forked from gitea/gitea
89 lines
1.8 KiB
Go
89 lines
1.8 KiB
Go
// Package lz4block provides LZ4 BlockSize types and pools of buffers.
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package lz4block
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import "sync"
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const (
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Block64Kb uint32 = 1 << (16 + iota*2)
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Block256Kb
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Block1Mb
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Block4Mb
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Block8Mb = 2 * Block4Mb
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legacyBlockSize = Block8Mb + Block8Mb/255 + 16 // CompressBound(Block8Mb)
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)
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var (
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BlockPool64K = sync.Pool{New: func() interface{} { return make([]byte, Block64Kb) }}
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BlockPool256K = sync.Pool{New: func() interface{} { return make([]byte, Block256Kb) }}
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BlockPool1M = sync.Pool{New: func() interface{} { return make([]byte, Block1Mb) }}
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BlockPool4M = sync.Pool{New: func() interface{} { return make([]byte, Block4Mb) }}
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BlockPool8M = sync.Pool{New: func() interface{} { return make([]byte, legacyBlockSize) }}
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)
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func Index(b uint32) BlockSizeIndex {
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switch b {
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case Block64Kb:
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return 4
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case Block256Kb:
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return 5
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case Block1Mb:
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return 6
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case Block4Mb:
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return 7
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case Block8Mb: // only valid in legacy mode
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return 3
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}
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return 0
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}
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func IsValid(b uint32) bool {
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return Index(b) > 0
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}
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type BlockSizeIndex uint8
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func (b BlockSizeIndex) IsValid() bool {
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switch b {
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case 4, 5, 6, 7:
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return true
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}
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return false
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}
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func (b BlockSizeIndex) Get() []byte {
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var buf interface{}
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switch b {
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case 4:
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buf = BlockPool64K.Get()
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case 5:
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buf = BlockPool256K.Get()
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case 6:
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buf = BlockPool1M.Get()
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case 7:
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buf = BlockPool4M.Get()
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case 3:
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buf = BlockPool8M.Get()
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}
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return buf.([]byte)
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}
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func Put(buf []byte) {
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// Safeguard: do not allow invalid buffers.
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switch c := cap(buf); uint32(c) {
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case Block64Kb:
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BlockPool64K.Put(buf[:c])
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case Block256Kb:
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BlockPool256K.Put(buf[:c])
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case Block1Mb:
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BlockPool1M.Put(buf[:c])
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case Block4Mb:
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BlockPool4M.Put(buf[:c])
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case legacyBlockSize:
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BlockPool8M.Put(buf[:c])
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}
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}
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type CompressionLevel uint32
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const Fast CompressionLevel = 0
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