/* LzmaDec.c -- LZMA Decoder 2021-04-01 : Igor Pavlov : Public domain */ #include "Precomp.h" #include <string.h> /* #include "CpuArch.h" */ #include "LzmaDec.h" #define kNumTopBits … #define kTopValue … #define kNumBitModelTotalBits … #define kBitModelTotal … #define RC_INIT_SIZE … #ifndef _LZMA_DEC_OPT #define kNumMoveBits … #define NORMALIZE … #define IF_BIT_0(p) … #define UPDATE_0(p) … #define UPDATE_1(p) … #define GET_BIT2(p, i, A0, A1) … #define TREE_GET_BIT(probs, i) … #define REV_BIT(p, i, A0, A1) … #define REV_BIT_VAR( p, i, m) … #define REV_BIT_CONST(p, i, m) … #define REV_BIT_LAST( p, i, m) … #define TREE_DECODE(probs, limit, i) … /* #define _LZMA_SIZE_OPT */ #ifdef _LZMA_SIZE_OPT #define TREE_6_DECODE … #else #define TREE_6_DECODE(probs, i) … #endif #define NORMAL_LITER_DEC … #define MATCHED_LITER_DEC … #endif // _LZMA_DEC_OPT #define NORMALIZE_CHECK … #define IF_BIT_0_CHECK(p) … #define UPDATE_0_CHECK … #define UPDATE_1_CHECK … #define GET_BIT2_CHECK(p, i, A0, A1) … #define GET_BIT_CHECK(p, i) … #define TREE_DECODE_CHECK(probs, limit, i) … #define REV_BIT_CHECK(p, i, m) … #define kNumPosBitsMax … #define kNumPosStatesMax … #define kLenNumLowBits … #define kLenNumLowSymbols … #define kLenNumHighBits … #define kLenNumHighSymbols … #define LenLow … #define LenHigh … #define kNumLenProbs … #define LenChoice … #define LenChoice2 … #define kNumStates … #define kNumStates2 … #define kNumLitStates … #define kStartPosModelIndex … #define kEndPosModelIndex … #define kNumFullDistances … #define kNumPosSlotBits … #define kNumLenToPosStates … #define kNumAlignBits … #define kAlignTableSize … #define kMatchMinLen … #define kMatchSpecLenStart … #define kMatchSpecLen_Error_Data … #define kMatchSpecLen_Error_Fail … /* External ASM code needs same CLzmaProb array layout. So don't change it. */ /* (probs_1664) is faster and better for code size at some platforms */ /* #ifdef MY_CPU_X86_OR_AMD64 */ #define kStartOffset … #define GET_PROBS … /* #define GET_PROBS p->probs + kStartOffset #else #define kStartOffset 0 #define GET_PROBS p->probs #endif */ #define SpecPos … #define IsRep0Long … #define RepLenCoder … #define LenCoder … #define IsMatch … #define Align … #define IsRep … #define IsRepG0 … #define IsRepG1 … #define IsRepG2 … #define PosSlot … #define Literal … #define NUM_BASE_PROBS … #if Align != 0 && kStartOffset != 0 #error Stop_Compiling_Bad_LZMA_kAlign #endif #if NUM_BASE_PROBS != 1984 #error Stop_Compiling_Bad_LZMA_PROBS #endif #define LZMA_LIT_SIZE … #define LzmaProps_GetNumProbs(p) … #define CALC_POS_STATE(processedPos, pbMask) … #define COMBINED_PS_STATE … #define GET_LEN_STATE … #define LZMA_DIC_MIN … /* p->remainLen : shows status of LZMA decoder: < kMatchSpecLenStart : the number of bytes to be copied with (p->rep0) offset = kMatchSpecLenStart : the LZMA stream was finished with end mark = kMatchSpecLenStart + 1 : need init range coder = kMatchSpecLenStart + 2 : need init range coder and state = kMatchSpecLen_Error_Fail : Internal Code Failure = kMatchSpecLen_Error_Data + [0 ... 273] : LZMA Data Error */ /* ---------- LZMA_DECODE_REAL ---------- */ /* LzmaDec_DecodeReal_3() can be implemented in external ASM file. 3 - is the code compatibility version of that function for check at link time. */ #define LZMA_DECODE_REAL … /* LZMA_DECODE_REAL() In: RangeCoder is normalized if (p->dicPos == limit) { LzmaDec_TryDummy() was called before to exclude LITERAL and MATCH-REP cases. So first symbol can be only MATCH-NON-REP. And if that MATCH-NON-REP symbol is not END_OF_PAYALOAD_MARKER, then the function doesn't write any byte to dictionary, the function returns SZ_OK, and the caller can use (p->remainLen) and (p->reps[0]) later. } Processing: The first LZMA symbol will be decoded in any case. All main checks for limits are at the end of main loop, It decodes additional LZMA-symbols while (p->buf < bufLimit && dicPos < limit), RangeCoder is still without last normalization when (p->buf < bufLimit) is being checked. But if (p->buf < bufLimit), the caller provided at least (LZMA_REQUIRED_INPUT_MAX + 1) bytes for next iteration before limit (bufLimit + LZMA_REQUIRED_INPUT_MAX), that is enough for worst case LZMA symbol with one additional RangeCoder normalization for one bit. So that function never reads bufLimit [LZMA_REQUIRED_INPUT_MAX] byte. Out: RangeCoder is normalized Result: SZ_OK - OK p->remainLen: < kMatchSpecLenStart : the number of bytes to be copied with (p->reps[0]) offset = kMatchSpecLenStart : the LZMA stream was finished with end mark SZ_ERROR_DATA - error, when the MATCH-Symbol refers out of dictionary p->remainLen : undefined p->reps[*] : undefined */ #ifdef _LZMA_DEC_OPT int MY_FAST_CALL LZMA_DECODE_REAL(CLzmaDec *p, SizeT limit, const Byte *bufLimit); #else static int MY_FAST_CALL LZMA_DECODE_REAL(CLzmaDec *p, SizeT limit, const Byte *bufLimit) { … } #endif static void MY_FAST_CALL LzmaDec_WriteRem(CLzmaDec *p, SizeT limit) { … } /* At staring of new stream we have one of the following symbols: - Literal - is allowed - Non-Rep-Match - is allowed only if it's end marker symbol - Rep-Match - is not allowed We use early check of (RangeCoder:Code) over kBadRepCode to simplify main decoding code */ #define kRange0 … #define kBound0 … #define kBadRepCode … #if kBadRepCode != (0xC0000000 - 0x400) #error Stop_Compiling_Bad_LZMA_Check #endif /* LzmaDec_DecodeReal2(): It calls LZMA_DECODE_REAL() and it adjusts limit according (p->checkDicSize). We correct (p->checkDicSize) after LZMA_DECODE_REAL() and in LzmaDec_WriteRem(), and we support the following state of (p->checkDicSize): if (total_processed < p->prop.dicSize) then { (total_processed == p->processedPos) (p->checkDicSize == 0) } else (p->checkDicSize == p->prop.dicSize) */ static int MY_FAST_CALL LzmaDec_DecodeReal2(CLzmaDec *p, SizeT limit, const Byte *bufLimit) { … } ELzmaDummy; #define IS_DUMMY_END_MARKER_POSSIBLE(dummyRes) … static ELzmaDummy LzmaDec_TryDummy(const CLzmaDec *p, const Byte *buf, const Byte **bufOut) { … } void LzmaDec_InitDicAndState(CLzmaDec *p, BoolInt initDic, BoolInt initState); void LzmaDec_InitDicAndState(CLzmaDec *p, BoolInt initDic, BoolInt initState) { … } void LzmaDec_Init(CLzmaDec *p) { … } /* LZMA supports optional end_marker. So the decoder can lookahead for one additional LZMA-Symbol to check end_marker. That additional LZMA-Symbol can require up to LZMA_REQUIRED_INPUT_MAX bytes in input stream. When the decoder reaches dicLimit, it looks (finishMode) parameter: if (finishMode == LZMA_FINISH_ANY), the decoder doesn't lookahead if (finishMode != LZMA_FINISH_ANY), the decoder lookahead, if end_marker is possible for current position When the decoder lookahead, and the lookahead symbol is not end_marker, we have two ways: 1) Strict mode (default) : the decoder returns SZ_ERROR_DATA. 2) The relaxed mode (alternative mode) : we could return SZ_OK, and the caller must check (status) value. The caller can show the error, if the end of stream is expected, and the (status) is noit LZMA_STATUS_FINISHED_WITH_MARK or LZMA_STATUS_MAYBE_FINISHED_WITHOUT_MARK. */ #define RETURN__NOT_FINISHED__FOR_FINISH … // return SZ_OK; // for relaxed mode SRes LzmaDec_DecodeToDic(CLzmaDec *p, SizeT dicLimit, const Byte *src, SizeT *srcLen, ELzmaFinishMode finishMode, ELzmaStatus *status) { … } SRes LzmaDec_DecodeToBuf(CLzmaDec *p, Byte *dest, SizeT *destLen, const Byte *src, SizeT *srcLen, ELzmaFinishMode finishMode, ELzmaStatus *status) { … } void LzmaDec_FreeProbs(CLzmaDec *p, ISzAllocPtr alloc) { … } static void LzmaDec_FreeDict(CLzmaDec *p, ISzAllocPtr alloc) { … } void LzmaDec_Free(CLzmaDec *p, ISzAllocPtr alloc) { … } SRes LzmaProps_Decode(CLzmaProps *p, const Byte *data, unsigned size) { … } static SRes LzmaDec_AllocateProbs2(CLzmaDec *p, const CLzmaProps *propNew, ISzAllocPtr alloc) { … } SRes LzmaDec_AllocateProbs(CLzmaDec *p, const Byte *props, unsigned propsSize, ISzAllocPtr alloc) { … } SRes LzmaDec_Allocate(CLzmaDec *p, const Byte *props, unsigned propsSize, ISzAllocPtr alloc) { … } SRes LzmaDecode(Byte *dest, SizeT *destLen, const Byte *src, SizeT *srcLen, const Byte *propData, unsigned propSize, ELzmaFinishMode finishMode, ELzmaStatus *status, ISzAllocPtr alloc) { … }
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