diff options
Diffstat (limited to 'lib/legacy/zstd_v07.c')
| -rw-r--r-- | lib/legacy/zstd_v07.c | 78 |
1 files changed, 1 insertions, 77 deletions
diff --git a/lib/legacy/zstd_v07.c b/lib/legacy/zstd_v07.c index aad9b1f659f8..114ce005b3ac 100644 --- a/lib/legacy/zstd_v07.c +++ b/lib/legacy/zstd_v07.c @@ -511,16 +511,6 @@ MEM_STATIC BITv07_DStream_status BITv07_reloadDStream(BITv07_DStream_t* bitD); MEM_STATIC unsigned BITv07_endOfDStream(const BITv07_DStream_t* bitD); -/* Start by invoking BITv07_initDStream(). -* A chunk of the bitStream is then stored into a local register. -* Local register size is 64-bits on 64-bits systems, 32-bits on 32-bits systems (size_t). -* You can then retrieve bitFields stored into the local register, **in reverse order**. -* Local register is explicitly reloaded from memory by the BITv07_reloadDStream() method. -* A reload guarantee a minimum of ((8*sizeof(bitD->bitContainer))-7) bits when its result is BITv07_DStream_unfinished. -* Otherwise, it can be less than that, so proceed accordingly. -* Checking if DStream has reached its end can be performed with BITv07_endOfDStream(). -*/ - /*-**************************************** * unsafe API @@ -533,7 +523,7 @@ MEM_STATIC size_t BITv07_readBitsFast(BITv07_DStream_t* bitD, unsigned nbBits); /*-************************************************************** * Internal functions ****************************************************************/ -MEM_STATIC unsigned BITv07_highbit32 (register U32 val) +MEM_STATIC unsigned BITv07_highbit32 (U32 val) { # if defined(_MSC_VER) /* Visual */ unsigned long r=0; @@ -599,13 +589,6 @@ MEM_STATIC size_t BITv07_initDStream(BITv07_DStream_t* bitD, const void* srcBuff } -/*! BITv07_lookBits() : - * Provides next n bits from local register. - * local register is not modified. - * On 32-bits, maxNbBits==24. - * On 64-bits, maxNbBits==56. - * @return : value extracted - */ MEM_STATIC size_t BITv07_lookBits(const BITv07_DStream_t* bitD, U32 nbBits) { U32 const bitMask = sizeof(bitD->bitContainer)*8 - 1; @@ -625,11 +608,6 @@ MEM_STATIC void BITv07_skipBits(BITv07_DStream_t* bitD, U32 nbBits) bitD->bitsConsumed += nbBits; } -/*! BITv07_readBits() : - * Read (consume) next n bits from local register and update. - * Pay attention to not read more than nbBits contained into local register. - * @return : extracted value. - */ MEM_STATIC size_t BITv07_readBits(BITv07_DStream_t* bitD, U32 nbBits) { size_t const value = BITv07_lookBits(bitD, nbBits); @@ -646,11 +624,6 @@ MEM_STATIC size_t BITv07_readBitsFast(BITv07_DStream_t* bitD, U32 nbBits) return value; } -/*! BITv07_reloadDStream() : -* Refill `BITv07_DStream_t` from src buffer previously defined (see BITv07_initDStream() ). -* This function is safe, it guarantees it will not read beyond src buffer. -* @return : status of `BITv07_DStream_t` internal register. - if status == unfinished, internal register is filled with >= (sizeof(bitD->bitContainer)*8 - 7) bits */ MEM_STATIC BITv07_DStream_status BITv07_reloadDStream(BITv07_DStream_t* bitD) { if (bitD->bitsConsumed > (sizeof(bitD->bitContainer)*8)) /* should not happen => corruption detected */ @@ -874,55 +847,6 @@ static void FSEv07_initDState(FSEv07_DState_t* DStatePtr, BITv07_DStream_t* static unsigned char FSEv07_decodeSymbol(FSEv07_DState_t* DStatePtr, BITv07_DStream_t* bitD); -/**< -Let's now decompose FSEv07_decompress_usingDTable() into its unitary components. -You will decode FSE-encoded symbols from the bitStream, -and also any other bitFields you put in, **in reverse order**. - -You will need a few variables to track your bitStream. They are : - -BITv07_DStream_t DStream; // Stream context -FSEv07_DState_t DState; // State context. Multiple ones are possible -FSEv07_DTable* DTablePtr; // Decoding table, provided by FSEv07_buildDTable() - -The first thing to do is to init the bitStream. - errorCode = BITv07_initDStream(&DStream, srcBuffer, srcSize); - -You should then retrieve your initial state(s) -(in reverse flushing order if you have several ones) : - errorCode = FSEv07_initDState(&DState, &DStream, DTablePtr); - -You can then decode your data, symbol after symbol. -For information the maximum number of bits read by FSEv07_decodeSymbol() is 'tableLog'. -Keep in mind that symbols are decoded in reverse order, like a LIFO stack (last in, first out). - unsigned char symbol = FSEv07_decodeSymbol(&DState, &DStream); - -You can retrieve any bitfield you eventually stored into the bitStream (in reverse order) -Note : maximum allowed nbBits is 25, for 32-bits compatibility - size_t bitField = BITv07_readBits(&DStream, nbBits); - -All above operations only read from local register (which size depends on size_t). -Refueling the register from memory is manually performed by the reload method. - endSignal = FSEv07_reloadDStream(&DStream); - -BITv07_reloadDStream() result tells if there is still some more data to read from DStream. -BITv07_DStream_unfinished : there is still some data left into the DStream. -BITv07_DStream_endOfBuffer : Dstream reached end of buffer. Its container may no longer be completely filled. -BITv07_DStream_completed : Dstream reached its exact end, corresponding in general to decompression completed. -BITv07_DStream_tooFar : Dstream went too far. Decompression result is corrupted. - -When reaching end of buffer (BITv07_DStream_endOfBuffer), progress slowly, notably if you decode multiple symbols per loop, -to properly detect the exact end of stream. -After each decoded symbol, check if DStream is fully consumed using this simple test : - BITv07_reloadDStream(&DStream) >= BITv07_DStream_completed - -When it's done, verify decompression is fully completed, by checking both DStream and the relevant states. -Checking if DStream has reached its end is performed by : - BITv07_endOfDStream(&DStream); -Check also the states. There might be some symbols left there, if some high probability ones (>50%) are possible. - FSEv07_endOfDState(&DState); -*/ - /* ***************************************** * FSE unsafe API |