| /* |
| 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; |
| } |
