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moby--moby/vendor/github.com/klauspost/compress/zstd/bytebuf.go
Sebastiaan van Stijn 0809bd6859
vendor: github.com/klauspost/compress v1.14.2
full diff: https://github.com/klauspost/compress/compare/v1.12.3...v1.14.2

Relevant changes affecting vendor:

- docs: Add combined LICENSE file
- Add snappy replacement package
- tests: Remove snappy dependency for tests
- huff0: Add size estimation function
- huff0: Improve 4X decompression speed
- huff0: Improve 4X decompression speed 5-10%
- huff0: Faster 1X Decompression
- zstd: Spawn decoder goroutine only if needed
- zstd: Detect short invalid signatures
- zstd: Add configurable Decoder window size
- zstd: Add stream content size
- zstd: Simplify hashing functions
- zstd: use SpeedBestCompression for level >= 10
- zstd: Fix WriteTo error forwarding
- zstd: Improve Best compression
- zstd: Fix incorrect encoding in best mode
- zstd: pooledZipWriter should return Writers to the same pool
- zstd: Upgrade xxhash
- zstd: Improve block encoding speed
- zstd: add arm64 xxhash assembly
- zstd: Minor decoder improvements
- zstd: Minor performance tweaks
- zstd: Add bigger default blocks
- zstd: Remove unused decompression buffer
- zstd: fix logically dead code
- zstd: Add noasm tag for xxhash
- zstd: improve header decoder

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
2022-02-23 19:41:14 +01:00

130 lines
2.4 KiB
Go

// Copyright 2019+ Klaus Post. All rights reserved.
// License information can be found in the LICENSE file.
// Based on work by Yann Collet, released under BSD License.
package zstd
import (
"fmt"
"io"
"io/ioutil"
)
type byteBuffer interface {
// Read up to 8 bytes.
// Returns io.ErrUnexpectedEOF if this cannot be satisfied.
readSmall(n int) ([]byte, error)
// Read >8 bytes.
// MAY use the destination slice.
readBig(n int, dst []byte) ([]byte, error)
// Read a single byte.
readByte() (byte, error)
// Skip n bytes.
skipN(n int) error
}
// in-memory buffer
type byteBuf []byte
func (b *byteBuf) readSmall(n int) ([]byte, error) {
if debugAsserts && n > 8 {
panic(fmt.Errorf("small read > 8 (%d). use readBig", n))
}
bb := *b
if len(bb) < n {
return nil, io.ErrUnexpectedEOF
}
r := bb[:n]
*b = bb[n:]
return r, nil
}
func (b *byteBuf) readBig(n int, dst []byte) ([]byte, error) {
bb := *b
if len(bb) < n {
return nil, io.ErrUnexpectedEOF
}
r := bb[:n]
*b = bb[n:]
return r, nil
}
func (b *byteBuf) remain() []byte {
return *b
}
func (b *byteBuf) readByte() (byte, error) {
bb := *b
if len(bb) < 1 {
return 0, nil
}
r := bb[0]
*b = bb[1:]
return r, nil
}
func (b *byteBuf) skipN(n int) error {
bb := *b
if len(bb) < n {
return io.ErrUnexpectedEOF
}
*b = bb[n:]
return nil
}
// wrapper around a reader.
type readerWrapper struct {
r io.Reader
tmp [8]byte
}
func (r *readerWrapper) readSmall(n int) ([]byte, error) {
if debugAsserts && n > 8 {
panic(fmt.Errorf("small read > 8 (%d). use readBig", n))
}
n2, err := io.ReadFull(r.r, r.tmp[:n])
// We only really care about the actual bytes read.
if err != nil {
if err == io.EOF {
return nil, io.ErrUnexpectedEOF
}
if debugDecoder {
println("readSmall: got", n2, "want", n, "err", err)
}
return nil, err
}
return r.tmp[:n], nil
}
func (r *readerWrapper) readBig(n int, dst []byte) ([]byte, error) {
if cap(dst) < n {
dst = make([]byte, n)
}
n2, err := io.ReadFull(r.r, dst[:n])
if err == io.EOF && n > 0 {
err = io.ErrUnexpectedEOF
}
return dst[:n2], err
}
func (r *readerWrapper) readByte() (byte, error) {
n2, err := r.r.Read(r.tmp[:1])
if err != nil {
return 0, err
}
if n2 != 1 {
return 0, io.ErrUnexpectedEOF
}
return r.tmp[0], nil
}
func (r *readerWrapper) skipN(n int) error {
n2, err := io.CopyN(ioutil.Discard, r.r, int64(n))
if n2 != int64(n) {
err = io.ErrUnexpectedEOF
}
return err
}