mirror of https://github.com/go-gitea/gitea.git
1159 lines
38 KiB
Go
1159 lines
38 KiB
Go
package brotli
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import (
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"io"
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"math"
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)
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/* Copyright 2016 Google Inc. All Rights Reserved.
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Distributed under MIT license.
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See file LICENSE for detail or copy at https://opensource.org/licenses/MIT
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*/
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/** Minimal value for ::BROTLI_PARAM_LGWIN parameter. */
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const minWindowBits = 10
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/**
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* Maximal value for ::BROTLI_PARAM_LGWIN parameter.
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*
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* @note equal to @c BROTLI_MAX_DISTANCE_BITS constant.
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*/
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const maxWindowBits = 24
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/**
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* Maximal value for ::BROTLI_PARAM_LGWIN parameter
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* in "Large Window Brotli" (32-bit).
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*/
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const largeMaxWindowBits = 30
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/** Minimal value for ::BROTLI_PARAM_LGBLOCK parameter. */
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const minInputBlockBits = 16
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/** Maximal value for ::BROTLI_PARAM_LGBLOCK parameter. */
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const maxInputBlockBits = 24
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/** Minimal value for ::BROTLI_PARAM_QUALITY parameter. */
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const minQuality = 0
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/** Maximal value for ::BROTLI_PARAM_QUALITY parameter. */
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const maxQuality = 11
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/** Options for ::BROTLI_PARAM_MODE parameter. */
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const (
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modeGeneric = 0
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modeText = 1
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modeFont = 2
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)
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/** Default value for ::BROTLI_PARAM_QUALITY parameter. */
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const defaultQuality = 11
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/** Default value for ::BROTLI_PARAM_LGWIN parameter. */
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const defaultWindow = 22
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/** Default value for ::BROTLI_PARAM_MODE parameter. */
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const defaultMode = modeGeneric
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/** Operations that can be performed by streaming encoder. */
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const (
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operationProcess = 0
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operationFlush = 1
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operationFinish = 2
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operationEmitMetadata = 3
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)
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const (
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streamProcessing = 0
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streamFlushRequested = 1
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streamFinished = 2
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streamMetadataHead = 3
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streamMetadataBody = 4
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)
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type Writer struct {
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dst io.Writer
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options WriterOptions
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err error
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params encoderParams
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hasher_ hasherHandle
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input_pos_ uint64
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ringbuffer_ ringBuffer
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commands []command
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num_literals_ uint
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last_insert_len_ uint
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last_flush_pos_ uint64
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last_processed_pos_ uint64
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dist_cache_ [numDistanceShortCodes]int
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saved_dist_cache_ [4]int
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prev_byte_ byte
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prev_byte2_ byte
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bw bitWriter
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small_table_ [1 << 10]int
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large_table_ []int
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large_table_size_ uint
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cmd_depths_ [128]byte
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cmd_bits_ [128]uint16
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cmd_code_ [512]byte
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cmd_code_numbits_ uint
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command_buf_ []uint32
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literal_buf_ []byte
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tiny_buf_ struct {
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u64 [2]uint64
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u8 [16]byte
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}
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remaining_metadata_bytes_ uint32
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stream_state_ int
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is_last_block_emitted_ bool
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is_initialized_ bool
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}
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func inputBlockSize(s *Writer) uint {
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return uint(1) << uint(s.params.lgblock)
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}
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func unprocessedInputSize(s *Writer) uint64 {
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return s.input_pos_ - s.last_processed_pos_
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}
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func remainingInputBlockSize(s *Writer) uint {
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var delta uint64 = unprocessedInputSize(s)
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var block_size uint = inputBlockSize(s)
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if delta >= uint64(block_size) {
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return 0
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}
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return block_size - uint(delta)
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}
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/* Wraps 64-bit input position to 32-bit ring-buffer position preserving
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"not-a-first-lap" feature. */
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func wrapPosition(position uint64) uint32 {
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var result uint32 = uint32(position)
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var gb uint64 = position >> 30
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if gb > 2 {
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/* Wrap every 2GiB; The first 3GB are continuous. */
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result = result&((1<<30)-1) | (uint32((gb-1)&1)+1)<<30
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}
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return result
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}
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func hashTableSize(max_table_size uint, input_size uint) uint {
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var htsize uint = 256
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for htsize < max_table_size && htsize < input_size {
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htsize <<= 1
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}
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return htsize
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}
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func getHashTable(s *Writer, quality int, input_size uint, table_size *uint) []int {
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var max_table_size uint = maxHashTableSize(quality)
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var htsize uint = hashTableSize(max_table_size, input_size)
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/* Use smaller hash table when input.size() is smaller, since we
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fill the table, incurring O(hash table size) overhead for
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compression, and if the input is short, we won't need that
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many hash table entries anyway. */
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var table []int
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assert(max_table_size >= 256)
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if quality == fastOnePassCompressionQuality {
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/* Only odd shifts are supported by fast-one-pass. */
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if htsize&0xAAAAA == 0 {
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htsize <<= 1
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}
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}
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if htsize <= uint(len(s.small_table_)) {
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table = s.small_table_[:]
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} else {
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if htsize > s.large_table_size_ {
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s.large_table_size_ = htsize
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s.large_table_ = nil
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s.large_table_ = make([]int, htsize)
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}
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table = s.large_table_
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}
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*table_size = htsize
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for i := 0; i < int(htsize); i++ {
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table[i] = 0
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}
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return table
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}
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func encodeWindowBits(lgwin int, large_window bool, bw *bitWriter) {
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if large_window {
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bw.writeBits(14, uint64((lgwin&0x3F)<<8|0x11))
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} else {
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if lgwin == 16 {
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bw.writeBits(1, 0)
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} else if lgwin == 17 {
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bw.writeBits(7, 1)
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} else if lgwin > 17 {
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bw.writeBits(4, uint64((lgwin-17)<<1|0x01))
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} else {
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bw.writeBits(7, uint64((lgwin-8)<<4|0x01))
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}
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}
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}
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/* Decide about the context map based on the ability of the prediction
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ability of the previous byte UTF8-prefix on the next byte. The
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prediction ability is calculated as Shannon entropy. Here we need
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Shannon entropy instead of 'BitsEntropy' since the prefix will be
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encoded with the remaining 6 bits of the following byte, and
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BitsEntropy will assume that symbol to be stored alone using Huffman
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coding. */
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var kStaticContextMapContinuation = [64]uint32{
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1, 1, 2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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}
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var kStaticContextMapSimpleUTF8 = [64]uint32{
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0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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}
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func chooseContextMap(quality int, bigram_histo []uint32, num_literal_contexts *uint, literal_context_map *[]uint32) {
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var monogram_histo = [3]uint32{0}
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var two_prefix_histo = [6]uint32{0}
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var total uint
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var i uint
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var dummy uint
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var entropy [4]float64
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for i = 0; i < 9; i++ {
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monogram_histo[i%3] += bigram_histo[i]
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two_prefix_histo[i%6] += bigram_histo[i]
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}
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entropy[1] = shannonEntropy(monogram_histo[:], 3, &dummy)
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entropy[2] = (shannonEntropy(two_prefix_histo[:], 3, &dummy) + shannonEntropy(two_prefix_histo[3:], 3, &dummy))
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entropy[3] = 0
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for i = 0; i < 3; i++ {
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entropy[3] += shannonEntropy(bigram_histo[3*i:], 3, &dummy)
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}
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total = uint(monogram_histo[0] + monogram_histo[1] + monogram_histo[2])
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assert(total != 0)
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entropy[0] = 1.0 / float64(total)
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entropy[1] *= entropy[0]
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entropy[2] *= entropy[0]
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entropy[3] *= entropy[0]
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if quality < minQualityForHqContextModeling {
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/* 3 context models is a bit slower, don't use it at lower qualities. */
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entropy[3] = entropy[1] * 10
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}
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/* If expected savings by symbol are less than 0.2 bits, skip the
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context modeling -- in exchange for faster decoding speed. */
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if entropy[1]-entropy[2] < 0.2 && entropy[1]-entropy[3] < 0.2 {
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*num_literal_contexts = 1
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} else if entropy[2]-entropy[3] < 0.02 {
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*num_literal_contexts = 2
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*literal_context_map = kStaticContextMapSimpleUTF8[:]
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} else {
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*num_literal_contexts = 3
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*literal_context_map = kStaticContextMapContinuation[:]
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}
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}
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/* Decide if we want to use a more complex static context map containing 13
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context values, based on the entropy reduction of histograms over the
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first 5 bits of literals. */
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var kStaticContextMapComplexUTF8 = [64]uint32{
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11, 11, 12, 12, /* 0 special */
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0, 0, 0, 0, /* 4 lf */
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1, 1, 9, 9, /* 8 space */
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2, 2, 2, 2, /* !, first after space/lf and after something else. */
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1, 1, 1, 1, /* " */
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8, 3, 3, 3, /* % */
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1, 1, 1, 1, /* ({[ */
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2, 2, 2, 2, /* }]) */
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8, 4, 4, 4, /* :; */
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8, 7, 4, 4, /* . */
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8, 0, 0, 0, /* > */
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3, 3, 3, 3, /* [0..9] */
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5, 5, 10, 5, /* [A-Z] */
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5, 5, 10, 5,
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6, 6, 6, 6, /* [a-z] */
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6, 6, 6, 6,
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}
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func shouldUseComplexStaticContextMap(input []byte, start_pos uint, length uint, mask uint, quality int, size_hint uint, num_literal_contexts *uint, literal_context_map *[]uint32) bool {
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/* Try the more complex static context map only for long data. */
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if size_hint < 1<<20 {
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return false
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} else {
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var end_pos uint = start_pos + length
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var combined_histo = [32]uint32{0}
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var context_histo = [13][32]uint32{[32]uint32{0}}
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var total uint32 = 0
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var entropy [3]float64
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var dummy uint
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var i uint
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var utf8_lut contextLUT = getContextLUT(contextUTF8)
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/* To make entropy calculations faster and to fit on the stack, we collect
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histograms over the 5 most significant bits of literals. One histogram
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without context and 13 additional histograms for each context value. */
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for ; start_pos+64 <= end_pos; start_pos += 4096 {
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var stride_end_pos uint = start_pos + 64
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var prev2 byte = input[start_pos&mask]
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var prev1 byte = input[(start_pos+1)&mask]
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var pos uint
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/* To make the analysis of the data faster we only examine 64 byte long
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strides at every 4kB intervals. */
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for pos = start_pos + 2; pos < stride_end_pos; pos++ {
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var literal byte = input[pos&mask]
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var context byte = byte(kStaticContextMapComplexUTF8[getContext(prev1, prev2, utf8_lut)])
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total++
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combined_histo[literal>>3]++
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context_histo[context][literal>>3]++
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prev2 = prev1
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prev1 = literal
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}
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}
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entropy[1] = shannonEntropy(combined_histo[:], 32, &dummy)
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entropy[2] = 0
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for i = 0; i < 13; i++ {
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entropy[2] += shannonEntropy(context_histo[i][0:], 32, &dummy)
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}
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entropy[0] = 1.0 / float64(total)
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entropy[1] *= entropy[0]
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entropy[2] *= entropy[0]
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/* The triggering heuristics below were tuned by compressing the individual
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files of the silesia corpus. If we skip this kind of context modeling
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for not very well compressible input (i.e. entropy using context modeling
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is 60% of maximal entropy) or if expected savings by symbol are less
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than 0.2 bits, then in every case when it triggers, the final compression
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ratio is improved. Note however that this heuristics might be too strict
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for some cases and could be tuned further. */
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if entropy[2] > 3.0 || entropy[1]-entropy[2] < 0.2 {
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return false
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} else {
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*num_literal_contexts = 13
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*literal_context_map = kStaticContextMapComplexUTF8[:]
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return true
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}
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}
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}
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func decideOverLiteralContextModeling(input []byte, start_pos uint, length uint, mask uint, quality int, size_hint uint, num_literal_contexts *uint, literal_context_map *[]uint32) {
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if quality < minQualityForContextModeling || length < 64 {
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return
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} else if shouldUseComplexStaticContextMap(input, start_pos, length, mask, quality, size_hint, num_literal_contexts, literal_context_map) {
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} else /* Context map was already set, nothing else to do. */
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{
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var end_pos uint = start_pos + length
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/* Gather bi-gram data of the UTF8 byte prefixes. To make the analysis of
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UTF8 data faster we only examine 64 byte long strides at every 4kB
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intervals. */
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var bigram_prefix_histo = [9]uint32{0}
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for ; start_pos+64 <= end_pos; start_pos += 4096 {
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var lut = [4]int{0, 0, 1, 2}
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var stride_end_pos uint = start_pos + 64
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var prev int = lut[input[start_pos&mask]>>6] * 3
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var pos uint
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for pos = start_pos + 1; pos < stride_end_pos; pos++ {
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var literal byte = input[pos&mask]
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bigram_prefix_histo[prev+lut[literal>>6]]++
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prev = lut[literal>>6] * 3
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}
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}
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chooseContextMap(quality, bigram_prefix_histo[0:], num_literal_contexts, literal_context_map)
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}
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}
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func shouldCompress_encode(data []byte, mask uint, last_flush_pos uint64, bytes uint, num_literals uint, num_commands uint) bool {
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/* TODO: find more precise minimal block overhead. */
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if bytes <= 2 {
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return false
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}
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if num_commands < (bytes>>8)+2 {
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if float64(num_literals) > 0.99*float64(bytes) {
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var literal_histo = [256]uint32{0}
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const kSampleRate uint32 = 13
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const kMinEntropy float64 = 7.92
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var bit_cost_threshold float64 = float64(bytes) * kMinEntropy / float64(kSampleRate)
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var t uint = uint((uint32(bytes) + kSampleRate - 1) / kSampleRate)
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var pos uint32 = uint32(last_flush_pos)
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var i uint
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for i = 0; i < t; i++ {
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literal_histo[data[pos&uint32(mask)]]++
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pos += kSampleRate
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}
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if bitsEntropy(literal_histo[:], 256) > bit_cost_threshold {
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return false
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}
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}
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}
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return true
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}
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/* Chooses the literal context mode for a metablock */
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func chooseContextMode(params *encoderParams, data []byte, pos uint, mask uint, length uint) int {
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/* We only do the computation for the option of something else than
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CONTEXT_UTF8 for the highest qualities */
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if params.quality >= minQualityForHqBlockSplitting && !isMostlyUTF8(data, pos, mask, length, kMinUTF8Ratio) {
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return contextSigned
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}
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return contextUTF8
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}
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func writeMetaBlockInternal(data []byte, mask uint, last_flush_pos uint64, bytes uint, is_last bool, literal_context_mode int, params *encoderParams, prev_byte byte, prev_byte2 byte, num_literals uint, commands []command, saved_dist_cache []int, dist_cache []int, bw *bitWriter) {
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var wrapped_last_flush_pos uint32 = wrapPosition(last_flush_pos)
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var literal_context_lut contextLUT = getContextLUT(literal_context_mode)
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var block_params encoderParams = *params
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if bytes == 0 {
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/* Write the ISLAST and ISEMPTY bits. */
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bw.writeBits(2, 3)
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bw.jumpToByteBoundary()
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return
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}
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if !shouldCompress_encode(data, mask, last_flush_pos, bytes, num_literals, uint(len(commands))) {
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/* Restore the distance cache, as its last update by
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CreateBackwardReferences is now unused. */
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copy(dist_cache, saved_dist_cache[:4])
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storeUncompressedMetaBlock(is_last, data, uint(wrapped_last_flush_pos), mask, bytes, bw)
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return
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}
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savedPos := bw.getPos()
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if params.quality <= maxQualityForStaticEntropyCodes {
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storeMetaBlockFast(data, uint(wrapped_last_flush_pos), bytes, mask, is_last, params, commands, bw)
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} else if params.quality < minQualityForBlockSplit {
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storeMetaBlockTrivial(data, uint(wrapped_last_flush_pos), bytes, mask, is_last, params, commands, bw)
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} else {
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mb := getMetaBlockSplit()
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if params.quality < minQualityForHqBlockSplitting {
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var num_literal_contexts uint = 1
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var literal_context_map []uint32 = nil
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if !params.disable_literal_context_modeling {
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decideOverLiteralContextModeling(data, uint(wrapped_last_flush_pos), bytes, mask, params.quality, params.size_hint, &num_literal_contexts, &literal_context_map)
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}
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buildMetaBlockGreedy(data, uint(wrapped_last_flush_pos), mask, prev_byte, prev_byte2, literal_context_lut, num_literal_contexts, literal_context_map, commands, mb)
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} else {
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buildMetaBlock(data, uint(wrapped_last_flush_pos), mask, &block_params, prev_byte, prev_byte2, commands, literal_context_mode, mb)
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}
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if params.quality >= minQualityForOptimizeHistograms {
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/* The number of distance symbols effectively used for distance
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histograms. It might be less than distance alphabet size
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for "Large Window Brotli" (32-bit). */
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var num_effective_dist_codes uint32 = block_params.dist.alphabet_size
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if num_effective_dist_codes > numHistogramDistanceSymbols {
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num_effective_dist_codes = numHistogramDistanceSymbols
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}
|
|
|
|
optimizeHistograms(num_effective_dist_codes, mb)
|
|
}
|
|
|
|
storeMetaBlock(data, uint(wrapped_last_flush_pos), bytes, mask, prev_byte, prev_byte2, is_last, &block_params, literal_context_mode, commands, mb, bw)
|
|
freeMetaBlockSplit(mb)
|
|
}
|
|
|
|
if bytes+4 < bw.getPos()>>3 {
|
|
/* Restore the distance cache and last byte. */
|
|
copy(dist_cache, saved_dist_cache[:4])
|
|
bw.rewind(savedPos)
|
|
storeUncompressedMetaBlock(is_last, data, uint(wrapped_last_flush_pos), mask, bytes, bw)
|
|
}
|
|
}
|
|
|
|
func chooseDistanceParams(params *encoderParams) {
|
|
var distance_postfix_bits uint32 = 0
|
|
var num_direct_distance_codes uint32 = 0
|
|
|
|
if params.quality >= minQualityForNonzeroDistanceParams {
|
|
var ndirect_msb uint32
|
|
if params.mode == modeFont {
|
|
distance_postfix_bits = 1
|
|
num_direct_distance_codes = 12
|
|
} else {
|
|
distance_postfix_bits = params.dist.distance_postfix_bits
|
|
num_direct_distance_codes = params.dist.num_direct_distance_codes
|
|
}
|
|
|
|
ndirect_msb = (num_direct_distance_codes >> distance_postfix_bits) & 0x0F
|
|
if distance_postfix_bits > maxNpostfix || num_direct_distance_codes > maxNdirect || ndirect_msb<<distance_postfix_bits != num_direct_distance_codes {
|
|
distance_postfix_bits = 0
|
|
num_direct_distance_codes = 0
|
|
}
|
|
}
|
|
|
|
initDistanceParams(params, distance_postfix_bits, num_direct_distance_codes)
|
|
}
|
|
|
|
func ensureInitialized(s *Writer) bool {
|
|
if s.is_initialized_ {
|
|
return true
|
|
}
|
|
|
|
s.bw.bits = 0
|
|
s.bw.nbits = 0
|
|
s.bw.dst = s.bw.dst[:0]
|
|
|
|
s.remaining_metadata_bytes_ = math.MaxUint32
|
|
|
|
sanitizeParams(&s.params)
|
|
s.params.lgblock = computeLgBlock(&s.params)
|
|
chooseDistanceParams(&s.params)
|
|
|
|
ringBufferSetup(&s.params, &s.ringbuffer_)
|
|
|
|
/* Initialize last byte with stream header. */
|
|
{
|
|
var lgwin int = int(s.params.lgwin)
|
|
if s.params.quality == fastOnePassCompressionQuality || s.params.quality == fastTwoPassCompressionQuality {
|
|
lgwin = brotli_max_int(lgwin, 18)
|
|
}
|
|
|
|
encodeWindowBits(lgwin, s.params.large_window, &s.bw)
|
|
}
|
|
|
|
if s.params.quality == fastOnePassCompressionQuality {
|
|
s.cmd_depths_ = [128]byte{
|
|
0, 4, 4, 5, 6, 6, 7, 7, 7, 7, 7, 8, 8, 8, 8, 8,
|
|
0, 0, 0, 4, 4, 4, 4, 4, 5, 5, 6, 6, 6, 6, 7, 7,
|
|
7, 7, 10, 10, 10, 10, 10, 10, 0, 4, 4, 5, 5, 5, 6, 6,
|
|
7, 8, 8, 9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10, 10,
|
|
5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
|
|
6, 6, 6, 6, 6, 6, 5, 5, 5, 5, 5, 5, 4, 4, 4, 4,
|
|
4, 4, 4, 5, 5, 5, 5, 5, 5, 6, 6, 7, 7, 7, 8, 10,
|
|
12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12,
|
|
}
|
|
s.cmd_bits_ = [128]uint16{
|
|
0, 0, 8, 9, 3, 35, 7, 71,
|
|
39, 103, 23, 47, 175, 111, 239, 31,
|
|
0, 0, 0, 4, 12, 2, 10, 6,
|
|
13, 29, 11, 43, 27, 59, 87, 55,
|
|
15, 79, 319, 831, 191, 703, 447, 959,
|
|
0, 14, 1, 25, 5, 21, 19, 51,
|
|
119, 159, 95, 223, 479, 991, 63, 575,
|
|
127, 639, 383, 895, 255, 767, 511, 1023,
|
|
14, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
|
|
27, 59, 7, 39, 23, 55, 30, 1, 17, 9, 25, 5, 0, 8, 4, 12,
|
|
2, 10, 6, 21, 13, 29, 3, 19, 11, 15, 47, 31, 95, 63, 127, 255,
|
|
767, 2815, 1791, 3839, 511, 2559, 1535, 3583, 1023, 3071, 2047, 4095,
|
|
}
|
|
s.cmd_code_ = [512]byte{
|
|
0xff, 0x77, 0xd5, 0xbf, 0xe7, 0xde, 0xea, 0x9e, 0x51, 0x5d, 0xde, 0xc6,
|
|
0x70, 0x57, 0xbc, 0x58, 0x58, 0x58, 0xd8, 0xd8, 0x58, 0xd5, 0xcb, 0x8c,
|
|
0xea, 0xe0, 0xc3, 0x87, 0x1f, 0x83, 0xc1, 0x60, 0x1c, 0x67, 0xb2, 0xaa,
|
|
0x06, 0x83, 0xc1, 0x60, 0x30, 0x18, 0xcc, 0xa1, 0xce, 0x88, 0x54, 0x94,
|
|
0x46, 0xe1, 0xb0, 0xd0, 0x4e, 0xb2, 0xf7, 0x04, 0x00,
|
|
}
|
|
s.cmd_code_numbits_ = 448
|
|
}
|
|
|
|
s.is_initialized_ = true
|
|
return true
|
|
}
|
|
|
|
func encoderInitParams(params *encoderParams) {
|
|
params.mode = defaultMode
|
|
params.large_window = false
|
|
params.quality = defaultQuality
|
|
params.lgwin = defaultWindow
|
|
params.lgblock = 0
|
|
params.size_hint = 0
|
|
params.disable_literal_context_modeling = false
|
|
initEncoderDictionary(¶ms.dictionary)
|
|
params.dist.distance_postfix_bits = 0
|
|
params.dist.num_direct_distance_codes = 0
|
|
params.dist.alphabet_size = uint32(distanceAlphabetSize(0, 0, maxDistanceBits))
|
|
params.dist.max_distance = maxDistance
|
|
}
|
|
|
|
func encoderInitState(s *Writer) {
|
|
encoderInitParams(&s.params)
|
|
s.input_pos_ = 0
|
|
s.commands = s.commands[:0]
|
|
s.num_literals_ = 0
|
|
s.last_insert_len_ = 0
|
|
s.last_flush_pos_ = 0
|
|
s.last_processed_pos_ = 0
|
|
s.prev_byte_ = 0
|
|
s.prev_byte2_ = 0
|
|
if s.hasher_ != nil {
|
|
s.hasher_.Common().is_prepared_ = false
|
|
}
|
|
s.cmd_code_numbits_ = 0
|
|
s.stream_state_ = streamProcessing
|
|
s.is_last_block_emitted_ = false
|
|
s.is_initialized_ = false
|
|
|
|
ringBufferInit(&s.ringbuffer_)
|
|
|
|
/* Initialize distance cache. */
|
|
s.dist_cache_[0] = 4
|
|
|
|
s.dist_cache_[1] = 11
|
|
s.dist_cache_[2] = 15
|
|
s.dist_cache_[3] = 16
|
|
|
|
/* Save the state of the distance cache in case we need to restore it for
|
|
emitting an uncompressed block. */
|
|
copy(s.saved_dist_cache_[:], s.dist_cache_[:])
|
|
}
|
|
|
|
/*
|
|
Copies the given input data to the internal ring buffer of the compressor.
|
|
No processing of the data occurs at this time and this function can be
|
|
called multiple times before calling WriteBrotliData() to process the
|
|
accumulated input. At most input_block_size() bytes of input data can be
|
|
copied to the ring buffer, otherwise the next WriteBrotliData() will fail.
|
|
*/
|
|
func copyInputToRingBuffer(s *Writer, input_size uint, input_buffer []byte) {
|
|
var ringbuffer_ *ringBuffer = &s.ringbuffer_
|
|
ringBufferWrite(input_buffer, input_size, ringbuffer_)
|
|
s.input_pos_ += uint64(input_size)
|
|
|
|
/* TL;DR: If needed, initialize 7 more bytes in the ring buffer to make the
|
|
hashing not depend on uninitialized data. This makes compression
|
|
deterministic and it prevents uninitialized memory warnings in Valgrind.
|
|
Even without erasing, the output would be valid (but nondeterministic).
|
|
|
|
Background information: The compressor stores short (at most 8 bytes)
|
|
substrings of the input already read in a hash table, and detects
|
|
repetitions by looking up such substrings in the hash table. If it
|
|
can find a substring, it checks whether the substring is really there
|
|
in the ring buffer (or it's just a hash collision). Should the hash
|
|
table become corrupt, this check makes sure that the output is
|
|
still valid, albeit the compression ratio would be bad.
|
|
|
|
The compressor populates the hash table from the ring buffer as it's
|
|
reading new bytes from the input. However, at the last few indexes of
|
|
the ring buffer, there are not enough bytes to build full-length
|
|
substrings from. Since the hash table always contains full-length
|
|
substrings, we erase with dummy zeros here to make sure that those
|
|
substrings will contain zeros at the end instead of uninitialized
|
|
data.
|
|
|
|
Please note that erasing is not necessary (because the
|
|
memory region is already initialized since he ring buffer
|
|
has a `tail' that holds a copy of the beginning,) so we
|
|
skip erasing if we have already gone around at least once in
|
|
the ring buffer.
|
|
|
|
Only clear during the first round of ring-buffer writes. On
|
|
subsequent rounds data in the ring-buffer would be affected. */
|
|
if ringbuffer_.pos_ <= ringbuffer_.mask_ {
|
|
/* This is the first time when the ring buffer is being written.
|
|
We clear 7 bytes just after the bytes that have been copied from
|
|
the input buffer.
|
|
|
|
The ring-buffer has a "tail" that holds a copy of the beginning,
|
|
but only once the ring buffer has been fully written once, i.e.,
|
|
pos <= mask. For the first time, we need to write values
|
|
in this tail (where index may be larger than mask), so that
|
|
we have exactly defined behavior and don't read uninitialized
|
|
memory. Due to performance reasons, hashing reads data using a
|
|
LOAD64, which can go 7 bytes beyond the bytes written in the
|
|
ring-buffer. */
|
|
for i := 0; i < int(7); i++ {
|
|
ringbuffer_.buffer_[ringbuffer_.pos_:][i] = 0
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Marks all input as processed.
|
|
Returns true if position wrapping occurs. */
|
|
func updateLastProcessedPos(s *Writer) bool {
|
|
var wrapped_last_processed_pos uint32 = wrapPosition(s.last_processed_pos_)
|
|
var wrapped_input_pos uint32 = wrapPosition(s.input_pos_)
|
|
s.last_processed_pos_ = s.input_pos_
|
|
return wrapped_input_pos < wrapped_last_processed_pos
|
|
}
|
|
|
|
func extendLastCommand(s *Writer, bytes *uint32, wrapped_last_processed_pos *uint32) {
|
|
var last_command *command = &s.commands[len(s.commands)-1]
|
|
var data []byte = s.ringbuffer_.buffer_
|
|
var mask uint32 = s.ringbuffer_.mask_
|
|
var max_backward_distance uint64 = ((uint64(1)) << s.params.lgwin) - windowGap
|
|
var last_copy_len uint64 = uint64(last_command.copy_len_) & 0x1FFFFFF
|
|
var last_processed_pos uint64 = s.last_processed_pos_ - last_copy_len
|
|
var max_distance uint64
|
|
if last_processed_pos < max_backward_distance {
|
|
max_distance = last_processed_pos
|
|
} else {
|
|
max_distance = max_backward_distance
|
|
}
|
|
var cmd_dist uint64 = uint64(s.dist_cache_[0])
|
|
var distance_code uint32 = commandRestoreDistanceCode(last_command, &s.params.dist)
|
|
if distance_code < numDistanceShortCodes || uint64(distance_code-(numDistanceShortCodes-1)) == cmd_dist {
|
|
if cmd_dist <= max_distance {
|
|
for *bytes != 0 && data[*wrapped_last_processed_pos&mask] == data[(uint64(*wrapped_last_processed_pos)-cmd_dist)&uint64(mask)] {
|
|
last_command.copy_len_++
|
|
(*bytes)--
|
|
(*wrapped_last_processed_pos)++
|
|
}
|
|
}
|
|
|
|
/* The copy length is at most the metablock size, and thus expressible. */
|
|
getLengthCode(uint(last_command.insert_len_), uint(int(last_command.copy_len_&0x1FFFFFF)+int(last_command.copy_len_>>25)), (last_command.dist_prefix_&0x3FF == 0), &last_command.cmd_prefix_)
|
|
}
|
|
}
|
|
|
|
/*
|
|
Processes the accumulated input data and writes
|
|
the new output meta-block to s.dest, if one has been
|
|
created (otherwise the processed input data is buffered internally).
|
|
If |is_last| or |force_flush| is true, an output meta-block is
|
|
always created. However, until |is_last| is true encoder may retain up
|
|
to 7 bits of the last byte of output. To force encoder to dump the remaining
|
|
bits use WriteMetadata() to append an empty meta-data block.
|
|
Returns false if the size of the input data is larger than
|
|
input_block_size().
|
|
*/
|
|
func encodeData(s *Writer, is_last bool, force_flush bool) bool {
|
|
var delta uint64 = unprocessedInputSize(s)
|
|
var bytes uint32 = uint32(delta)
|
|
var wrapped_last_processed_pos uint32 = wrapPosition(s.last_processed_pos_)
|
|
var data []byte
|
|
var mask uint32
|
|
var literal_context_mode int
|
|
|
|
data = s.ringbuffer_.buffer_
|
|
mask = s.ringbuffer_.mask_
|
|
|
|
/* Adding more blocks after "last" block is forbidden. */
|
|
if s.is_last_block_emitted_ {
|
|
return false
|
|
}
|
|
if is_last {
|
|
s.is_last_block_emitted_ = true
|
|
}
|
|
|
|
if delta > uint64(inputBlockSize(s)) {
|
|
return false
|
|
}
|
|
|
|
if s.params.quality == fastTwoPassCompressionQuality {
|
|
if s.command_buf_ == nil || cap(s.command_buf_) < int(kCompressFragmentTwoPassBlockSize) {
|
|
s.command_buf_ = make([]uint32, kCompressFragmentTwoPassBlockSize)
|
|
s.literal_buf_ = make([]byte, kCompressFragmentTwoPassBlockSize)
|
|
} else {
|
|
s.command_buf_ = s.command_buf_[:kCompressFragmentTwoPassBlockSize]
|
|
s.literal_buf_ = s.literal_buf_[:kCompressFragmentTwoPassBlockSize]
|
|
}
|
|
}
|
|
|
|
if s.params.quality == fastOnePassCompressionQuality || s.params.quality == fastTwoPassCompressionQuality {
|
|
var table_size uint
|
|
var table []int
|
|
|
|
if delta == 0 && !is_last {
|
|
/* We have no new input data and we don't have to finish the stream, so
|
|
nothing to do. */
|
|
return true
|
|
}
|
|
|
|
table = getHashTable(s, s.params.quality, uint(bytes), &table_size)
|
|
if s.params.quality == fastOnePassCompressionQuality {
|
|
compressFragmentFast(data[wrapped_last_processed_pos&mask:], uint(bytes), is_last, table, table_size, s.cmd_depths_[:], s.cmd_bits_[:], &s.cmd_code_numbits_, s.cmd_code_[:], &s.bw)
|
|
} else {
|
|
compressFragmentTwoPass(data[wrapped_last_processed_pos&mask:], uint(bytes), is_last, s.command_buf_, s.literal_buf_, table, table_size, &s.bw)
|
|
}
|
|
|
|
updateLastProcessedPos(s)
|
|
s.writeOutput(s.bw.dst)
|
|
s.bw.dst = s.bw.dst[:0]
|
|
return true
|
|
}
|
|
{
|
|
/* Theoretical max number of commands is 1 per 2 bytes. */
|
|
newsize := len(s.commands) + int(bytes)/2 + 1
|
|
if newsize > cap(s.commands) {
|
|
/* Reserve a bit more memory to allow merging with a next block
|
|
without reallocation: that would impact speed. */
|
|
newsize += int(bytes/4) + 16
|
|
|
|
new_commands := make([]command, len(s.commands), newsize)
|
|
if s.commands != nil {
|
|
copy(new_commands, s.commands)
|
|
}
|
|
|
|
s.commands = new_commands
|
|
}
|
|
}
|
|
|
|
initOrStitchToPreviousBlock(&s.hasher_, data, uint(mask), &s.params, uint(wrapped_last_processed_pos), uint(bytes), is_last)
|
|
|
|
literal_context_mode = chooseContextMode(&s.params, data, uint(wrapPosition(s.last_flush_pos_)), uint(mask), uint(s.input_pos_-s.last_flush_pos_))
|
|
|
|
if len(s.commands) != 0 && s.last_insert_len_ == 0 {
|
|
extendLastCommand(s, &bytes, &wrapped_last_processed_pos)
|
|
}
|
|
|
|
if s.params.quality == zopflificationQuality {
|
|
assert(s.params.hasher.type_ == 10)
|
|
createZopfliBackwardReferences(uint(bytes), uint(wrapped_last_processed_pos), data, uint(mask), &s.params, s.hasher_.(*h10), s.dist_cache_[:], &s.last_insert_len_, &s.commands, &s.num_literals_)
|
|
} else if s.params.quality == hqZopflificationQuality {
|
|
assert(s.params.hasher.type_ == 10)
|
|
createHqZopfliBackwardReferences(uint(bytes), uint(wrapped_last_processed_pos), data, uint(mask), &s.params, s.hasher_, s.dist_cache_[:], &s.last_insert_len_, &s.commands, &s.num_literals_)
|
|
} else {
|
|
createBackwardReferences(uint(bytes), uint(wrapped_last_processed_pos), data, uint(mask), &s.params, s.hasher_, s.dist_cache_[:], &s.last_insert_len_, &s.commands, &s.num_literals_)
|
|
}
|
|
{
|
|
var max_length uint = maxMetablockSize(&s.params)
|
|
var max_literals uint = max_length / 8
|
|
max_commands := int(max_length / 8)
|
|
var processed_bytes uint = uint(s.input_pos_ - s.last_flush_pos_)
|
|
var next_input_fits_metablock bool = (processed_bytes+inputBlockSize(s) <= max_length)
|
|
var should_flush bool = (s.params.quality < minQualityForBlockSplit && s.num_literals_+uint(len(s.commands)) >= maxNumDelayedSymbols)
|
|
/* If maximal possible additional block doesn't fit metablock, flush now. */
|
|
/* TODO: Postpone decision until next block arrives? */
|
|
|
|
/* If block splitting is not used, then flush as soon as there is some
|
|
amount of commands / literals produced. */
|
|
if !is_last && !force_flush && !should_flush && next_input_fits_metablock && s.num_literals_ < max_literals && len(s.commands) < max_commands {
|
|
/* Merge with next input block. Everything will happen later. */
|
|
if updateLastProcessedPos(s) {
|
|
hasherReset(s.hasher_)
|
|
}
|
|
|
|
return true
|
|
}
|
|
}
|
|
|
|
/* Create the last insert-only command. */
|
|
if s.last_insert_len_ > 0 {
|
|
s.commands = append(s.commands, makeInsertCommand(s.last_insert_len_))
|
|
s.num_literals_ += s.last_insert_len_
|
|
s.last_insert_len_ = 0
|
|
}
|
|
|
|
if !is_last && s.input_pos_ == s.last_flush_pos_ {
|
|
/* We have no new input data and we don't have to finish the stream, so
|
|
nothing to do. */
|
|
return true
|
|
}
|
|
|
|
assert(s.input_pos_ >= s.last_flush_pos_)
|
|
assert(s.input_pos_ > s.last_flush_pos_ || is_last)
|
|
assert(s.input_pos_-s.last_flush_pos_ <= 1<<24)
|
|
{
|
|
var metablock_size uint32 = uint32(s.input_pos_ - s.last_flush_pos_)
|
|
writeMetaBlockInternal(data, uint(mask), s.last_flush_pos_, uint(metablock_size), is_last, literal_context_mode, &s.params, s.prev_byte_, s.prev_byte2_, s.num_literals_, s.commands, s.saved_dist_cache_[:], s.dist_cache_[:], &s.bw)
|
|
s.last_flush_pos_ = s.input_pos_
|
|
if updateLastProcessedPos(s) {
|
|
hasherReset(s.hasher_)
|
|
}
|
|
|
|
if s.last_flush_pos_ > 0 {
|
|
s.prev_byte_ = data[(uint32(s.last_flush_pos_)-1)&mask]
|
|
}
|
|
|
|
if s.last_flush_pos_ > 1 {
|
|
s.prev_byte2_ = data[uint32(s.last_flush_pos_-2)&mask]
|
|
}
|
|
|
|
s.commands = s.commands[:0]
|
|
s.num_literals_ = 0
|
|
|
|
/* Save the state of the distance cache in case we need to restore it for
|
|
emitting an uncompressed block. */
|
|
copy(s.saved_dist_cache_[:], s.dist_cache_[:])
|
|
|
|
s.writeOutput(s.bw.dst)
|
|
s.bw.dst = s.bw.dst[:0]
|
|
return true
|
|
}
|
|
}
|
|
|
|
/* Dumps remaining output bits and metadata header to s.bw.
|
|
REQUIRED: |block_size| <= (1 << 24). */
|
|
func writeMetadataHeader(s *Writer, block_size uint) {
|
|
bw := &s.bw
|
|
|
|
bw.writeBits(1, 0)
|
|
bw.writeBits(2, 3)
|
|
bw.writeBits(1, 0)
|
|
if block_size == 0 {
|
|
bw.writeBits(2, 0)
|
|
} else {
|
|
var nbits uint32
|
|
if block_size == 1 {
|
|
nbits = 0
|
|
} else {
|
|
nbits = log2FloorNonZero(uint(uint32(block_size)-1)) + 1
|
|
}
|
|
var nbytes uint32 = (nbits + 7) / 8
|
|
bw.writeBits(2, uint64(nbytes))
|
|
bw.writeBits(uint(8*nbytes), uint64(block_size)-1)
|
|
}
|
|
|
|
bw.jumpToByteBoundary()
|
|
}
|
|
|
|
func injectBytePaddingBlock(s *Writer) {
|
|
/* is_last = 0, data_nibbles = 11, reserved = 0, meta_nibbles = 00 */
|
|
s.bw.writeBits(6, 0x6)
|
|
s.bw.jumpToByteBoundary()
|
|
s.writeOutput(s.bw.dst)
|
|
s.bw.dst = s.bw.dst[:0]
|
|
}
|
|
|
|
func checkFlushComplete(s *Writer) {
|
|
if s.stream_state_ == streamFlushRequested && s.err == nil {
|
|
s.stream_state_ = streamProcessing
|
|
}
|
|
}
|
|
|
|
func encoderCompressStreamFast(s *Writer, op int, available_in *uint, next_in *[]byte) bool {
|
|
var block_size_limit uint = uint(1) << s.params.lgwin
|
|
var buf_size uint = brotli_min_size_t(kCompressFragmentTwoPassBlockSize, brotli_min_size_t(*available_in, block_size_limit))
|
|
var command_buf []uint32 = nil
|
|
var literal_buf []byte = nil
|
|
if s.params.quality != fastOnePassCompressionQuality && s.params.quality != fastTwoPassCompressionQuality {
|
|
return false
|
|
}
|
|
|
|
if s.params.quality == fastTwoPassCompressionQuality {
|
|
if s.command_buf_ == nil || cap(s.command_buf_) < int(buf_size) {
|
|
s.command_buf_ = make([]uint32, buf_size)
|
|
s.literal_buf_ = make([]byte, buf_size)
|
|
} else {
|
|
s.command_buf_ = s.command_buf_[:buf_size]
|
|
s.literal_buf_ = s.literal_buf_[:buf_size]
|
|
}
|
|
|
|
command_buf = s.command_buf_
|
|
literal_buf = s.literal_buf_
|
|
}
|
|
|
|
for {
|
|
if s.stream_state_ == streamFlushRequested && s.bw.nbits&7 != 0 {
|
|
injectBytePaddingBlock(s)
|
|
continue
|
|
}
|
|
|
|
/* Compress block only when stream is not
|
|
finished, there is no pending flush request, and there is either
|
|
additional input or pending operation. */
|
|
if s.stream_state_ == streamProcessing && (*available_in != 0 || op != int(operationProcess)) {
|
|
var block_size uint = brotli_min_size_t(block_size_limit, *available_in)
|
|
var is_last bool = (*available_in == block_size) && (op == int(operationFinish))
|
|
var force_flush bool = (*available_in == block_size) && (op == int(operationFlush))
|
|
var table_size uint
|
|
var table []int
|
|
|
|
if force_flush && block_size == 0 {
|
|
s.stream_state_ = streamFlushRequested
|
|
continue
|
|
}
|
|
|
|
table = getHashTable(s, s.params.quality, block_size, &table_size)
|
|
|
|
if s.params.quality == fastOnePassCompressionQuality {
|
|
compressFragmentFast(*next_in, block_size, is_last, table, table_size, s.cmd_depths_[:], s.cmd_bits_[:], &s.cmd_code_numbits_, s.cmd_code_[:], &s.bw)
|
|
} else {
|
|
compressFragmentTwoPass(*next_in, block_size, is_last, command_buf, literal_buf, table, table_size, &s.bw)
|
|
}
|
|
|
|
*next_in = (*next_in)[block_size:]
|
|
*available_in -= block_size
|
|
s.writeOutput(s.bw.dst)
|
|
s.bw.dst = s.bw.dst[:0]
|
|
|
|
if force_flush {
|
|
s.stream_state_ = streamFlushRequested
|
|
}
|
|
if is_last {
|
|
s.stream_state_ = streamFinished
|
|
}
|
|
continue
|
|
}
|
|
|
|
break
|
|
}
|
|
|
|
checkFlushComplete(s)
|
|
return true
|
|
}
|
|
|
|
func processMetadata(s *Writer, available_in *uint, next_in *[]byte) bool {
|
|
if *available_in > 1<<24 {
|
|
return false
|
|
}
|
|
|
|
/* Switch to metadata block workflow, if required. */
|
|
if s.stream_state_ == streamProcessing {
|
|
s.remaining_metadata_bytes_ = uint32(*available_in)
|
|
s.stream_state_ = streamMetadataHead
|
|
}
|
|
|
|
if s.stream_state_ != streamMetadataHead && s.stream_state_ != streamMetadataBody {
|
|
return false
|
|
}
|
|
|
|
for {
|
|
if s.stream_state_ == streamFlushRequested && s.bw.nbits&7 != 0 {
|
|
injectBytePaddingBlock(s)
|
|
continue
|
|
}
|
|
|
|
if s.input_pos_ != s.last_flush_pos_ {
|
|
var result bool = encodeData(s, false, true)
|
|
if !result {
|
|
return false
|
|
}
|
|
continue
|
|
}
|
|
|
|
if s.stream_state_ == streamMetadataHead {
|
|
writeMetadataHeader(s, uint(s.remaining_metadata_bytes_))
|
|
s.writeOutput(s.bw.dst)
|
|
s.bw.dst = s.bw.dst[:0]
|
|
s.stream_state_ = streamMetadataBody
|
|
continue
|
|
} else {
|
|
/* Exit workflow only when there is no more input and no more output.
|
|
Otherwise client may continue producing empty metadata blocks. */
|
|
if s.remaining_metadata_bytes_ == 0 {
|
|
s.remaining_metadata_bytes_ = math.MaxUint32
|
|
s.stream_state_ = streamProcessing
|
|
break
|
|
}
|
|
|
|
/* This guarantees progress in "TakeOutput" workflow. */
|
|
var c uint32 = brotli_min_uint32_t(s.remaining_metadata_bytes_, 16)
|
|
copy(s.tiny_buf_.u8[:], (*next_in)[:c])
|
|
*next_in = (*next_in)[c:]
|
|
*available_in -= uint(c)
|
|
s.remaining_metadata_bytes_ -= c
|
|
s.writeOutput(s.tiny_buf_.u8[:c])
|
|
|
|
continue
|
|
}
|
|
}
|
|
|
|
return true
|
|
}
|
|
|
|
func updateSizeHint(s *Writer, available_in uint) {
|
|
if s.params.size_hint == 0 {
|
|
var delta uint64 = unprocessedInputSize(s)
|
|
var tail uint64 = uint64(available_in)
|
|
var limit uint32 = 1 << 30
|
|
var total uint32
|
|
if (delta >= uint64(limit)) || (tail >= uint64(limit)) || ((delta + tail) >= uint64(limit)) {
|
|
total = limit
|
|
} else {
|
|
total = uint32(delta + tail)
|
|
}
|
|
|
|
s.params.size_hint = uint(total)
|
|
}
|
|
}
|
|
|
|
func encoderCompressStream(s *Writer, op int, available_in *uint, next_in *[]byte) bool {
|
|
if !ensureInitialized(s) {
|
|
return false
|
|
}
|
|
|
|
/* Unfinished metadata block; check requirements. */
|
|
if s.remaining_metadata_bytes_ != math.MaxUint32 {
|
|
if uint32(*available_in) != s.remaining_metadata_bytes_ {
|
|
return false
|
|
}
|
|
if op != int(operationEmitMetadata) {
|
|
return false
|
|
}
|
|
}
|
|
|
|
if op == int(operationEmitMetadata) {
|
|
updateSizeHint(s, 0) /* First data metablock might be emitted here. */
|
|
return processMetadata(s, available_in, next_in)
|
|
}
|
|
|
|
if s.stream_state_ == streamMetadataHead || s.stream_state_ == streamMetadataBody {
|
|
return false
|
|
}
|
|
|
|
if s.stream_state_ != streamProcessing && *available_in != 0 {
|
|
return false
|
|
}
|
|
|
|
if s.params.quality == fastOnePassCompressionQuality || s.params.quality == fastTwoPassCompressionQuality {
|
|
return encoderCompressStreamFast(s, op, available_in, next_in)
|
|
}
|
|
|
|
for {
|
|
var remaining_block_size uint = remainingInputBlockSize(s)
|
|
|
|
if remaining_block_size != 0 && *available_in != 0 {
|
|
var copy_input_size uint = brotli_min_size_t(remaining_block_size, *available_in)
|
|
copyInputToRingBuffer(s, copy_input_size, *next_in)
|
|
*next_in = (*next_in)[copy_input_size:]
|
|
*available_in -= copy_input_size
|
|
continue
|
|
}
|
|
|
|
if s.stream_state_ == streamFlushRequested && s.bw.nbits&7 != 0 {
|
|
injectBytePaddingBlock(s)
|
|
continue
|
|
}
|
|
|
|
/* Compress data only when stream is not
|
|
finished and there is no pending flush request. */
|
|
if s.stream_state_ == streamProcessing {
|
|
if remaining_block_size == 0 || op != int(operationProcess) {
|
|
var is_last bool = ((*available_in == 0) && op == int(operationFinish))
|
|
var force_flush bool = ((*available_in == 0) && op == int(operationFlush))
|
|
var result bool
|
|
updateSizeHint(s, *available_in)
|
|
result = encodeData(s, is_last, force_flush)
|
|
if !result {
|
|
return false
|
|
}
|
|
if force_flush {
|
|
s.stream_state_ = streamFlushRequested
|
|
}
|
|
if is_last {
|
|
s.stream_state_ = streamFinished
|
|
}
|
|
continue
|
|
}
|
|
}
|
|
|
|
break
|
|
}
|
|
|
|
checkFlushComplete(s)
|
|
return true
|
|
}
|
|
|
|
func (w *Writer) writeOutput(data []byte) {
|
|
if w.err != nil {
|
|
return
|
|
}
|
|
|
|
_, w.err = w.dst.Write(data)
|
|
if w.err == nil {
|
|
checkFlushComplete(w)
|
|
}
|
|
}
|