diff options
Diffstat (limited to 'vendor/github.com/pierrec/lz4/v3/lz4.go')
| -rw-r--r-- | vendor/github.com/pierrec/lz4/v3/lz4.go | 113 |
1 files changed, 0 insertions, 113 deletions
diff --git a/vendor/github.com/pierrec/lz4/v3/lz4.go b/vendor/github.com/pierrec/lz4/v3/lz4.go deleted file mode 100644 index 6c73539a34..0000000000 --- a/vendor/github.com/pierrec/lz4/v3/lz4.go +++ /dev/null @@ -1,113 +0,0 @@ -// Package lz4 implements reading and writing lz4 compressed data (a frame), -// as specified in http://fastcompression.blogspot.fr/2013/04/lz4-streaming-format-final.html. -// -// Although the block level compression and decompression functions are exposed and are fully compatible -// with the lz4 block format definition, they are low level and should not be used directly. -// For a complete description of an lz4 compressed block, see: -// http://fastcompression.blogspot.fr/2011/05/lz4-explained.html -// -// See https://github.com/Cyan4973/lz4 for the reference C implementation. -// -package lz4 - -import "math/bits" - -import "sync" - -const ( - // Extension is the LZ4 frame file name extension - Extension = ".lz4" - // Version is the LZ4 frame format version - Version = 1 - - frameMagic uint32 = 0x184D2204 - frameSkipMagic uint32 = 0x184D2A50 - - // The following constants are used to setup the compression algorithm. - minMatch = 4 // the minimum size of the match sequence size (4 bytes) - winSizeLog = 16 // LZ4 64Kb window size limit - winSize = 1 << winSizeLog - winMask = winSize - 1 // 64Kb window of previous data for dependent blocks - compressedBlockFlag = 1 << 31 - compressedBlockMask = compressedBlockFlag - 1 - - // hashLog determines the size of the hash table used to quickly find a previous match position. - // Its value influences the compression speed and memory usage, the lower the faster, - // but at the expense of the compression ratio. - // 16 seems to be the best compromise for fast compression. - hashLog = 16 - htSize = 1 << hashLog - - mfLimit = 10 + minMatch // The last match cannot start within the last 14 bytes. -) - -// map the block max size id with its value in bytes: 64Kb, 256Kb, 1Mb and 4Mb. -const ( - blockSize64K = 1 << (16 + 2*iota) - blockSize256K - blockSize1M - blockSize4M -) - -var ( - // Keep a pool of buffers for each valid block sizes. - bsMapValue = [...]*sync.Pool{ - newBufferPool(2 * blockSize64K), - newBufferPool(2 * blockSize256K), - newBufferPool(2 * blockSize1M), - newBufferPool(2 * blockSize4M), - } -) - -// newBufferPool returns a pool for buffers of the given size. -func newBufferPool(size int) *sync.Pool { - return &sync.Pool{ - New: func() interface{} { - return make([]byte, size) - }, - } -} - -// getBuffer returns a buffer to its pool. -func getBuffer(size int) []byte { - idx := blockSizeValueToIndex(size) - 4 - return bsMapValue[idx].Get().([]byte) -} - -// putBuffer returns a buffer to its pool. -func putBuffer(size int, buf []byte) { - if cap(buf) > 0 { - idx := blockSizeValueToIndex(size) - 4 - bsMapValue[idx].Put(buf[:cap(buf)]) - } -} -func blockSizeIndexToValue(i byte) int { - return 1 << (16 + 2*uint(i)) -} -func isValidBlockSize(size int) bool { - const blockSizeMask = blockSize64K | blockSize256K | blockSize1M | blockSize4M - - return size&blockSizeMask > 0 && bits.OnesCount(uint(size)) == 1 -} -func blockSizeValueToIndex(size int) byte { - return 4 + byte(bits.TrailingZeros(uint(size)>>16)/2) -} - -// Header describes the various flags that can be set on a Writer or obtained from a Reader. -// The default values match those of the LZ4 frame format definition -// (http://fastcompression.blogspot.com/2013/04/lz4-streaming-format-final.html). -// -// NB. in a Reader, in case of concatenated frames, the Header values may change between Read() calls. -// It is the caller's responsibility to check them if necessary. -type Header struct { - BlockChecksum bool // Compressed blocks checksum flag. - NoChecksum bool // Frame checksum flag. - BlockMaxSize int // Size of the uncompressed data block (one of [64KB, 256KB, 1MB, 4MB]). Default=4MB. - Size uint64 // Frame total size. It is _not_ computed by the Writer. - CompressionLevel int // Compression level (higher is better, use 0 for fastest compression). - done bool // Header processed flag (Read or Write and checked). -} - -func (h *Header) Reset() { - h.done = false -} |