30802fac73
zstd is a compression algorithm that has a very fast decoder, while providing also good compression ratios. The fast decoder makes it suitable for container images, as decompressing the tarballs is a very expensive operation. https://github.com/opencontainers/image-spec/pull/788 added support for zstd to the OCI image specs. Signed-off-by: Giuseppe Scrivano <gscrivan@redhat.com>
55 lines
1.4 KiB
Go
55 lines
1.4 KiB
Go
// Copyright 2018 Klaus Post. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Based on work Copyright (c) 2013, Yann Collet, released under BSD License.
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package huff0
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// byteReader provides a byte reader that reads
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// little endian values from a byte stream.
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// The input stream is manually advanced.
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// The reader performs no bounds checks.
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type byteReader struct {
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b []byte
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off int
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}
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// init will initialize the reader and set the input.
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func (b *byteReader) init(in []byte) {
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b.b = in
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b.off = 0
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}
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// advance the stream b n bytes.
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func (b *byteReader) advance(n uint) {
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b.off += int(n)
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}
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// Int32 returns a little endian int32 starting at current offset.
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func (b byteReader) Int32() int32 {
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v3 := int32(b.b[b.off+3])
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v2 := int32(b.b[b.off+2])
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v1 := int32(b.b[b.off+1])
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v0 := int32(b.b[b.off])
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return (v3 << 24) | (v2 << 16) | (v1 << 8) | v0
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}
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// Uint32 returns a little endian uint32 starting at current offset.
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func (b byteReader) Uint32() uint32 {
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v3 := uint32(b.b[b.off+3])
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v2 := uint32(b.b[b.off+2])
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v1 := uint32(b.b[b.off+1])
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v0 := uint32(b.b[b.off])
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return (v3 << 24) | (v2 << 16) | (v1 << 8) | v0
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}
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// unread returns the unread portion of the input.
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func (b byteReader) unread() []byte {
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return b.b[b.off:]
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}
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// remain will return the number of bytes remaining.
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func (b byteReader) remain() int {
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return len(b.b) - b.off
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}
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