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Dump: add output format tar and output to stdout (#10376)

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* Dump: Use mholt/archive/v3 to support tar including many compressions

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Dump: Allow dump output to stdout

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Dump: Fixed bug present since #6677 where SessionConfig.Provider is never "file"

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Dump: never pack RepoRootPath, LFS.ContentPath and LogRootPath when they are below AppDataPath

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Dump: also dump LFS (fixes #10058)

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Dump: never dump CustomPath if CustomPath is a subdir of or equal to AppDataPath (fixes #10365)

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* Use log.Info instead of fmt.Fprintf

Signed-off-by: Philipp Homann <homann.philipp@googlemail.com>

* import ordering

* make fmt

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>
Co-authored-by: Matti R <matti@mdranta.net>
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# Finite State Entropy
This package provides Finite State Entropy encoding and decoding.
Finite State Entropy (also referenced as [tANS](https://en.wikipedia.org/wiki/Asymmetric_numeral_systems#tANS))
encoding provides a fast near-optimal symbol encoding/decoding
for byte blocks as implemented in [zstandard](https://github.com/facebook/zstd).
This can be used for compressing input with a lot of similar input values to the smallest number of bytes.
This does not perform any multi-byte [dictionary coding](https://en.wikipedia.org/wiki/Dictionary_coder) as LZ coders,
but it can be used as a secondary step to compressors (like Snappy) that does not do entropy encoding.
* [Godoc documentation](https://godoc.org/github.com/klauspost/compress/fse)
## News
* Feb 2018: First implementation released. Consider this beta software for now.
# Usage
This package provides a low level interface that allows to compress single independent blocks.
Each block is separate, and there is no built in integrity checks.
This means that the caller should keep track of block sizes and also do checksums if needed.
Compressing a block is done via the [`Compress`](https://godoc.org/github.com/klauspost/compress/fse#Compress) function.
You must provide input and will receive the output and maybe an error.
These error values can be returned:
| Error | Description |
|---------------------|-----------------------------------------------------------------------------|
| `<nil>` | Everything ok, output is returned |
| `ErrIncompressible` | Returned when input is judged to be too hard to compress |
| `ErrUseRLE` | Returned from the compressor when the input is a single byte value repeated |
| `(error)` | An internal error occurred. |
As can be seen above there are errors that will be returned even under normal operation so it is important to handle these.
To reduce allocations you can provide a [`Scratch`](https://godoc.org/github.com/klauspost/compress/fse#Scratch) object
that can be re-used for successive calls. Both compression and decompression accepts a `Scratch` object, and the same
object can be used for both.
Be aware, that when re-using a `Scratch` object that the *output* buffer is also re-used, so if you are still using this
you must set the `Out` field in the scratch to nil. The same buffer is used for compression and decompression output.
Decompressing is done by calling the [`Decompress`](https://godoc.org/github.com/klauspost/compress/fse#Decompress) function.
You must provide the output from the compression stage, at exactly the size you got back. If you receive an error back
your input was likely corrupted.
It is important to note that a successful decoding does *not* mean your output matches your original input.
There are no integrity checks, so relying on errors from the decompressor does not assure your data is valid.
For more detailed usage, see examples in the [godoc documentation](https://godoc.org/github.com/klauspost/compress/fse#pkg-examples).
# Performance
A lot of factors are affecting speed. Block sizes and compressibility of the material are primary factors.
All compression functions are currently only running on the calling goroutine so only one core will be used per block.
The compressor is significantly faster if symbols are kept as small as possible. The highest byte value of the input
is used to reduce some of the processing, so if all your input is above byte value 64 for instance, it may be
beneficial to transpose all your input values down by 64.
With moderate block sizes around 64k speed are typically 200MB/s per core for compression and
around 300MB/s decompression speed.
The same hardware typically does Huffman (deflate) encoding at 125MB/s and decompression at 100MB/s.
# Plans
At one point, more internals will be exposed to facilitate more "expert" usage of the components.
A streaming interface is also likely to be implemented. Likely compatible with [FSE stream format](https://github.com/Cyan4973/FiniteStateEntropy/blob/dev/programs/fileio.c#L261).
# Contributing
Contributions are always welcome. Be aware that adding public functions will require good justification and breaking
changes will likely not be accepted. If in doubt open an issue before writing the PR.

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// Copyright 2018 Klaus Post. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
package fse
import (
"errors"
"io"
)
// bitReader reads a bitstream in reverse.
// The last set bit indicates the start of the stream and is used
// for aligning the input.
type bitReader struct {
in []byte
off uint // next byte to read is at in[off - 1]
value uint64
bitsRead uint8
}
// init initializes and resets the bit reader.
func (b *bitReader) init(in []byte) error {
if len(in) < 1 {
return errors.New("corrupt stream: too short")
}
b.in = in
b.off = uint(len(in))
// The highest bit of the last byte indicates where to start
v := in[len(in)-1]
if v == 0 {
return errors.New("corrupt stream, did not find end of stream")
}
b.bitsRead = 64
b.value = 0
b.fill()
b.fill()
b.bitsRead += 8 - uint8(highBits(uint32(v)))
return nil
}
// getBits will return n bits. n can be 0.
func (b *bitReader) getBits(n uint8) uint16 {
if n == 0 || b.bitsRead >= 64 {
return 0
}
return b.getBitsFast(n)
}
// getBitsFast requires that at least one bit is requested every time.
// There are no checks if the buffer is filled.
func (b *bitReader) getBitsFast(n uint8) uint16 {
const regMask = 64 - 1
v := uint16((b.value << (b.bitsRead & regMask)) >> ((regMask + 1 - n) & regMask))
b.bitsRead += n
return v
}
// fillFast() will make sure at least 32 bits are available.
// There must be at least 4 bytes available.
func (b *bitReader) fillFast() {
if b.bitsRead < 32 {
return
}
// Do single re-slice to avoid bounds checks.
v := b.in[b.off-4 : b.off]
low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24)
b.value = (b.value << 32) | uint64(low)
b.bitsRead -= 32
b.off -= 4
}
// fill() will make sure at least 32 bits are available.
func (b *bitReader) fill() {
if b.bitsRead < 32 {
return
}
if b.off > 4 {
v := b.in[b.off-4 : b.off]
low := (uint32(v[0])) | (uint32(v[1]) << 8) | (uint32(v[2]) << 16) | (uint32(v[3]) << 24)
b.value = (b.value << 32) | uint64(low)
b.bitsRead -= 32
b.off -= 4
return
}
for b.off > 0 {
b.value = (b.value << 8) | uint64(b.in[b.off-1])
b.bitsRead -= 8
b.off--
}
}
// finished returns true if all bits have been read from the bit stream.
func (b *bitReader) finished() bool {
return b.off == 0 && b.bitsRead >= 64
}
// close the bitstream and returns an error if out-of-buffer reads occurred.
func (b *bitReader) close() error {
// Release reference.
b.in = nil
if b.bitsRead > 64 {
return io.ErrUnexpectedEOF
}
return nil
}

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// Copyright 2018 Klaus Post. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
package fse
import "fmt"
// bitWriter will write bits.
// First bit will be LSB of the first byte of output.
type bitWriter struct {
bitContainer uint64
nBits uint8
out []byte
}
// bitMask16 is bitmasks. Has extra to avoid bounds check.
var bitMask16 = [32]uint16{
0, 1, 3, 7, 0xF, 0x1F,
0x3F, 0x7F, 0xFF, 0x1FF, 0x3FF, 0x7FF,
0xFFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF, 0xFFFF,
0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF, 0xFFFF,
0xFFFF, 0xFFFF} /* up to 16 bits */
// addBits16NC will add up to 16 bits.
// It will not check if there is space for them,
// so the caller must ensure that it has flushed recently.
func (b *bitWriter) addBits16NC(value uint16, bits uint8) {
b.bitContainer |= uint64(value&bitMask16[bits&31]) << (b.nBits & 63)
b.nBits += bits
}
// addBits16Clean will add up to 16 bits. value may not contain more set bits than indicated.
// It will not check if there is space for them, so the caller must ensure that it has flushed recently.
func (b *bitWriter) addBits16Clean(value uint16, bits uint8) {
b.bitContainer |= uint64(value) << (b.nBits & 63)
b.nBits += bits
}
// addBits16ZeroNC will add up to 16 bits.
// It will not check if there is space for them,
// so the caller must ensure that it has flushed recently.
// This is fastest if bits can be zero.
func (b *bitWriter) addBits16ZeroNC(value uint16, bits uint8) {
if bits == 0 {
return
}
value <<= (16 - bits) & 15
value >>= (16 - bits) & 15
b.bitContainer |= uint64(value) << (b.nBits & 63)
b.nBits += bits
}
// flush will flush all pending full bytes.
// There will be at least 56 bits available for writing when this has been called.
// Using flush32 is faster, but leaves less space for writing.
func (b *bitWriter) flush() {
v := b.nBits >> 3
switch v {
case 0:
case 1:
b.out = append(b.out,
byte(b.bitContainer),
)
case 2:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
)
case 3:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
)
case 4:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
)
case 5:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
byte(b.bitContainer>>32),
)
case 6:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
byte(b.bitContainer>>32),
byte(b.bitContainer>>40),
)
case 7:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
byte(b.bitContainer>>32),
byte(b.bitContainer>>40),
byte(b.bitContainer>>48),
)
case 8:
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24),
byte(b.bitContainer>>32),
byte(b.bitContainer>>40),
byte(b.bitContainer>>48),
byte(b.bitContainer>>56),
)
default:
panic(fmt.Errorf("bits (%d) > 64", b.nBits))
}
b.bitContainer >>= v << 3
b.nBits &= 7
}
// flush32 will flush out, so there are at least 32 bits available for writing.
func (b *bitWriter) flush32() {
if b.nBits < 32 {
return
}
b.out = append(b.out,
byte(b.bitContainer),
byte(b.bitContainer>>8),
byte(b.bitContainer>>16),
byte(b.bitContainer>>24))
b.nBits -= 32
b.bitContainer >>= 32
}
// flushAlign will flush remaining full bytes and align to next byte boundary.
func (b *bitWriter) flushAlign() {
nbBytes := (b.nBits + 7) >> 3
for i := uint8(0); i < nbBytes; i++ {
b.out = append(b.out, byte(b.bitContainer>>(i*8)))
}
b.nBits = 0
b.bitContainer = 0
}
// close will write the alignment bit and write the final byte(s)
// to the output.
func (b *bitWriter) close() error {
// End mark
b.addBits16Clean(1, 1)
// flush until next byte.
b.flushAlign()
return nil
}
// reset and continue writing by appending to out.
func (b *bitWriter) reset(out []byte) {
b.bitContainer = 0
b.nBits = 0
b.out = out
}

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// Copyright 2018 Klaus Post. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
package fse
// byteReader provides a byte reader that reads
// little endian values from a byte stream.
// The input stream is manually advanced.
// The reader performs no bounds checks.
type byteReader struct {
b []byte
off int
}
// init will initialize the reader and set the input.
func (b *byteReader) init(in []byte) {
b.b = in
b.off = 0
}
// advance the stream b n bytes.
func (b *byteReader) advance(n uint) {
b.off += int(n)
}
// Int32 returns a little endian int32 starting at current offset.
func (b byteReader) Int32() int32 {
b2 := b.b[b.off : b.off+4 : b.off+4]
v3 := int32(b2[3])
v2 := int32(b2[2])
v1 := int32(b2[1])
v0 := int32(b2[0])
return v0 | (v1 << 8) | (v2 << 16) | (v3 << 24)
}
// Uint32 returns a little endian uint32 starting at current offset.
func (b byteReader) Uint32() uint32 {
b2 := b.b[b.off : b.off+4 : b.off+4]
v3 := uint32(b2[3])
v2 := uint32(b2[2])
v1 := uint32(b2[1])
v0 := uint32(b2[0])
return v0 | (v1 << 8) | (v2 << 16) | (v3 << 24)
}
// unread returns the unread portion of the input.
func (b byteReader) unread() []byte {
return b.b[b.off:]
}
// remain will return the number of bytes remaining.
func (b byteReader) remain() int {
return len(b.b) - b.off
}

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// Copyright 2018 Klaus Post. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
package fse
import (
"errors"
"fmt"
)
// Compress the input bytes. Input must be < 2GB.
// Provide a Scratch buffer to avoid memory allocations.
// Note that the output is also kept in the scratch buffer.
// If input is too hard to compress, ErrIncompressible is returned.
// If input is a single byte value repeated ErrUseRLE is returned.
func Compress(in []byte, s *Scratch) ([]byte, error) {
if len(in) <= 1 {
return nil, ErrIncompressible
}
if len(in) > (2<<30)-1 {
return nil, errors.New("input too big, must be < 2GB")
}
s, err := s.prepare(in)
if err != nil {
return nil, err
}
// Create histogram, if none was provided.
maxCount := s.maxCount
if maxCount == 0 {
maxCount = s.countSimple(in)
}
// Reset for next run.
s.clearCount = true
s.maxCount = 0
if maxCount == len(in) {
// One symbol, use RLE
return nil, ErrUseRLE
}
if maxCount == 1 || maxCount < (len(in)>>7) {
// Each symbol present maximum once or too well distributed.
return nil, ErrIncompressible
}
s.optimalTableLog()
err = s.normalizeCount()
if err != nil {
return nil, err
}
err = s.writeCount()
if err != nil {
return nil, err
}
if false {
err = s.validateNorm()
if err != nil {
return nil, err
}
}
err = s.buildCTable()
if err != nil {
return nil, err
}
err = s.compress(in)
if err != nil {
return nil, err
}
s.Out = s.bw.out
// Check if we compressed.
if len(s.Out) >= len(in) {
return nil, ErrIncompressible
}
return s.Out, nil
}
// cState contains the compression state of a stream.
type cState struct {
bw *bitWriter
stateTable []uint16
state uint16
}
// init will initialize the compression state to the first symbol of the stream.
func (c *cState) init(bw *bitWriter, ct *cTable, tableLog uint8, first symbolTransform) {
c.bw = bw
c.stateTable = ct.stateTable
nbBitsOut := (first.deltaNbBits + (1 << 15)) >> 16
im := int32((nbBitsOut << 16) - first.deltaNbBits)
lu := (im >> nbBitsOut) + first.deltaFindState
c.state = c.stateTable[lu]
return
}
// encode the output symbol provided and write it to the bitstream.
func (c *cState) encode(symbolTT symbolTransform) {
nbBitsOut := (uint32(c.state) + symbolTT.deltaNbBits) >> 16
dstState := int32(c.state>>(nbBitsOut&15)) + symbolTT.deltaFindState
c.bw.addBits16NC(c.state, uint8(nbBitsOut))
c.state = c.stateTable[dstState]
}
// encode the output symbol provided and write it to the bitstream.
func (c *cState) encodeZero(symbolTT symbolTransform) {
nbBitsOut := (uint32(c.state) + symbolTT.deltaNbBits) >> 16
dstState := int32(c.state>>(nbBitsOut&15)) + symbolTT.deltaFindState
c.bw.addBits16ZeroNC(c.state, uint8(nbBitsOut))
c.state = c.stateTable[dstState]
}
// flush will write the tablelog to the output and flush the remaining full bytes.
func (c *cState) flush(tableLog uint8) {
c.bw.flush32()
c.bw.addBits16NC(c.state, tableLog)
c.bw.flush()
}
// compress is the main compression loop that will encode the input from the last byte to the first.
func (s *Scratch) compress(src []byte) error {
if len(src) <= 2 {
return errors.New("compress: src too small")
}
tt := s.ct.symbolTT[:256]
s.bw.reset(s.Out)
// Our two states each encodes every second byte.
// Last byte encoded (first byte decoded) will always be encoded by c1.
var c1, c2 cState
// Encode so remaining size is divisible by 4.
ip := len(src)
if ip&1 == 1 {
c1.init(&s.bw, &s.ct, s.actualTableLog, tt[src[ip-1]])
c2.init(&s.bw, &s.ct, s.actualTableLog, tt[src[ip-2]])
c1.encodeZero(tt[src[ip-3]])
ip -= 3
} else {
c2.init(&s.bw, &s.ct, s.actualTableLog, tt[src[ip-1]])
c1.init(&s.bw, &s.ct, s.actualTableLog, tt[src[ip-2]])
ip -= 2
}
if ip&2 != 0 {
c2.encodeZero(tt[src[ip-1]])
c1.encodeZero(tt[src[ip-2]])
ip -= 2
}
// Main compression loop.
switch {
case !s.zeroBits && s.actualTableLog <= 8:
// We can encode 4 symbols without requiring a flush.
// We do not need to check if any output is 0 bits.
for ip >= 4 {
s.bw.flush32()
v3, v2, v1, v0 := src[ip-4], src[ip-3], src[ip-2], src[ip-1]
c2.encode(tt[v0])
c1.encode(tt[v1])
c2.encode(tt[v2])
c1.encode(tt[v3])
ip -= 4
}
case !s.zeroBits:
// We do not need to check if any output is 0 bits.
for ip >= 4 {
s.bw.flush32()
v3, v2, v1, v0 := src[ip-4], src[ip-3], src[ip-2], src[ip-1]
c2.encode(tt[v0])
c1.encode(tt[v1])
s.bw.flush32()
c2.encode(tt[v2])
c1.encode(tt[v3])
ip -= 4
}
case s.actualTableLog <= 8:
// We can encode 4 symbols without requiring a flush
for ip >= 4 {
s.bw.flush32()
v3, v2, v1, v0 := src[ip-4], src[ip-3], src[ip-2], src[ip-1]
c2.encodeZero(tt[v0])
c1.encodeZero(tt[v1])
c2.encodeZero(tt[v2])
c1.encodeZero(tt[v3])
ip -= 4
}
default:
for ip >= 4 {
s.bw.flush32()
v3, v2, v1, v0 := src[ip-4], src[ip-3], src[ip-2], src[ip-1]
c2.encodeZero(tt[v0])
c1.encodeZero(tt[v1])
s.bw.flush32()
c2.encodeZero(tt[v2])
c1.encodeZero(tt[v3])
ip -= 4
}
}
// Flush final state.
// Used to initialize state when decoding.
c2.flush(s.actualTableLog)
c1.flush(s.actualTableLog)
return s.bw.close()
}
// writeCount will write the normalized histogram count to header.
// This is read back by readNCount.
func (s *Scratch) writeCount() error {
var (
tableLog = s.actualTableLog
tableSize = 1 << tableLog
previous0 bool
charnum uint16
maxHeaderSize = ((int(s.symbolLen) * int(tableLog)) >> 3) + 3
// Write Table Size
bitStream = uint32(tableLog - minTablelog)
bitCount = uint(4)
remaining = int16(tableSize + 1) /* +1 for extra accuracy */
threshold = int16(tableSize)
nbBits = uint(tableLog + 1)
)
if cap(s.Out) < maxHeaderSize {
s.Out = make([]byte, 0, s.br.remain()+maxHeaderSize)
}
outP := uint(0)
out := s.Out[:maxHeaderSize]
// stops at 1
for remaining > 1 {
if previous0 {
start := charnum
for s.norm[charnum] == 0 {
charnum++
}
for charnum >= start+24 {
start += 24
bitStream += uint32(0xFFFF) << bitCount
out[outP] = byte(bitStream)
out[outP+1] = byte(bitStream >> 8)
outP += 2
bitStream >>= 16
}
for charnum >= start+3 {
start += 3
bitStream += 3 << bitCount
bitCount += 2
}
bitStream += uint32(charnum-start) << bitCount
bitCount += 2
if bitCount > 16 {
out[outP] = byte(bitStream)
out[outP+1] = byte(bitStream >> 8)
outP += 2
bitStream >>= 16
bitCount -= 16
}
}
count := s.norm[charnum]
charnum++
max := (2*threshold - 1) - remaining
if count < 0 {
remaining += count
} else {
remaining -= count
}
count++ // +1 for extra accuracy
if count >= threshold {
count += max // [0..max[ [max..threshold[ (...) [threshold+max 2*threshold[
}
bitStream += uint32(count) << bitCount
bitCount += nbBits
if count < max {
bitCount--
}
previous0 = count == 1
if remaining < 1 {
return errors.New("internal error: remaining<1")
}
for remaining < threshold {
nbBits--
threshold >>= 1
}
if bitCount > 16 {
out[outP] = byte(bitStream)
out[outP+1] = byte(bitStream >> 8)
outP += 2
bitStream >>= 16
bitCount -= 16
}
}
out[outP] = byte(bitStream)
out[outP+1] = byte(bitStream >> 8)
outP += (bitCount + 7) / 8
if uint16(charnum) > s.symbolLen {
return errors.New("internal error: charnum > s.symbolLen")
}
s.Out = out[:outP]
return nil
}
// symbolTransform contains the state transform for a symbol.
type symbolTransform struct {
deltaFindState int32
deltaNbBits uint32
}
// String prints values as a human readable string.
func (s symbolTransform) String() string {
return fmt.Sprintf("dnbits: %08x, fs:%d", s.deltaNbBits, s.deltaFindState)
}
// cTable contains tables used for compression.
type cTable struct {
tableSymbol []byte
stateTable []uint16
symbolTT []symbolTransform
}
// allocCtable will allocate tables needed for compression.
// If existing tables a re big enough, they are simply re-used.
func (s *Scratch) allocCtable() {
tableSize := 1 << s.actualTableLog
// get tableSymbol that is big enough.
if cap(s.ct.tableSymbol) < int(tableSize) {
s.ct.tableSymbol = make([]byte, tableSize)
}
s.ct.tableSymbol = s.ct.tableSymbol[:tableSize]
ctSize := tableSize
if cap(s.ct.stateTable) < ctSize {
s.ct.stateTable = make([]uint16, ctSize)
}
s.ct.stateTable = s.ct.stateTable[:ctSize]
if cap(s.ct.symbolTT) < 256 {
s.ct.symbolTT = make([]symbolTransform, 256)
}
s.ct.symbolTT = s.ct.symbolTT[:256]
}
// buildCTable will populate the compression table so it is ready to be used.
func (s *Scratch) buildCTable() error {
tableSize := uint32(1 << s.actualTableLog)
highThreshold := tableSize - 1
var cumul [maxSymbolValue + 2]int16
s.allocCtable()
tableSymbol := s.ct.tableSymbol[:tableSize]
// symbol start positions
{
cumul[0] = 0
for ui, v := range s.norm[:s.symbolLen-1] {
u := byte(ui) // one less than reference
if v == -1 {
// Low proba symbol
cumul[u+1] = cumul[u] + 1
tableSymbol[highThreshold] = u
highThreshold--
} else {
cumul[u+1] = cumul[u] + v
}
}
// Encode last symbol separately to avoid overflowing u
u := int(s.symbolLen - 1)
v := s.norm[s.symbolLen-1]
if v == -1 {
// Low proba symbol
cumul[u+1] = cumul[u] + 1
tableSymbol[highThreshold] = byte(u)
highThreshold--
} else {
cumul[u+1] = cumul[u] + v
}
if uint32(cumul[s.symbolLen]) != tableSize {
return fmt.Errorf("internal error: expected cumul[s.symbolLen] (%d) == tableSize (%d)", cumul[s.symbolLen], tableSize)
}
cumul[s.symbolLen] = int16(tableSize) + 1
}
// Spread symbols
s.zeroBits = false
{
step := tableStep(tableSize)
tableMask := tableSize - 1
var position uint32
// if any symbol > largeLimit, we may have 0 bits output.
largeLimit := int16(1 << (s.actualTableLog - 1))
for ui, v := range s.norm[:s.symbolLen] {
symbol := byte(ui)
if v > largeLimit {
s.zeroBits = true
}
for nbOccurrences := int16(0); nbOccurrences < v; nbOccurrences++ {
tableSymbol[position] = symbol
position = (position + step) & tableMask
for position > highThreshold {
position = (position + step) & tableMask
} /* Low proba area */
}
}
// Check if we have gone through all positions
if position != 0 {
return errors.New("position!=0")
}
}
// Build table
table := s.ct.stateTable
{
tsi := int(tableSize)
for u, v := range tableSymbol {
// TableU16 : sorted by symbol order; gives next state value
table[cumul[v]] = uint16(tsi + u)
cumul[v]++
}
}
// Build Symbol Transformation Table
{
total := int16(0)
symbolTT := s.ct.symbolTT[:s.symbolLen]
tableLog := s.actualTableLog
tl := (uint32(tableLog) << 16) - (1 << tableLog)
for i, v := range s.norm[:s.symbolLen] {
switch v {
case 0:
case -1, 1:
symbolTT[i].deltaNbBits = tl
symbolTT[i].deltaFindState = int32(total - 1)
total++
default:
maxBitsOut := uint32(tableLog) - highBits(uint32(v-1))
minStatePlus := uint32(v) << maxBitsOut
symbolTT[i].deltaNbBits = (maxBitsOut << 16) - minStatePlus
symbolTT[i].deltaFindState = int32(total - v)
total += v
}
}
if total != int16(tableSize) {
return fmt.Errorf("total mismatch %d (got) != %d (want)", total, tableSize)
}
}
return nil
}
// countSimple will create a simple histogram in s.count.
// Returns the biggest count.
// Does not update s.clearCount.
func (s *Scratch) countSimple(in []byte) (max int) {
for _, v := range in {
s.count[v]++
}
m := uint32(0)
for i, v := range s.count[:] {
if v > m {
m = v
}
if v > 0 {
s.symbolLen = uint16(i) + 1
}
}
return int(m)
}
// minTableLog provides the minimum logSize to safely represent a distribution.
func (s *Scratch) minTableLog() uint8 {
minBitsSrc := highBits(uint32(s.br.remain()-1)) + 1
minBitsSymbols := highBits(uint32(s.symbolLen-1)) + 2
if minBitsSrc < minBitsSymbols {
return uint8(minBitsSrc)
}
return uint8(minBitsSymbols)
}
// optimalTableLog calculates and sets the optimal tableLog in s.actualTableLog
func (s *Scratch) optimalTableLog() {
tableLog := s.TableLog
minBits := s.minTableLog()
maxBitsSrc := uint8(highBits(uint32(s.br.remain()-1))) - 2
if maxBitsSrc < tableLog {
// Accuracy can be reduced
tableLog = maxBitsSrc
}
if minBits > tableLog {
tableLog = minBits
}
// Need a minimum to safely represent all symbol values
if tableLog < minTablelog {
tableLog = minTablelog
}
if tableLog > maxTableLog {
tableLog = maxTableLog
}
s.actualTableLog = tableLog
}
var rtbTable = [...]uint32{0, 473195, 504333, 520860, 550000, 700000, 750000, 830000}
// normalizeCount will normalize the count of the symbols so
// the total is equal to the table size.
func (s *Scratch) normalizeCount() error {
var (
tableLog = s.actualTableLog
scale = 62 - uint64(tableLog)
step = (1 << 62) / uint64(s.br.remain())
vStep = uint64(1) << (scale - 20)
stillToDistribute = int16(1 << tableLog)
largest int
largestP int16
lowThreshold = (uint32)(s.br.remain() >> tableLog)
)
for i, cnt := range s.count[:s.symbolLen] {
// already handled
// if (count[s] == s.length) return 0; /* rle special case */
if cnt == 0 {
s.norm[i] = 0
continue
}
if cnt <= lowThreshold {
s.norm[i] = -1
stillToDistribute--
} else {
proba := (int16)((uint64(cnt) * step) >> scale)
if proba < 8 {
restToBeat := vStep * uint64(rtbTable[proba])
v := uint64(cnt)*step - (uint64(proba) << scale)
if v > restToBeat {
proba++
}
}
if proba > largestP {
largestP = proba
largest = i
}
s.norm[i] = proba
stillToDistribute -= proba
}
}
if -stillToDistribute >= (s.norm[largest] >> 1) {
// corner case, need another normalization method
return s.normalizeCount2()
}
s.norm[largest] += stillToDistribute
return nil
}
// Secondary normalization method.
// To be used when primary method fails.
func (s *Scratch) normalizeCount2() error {
const notYetAssigned = -2
var (
distributed uint32
total = uint32(s.br.remain())
tableLog = s.actualTableLog
lowThreshold = uint32(total >> tableLog)
lowOne = uint32((total * 3) >> (tableLog + 1))
)
for i, cnt := range s.count[:s.symbolLen] {
if cnt == 0 {
s.norm[i] = 0
continue
}
if cnt <= lowThreshold {
s.norm[i] = -1
distributed++
total -= cnt
continue
}
if cnt <= lowOne {
s.norm[i] = 1
distributed++
total -= cnt
continue
}
s.norm[i] = notYetAssigned
}
toDistribute := (1 << tableLog) - distributed
if (total / toDistribute) > lowOne {
// risk of rounding to zero
lowOne = uint32((total * 3) / (toDistribute * 2))
for i, cnt := range s.count[:s.symbolLen] {
if (s.norm[i] == notYetAssigned) && (cnt <= lowOne) {
s.norm[i] = 1
distributed++
total -= cnt
continue
}
}
toDistribute = (1 << tableLog) - distributed
}
if distributed == uint32(s.symbolLen)+1 {
// all values are pretty poor;
// probably incompressible data (should have already been detected);
// find max, then give all remaining points to max
var maxV int
var maxC uint32
for i, cnt := range s.count[:s.symbolLen] {
if cnt > maxC {
maxV = i
maxC = cnt
}
}
s.norm[maxV] += int16(toDistribute)
return nil
}
if total == 0 {
// all of the symbols were low enough for the lowOne or lowThreshold
for i := uint32(0); toDistribute > 0; i = (i + 1) % (uint32(s.symbolLen)) {
if s.norm[i] > 0 {
toDistribute--
s.norm[i]++
}
}
return nil
}
var (
vStepLog = 62 - uint64(tableLog)
mid = uint64((1 << (vStepLog - 1)) - 1)
rStep = (((1 << vStepLog) * uint64(toDistribute)) + mid) / uint64(total) // scale on remaining
tmpTotal = mid
)
for i, cnt := range s.count[:s.symbolLen] {
if s.norm[i] == notYetAssigned {
var (
end = tmpTotal + uint64(cnt)*rStep
sStart = uint32(tmpTotal >> vStepLog)
sEnd = uint32(end >> vStepLog)
weight = sEnd - sStart
)
if weight < 1 {
return errors.New("weight < 1")
}
s.norm[i] = int16(weight)
tmpTotal = end
}
}
return nil
}
// validateNorm validates the normalized histogram table.
func (s *Scratch) validateNorm() (err error) {
var total int
for _, v := range s.norm[:s.symbolLen] {
if v >= 0 {
total += int(v)
} else {
total -= int(v)
}
}
defer func() {
if err == nil {
return
}
fmt.Printf("selected TableLog: %d, Symbol length: %d\n", s.actualTableLog, s.symbolLen)
for i, v := range s.norm[:s.symbolLen] {
fmt.Printf("%3d: %5d -> %4d \n", i, s.count[i], v)
}
}()
if total != (1 << s.actualTableLog) {
return fmt.Errorf("warning: Total == %d != %d", total, 1<<s.actualTableLog)
}
for i, v := range s.count[s.symbolLen:] {
if v != 0 {
return fmt.Errorf("warning: Found symbol out of range, %d after cut", i)
}
}
return nil
}

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package fse
import (
"errors"
"fmt"
)
const (
tablelogAbsoluteMax = 15
)
// Decompress a block of data.
// You can provide a scratch buffer to avoid allocations.
// If nil is provided a temporary one will be allocated.
// It is possible, but by no way guaranteed that corrupt data will
// return an error.
// It is up to the caller to verify integrity of the returned data.
// Use a predefined Scrach to set maximum acceptable output size.
func Decompress(b []byte, s *Scratch) ([]byte, error) {
s, err := s.prepare(b)
if err != nil {
return nil, err
}
s.Out = s.Out[:0]
err = s.readNCount()
if err != nil {
return nil, err
}
err = s.buildDtable()
if err != nil {
return nil, err
}
err = s.decompress()
if err != nil {
return nil, err
}
return s.Out, nil
}
// readNCount will read the symbol distribution so decoding tables can be constructed.
func (s *Scratch) readNCount() error {
var (
charnum uint16
previous0 bool
b = &s.br
)
iend := b.remain()
if iend < 4 {
return errors.New("input too small")
}
bitStream := b.Uint32()
nbBits := uint((bitStream & 0xF) + minTablelog) // extract tableLog
if nbBits > tablelogAbsoluteMax {
return errors.New("tableLog too large")
}
bitStream >>= 4
bitCount := uint(4)
s.actualTableLog = uint8(nbBits)
remaining := int32((1 << nbBits) + 1)
threshold := int32(1 << nbBits)
gotTotal := int32(0)
nbBits++
for remaining > 1 {
if previous0 {
n0 := charnum
for (bitStream & 0xFFFF) == 0xFFFF {
n0 += 24
if b.off < iend-5 {
b.advance(2)
bitStream = b.Uint32() >> bitCount
} else {
bitStream >>= 16
bitCount += 16
}
}
for (bitStream & 3) == 3 {
n0 += 3
bitStream >>= 2
bitCount += 2
}
n0 += uint16(bitStream & 3)
bitCount += 2
if n0 > maxSymbolValue {
return errors.New("maxSymbolValue too small")
}
for charnum < n0 {
s.norm[charnum&0xff] = 0
charnum++
}
if b.off <= iend-7 || b.off+int(bitCount>>3) <= iend-4 {
b.advance(bitCount >> 3)
bitCount &= 7
bitStream = b.Uint32() >> bitCount
} else {
bitStream >>= 2
}
}
max := (2*(threshold) - 1) - (remaining)
var count int32
if (int32(bitStream) & (threshold - 1)) < max {
count = int32(bitStream) & (threshold - 1)
bitCount += nbBits - 1
} else {
count = int32(bitStream) & (2*threshold - 1)
if count >= threshold {
count -= max
}
bitCount += nbBits
}
count-- // extra accuracy
if count < 0 {
// -1 means +1
remaining += count
gotTotal -= count
} else {
remaining -= count
gotTotal += count
}
s.norm[charnum&0xff] = int16(count)
charnum++
previous0 = count == 0
for remaining < threshold {
nbBits--
threshold >>= 1
}
if b.off <= iend-7 || b.off+int(bitCount>>3) <= iend-4 {
b.advance(bitCount >> 3)
bitCount &= 7
} else {
bitCount -= (uint)(8 * (len(b.b) - 4 - b.off))
b.off = len(b.b) - 4
}
bitStream = b.Uint32() >> (bitCount & 31)
}
s.symbolLen = charnum
if s.symbolLen <= 1 {
return fmt.Errorf("symbolLen (%d) too small", s.symbolLen)
}
if s.symbolLen > maxSymbolValue+1 {
return fmt.Errorf("symbolLen (%d) too big", s.symbolLen)
}
if remaining != 1 {
return fmt.Errorf("corruption detected (remaining %d != 1)", remaining)
}
if bitCount > 32 {
return fmt.Errorf("corruption detected (bitCount %d > 32)", bitCount)
}
if gotTotal != 1<<s.actualTableLog {
return fmt.Errorf("corruption detected (total %d != %d)", gotTotal, 1<<s.actualTableLog)
}
b.advance((bitCount + 7) >> 3)
return nil
}
// decSymbol contains information about a state entry,
// Including the state offset base, the output symbol and
// the number of bits to read for the low part of the destination state.
type decSymbol struct {
newState uint16
symbol uint8
nbBits uint8
}
// allocDtable will allocate decoding tables if they are not big enough.
func (s *Scratch) allocDtable() {
tableSize := 1 << s.actualTableLog
if cap(s.decTable) < int(tableSize) {
s.decTable = make([]decSymbol, tableSize)
}
s.decTable = s.decTable[:tableSize]
if cap(s.ct.tableSymbol) < 256 {
s.ct.tableSymbol = make([]byte, 256)
}
s.ct.tableSymbol = s.ct.tableSymbol[:256]
if cap(s.ct.stateTable) < 256 {
s.ct.stateTable = make([]uint16, 256)
}
s.ct.stateTable = s.ct.stateTable[:256]
}
// buildDtable will build the decoding table.
func (s *Scratch) buildDtable() error {
tableSize := uint32(1 << s.actualTableLog)
highThreshold := tableSize - 1
s.allocDtable()
symbolNext := s.ct.stateTable[:256]
// Init, lay down lowprob symbols
s.zeroBits = false
{
largeLimit := int16(1 << (s.actualTableLog - 1))
for i, v := range s.norm[:s.symbolLen] {
if v == -1 {
s.decTable[highThreshold].symbol = uint8(i)
highThreshold--
symbolNext[i] = 1
} else {
if v >= largeLimit {
s.zeroBits = true
}
symbolNext[i] = uint16(v)
}
}
}
// Spread symbols
{
tableMask := tableSize - 1
step := tableStep(tableSize)
position := uint32(0)
for ss, v := range s.norm[:s.symbolLen] {
for i := 0; i < int(v); i++ {
s.decTable[position].symbol = uint8(ss)
position = (position + step) & tableMask
for position > highThreshold {
// lowprob area
position = (position + step) & tableMask
}
}
}
if position != 0 {
// position must reach all cells once, otherwise normalizedCounter is incorrect
return errors.New("corrupted input (position != 0)")
}
}
// Build Decoding table
{
tableSize := uint16(1 << s.actualTableLog)
for u, v := range s.decTable {
symbol := v.symbol
nextState := symbolNext[symbol]
symbolNext[symbol] = nextState + 1
nBits := s.actualTableLog - byte(highBits(uint32(nextState)))
s.decTable[u].nbBits = nBits
newState := (nextState << nBits) - tableSize
if newState >= tableSize {
return fmt.Errorf("newState (%d) outside table size (%d)", newState, tableSize)
}
if newState == uint16(u) && nBits == 0 {
// Seems weird that this is possible with nbits > 0.
return fmt.Errorf("newState (%d) == oldState (%d) and no bits", newState, u)
}
s.decTable[u].newState = newState
}
}
return nil
}
// decompress will decompress the bitstream.
// If the buffer is over-read an error is returned.
func (s *Scratch) decompress() error {
br := &s.bits
br.init(s.br.unread())
var s1, s2 decoder
// Initialize and decode first state and symbol.
s1.init(br, s.decTable, s.actualTableLog)
s2.init(br, s.decTable, s.actualTableLog)
// Use temp table to avoid bound checks/append penalty.
var tmp = s.ct.tableSymbol[:256]
var off uint8
// Main part
if !s.zeroBits {
for br.off >= 8 {
br.fillFast()
tmp[off+0] = s1.nextFast()
tmp[off+1] = s2.nextFast()
br.fillFast()
tmp[off+2] = s1.nextFast()
tmp[off+3] = s2.nextFast()
off += 4
// When off is 0, we have overflowed and should write.
if off == 0 {
s.Out = append(s.Out, tmp...)
if len(s.Out) >= s.DecompressLimit {
return fmt.Errorf("output size (%d) > DecompressLimit (%d)", len(s.Out), s.DecompressLimit)
}
}
}
} else {
for br.off >= 8 {
br.fillFast()
tmp[off+0] = s1.next()
tmp[off+1] = s2.next()
br.fillFast()
tmp[off+2] = s1.next()
tmp[off+3] = s2.next()
off += 4
if off == 0 {
s.Out = append(s.Out, tmp...)
// When off is 0, we have overflowed and should write.
if len(s.Out) >= s.DecompressLimit {
return fmt.Errorf("output size (%d) > DecompressLimit (%d)", len(s.Out), s.DecompressLimit)
}
}
}
}
s.Out = append(s.Out, tmp[:off]...)
// Final bits, a bit more expensive check
for {
if s1.finished() {
s.Out = append(s.Out, s1.final(), s2.final())
break
}
br.fill()
s.Out = append(s.Out, s1.next())
if s2.finished() {
s.Out = append(s.Out, s2.final(), s1.final())
break
}
s.Out = append(s.Out, s2.next())
if len(s.Out) >= s.DecompressLimit {
return fmt.Errorf("output size (%d) > DecompressLimit (%d)", len(s.Out), s.DecompressLimit)
}
}
return br.close()
}
// decoder keeps track of the current state and updates it from the bitstream.
type decoder struct {
state uint16
br *bitReader
dt []decSymbol
}
// init will initialize the decoder and read the first state from the stream.
func (d *decoder) init(in *bitReader, dt []decSymbol, tableLog uint8) {
d.dt = dt
d.br = in
d.state = uint16(in.getBits(tableLog))
}
// next returns the next symbol and sets the next state.
// At least tablelog bits must be available in the bit reader.
func (d *decoder) next() uint8 {
n := &d.dt[d.state]
lowBits := d.br.getBits(n.nbBits)
d.state = n.newState + lowBits
return n.symbol
}
// finished returns true if all bits have been read from the bitstream
// and the next state would require reading bits from the input.
func (d *decoder) finished() bool {
return d.br.finished() && d.dt[d.state].nbBits > 0
}
// final returns the current state symbol without decoding the next.
func (d *decoder) final() uint8 {
return d.dt[d.state].symbol
}
// nextFast returns the next symbol and sets the next state.
// This can only be used if no symbols are 0 bits.
// At least tablelog bits must be available in the bit reader.
func (d *decoder) nextFast() uint8 {
n := d.dt[d.state]
lowBits := d.br.getBitsFast(n.nbBits)
d.state = n.newState + lowBits
return n.symbol
}

143
vendor/github.com/klauspost/compress/fse/fse.go generated vendored Normal file
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// Copyright 2018 Klaus Post. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
// Package fse provides Finite State Entropy encoding and decoding.
//
// Finite State Entropy encoding provides a fast near-optimal symbol encoding/decoding
// for byte blocks as implemented in zstd.
//
// See https://github.com/klauspost/compress/tree/master/fse for more information.
package fse
import (
"errors"
"fmt"
"math/bits"
)
const (
/*!MEMORY_USAGE :
* Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
* Increasing memory usage improves compression ratio
* Reduced memory usage can improve speed, due to cache effect
* Recommended max value is 14, for 16KB, which nicely fits into Intel x86 L1 cache */
maxMemoryUsage = 14
defaultMemoryUsage = 13
maxTableLog = maxMemoryUsage - 2
maxTablesize = 1 << maxTableLog
defaultTablelog = defaultMemoryUsage - 2
minTablelog = 5
maxSymbolValue = 255
)
var (
// ErrIncompressible is returned when input is judged to be too hard to compress.
ErrIncompressible = errors.New("input is not compressible")
// ErrUseRLE is returned from the compressor when the input is a single byte value repeated.
ErrUseRLE = errors.New("input is single value repeated")
)
// Scratch provides temporary storage for compression and decompression.
type Scratch struct {
// Private
count [maxSymbolValue + 1]uint32
norm [maxSymbolValue + 1]int16
symbolLen uint16 // Length of active part of the symbol table.
actualTableLog uint8 // Selected tablelog.
br byteReader
bits bitReader
bw bitWriter
ct cTable // Compression tables.
decTable []decSymbol // Decompression table.
zeroBits bool // no bits has prob > 50%.
clearCount bool // clear count
maxCount int // count of the most probable symbol
// Per block parameters.
// These can be used to override compression parameters of the block.
// Do not touch, unless you know what you are doing.
// Out is output buffer.
// If the scratch is re-used before the caller is done processing the output,
// set this field to nil.
// Otherwise the output buffer will be re-used for next Compression/Decompression step
// and allocation will be avoided.
Out []byte
// MaxSymbolValue will override the maximum symbol value of the next block.
MaxSymbolValue uint8
// TableLog will attempt to override the tablelog for the next block.
TableLog uint8
// DecompressLimit limits the maximum decoded size acceptable.
// If > 0 decompression will stop when approximately this many bytes
// has been decoded.
// If 0, maximum size will be 2GB.
DecompressLimit int
}
// Histogram allows to populate the histogram and skip that step in the compression,
// It otherwise allows to inspect the histogram when compression is done.
// To indicate that you have populated the histogram call HistogramFinished
// with the value of the highest populated symbol, as well as the number of entries
// in the most populated entry. These are accepted at face value.
// The returned slice will always be length 256.
func (s *Scratch) Histogram() []uint32 {
return s.count[:]
}
// HistogramFinished can be called to indicate that the histogram has been populated.
// maxSymbol is the index of the highest set symbol of the next data segment.
// maxCount is the number of entries in the most populated entry.
// These are accepted at face value.
func (s *Scratch) HistogramFinished(maxSymbol uint8, maxCount int) {
s.maxCount = maxCount
s.symbolLen = uint16(maxSymbol) + 1
s.clearCount = maxCount != 0
}
// prepare will prepare and allocate scratch tables used for both compression and decompression.
func (s *Scratch) prepare(in []byte) (*Scratch, error) {
if s == nil {
s = &Scratch{}
}
if s.MaxSymbolValue == 0 {
s.MaxSymbolValue = 255
}
if s.TableLog == 0 {
s.TableLog = defaultTablelog
}
if s.TableLog > maxTableLog {
return nil, fmt.Errorf("tableLog (%d) > maxTableLog (%d)", s.TableLog, maxTableLog)
}
if cap(s.Out) == 0 {
s.Out = make([]byte, 0, len(in))
}
if s.clearCount && s.maxCount == 0 {
for i := range s.count {
s.count[i] = 0
}
s.clearCount = false
}
s.br.init(in)
if s.DecompressLimit == 0 {
// Max size 2GB.
s.DecompressLimit = (2 << 30) - 1
}
return s, nil
}
// tableStep returns the next table index.
func tableStep(tableSize uint32) uint32 {
return (tableSize >> 1) + (tableSize >> 3) + 3
}
func highBits(val uint32) (n uint32) {
return uint32(bits.Len32(val) - 1)
}