| /* | |
| LZ4 - Fast LZ compression algorithm | |
| Copyright (C) 2011-2015, Yann Collet. | |
| SPDX-License-Identifier: BSD-2-Clause | |
| You can contact the author at : | |
| - LZ4 source repository : https://github.com/Cyan4973/lz4 | |
| - LZ4 public forum : https://groups.google.com/forum/#!forum/lz4c | |
| */ | |
| /************************************** | |
| * Reading and writing into memory | |
| **************************************/ | |
| /* customized version of memcpy, which may overwrite up to 7 bytes beyond dstEnd */ | |
| static void LZ4_wildCopy(void* dstPtr, const void* srcPtr, void* dstEnd) | |
| { | |
| BYTE* d = (BYTE*)dstPtr; | |
| const BYTE* s = (const BYTE*)srcPtr; | |
| BYTE* e = (BYTE*)dstEnd; | |
| do { LZ4_copy8(d,s); d+=8; s+=8; } while (d<e); | |
| } | |
| /************************************** | |
| * Common Constants | |
| **************************************/ | |
| #define MINMATCH 4 | |
| #define COPYLENGTH 8 | |
| #define LASTLITERALS 5 | |
| #define MFLIMIT (COPYLENGTH+MINMATCH) | |
| static const int LZ4_minLength = (MFLIMIT+1); | |
| #define KB *(1 <<10) | |
| #define MB *(1 <<20) | |
| #define GB *(1U<<30) | |
| #define MAXD_LOG 16 | |
| #define MAX_DISTANCE ((1 << MAXD_LOG) - 1) | |
| #define ML_BITS 4 | |
| #define ML_MASK ((1U<<ML_BITS)-1) | |
| #define RUN_BITS (8-ML_BITS) | |
| #define RUN_MASK ((1U<<RUN_BITS)-1) | |
| /************************************** | |
| * Local Structures and types | |
| **************************************/ | |
| typedef enum { noDict = 0, withPrefix64k, usingExtDict } dict_directive; | |
| typedef enum { endOnOutputSize = 0, endOnInputSize = 1 } endCondition_directive; | |
| typedef enum { full = 0, partial = 1 } earlyEnd_directive; | |
| /******************************* | |
| * Decompression functions | |
| *******************************/ | |
| /* | |
| * This generic decompression function cover all use cases. | |
| * It shall be instantiated several times, using different sets of directives | |
| * Note that it is essential this generic function is really inlined, | |
| * in order to remove useless branches during compilation optimization. | |
| */ | |
| FORCE_INLINE int LZ4_decompress_generic( | |
| const char* const source, | |
| char* const dest, | |
| int inputSize, | |
| int outputSize, /* If endOnInput==endOnInputSize, this value is the max size of Output Buffer. */ | |
| int endOnInput, /* endOnOutputSize, endOnInputSize */ | |
| int partialDecoding, /* full, partial */ | |
| int targetOutputSize, /* only used if partialDecoding==partial */ | |
| int dict, /* noDict, withPrefix64k, usingExtDict */ | |
| const BYTE* const lowPrefix, /* == dest if dict == noDict */ | |
| const BYTE* const dictStart, /* only if dict==usingExtDict */ | |
| const size_t dictSize /* note : = 0 if noDict */ | |
| ) | |
| { | |
| /* Local Variables */ | |
| const BYTE* ip = (const BYTE*) source; | |
| const BYTE* const iend = ip + inputSize; | |
| BYTE* op = (BYTE*) dest; | |
| BYTE* const oend = op + outputSize; | |
| BYTE* cpy; | |
| BYTE* oexit = op + targetOutputSize; | |
| const BYTE* const lowLimit = lowPrefix - dictSize; | |
| const BYTE* const dictEnd = (const BYTE*)dictStart + dictSize; | |
| const size_t dec32table[] = {4, 1, 2, 1, 4, 4, 4, 4}; | |
| const size_t dec64table[] = {0, 0, 0, (size_t)-1, 0, 1, 2, 3}; | |
| const int safeDecode = (endOnInput==endOnInputSize); | |
| const int checkOffset = ((safeDecode) && (dictSize < (int)(64 KB))); | |
| /* Special cases */ | |
| if ((partialDecoding) && (oexit> oend-MFLIMIT)) oexit = oend-MFLIMIT; /* targetOutputSize too high => decode everything */ | |
| if ((endOnInput) && (unlikely(outputSize==0))) return ((inputSize==1) && (*ip==0)) ? 0 : -1; /* Empty output buffer */ | |
| if ((!endOnInput) && (unlikely(outputSize==0))) return (*ip==0?1:-1); | |
| /* Main Loop */ | |
| while (1) | |
| { | |
| unsigned token; | |
| size_t length; | |
| const BYTE* match; | |
| /* get literal length */ | |
| token = *ip++; | |
| if ((length=(token>>ML_BITS)) == RUN_MASK) | |
| { | |
| unsigned s; | |
| do | |
| { | |
| s = *ip++; | |
| length += s; | |
| } | |
| while (likely((endOnInput)?ip<iend-RUN_MASK:1) && (s==255)); | |
| if ((safeDecode) && unlikely((size_t)(op+length)<(size_t)(op))) goto _output_error; /* overflow detection */ | |
| if ((safeDecode) && unlikely((size_t)(ip+length)<(size_t)(ip))) goto _output_error; /* overflow detection */ | |
| } | |
| /* copy literals */ | |
| cpy = op+length; | |
| if (((endOnInput) && ((cpy>(partialDecoding?oexit:oend-MFLIMIT)) || (ip+length>iend-(2+1+LASTLITERALS))) ) | |
| || ((!endOnInput) && (cpy>oend-COPYLENGTH))) | |
| { | |
| if (partialDecoding) | |
| { | |
| if (cpy > oend) goto _output_error; /* Error : write attempt beyond end of output buffer */ | |
| if ((endOnInput) && (ip+length > iend)) goto _output_error; /* Error : read attempt beyond end of input buffer */ | |
| } | |
| else | |
| { | |
| if ((!endOnInput) && (cpy != oend)) goto _output_error; /* Error : block decoding must stop exactly there */ | |
| if ((endOnInput) && ((ip+length != iend) || (cpy > oend))) goto _output_error; /* Error : input must be consumed */ | |
| } | |
| memcpy(op, ip, length); | |
| ip += length; | |
| op += length; | |
| break; /* Necessarily EOF, due to parsing restrictions */ | |
| } | |
| LZ4_wildCopy(op, ip, cpy); | |
| ip += length; op = cpy; | |
| /* get offset */ | |
| match = cpy - LZ4_readLE16(ip); ip+=2; | |
| if ((checkOffset) && (unlikely(match < lowLimit))) goto _output_error; /* Error : offset outside destination buffer */ | |
| /* get matchlength */ | |
| length = token & ML_MASK; | |
| if (length == ML_MASK) | |
| { | |
| unsigned s; | |
| do | |
| { | |
| if ((endOnInput) && (ip > iend-LASTLITERALS)) goto _output_error; | |
| s = *ip++; | |
| length += s; | |
| } while (s==255); | |
| if ((safeDecode) && unlikely((size_t)(op+length)<(size_t)op)) goto _output_error; /* overflow detection */ | |
| } | |
| length += MINMATCH; | |
| /* check external dictionary */ | |
| if ((dict==usingExtDict) && (match < lowPrefix)) | |
| { | |
| if (unlikely(op+length > oend-LASTLITERALS)) goto _output_error; /* doesn't respect parsing restriction */ | |
| if (length <= (size_t)(lowPrefix-match)) | |
| { | |
| /* match can be copied as a single segment from external dictionary */ | |
| match = dictEnd - (lowPrefix-match); | |
| memmove(op, match, length); op += length; | |
| } | |
| else | |
| { | |
| /* match encompass external dictionary and current segment */ | |
| size_t copySize = (size_t)(lowPrefix-match); | |
| memcpy(op, dictEnd - copySize, copySize); | |
| op += copySize; | |
| copySize = length - copySize; | |
| if (copySize > (size_t)(op-lowPrefix)) /* overlap within current segment */ | |
| { | |
| BYTE* const endOfMatch = op + copySize; | |
| const BYTE* copyFrom = lowPrefix; | |
| while (op < endOfMatch) *op++ = *copyFrom++; | |
| } | |
| else | |
| { | |
| memcpy(op, lowPrefix, copySize); | |
| op += copySize; | |
| } | |
| } | |
| continue; | |
| } | |
| /* copy repeated sequence */ | |
| cpy = op + length; | |
| if (unlikely((op-match)<8)) | |
| { | |
| const size_t dec64 = dec64table[op-match]; | |
| op[0] = match[0]; | |
| op[1] = match[1]; | |
| op[2] = match[2]; | |
| op[3] = match[3]; | |
| match += dec32table[op-match]; | |
| LZ4_copy4(op+4, match); | |
| op += 8; match -= dec64; | |
| } else { LZ4_copy8(op, match); op+=8; match+=8; } | |
| if (unlikely(cpy>oend-12)) | |
| { | |
| if (cpy > oend-LASTLITERALS) goto _output_error; /* Error : last LASTLITERALS bytes must be literals */ | |
| if (op < oend-8) | |
| { | |
| LZ4_wildCopy(op, match, oend-8); | |
| match += (oend-8) - op; | |
| op = oend-8; | |
| } | |
| while (op<cpy) *op++ = *match++; | |
| } | |
| else | |
| LZ4_wildCopy(op, match, cpy); | |
| op=cpy; /* correction */ | |
| } | |
| /* end of decoding */ | |
| if (endOnInput) | |
| return (int) (((char*)op)-dest); /* Nb of output bytes decoded */ | |
| else | |
| return (int) (((const char*)ip)-source); /* Nb of input bytes read */ | |
| /* Overflow error detected */ | |
| _output_error: | |
| return (int) (-(((const char*)ip)-source))-1; | |
| } |