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authorWim <wim@42.be>2021-10-17 00:47:22 +0200
committerGitHub <noreply@github.com>2021-10-17 00:47:22 +0200
commit4dd8bae5c91fa4aef09d865d8fef1acd84f90925 (patch)
treeffad9b242daccaf8c86d1c1fbd59032302bd3be9 /vendor/golang.org/x/image/tiff/lzw
parent7ae45c42e712bd0e66c101f3f714c05aa1dc2104 (diff)
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Update dependencies (#1610)
* Update dependencies * Update module to go 1.17
Diffstat (limited to 'vendor/golang.org/x/image/tiff/lzw')
-rw-r--r--vendor/golang.org/x/image/tiff/lzw/reader.go272
1 files changed, 0 insertions, 272 deletions
diff --git a/vendor/golang.org/x/image/tiff/lzw/reader.go b/vendor/golang.org/x/image/tiff/lzw/reader.go
deleted file mode 100644
index 78204ba9..00000000
--- a/vendor/golang.org/x/image/tiff/lzw/reader.go
+++ /dev/null
@@ -1,272 +0,0 @@
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// Package lzw implements the Lempel-Ziv-Welch compressed data format,
-// described in T. A. Welch, ``A Technique for High-Performance Data
-// Compression'', Computer, 17(6) (June 1984), pp 8-19.
-//
-// In particular, it implements LZW as used by the TIFF file format, including
-// an "off by one" algorithmic difference when compared to standard LZW.
-package lzw // import "golang.org/x/image/tiff/lzw"
-
-/*
-This file was branched from src/pkg/compress/lzw/reader.go in the
-standard library. Differences from the original are marked with "NOTE".
-
-The tif_lzw.c file in the libtiff C library has this comment:
-
-----
-The 5.0 spec describes a different algorithm than Aldus
-implements. Specifically, Aldus does code length transitions
-one code earlier than should be done (for real LZW).
-Earlier versions of this library implemented the correct
-LZW algorithm, but emitted codes in a bit order opposite
-to the TIFF spec. Thus, to maintain compatibility w/ Aldus
-we interpret MSB-LSB ordered codes to be images written w/
-old versions of this library, but otherwise adhere to the
-Aldus "off by one" algorithm.
-----
-
-The Go code doesn't read (invalid) TIFF files written by old versions of
-libtiff, but the LZW algorithm in this package still differs from the one in
-Go's standard package library to accomodate this "off by one" in valid TIFFs.
-*/
-
-import (
- "bufio"
- "errors"
- "fmt"
- "io"
-)
-
-// Order specifies the bit ordering in an LZW data stream.
-type Order int
-
-const (
- // LSB means Least Significant Bits first, as used in the GIF file format.
- LSB Order = iota
- // MSB means Most Significant Bits first, as used in the TIFF and PDF
- // file formats.
- MSB
-)
-
-const (
- maxWidth = 12
- decoderInvalidCode = 0xffff
- flushBuffer = 1 << maxWidth
-)
-
-// decoder is the state from which the readXxx method converts a byte
-// stream into a code stream.
-type decoder struct {
- r io.ByteReader
- bits uint32
- nBits uint
- width uint
- read func(*decoder) (uint16, error) // readLSB or readMSB
- litWidth int // width in bits of literal codes
- err error
-
- // The first 1<<litWidth codes are literal codes.
- // The next two codes mean clear and EOF.
- // Other valid codes are in the range [lo, hi] where lo := clear + 2,
- // with the upper bound incrementing on each code seen.
- // overflow is the code at which hi overflows the code width. NOTE: TIFF's LZW is "off by one".
- // last is the most recently seen code, or decoderInvalidCode.
- clear, eof, hi, overflow, last uint16
-
- // Each code c in [lo, hi] expands to two or more bytes. For c != hi:
- // suffix[c] is the last of these bytes.
- // prefix[c] is the code for all but the last byte.
- // This code can either be a literal code or another code in [lo, c).
- // The c == hi case is a special case.
- suffix [1 << maxWidth]uint8
- prefix [1 << maxWidth]uint16
-
- // output is the temporary output buffer.
- // Literal codes are accumulated from the start of the buffer.
- // Non-literal codes decode to a sequence of suffixes that are first
- // written right-to-left from the end of the buffer before being copied
- // to the start of the buffer.
- // It is flushed when it contains >= 1<<maxWidth bytes,
- // so that there is always room to decode an entire code.
- output [2 * 1 << maxWidth]byte
- o int // write index into output
- toRead []byte // bytes to return from Read
-}
-
-// readLSB returns the next code for "Least Significant Bits first" data.
-func (d *decoder) readLSB() (uint16, error) {
- for d.nBits < d.width {
- x, err := d.r.ReadByte()
- if err != nil {
- return 0, err
- }
- d.bits |= uint32(x) << d.nBits
- d.nBits += 8
- }
- code := uint16(d.bits & (1<<d.width - 1))
- d.bits >>= d.width
- d.nBits -= d.width
- return code, nil
-}
-
-// readMSB returns the next code for "Most Significant Bits first" data.
-func (d *decoder) readMSB() (uint16, error) {
- for d.nBits < d.width {
- x, err := d.r.ReadByte()
- if err != nil {
- return 0, err
- }
- d.bits |= uint32(x) << (24 - d.nBits)
- d.nBits += 8
- }
- code := uint16(d.bits >> (32 - d.width))
- d.bits <<= d.width
- d.nBits -= d.width
- return code, nil
-}
-
-func (d *decoder) Read(b []byte) (int, error) {
- for {
- if len(d.toRead) > 0 {
- n := copy(b, d.toRead)
- d.toRead = d.toRead[n:]
- return n, nil
- }
- if d.err != nil {
- return 0, d.err
- }
- d.decode()
- }
-}
-
-// decode decompresses bytes from r and leaves them in d.toRead.
-// read specifies how to decode bytes into codes.
-// litWidth is the width in bits of literal codes.
-func (d *decoder) decode() {
- // Loop over the code stream, converting codes into decompressed bytes.
-loop:
- for {
- code, err := d.read(d)
- if err != nil {
- if err == io.EOF {
- err = io.ErrUnexpectedEOF
- }
- d.err = err
- break
- }
- switch {
- case code < d.clear:
- // We have a literal code.
- d.output[d.o] = uint8(code)
- d.o++
- if d.last != decoderInvalidCode {
- // Save what the hi code expands to.
- d.suffix[d.hi] = uint8(code)
- d.prefix[d.hi] = d.last
- }
- case code == d.clear:
- d.width = 1 + uint(d.litWidth)
- d.hi = d.eof
- d.overflow = 1 << d.width
- d.last = decoderInvalidCode
- continue
- case code == d.eof:
- d.err = io.EOF
- break loop
- case code <= d.hi:
- c, i := code, len(d.output)-1
- if code == d.hi && d.last != decoderInvalidCode {
- // code == hi is a special case which expands to the last expansion
- // followed by the head of the last expansion. To find the head, we walk
- // the prefix chain until we find a literal code.
- c = d.last
- for c >= d.clear {
- c = d.prefix[c]
- }
- d.output[i] = uint8(c)
- i--
- c = d.last
- }
- // Copy the suffix chain into output and then write that to w.
- for c >= d.clear {
- d.output[i] = d.suffix[c]
- i--
- c = d.prefix[c]
- }
- d.output[i] = uint8(c)
- d.o += copy(d.output[d.o:], d.output[i:])
- if d.last != decoderInvalidCode {
- // Save what the hi code expands to.
- d.suffix[d.hi] = uint8(c)
- d.prefix[d.hi] = d.last
- }
- default:
- d.err = errors.New("lzw: invalid code")
- break loop
- }
- d.last, d.hi = code, d.hi+1
- if d.hi+1 >= d.overflow { // NOTE: the "+1" is where TIFF's LZW differs from the standard algorithm.
- if d.width == maxWidth {
- d.last = decoderInvalidCode
- } else {
- d.width++
- d.overflow <<= 1
- }
- }
- if d.o >= flushBuffer {
- break
- }
- }
- // Flush pending output.
- d.toRead = d.output[:d.o]
- d.o = 0
-}
-
-var errClosed = errors.New("lzw: reader/writer is closed")
-
-func (d *decoder) Close() error {
- d.err = errClosed // in case any Reads come along
- return nil
-}
-
-// NewReader creates a new io.ReadCloser.
-// Reads from the returned io.ReadCloser read and decompress data from r.
-// If r does not also implement io.ByteReader,
-// the decompressor may read more data than necessary from r.
-// It is the caller's responsibility to call Close on the ReadCloser when
-// finished reading.
-// The number of bits to use for literal codes, litWidth, must be in the
-// range [2,8] and is typically 8. It must equal the litWidth
-// used during compression.
-func NewReader(r io.Reader, order Order, litWidth int) io.ReadCloser {
- d := new(decoder)
- switch order {
- case LSB:
- d.read = (*decoder).readLSB
- case MSB:
- d.read = (*decoder).readMSB
- default:
- d.err = errors.New("lzw: unknown order")
- return d
- }
- if litWidth < 2 || 8 < litWidth {
- d.err = fmt.Errorf("lzw: litWidth %d out of range", litWidth)
- return d
- }
- if br, ok := r.(io.ByteReader); ok {
- d.r = br
- } else {
- d.r = bufio.NewReader(r)
- }
- d.litWidth = litWidth
- d.width = 1 + uint(litWidth)
- d.clear = uint16(1) << uint(litWidth)
- d.eof, d.hi = d.clear+1, d.clear+1
- d.overflow = uint16(1) << d.width
- d.last = decoderInvalidCode
-
- return d
-}