diff options
Diffstat (limited to 'vendor/github.com/ulikunitz/xz/lzma/decoderdict.go')
-rw-r--r-- | vendor/github.com/ulikunitz/xz/lzma/decoderdict.go | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/vendor/github.com/ulikunitz/xz/lzma/decoderdict.go b/vendor/github.com/ulikunitz/xz/lzma/decoderdict.go new file mode 100644 index 000000000..564a12b83 --- /dev/null +++ b/vendor/github.com/ulikunitz/xz/lzma/decoderdict.go @@ -0,0 +1,135 @@ +// Copyright 2014-2017 Ulrich Kunitz. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package lzma + +import ( + "errors" + "fmt" +) + +// decoderDict provides the dictionary for the decoder. The whole +// dictionary is used as reader buffer. +type decoderDict struct { + buf buffer + head int64 +} + +// newDecoderDict creates a new decoder dictionary. The whole dictionary +// will be used as reader buffer. +func newDecoderDict(dictCap int) (d *decoderDict, err error) { + // lower limit supports easy test cases + if !(1 <= dictCap && int64(dictCap) <= MaxDictCap) { + return nil, errors.New("lzma: dictCap out of range") + } + d = &decoderDict{buf: *newBuffer(dictCap)} + return d, nil +} + +// Reset clears the dictionary. The read buffer is not changed, so the +// buffered data can still be read. +func (d *decoderDict) Reset() { + d.head = 0 +} + +// WriteByte writes a single byte into the dictionary. It is used to +// write literals into the dictionary. +func (d *decoderDict) WriteByte(c byte) error { + if err := d.buf.WriteByte(c); err != nil { + return err + } + d.head++ + return nil +} + +// pos returns the position of the dictionary head. +func (d *decoderDict) pos() int64 { return d.head } + +// dictLen returns the actual length of the dictionary. +func (d *decoderDict) dictLen() int { + capacity := d.buf.Cap() + if d.head >= int64(capacity) { + return capacity + } + return int(d.head) +} + +// byteAt returns a byte stored in the dictionary. If the distance is +// non-positive or exceeds the current length of the dictionary the zero +// byte is returned. +func (d *decoderDict) byteAt(dist int) byte { + if !(0 < dist && dist <= d.dictLen()) { + return 0 + } + i := d.buf.front - dist + if i < 0 { + i += len(d.buf.data) + } + return d.buf.data[i] +} + +// writeMatch writes the match at the top of the dictionary. The given +// distance must point in the current dictionary and the length must not +// exceed the maximum length 273 supported in LZMA. +// +// The error value ErrNoSpace indicates that no space is available in +// the dictionary for writing. You need to read from the dictionary +// first. +func (d *decoderDict) writeMatch(dist int64, length int) error { + if !(0 < dist && dist <= int64(d.dictLen())) { + return errors.New("writeMatch: distance out of range") + } + if !(0 < length && length <= maxMatchLen) { + return errors.New("writeMatch: length out of range") + } + if length > d.buf.Available() { + return ErrNoSpace + } + d.head += int64(length) + + i := d.buf.front - int(dist) + if i < 0 { + i += len(d.buf.data) + } + for length > 0 { + var p []byte + if i >= d.buf.front { + p = d.buf.data[i:] + i = 0 + } else { + p = d.buf.data[i:d.buf.front] + i = d.buf.front + } + if len(p) > length { + p = p[:length] + } + if _, err := d.buf.Write(p); err != nil { + panic(fmt.Errorf("d.buf.Write returned error %s", err)) + } + length -= len(p) + } + return nil +} + +// Write writes the given bytes into the dictionary and advances the +// head. +func (d *decoderDict) Write(p []byte) (n int, err error) { + n, err = d.buf.Write(p) + d.head += int64(n) + return n, err +} + +// Available returns the number of available bytes for writing into the +// decoder dictionary. +func (d *decoderDict) Available() int { return d.buf.Available() } + +// Read reads data from the buffer contained in the decoder dictionary. +func (d *decoderDict) Read(p []byte) (n int, err error) { return d.buf.Read(p) } + +// Buffered returns the number of bytes currently buffered in the +// decoder dictionary. +func (d *decoderDict) buffered() int { return d.buf.Buffered() } + +// Peek gets data from the buffer without advancing the rear index. +func (d *decoderDict) peek(p []byte) (n int, err error) { return d.buf.Peek(p) } |