNIT_SIZE)
  33 #define U2I(nu) (p->Units2Indx[(nu) - 1])
  34 #define I2U(indx) (p->Indx2Units[indx])
  35
  36 #ifdef PPMD_32BIT
  37   #define REF(ptr) (ptr)
  38 #else
  39   #define REF(ptr) ((UInt32)((Byte *)(ptr) - (p)->Base))
  40 #endif
  41
  42 #define STATS_REF(ptr) ((CPpmd_State_Ref)REF(ptr))
  43
  44 #define CTX(ref) ((CPpmd7_Context *)Ppmd7_GetContext(p, ref))
  45 #define STATS(ctx) Ppmd7_GetStats(p, ctx)
  46 #define ONE_STATE(ctx) Ppmd7Context_OneState(ctx)
  47 #define SUFFIX(ctx) CTX((ctx)->Suffix)
  48
  49 static const UInt16 kInitBinEsc[] = { 0x3CDD, 0x1F3F, 0x59BF, 0x48F3, 0x64A1, 0x5ABC, 0x6632, 0x6051};
  50 static const Byte PPMD7_kExpEscape[16] = { 25, 14, 9, 7, 5, 5, 4, 4, 4, 3, 3, 3, 2, 2, 2, 2 };
  51
  52 typedef CPpmd7_Context * CTX_PTR;
  53
  54 struct CPpmd7_Node_;
  55
  56 typedef
  57   #ifdef PPMD_32BIT
  58     struct CPpmd7_Node_ *
  59   #else
  60     UInt32
  61   #endif
  62   CPpmd7_Node_Ref;
  63
  64 typedef struct CPpmd7_Node_
  65 {
  66   UInt16 Stamp; /* must be at offset 0 as CPpmd7_Context::NumStats. Stamp=0 means free */
  67   UInt16 NU;
  68   CPpmd7_Node_Ref Next; /* must be at offset >= 4 */
  69   CPpmd7_Node_Ref Prev;
  70 } CPpmd7_Node;
  71
  72 #ifdef PPMD_32BIT
  73   #define NODE(ptr) (ptr)
  74 #else
  75   #define NODE(offs) ((CPpmd7_Node *)(p->Base + (offs)))
  76 #endif
  77
  78 static void Ppmd7_Update1(CPpmd7 *p);
  79 static void Ppmd7_Update1_0(CPpmd7 *p);
  80 static void Ppmd7_Update2(CPpmd7 *p);
  81 static void Ppmd7_UpdateBin(CPpmd7 *p);
  82 static CPpmd_See *Ppmd7_MakeEscFreq(CPpmd7 *p, unsigned numMasked,
  83                                     UInt32 *scale);
  84
  85 /* ----------- Base ----------- */
  86
  87 static void Ppmd7_Construct(CPpmd7 *p)
  88 {
  89   unsigned i, k, m;
  90
  91   p->Base = 0;
  92
  93   for (i = 0, k = 0; i < PPMD_NUM_INDEXES; i++)
  94   {
  95     unsigned step = (i >= 12 ? 4 : (i >> 2) + 1);
  96     do { p->Units2Indx[k++] = (Byte)i; } while(--step);
  97     p->Indx2Units[i] = (Byte)k;
  98   }
  99
 100   p->NS2BSIndx[0] = (0 << 1);
 101   p->NS2BSIndx[1] = (1 << 1);
 102   memset(p->NS2BSIndx + 2, (2 << 1), 9);
 103   memset(p->NS2BSIndx + 11, (3 << 1), 256 - 11);
 104
 105   for (i = 0; i < 3; i++)
 106     p->NS2Indx[i] = (Byte)i;
 107   for (m = i, k = 1; i < 256; i++)
 108   {
 109     p->NS2Indx[i] = (Byte)m;
 110     if (--k == 0)
 111       k = (++m) - 2;
 112   }
 113
 114   memset(p->HB2Flag, 0, 0x40);
 115   memset(p->HB2Flag + 0x40, 8, 0x100 - 0x40);
 116 }
 117
 118 static void Ppmd7_Free(CPpmd7 *p, ISzAlloc *alloc)
 119 {
 120   alloc->Free(alloc, p->Base);
 121   p->Size = 0;
 122   p->Base = 0;
 123 }
 124
 125 static Bool Ppmd7_Alloc(CPpmd7 *p, UInt32 size, ISzAlloc *alloc)
 126 {
 127   if (p->Base == 0 || p->Size != size)
 128   {
 129     Ppmd7_Free(p, alloc);
 130     p->AlignOffset =
 131       #ifdef PPMD_32BIT
 132         (4 - size) & 3;
 133       #else
 134         4 - (size & 3);
 135       #endif
 136     if ((p->Base = (Byte *)alloc->Alloc(alloc, p->AlignOffset + size
 137         #ifndef PPMD_32BIT
 138         + UNIT_SIZE
 139         #endif
 140         )) == 0)
 141       return False;
 142     p->Size = size;
 143   }
 144   return True;
 145 }
 146
 147 static void InsertNode(CPpmd7 *p, void *node, unsigned indx)
 148 {
 149   *((CPpmd_Void_Ref *)node) = p->FreeList[indx];
 150   p->FreeList[indx] = REF(node);
 151 }
 152
 153 static void *RemoveNode(CPpmd7 *p, unsigned indx)
 154 {
 155   CPpmd_Void_Ref *node = (CPpmd_Void_Ref *)Ppmd7_GetPtr(p, p->FreeList[indx]);
 156   p->FreeList[indx] = *node;
 157   return node;
 158 }
 159
 160 static void SplitBlock(CPpmd7 *p, void *ptr, unsigned oldIndx, unsigned newIndx)
 161 {
 162   unsigned i, nu = I2U(oldIndx) - I2U(newIndx);
 163   ptr = (Byte *)ptr + U2B(I2U(newIndx));
 164   if (I2U(i = U2I(nu)) != nu)
 165   {
 166     unsigned k = I2U(--i);
 167     InsertNode(p, ((Byte *)ptr) + U2B(k), nu - k - 1);
 168   }
 169   InsertNode(p, ptr, i);
 170 }
 171
 172 static void GlueFreeBlocks(CPpmd7 *p)
 173 {
 174   #ifdef PPMD_32BIT
 175   CPpmd7_Node headItem;
 176   CPpmd7_Node_Ref head = &headItem;
 177   #else
 178   CPpmd7_Node_Ref head = p->AlignOffset + p->Size;
 179   #endif
 180
 181   CPpmd7_Node_Ref n = head;
 182   unsigned i;
 183
 184   p->GlueCount = 255;
 185
 186   /* create doubly-linked list of free blocks */
 187   for (i = 0; i < PPMD_NUM_INDEXES; i++)
 188   {
 189     UInt16 nu = I2U(i);
 190     CPpmd7_Node_Ref next = (CPpmd7_Node_Ref)p->FreeList[i];
 191     p->FreeList[i] = 0;
 192     while (next != 0)
 193     {
 194       CPpmd7_Node *node = NODE(next);
 195       node->Next = n;
 196       n = NODE(n)->Prev = next;
 197       next = *(const CPpmd7_Node_Ref *)node;
 198       node->Stamp = 0;
 199       node->NU = (UInt16)nu;
 200     }
 201   }
 202   NODE(head)->Stamp = 1;
 203   NODE(head)->Next = n;
 204   NODE(n)->Prev = head;
 205   if (p->LoUnit != p->HiUnit)
 206     ((CPpmd7_Node *)p->LoUnit)->Stamp = 1;
 207
 208   /* Glue free blocks */
 209   while (n != head)
 210   {
 211     CPpmd7_Node *node = NODE(n);
 212     UInt32 nu = (UInt32)node->NU;
 213     for (;;)
 214     {
 215       CPpmd7_Node *node2 = NODE(n) + nu;
 216       nu += node2->NU;
 217       if (node2->Stamp != 0 || nu >= 0x10000)
 218         break;
 219       NODE(node2->Prev)->Next = node2->Next;
 220       NODE(node2->Next)->Prev = node2->Prev;
 221       node->NU = (UInt16)nu;
 222     }
 223     n = node->Next;
 224   }
 225
 226   /* Fill lists of free blocks */
 227   for (n = NODE(head)->Next; n != head;)
 228   {
 229     CPpmd7_Node *node = NODE(n);
 230     unsigned nu;
 231     CPpmd7_Node_Ref next = node->Next;
 232     for (nu = node->NU; nu > 128; nu -= 128, node += 128)
 233       InsertNode(p, node, PPMD_NUM_INDEXES - 1);
 234     if (I2U(i = U2I(nu)) != nu)
 235     {
 236       unsigned k = I2U(--i);
 237       InsertNode(p, node + k, nu - k - 1);
 238     }
 239     InsertNode(p, node, i);
 240     n = next;
 241   }
 242 }
 243
 244 static void *AllocUnitsRare(CPpmd7 *p, unsigned indx)
 245 {
 246   unsigned i;
 247   void *retVal;
 248   if (p->GlueCount == 0)
 249   {
 250     GlueFreeBlocks(p);
 251     if (p->FreeList[indx] != 0)
 252       return RemoveNode(p, indx);
 253   }
 254   i = indx;
 255   do
 256   {
 257     if (++i == PPMD_NUM_INDEXES)
 258     {
 259       UInt32 numBytes = U2B(I2U(indx));
 260       p->GlueCount--;
 261       return ((UInt32)(p->UnitsStart - p->Text) > numBytes) ? (p->UnitsStart -= numBytes) : (NULL);
 262     }
 263   }
 264   while (p->FreeList[i] == 0);
 265   retVal = RemoveNode(p, i);
 266   SplitBlock(p, retVal, i, indx);
 267   return retVal;
 268 }
 269
 270 static void *AllocUnits(CPpmd7 *p, unsigned indx)
 271 {
 272   UInt32 numBytes;
 273   if (p->FreeList[indx] != 0)
 274     return RemoveNode(p, indx);
 275   numBytes = U2B(I2U(indx));
 276   if (numBytes <= (UInt32)(p->HiUnit - p->LoUnit))
 277   {
 278     void *retVal = p->LoUnit;
 279     p->LoUnit += numBytes;
 280     return retVal;
 281   }
 282   return AllocUnitsRare(p, indx);
 283 }
 284
 285 #define MyMem12Cpy(dest, src, num) \
 286   { UInt32 *d = (UInt32 *)dest; const UInt32 *s = (const UInt32 *)src; UInt32 n = num; \
 287     do { d[0] = s[0]; d[1] = s[1]; d[2] = s[2]; s += 3; d += 3; } while(--n); }
 288
 289 static void *ShrinkUnits(CPpmd7 *p, void *oldPtr, unsigned oldNU, unsigned newNU)
 290 {
 291   unsigned i0 = U2I(oldNU);
 292   unsigned i1 = U2I(newNU);
 293   if (i0 == i1)
 294     return oldPtr;
 295   if (p->FreeList[i1] != 0)
 296   {
 297     void *ptr = RemoveNode(p, i1);
 298     MyMem12Cpy(ptr, oldPtr, newNU);
 299     InsertNode(p, oldPtr, i0);
 300     return ptr;
 301   }
 302   SplitBlock(p, oldPtr, i0, i1);
 303   return oldPtr;
 304 }
 305
 306 #define SUCCESSOR(p) ((CPpmd_Void_Ref)((p)->SuccessorLow | ((UInt32)(p)->SuccessorHigh << 16)))
 307
 308 static void SetSuccessor(CPpmd_State *p, CPpmd_Void_Ref v)
 309 {
 310   (p)->SuccessorLow = (UInt16)((UInt32)(v) & 0xFFFF);
 311   (p)->SuccessorHigh = (UInt16)(((UInt32)(v) >> 16) & 0xFFFF);
 312 }
 313
 314 static void RestartModel(CPpmd7 *p)
 315 {
 316   unsigned i, k, m;
 317
 318   memset(p->FreeList, 0, sizeof(p->FreeList));
 319   p->Text = p->Base + p->AlignOffset;
 320   p->HiUnit = p->Text + p->Size;
 321   p->LoUnit = p->UnitsStart = p->HiUnit - p->Size / 8 / UNIT_SIZE * 7 * UNIT_SIZE;
 322   p->GlueCount = 0;
 323
 324   p->OrderFall = p->MaxOrder;
 325   p->RunLength = p->InitRL = -(Int32)((p->MaxOrder < 12) ? p->MaxOrder : 12) - 1;
 326   p->PrevSuccess = 0;
 327
 328   p->MinContext = p->MaxContext = (CTX_PTR)(p->HiUnit -= UNIT_SIZE); /* AllocContext(p); */
 329   p->MinContext->Suffix = 0;
 330   p->MinContext->NumStats = 256;
 331   p->MinContext->SummFreq = 256 + 1;
 332   p->FoundState = (CPpmd_State *)p->LoUnit; /* AllocUnits(p, PPMD_NUM_INDEXES - 1); */
 333   p->LoUnit += U2B(256 / 2);
 334   p->MinContext->Stats = REF(p->FoundState);
 335   for (i = 0; i < 256; i++)
 336   {
 337     CPpmd_State *s = &p->FoundState[i];
 338     s->Symbol = (Byte)i;
 339     s->Freq = 1;
 340     SetSuccessor(s, 0);
 341   }
 342
 343   for (i = 0; i < 128; i++)
 344     for (k = 0; k < 8; k++)
 345     {
 346       UInt16 *dest = p->BinSumm[i] + k;
 347       UInt16 val = (UInt16)(PPMD_BIN_SCALE - kInitBinEsc[k] / (i + 2));
 348       for (m = 0; m < 64; m += 8)
 349         dest[m] = val;
 350     }
 351
 352   for (i = 0; i < 25; i++)
 353     for (k = 0; k < 16; k++)
 354     {
 355       CPpmd_See *s = &p->See[i][k];
 356       s->Summ = (UInt16)((5 * i + 10) << (s->Shift = PPMD_PERIOD_BITS - 4));
 357       s->Count = 4;
 358     }
 359 }
 360
 361 static void Ppmd7_Init(CPpmd7 *p, unsigned maxOrder)
 362 {
 363   p->MaxOrder = maxOrder;
 364   RestartModel(p);
 365   p->DummySee.Shift = PPMD_PERIOD_BITS;
 366   p->DummySee.Summ = 0; /* unused */
 367   p->DummySee.Count = 64; /* unused */
 368 }
 369
 370 static CTX_PTR CreateSuccessors(CPpmd7 *p, Bool skip)
 371 {
 372   CPpmd_State upState;
 373   CTX_PTR c = p->MinContext;
 374   CPpmd_Byte_Ref upBranch = (CPpmd_Byte_Ref)SUCCESSOR(p->FoundState);
 375   CPpmd_State *ps[PPMD7_MAX_ORDER];
 376   unsigned numPs = 0;
 377
 378   if (!skip)
 379     ps[numPs++] = p->FoundState;
 380
 381   while (c->Suffix)
 382   {
 383     CPpmd_Void_Ref successor;
 384     CPpmd_State *s;
 385     c = SUFFIX(c);
 386     if (c->NumStats != 1)
 387     {
 388       for (s = STATS(c); s->Symbol != p->FoundState->Symbol; s++);
 389     }
 390     else
 391       s = ONE_STATE(c);
 392     successor = SUCCESSOR(s);
 393     if (successor != upBranch)
 394     {
 395       c = CTX(successor);
 396       if (numPs == 0)
 397         return c;
 398       break;
 399     }
 400     ps[numPs++] = s;
 401   }
 402
 403   upState.Symbol = *(const Byte *)Ppmd7_GetPtr(p, upBranch);
 404   SetSuccessor(&upState, upBranch + 1);
 405
 406   if (c->NumStats == 1)
 407     upState.Freq = ONE_STATE(c)->Freq;
 408   else
 409   {
 410     UInt32 cf, s0;
 411     CPpmd_State *s;
 412     for (s = STATS(c); s->Symbol != upState.Symbol; s++);
 413     cf = s->Freq - 1;
 414     s0 = c->SummFreq - c->NumStats - cf;
 415     upState.Freq = (Byte)(1 + ((2 * cf <= s0) ? (5 * cf > s0) : ((2 * cf + 3 * s0 - 1) / (2 * s0))));
 416   }
 417
 418   while (numPs != 0)
 419   {
 420     /* Create Child */
 421     CTX_PTR c1; /* = AllocContext(p); */
 422     if (p->HiUnit != p->LoUnit)
 423       c1 = (CTX_PTR)(p->HiUnit -= UNIT_SIZE);
 424     else if (p->FreeList[0] != 0)
 425       c1 = (CTX_PTR)RemoveNode(p, 0);
 426     else
 427     {
 428       c1 = (CTX_PTR)AllocUnitsRare(p, 0);
 429       if (!c1)
 430         return NULL;
 431     }
 432     c1->NumStats = 1;
 433     *ONE_STATE(c1) = upState;
 434     c1->Suffix = REF(c);
 435     SetSuccessor(ps[--numPs], REF(c1));
 436     c = c1;
 437   }
 438
 439   return c;
 440 }
 441
 442 static void SwapStates(CPpmd_State *t1, CPpmd_State *t2)
 443 {
 444   CPpmd_State tmp = *t1;
 445   *t1 = *t2;
 446   *t2 = tmp;
 447 }
 448
 449 static void UpdateModel(CPpmd7 *p)
 450 {
 451   CPpmd_Void_Ref successor, fSuccessor = SUCCESSOR(p->FoundState);
 452   CTX_PTR c;
 453   unsigned s0, ns;
 454
 455   if (p->FoundState->Freq < MAX_FREQ / 4 && p->MinContext->Suffix != 0)
 456   {
 457     c = SUFFIX(p->MinContext);
 458
 459     if (c->NumStats == 1)
 460     {
 461       CPpmd_State *s = ONE_STATE(c);
 462       if (s->Freq < 32)
 463         s->Freq++;
 464     }
 465     else
 466     {
 467       CPpmd_State *s = STATS(c);
 468       if (s->Symbol != p->FoundState->Symbol)
 469       {
 470         do { s++; } while (s->Symbol != p->FoundState->Symbol);
 471         if (s[0].Freq >= s[-1].Freq)
 472         {
 473           SwapStates(&s[0], &s[-1]);
 474           s--;
 475         }
 476       }
 477       if (s->Freq < MAX_FREQ - 9)
 478       {
 479         s->Freq += 2;
 480         c->SummFreq += 2;
 481       }
 482     }
 483   }
 484
 485   if (p->OrderFall == 0)
 486   {
 487     p->MinContext = p->MaxContext = CreateSuccessors(p, True);
 488     if (p->MinContext == 0)
 489     {
 490       RestartModel(p);
 491       return;
 492     }
 493     SetSuccessor(p->FoundState, REF(p->MinContext));
 494     return;
 495   }
 496
 497   *p->Text++ = p->FoundState->Symbol;
 498   successor = REF(p->Text);
 499   if (p->Text >= p->UnitsStart)
 500   {
 501     RestartModel(p);
 502     return;
 503   }
 504
 505   if (fSuccessor)
 506   {
 507     if (fSuccessor <= successor)
 508     {
 509       CTX_PTR cs = CreateSuccessors(p, False);
 510       if (cs == NULL)
 511       {
 512         RestartModel(p);
 513         return;
 514       }
 515       fSuccessor = REF(cs);
 516     }
 517     if (--p->OrderFall == 0)
 518     {
 519       successor = fSuccessor;
 520       p->Text -= (p->MaxContext != p->MinContext);
 521     }
 522   }
 523   else
 524   {
 525     SetSuccessor(p->FoundState, successor);
 526     fSuccessor = REF(p->MinContext);
 527   }
 528
 529   s0 = p->MinContext->SummFreq - (ns = p->MinContext->NumStats) - (p->FoundState->Freq - 1);
 530
 531   for (c = p->MaxContext; c != p->MinContext; c = SUFFIX(c))
 532   {
 533     unsigned ns1;
 534     UInt32 cf, sf;
 535     if ((ns1 = c->NumStats) != 1)
 536     {
 537       if ((ns1 & 1) == 0)
 538       {
 539         /* Expand for one UNIT */
 540         unsigned oldNU = ns1 >> 1;
 541         unsigned i = U2I(oldNU);
 542         if (i != U2I(oldNU + 1))
 543         {
 544           void *ptr = AllocUnits(p, i + 1);
 545           void *oldPtr;
 546           if (!ptr)
 547           {
 548             RestartModel(p);
 549             return;
 550           }
 551           oldPtr = STATS(c);
 552           MyMem12Cpy(ptr, oldPtr, oldNU);
 553           InsertNode(p, oldPtr, i);
 554           c->Stats = STATS_REF(ptr);
 555         }
 556       }
 557       c->SummFreq = (UInt16)(c->SummFreq + (2 * ns1 < ns) + 2 * ((4 * ns1 <= ns) & (c->SummFreq <= 8 * ns1)));
 558     }
 559     else
 560     {
 561       CPpmd_State *s = (CPpmd_State*)AllocUnits(p, 0);
 562       if (!s)
 563       {
 564         RestartModel(p);
 565         return;
 566       }
 567       *s = *ONE_STATE(c);
 568       c->Stats = REF(s);
 569       if (s->Freq < MAX_FREQ / 4 - 1)
 570         s->Freq <<= 1;
 571       else
 572         s->Freq = MAX_FREQ - 4;
 573       c->SummFreq = (UInt16)(s->Freq + p->InitEsc + (ns > 3));
 574     }
 575     cf = 2 * (UInt32)p->FoundState->Freq * (c->SummFreq + 6);
 576     sf = (UInt32)s0 + c->SummFreq;
 577     if (cf < 6 * sf)
 578     {
 579       cf = 1 + (cf > sf) + (cf >= 4 * sf);
 580       c->SummFreq += 3;
 581     }
 582     else
 583     {
 584       cf = 4 + (cf >= 9 * sf) + (cf >= 12 * sf) + (cf >= 15 * sf);
 585       c->SummFreq = (UInt16)(c->SummFreq + cf);
 586     }
 587     {
 588       CPpmd_State *s = STATS(c) + ns1;
 589       SetSuccessor(s, successor);
 590       s->Symbol = p->FoundState->Symbol;
 591       s->Freq = (Byte)cf;
 592       c->NumStats = (UInt16)(ns1 + 1);
 593     }
 594   }
 595   p->MaxContext = p->MinContext = CTX(fSuccessor);
 596 }
 597
 598 static void Rescale(CPpmd7 *p)
 599 {
 600   unsigned i, adder, sumFreq, escFreq;
 601   CPpmd_State *stats = STATS(p->MinContext);
 602   CPpmd_State *s = p->FoundState;
 603   {
 604     CPpmd_State tmp = *s;
 605     for (; s != stats; s--)
 606       s[0] = s[-1];
 607     *s = tmp;
 608   }
 609   escFreq = p->MinContext->SummFreq - s->Freq;
 610   s->Freq += 4;
 611   adder = (p->OrderFall != 0);
 612   s->Freq = (Byte)((s->Freq + adder) >> 1);
 613   sumFreq = s->Freq;
 614
 615   i = p->MinContext->NumStats - 1;
 616   do
 617   {
 618     escFreq -= (++s)->Freq;
 619     s->Freq = (Byte)((s->Freq + adder) >> 1);
 620     sumFreq += s->Freq;
 621     if (s[0].Freq > s[-1].Freq)
 622     {
 623       CPpmd_State *s1 = s;
 624       CPpmd_State tmp = *s1;
 625       do
 626         s1[0] = s1[-1];
 627       while (--s1 != stats && tmp.Freq > s1[-1].Freq);
 628       *s1 = tmp;
 629     }
 630   }
 631   while (--i);
 632
 633   if (s->Freq == 0)
 634   {
 635     unsigned numStats = p->MinContext->NumStats;
 636     unsigned n0, n1;
 637     do { i++; } while ((--s)->Freq == 0);
 638     escFreq += i;
 639     p->MinContext->NumStats = (UInt16)(p->MinContext->NumStats - i);
 640     if (p->MinContext->NumStats == 1)
 641     {
 642       CPpmd_State tmp = *stats;
 643       do
 644       {
 645         tmp.Freq = (Byte)(tmp.Freq - (tmp.Freq >> 1));
 646         escFreq >>= 1;
 647       }
 648       while (escFreq > 1);
 649       InsertNode(p, stats, U2I(((numStats + 1) >> 1)));
 650       *(p->FoundState = ONE_STATE(p->MinContext)) = tmp;
 651       return;
 652     }
 653     n0 = (numStats + 1) >> 1;
 654     n1 = (p->MinContext->NumStats + 1) >> 1;
 655     if (n0 != n1)
 656       p->MinContext->Stats = STATS_REF(ShrinkUnits(p, stats, n0, n1));
 657   }
 658   p->MinContext->SummFreq = (UInt16)(sumFreq + escFreq - (escFreq >> 1));
 659   p->FoundState = STATS(p->MinContext);
 660 }
 661
 662 static CPpmd_See *Ppmd7_MakeEscFreq(CPpmd7 *p, unsigned numMasked, UInt32 *escFreq)
 663 {
 664   CPpmd_See *see;
 665   unsigned nonMasked = p->MinContext->NumStats - numMasked;
 666   if (p->MinContext->NumStats != 256)
 667   {
 668     see = p->See[p->NS2Indx[nonMasked - 1]] +
 669         (nonMasked < (unsigned)SUFFIX(p->MinContext)->NumStats - p->MinContext->NumStats) +
 670         2 * (p->MinContext->SummFreq < 11 * p->MinContext->NumStats) +
 671         4 * (numMasked > nonMasked) +
 672         p->HiBitsFlag;
 673     {
 674       unsigned r = (see->Summ >> see->Shift);
 675       see->Summ = (UInt16)(see->Summ - r);
 676       *escFreq = r + (r == 0);
 677     }
 678   }
 679   else
 680   {
 681     see = &p->DummySee;
 682     *escFreq = 1;
 683   }
 684   return see;
 685 }
 686
 687 static void NextContext(CPpmd7 *p)
 688 {
 689   CTX_PTR c = CTX(SUCCESSOR(p->FoundState));
 690   if (p->OrderFall == 0 && (Byte *)c > p->Text)
 691     p->MinContext = p->MaxContext = c;
 692   else
 693     UpdateModel(p);
 694 }
 695
 696 static void Ppmd7_Update1(CPpmd7 *p)
 697 {
 698   CPpmd_State *s = p->FoundState;
 699   s->Freq += 4;
 700   p->MinContext->SummFreq += 4;
 701   if (s[0].Freq > s[-1].Freq)
 702   {
 703     SwapStates(&s[0], &s[-1]);
 704     p->FoundState = --s;
 705     if (s->Freq > MAX_FREQ)
 706       Rescale(p);
 707   }
 708   NextContext(p);
 709 }
 710
 711 static void Ppmd7_Update1_0(CPpmd7 *p)
 712 {
 713   p->PrevSuccess = (2 * p->FoundState->Freq > p->MinContext->SummFreq);
 714   p->RunLength += p->PrevSuccess;
 715   p->MinContext->SummFreq += 4;
 716   if ((p->FoundState->Freq += 4) > MAX_FREQ)
 717     Rescale(p);
 718   NextContext(p);
 719 }
 720
 721 static void Ppmd7_UpdateBin(CPpmd7 *p)
 722 {
 723   p->FoundState->Freq = (Byte)(p->FoundState->Freq + (p->FoundState->Freq < 128 ? 1: 0));
 724   p->PrevSuccess = 1;
 725   p->RunLength++;
 726   NextContext(p);
 727 }
 728
 729 static void Ppmd7_Update2(CPpmd7 *p)
 730 {
 731   p->MinContext->SummFreq += 4;
 732   if ((p->FoundState->Freq += 4) > MAX_FREQ)
 733     Rescale(p);
 734   p->RunLength = p->InitRL;
 735   UpdateModel(p);
 736 }
 737
 738 /* ---------- Decode ---------- */
 739
 740 static Bool Ppmd_RangeDec_Init(CPpmd7z_RangeDec *p)
 741 {
 742   unsigned i;
 743   p->Low = p->Bottom = 0;
 744   p->Range = 0xFFFFFFFF;
 745   for (i = 0; i < 4; i++)
 746     p->Code = (p->Code << 8) | p->Stream->Read((void *)p->Stream);
 747   return (p->Code < 0xFFFFFFFF);
 748 }
 749
 750 static Bool Ppmd7z_RangeDec_Init(CPpmd7z_RangeDec *p)
 751 {
 752   if (p->Stream->Read((void *)p->Stream) != 0)
 753     return False;
 754   return Ppmd_RangeDec_Init(p);
 755 }
 756
 757 static Bool PpmdRAR_RangeDec_Init(CPpmd7z_RangeDec *p)
 758 {
 759   if (!Ppmd_RangeDec_Init(p))
 760     return False;
 761   p->Bottom = 0x8000;
 762   return True;
 763 }
 764
 765 static UInt32 Range_GetThreshold(void *pp, UInt32 total)
 766 {
 767   CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;
 768   return (p->Code - p->Low) / (p->Range /= total);
 769 }
 770
 771 static void Range_Normalize(CPpmd7z_RangeDec *p)
 772 {
 773   while (1)
 774   {
 775     if((p->Low ^ (p->Low + p->Range)) >= kTopValue)
 776     {
 777       if(p->Range >= p->Bottom)
 778         break;
 779       else
 780         p->Range = ((uint32_t)(-(int32_t)p->Low)) & (p->Bottom - 1);
 781     }
 782     p->Code = (p->Code << 8) | p->Stream->Read((void *)p->Stream);
 783     p->Range <<= 8;
 784     p->Low <<= 8;
 785   }
 786 }
 787
 788 static void Range_Decode_7z(void *pp, UInt32 start, UInt32 size)
 789 {
 790   CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;
 791   p->Code -= start * p->Range;
 792   p->Range *= size;
 793   Range_Normalize(p);
 794 }
 795
 796 static void Range_Decode_RAR(void *pp, UInt32 start, UInt32 size)
 797 {
 798   CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;
 799   p->Low += start * p->Range;
 800   p->Range *= size;
 801   Range_Normalize(p);
 802 }
 803
 804 static UInt32 Range_DecodeBit_7z(void *pp, UInt32 size0)
 805 {
 806   CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;
 807   UInt32 newBound = (p->Range >> 14) * size0;
 808   UInt32 symbol;
 809   if (p->Code < newBound)
 810   {
 811     symbol = 0;
 812     p->Range = newBound;
 813   }
 814   else
 815   {
 816     symbol = 1;
 817     p->Code -= newBound;
 818     p->Range -= newBound;
 819   }
 820   Range_Normalize(p);
 821   return symbol;
 822 }
 823
 824 static UInt32 Range_DecodeBit_RAR(void *pp, UInt32 size0)
 825 {
 826   CPpmd7z_RangeDec *p = (CPpmd7z_RangeDec *)pp;
 827   UInt32 bit, value = p->p.GetThreshold(p, PPMD_BIN_SCALE);
 828   if(value < size0)
 829   {
 830     bit = 0;
 831     p->p.Decode(p, 0, size0);
 832   }
 833   else
 834   {
 835     bit = 1;
 836     p->p.Decode(p, size0, PPMD_BIN_SCALE - size0);
 837   }
 838   return bit;
 839 }
 840
 841 static void Ppmd7z_RangeDec_CreateVTable(CPpmd7z_RangeDec *p)
 842 {
 843   p->p.GetThreshold = Range_GetThreshold;
 844   p->p.Decode = Range_Decode_7z;
 845   p->p.DecodeBit = Range_DecodeBit_7z;
 846 }
 847
 848 static void PpmdRAR_RangeDec_CreateVTable(CPpmd7z_RangeDec *p)
 849 {
 850   p->p.GetThreshold = Range_GetThreshold;
 851   p->p.Decode = Range_Decode_RAR;
 852   p->p.DecodeBit = Range_DecodeBit_RAR;
 853 }
 854
 855 #define MASK(sym) ((signed char *)charMask)[sym]
 856
 857 static int Ppmd7_DecodeSymbol(CPpmd7 *p, IPpmd7_RangeDec *rc)
 858 {
 859   size_t charMask[256 / sizeof(size_t)];
 860   if (p->MinContext->NumStats != 1)
 861   {
 862     CPpmd_State *s = Ppmd7_GetStats(p, p->MinContext);
 863     unsigned i;
 864     UInt32 count, hiCnt;
 865     if ((count = rc->GetThreshold(rc, p->MinContext->SummFreq)) < (hiCnt = s->Freq))
 866     {
 867       Byte symbol;
 868       rc->Decode(rc, 0, s->Freq);
 869       p->FoundState = s;
 870       symbol = s->Symbol;
 871       Ppmd7_Update1_0(p);
 872       return symbol;
 873     }
 874     p->PrevSuccess = 0;
 875     i = p->MinContext->NumStats - 1;
 876     do
 877     {
 878       if ((hiCnt += (++s)->Freq) > count)
 879       {
 880         Byte symbol;
 881         rc->Decode(rc, hiCnt - s->Freq, s->Freq);
 882         p->FoundState = s;
 883         symbol = s->Symbol;
 884         Ppmd7_Update1(p);
 885         return symbol;
 886       }
 887     }
 888     while (--i);
 889     if (count >= p->MinContext->SummFreq)
 890       return -2;
 891     p->HiBitsFlag = p->HB2Flag[p->FoundState->Symbol];
 892     rc->Decode(rc, hiCnt, p->MinContext->SummFreq - hiCnt);
 893     PPMD_SetAllBitsIn256Bytes(charMask);
 894     MASK(s->Symbol) = 0;
 895     i = p->MinContext->NumStats - 1;
 896     do { MASK((--s)->Symbol) = 0; } while (--i);
 897   }
 898   else
 899   {
 900     UInt16 *prob = Ppmd7_GetBinSumm(p);
 901     if (rc->DecodeBit(rc, *prob) == 0)
 902     {
 903       Byte symbol;
 904       *prob = (UInt16)PPMD_UPDATE_PROB_0(*prob);
 905       symbol = (p->FoundState = Ppmd7Context_OneState(p->MinContext))->Symbol;
 906       Ppmd7_UpdateBin(p);
 907       return symbol;
 908     }
 909     *prob = (UInt16)PPMD_UPDATE_PROB_1(*prob);
 910     p->InitEsc = PPMD7_kExpEscape[*prob >> 10];
 911     PPMD_SetAllBitsIn256Bytes(charMask);
 912     MASK(Ppmd7Context_OneState(p->MinContext)->Symbol) = 0;
 913     p->PrevSuccess = 0;
 914   }
 915   for (;;)
 916   {
 917     CPpmd_State *ps[256], *s;
 918     UInt32 freqSum, count, hiCnt;
 919     CPpmd_See *see;
 920     unsigned i, num, numMasked = p->MinContext->NumStats;
 921     do
 922     {
 923       p->OrderFall++;
 924       if (!p->MinContext->Suffix)
 925         return -1;
 926       p->MinContext = Ppmd7_GetContext(p, p->MinContext->Suffix);
 927     }
 928     while (p->MinContext->NumStats == numMasked);
 929     hiCnt = 0;
 930     s = Ppmd7_GetStats(p, p->MinContext);
 931     i = 0;
 932     num = p->MinContext->NumStats - numMasked;
 933     do
 934     {
 935       int k = (int)(MASK(s->Symbol));
 936       hiCnt += (s->Freq & k);
 937       ps[i] = s++;
 938       i -= k;
 939     }
 940     while (i != num);
 941
 942     see = Ppmd7_MakeEscFreq(p, numMasked, &freqSum);
 943     freqSum += hiCnt;
 944     count = rc->GetThreshold(rc, freqSum);
 945
 946     if (count < hiCnt)
 947     {
 948       Byte symbol;
 949       CPpmd_State **pps = ps;
 950       for (hiCnt = 0; (hiCnt += (*pps)->Freq) <= count; pps++);
 951       s = *pps;
 952       rc->Decode(rc, hiCnt - s->Freq, s->Freq);
 953       Ppmd_See_Update(see);
 954       p->FoundState = s;
 955       symbol = s->Symbol;
 956       Ppmd7_Update2(p);
 957       return symbol;
 958     }
 959     if (count >= freqSum)
 960       return -2;
 961     rc->Decode(rc, hiCnt, freqSum - hiCnt);
 962     see->Summ = (UInt16)(see->Summ + freqSum);
 963     do { MASK(ps[--i]->Symbol) = 0; } while (i != 0);
 964   }
 965 }
 966
 967 /* ---------- Encode ---------- Ppmd7Enc.c */
 968
 969 #define kTopValue (1 << 24)
 970
 971 static void Ppmd7z_RangeEnc_Init(CPpmd7z_RangeEnc *p)
 972 {
 973   p->Low = 0;
 974   p->Range = 0xFFFFFFFF;
 975   p->Cache = 0;
 976   p->CacheSize = 1;
 977 }
 978
 979 static void RangeEnc_ShiftLow(CPpmd7z_RangeEnc *p)
 980 {
 981   if ((UInt32)p->Low < (UInt32)0xFF000000 || (unsigned)(p->Low >> 32) != 0)
 982   {
 983     Byte temp = p->Cache;
 984     do
 985     {
 986       p->Stream->Write(p->Stream, (Byte)(temp + (Byte)(p->Low >> 32)));
 987       temp = 0xFF;
 988     }
 989     while(--p->CacheSize != 0);
 990     p->Cache = (Byte)((UInt32)p->Low >> 24);
 991   }
 992   p->CacheSize++;
 993   p->Low = ((UInt32)p->Low << 8) & 0xFFFFFFFF;
 994 }
 995
 996 static void RangeEnc_Encode(CPpmd7z_RangeEnc *p, UInt32 start, UInt32 size, UInt32 total)
 997 {
 998   p->Low += start * (p->Range /= total);
 999   p->Range *= size;
1000   while (p->Range < kTopValue)
1001   {
1002     p->Range <<= 8;
1003     RangeEnc_ShiftLow(p);
1004   }
1005 }
1006
1007 static void RangeEnc_EncodeBit_0(CPpmd7z_RangeEnc *p, UInt32 size0)
1008 {
1009   p->Range = (p->Range >> 14) * size0;
1010   while (p->Range < kTopValue)
1011   {
1012     p->Range <<= 8;
1013     RangeEnc_ShiftLow(p);
1014   }
1015 }
1016
1017 static void RangeEnc_EncodeBit_1(CPpmd7z_RangeEnc *p, UInt32 size0)
1018 {
1019   UInt32 newBound = (p->Range >> 14) * size0;
1020   p->Low += newBound;
1021   p->Range -= newBound;
1022   while (p->Range < kTopValue)
1023   {
1024     p->Range <<= 8;
1025     RangeEnc_ShiftLow(p);
1026   }
1027 }
1028
1029 static void Ppmd7z_RangeEnc_FlushData(CPpmd7z_RangeEnc *p)
1030 {
1031   unsigned i;
1032   for (i = 0; i < 5; i++)
1033     RangeEnc_ShiftLow(p);
1034 }
1035
1036
1037 #define MASK(sym) ((signed char *)charMask)[sym]
1038
1039 static void Ppmd7_EncodeSymbol(CPpmd7 *p, CPpmd7z_RangeEnc *rc, int symbol)
1040 {
1041   size_t charMask[256 / sizeof(size_t)];
1042   if (p->MinContext->NumStats != 1)
1043   {
1044     CPpmd_State *s = Ppmd7_GetStats(p, p->MinContext);
1045     UInt32 sum;
1046     unsigned i;
1047     if (s->Symbol == symbol)
1048     {
1049       RangeEnc_Encode(rc, 0, s->Freq, p->MinContext->SummFreq);
1050       p->FoundState = s;
1051       Ppmd7_Update1_0(p);
1052       return;
1053     }
1054     p->PrevSuccess = 0;
1055     sum = s->Freq;
1056     i = p->MinContext->NumStats - 1;
1057     do
1058     {
1059       if ((++s)->Symbol == symbol)
1060       {
1061         RangeEnc_Encode(rc, sum, s->Freq, p->MinContext->SummFreq);
1062         p->FoundState = s;
1063         Ppmd7_Update1(p);
1064         return;
1065       }
1066       sum += s->Freq;
1067     }
1068     while (--i);
1069
1070     p->HiBitsFlag = p->HB2Flag[p->FoundState->Symbol];
1071     PPMD_SetAllBitsIn256Bytes(charMask);
1072     MASK(s->Symbol) = 0;
1073     i = p->MinContext->NumStats - 1;
1074     do { MASK((--s)->Symbol) = 0; } while (--i);
1075     RangeEnc_Encode(rc, sum, p->MinContext->SummFreq - sum, p->MinContext->SummFreq);
1076   }
1077   else
1078   {
1079     UInt16 *prob = Ppmd7_GetBinSumm(p);
1080     CPpmd_State *s = Ppmd7Context_OneState(p->MinContext);
1081     if (s->Symbol == symbol)
1082     {
1083       RangeEnc_EncodeBit_0(rc, *prob);
1084       *prob = (UInt16)PPMD_UPDATE_PROB_0(*prob);
1085       p->FoundState = s;
1086       Ppmd7_UpdateBin(p);
1087       return;
1088     }
1089     else
1090     {
1091       RangeEnc_EncodeBit_1(rc, *prob);
1092       *prob = (UInt16)PPMD_UPDATE_PROB_1(*prob);
1093       p->InitEsc = PPMD7_kExpEscape[*prob >> 10];
1094       PPMD_SetAllBitsIn256Bytes(charMask);
1095       MASK(s->Symbol) = 0;
1096       p->PrevSuccess = 0;
1097     }
1098   }
1099   for (;;)
1100   {
1101     UInt32 escFreq;
1102     CPpmd_See *see;
1103     CPpmd_State *s;
1104     UInt32 sum;
1105     unsigned i, numMasked = p->MinContext->NumStats;
1106     do
1107     {
1108       p->OrderFall++;
1109       if (!p->MinContext->Suffix)
1110         return; /* EndMarker (symbol = -1) */
1111       p->MinContext = Ppmd7_GetContext(p, p->MinContext->Suffix);
1112     }
1113     while (p->MinContext->NumStats == numMasked);
1114
1115     see = Ppmd7_MakeEscFreq(p, numMasked, &escFreq);
1116     s = Ppmd7_GetStats(p, p->MinContext);
1117     sum = 0;
1118     i = p->MinContext->NumStats;
1119     do
1120     {
1121       int cur = s->Symbol;
1122       if (cur == symbol)
1123       {
1124         UInt32 low = sum;
1125         CPpmd_State *s1 = s;
1126         do
1127         {
1128           sum += (s->Freq & (int)(MASK(s->Symbol)));
1129           s++;
1130         }
1131         while (--i);
1132         RangeEnc_Encode(rc, low, s1->Freq, sum + escFreq);
1133         Ppmd_See_Update(see);
1134         p->FoundState = s1;
1135         Ppmd7_Update2(p);
1136         return;
1137       }
1138       sum += (s->Freq & (int)(MASK(cur)));
1139       MASK(cur) = 0;
1140       s++;
1141     }
1142     while (--i);
1143
1144     RangeEnc_Encode(rc, sum, escFreq, sum + escFreq);
1145     see->Summ = (UInt16)(see->Summ + sum + escFreq);
1146   }
1147 }
1148
1149 const IPpmd7 __archive_ppmd7_functions =
1150 {
1151   &Ppmd7_Construct,
1152   &Ppmd7_Alloc,
1153   &Ppmd7_Free,
1154   &Ppmd7_Init,
1155   &Ppmd7z_RangeDec_CreateVTable,
1156   &PpmdRAR_RangeDec_CreateVTable,
1157   &Ppmd7z_RangeDec_Init,
1158   &PpmdRAR_RangeDec_Init,
1159   &Ppmd7_DecodeSymbol,
1160   &Ppmd7z_RangeEnc_Init,
1161   &Ppmd7z_RangeEnc_FlushData,
1162   &Ppmd7_EncodeSymbol
1163 };