480 lines
9.5 KiB
Go
480 lines
9.5 KiB
Go
// Copyright 2014 The Go Authors. 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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package hpack
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import (
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"fmt"
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)
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// headerFieldTable implements a list of HeaderFields.
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// This is used to implement the static and dynamic tables.
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type headerFieldTable struct {
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// For static tables, entries are never evicted.
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//
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// For dynamic tables, entries are evicted from ents[0] and added to the end.
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// Each entry has a unique id that starts at one and increments for each
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// entry that is added. This unique id is stable across evictions, meaning
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// it can be used as a pointer to a specific entry. As in hpack, unique ids
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// are 1-based. The unique id for ents[k] is k + evictCount + 1.
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//
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// Zero is not a valid unique id.
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//
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// evictCount should not overflow in any remotely practical situation. In
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// practice, we will have one dynamic table per HTTP/2 connection. If we
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// assume a very powerful server that handles 1M QPS per connection and each
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// request adds (then evicts) 100 entries from the table, it would still take
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// 2M years for evictCount to overflow.
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ents []HeaderField
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evictCount uint64
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// byName maps a HeaderField name to the unique id of the newest entry with
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// the same name. See above for a definition of "unique id".
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byName map[string]uint64
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// byNameValue maps a HeaderField name/value pair to the unique id of the newest
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// entry with the same name and value. See above for a definition of "unique id".
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byNameValue map[pairNameValue]uint64
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}
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type pairNameValue struct {
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name, value string
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}
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func (t *headerFieldTable) init() {
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t.byName = make(map[string]uint64)
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t.byNameValue = make(map[pairNameValue]uint64)
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}
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// len reports the number of entries in the table.
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func (t *headerFieldTable) len() int {
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return len(t.ents)
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}
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// addEntry adds a new entry.
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func (t *headerFieldTable) addEntry(f HeaderField) {
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id := uint64(t.len()) + t.evictCount + 1
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t.byName[f.Name] = id
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t.byNameValue[pairNameValue{f.Name, f.Value}] = id
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t.ents = append(t.ents, f)
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}
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// evictOldest evicts the n oldest entries in the table.
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func (t *headerFieldTable) evictOldest(n int) {
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if n > t.len() {
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panic(fmt.Sprintf("evictOldest(%v) on table with %v entries", n, t.len()))
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}
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for k := 0; k < n; k++ {
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f := t.ents[k]
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id := t.evictCount + uint64(k) + 1
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if t.byName[f.Name] == id {
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delete(t.byName, f.Name)
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}
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if p := (pairNameValue{f.Name, f.Value}); t.byNameValue[p] == id {
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delete(t.byNameValue, p)
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}
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}
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copy(t.ents, t.ents[n:])
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for k := t.len() - n; k < t.len(); k++ {
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t.ents[k] = HeaderField{} // so strings can be garbage collected
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}
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t.ents = t.ents[:t.len()-n]
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if t.evictCount+uint64(n) < t.evictCount {
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panic("evictCount overflow")
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}
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t.evictCount += uint64(n)
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}
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// search finds f in the table. If there is no match, i is 0.
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// If both name and value match, i is the matched index and nameValueMatch
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// becomes true. If only name matches, i points to that index and
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// nameValueMatch becomes false.
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//
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// The returned index is a 1-based HPACK index. For dynamic tables, HPACK says
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// that index 1 should be the newest entry, but t.ents[0] is the oldest entry,
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// meaning t.ents is reversed for dynamic tables. Hence, when t is a dynamic
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// table, the return value i actually refers to the entry t.ents[t.len()-i].
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//
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// All tables are assumed to be a dynamic tables except for the global
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// staticTable pointer.
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//
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// See Section 2.3.3.
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func (t *headerFieldTable) search(f HeaderField) (i uint64, nameValueMatch bool) {
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if !f.Sensitive {
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if id := t.byNameValue[pairNameValue{f.Name, f.Value}]; id != 0 {
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return t.idToIndex(id), true
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}
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}
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if id := t.byName[f.Name]; id != 0 {
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return t.idToIndex(id), false
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}
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return 0, false
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}
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// idToIndex converts a unique id to an HPACK index.
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// See Section 2.3.3.
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func (t *headerFieldTable) idToIndex(id uint64) uint64 {
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if id <= t.evictCount {
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panic(fmt.Sprintf("id (%v) <= evictCount (%v)", id, t.evictCount))
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}
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k := id - t.evictCount - 1 // convert id to an index t.ents[k]
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if t != staticTable {
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return uint64(t.len()) - k // dynamic table
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}
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return k + 1
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}
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// http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-07#appendix-B
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var staticTable = newStaticTable()
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var staticTableEntries = [...]HeaderField{
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{Name: ":authority"},
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{Name: ":method", Value: "GET"},
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{Name: ":method", Value: "POST"},
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{Name: ":path", Value: "/"},
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{Name: ":path", Value: "/index.html"},
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{Name: ":scheme", Value: "http"},
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{Name: ":scheme", Value: "https"},
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{Name: ":status", Value: "200"},
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{Name: ":status", Value: "204"},
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{Name: ":status", Value: "206"},
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{Name: ":status", Value: "304"},
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{Name: ":status", Value: "400"},
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{Name: ":status", Value: "404"},
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{Name: ":status", Value: "500"},
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{Name: "accept-charset"},
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{Name: "accept-encoding", Value: "gzip, deflate"},
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{Name: "accept-language"},
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{Name: "accept-ranges"},
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{Name: "accept"},
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{Name: "access-control-allow-origin"},
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{Name: "age"},
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{Name: "allow"},
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{Name: "authorization"},
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{Name: "cache-control"},
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{Name: "content-disposition"},
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{Name: "content-encoding"},
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{Name: "content-language"},
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{Name: "content-length"},
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{Name: "content-location"},
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{Name: "content-range"},
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{Name: "content-type"},
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{Name: "cookie"},
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{Name: "date"},
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{Name: "etag"},
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{Name: "expect"},
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{Name: "expires"},
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{Name: "from"},
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{Name: "host"},
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{Name: "if-match"},
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{Name: "if-modified-since"},
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{Name: "if-none-match"},
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{Name: "if-range"},
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{Name: "if-unmodified-since"},
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{Name: "last-modified"},
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{Name: "link"},
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{Name: "location"},
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{Name: "max-forwards"},
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{Name: "proxy-authenticate"},
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{Name: "proxy-authorization"},
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{Name: "range"},
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{Name: "referer"},
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{Name: "refresh"},
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{Name: "retry-after"},
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{Name: "server"},
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{Name: "set-cookie"},
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{Name: "strict-transport-security"},
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{Name: "transfer-encoding"},
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{Name: "user-agent"},
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{Name: "vary"},
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{Name: "via"},
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{Name: "www-authenticate"},
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}
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func newStaticTable() *headerFieldTable {
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t := &headerFieldTable{}
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t.init()
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for _, e := range staticTableEntries[:] {
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t.addEntry(e)
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}
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return t
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}
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var huffmanCodes = [256]uint32{
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0x1ff8,
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0x7fffd8,
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0xfffffe2,
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0xfffffe3,
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0xfffffe4,
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0xfffffe5,
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0xfffffe6,
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0xfffffe7,
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0xfffffe8,
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0xffffea,
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0x3ffffffc,
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0xfffffe9,
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0xfffffea,
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0x3ffffffd,
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0xfffffeb,
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0xfffffec,
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0xfffffed,
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0xfffffee,
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0xfffffef,
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0xffffff0,
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0xffffff1,
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0xffffff2,
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0x3ffffffe,
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0xffffff3,
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0xffffff4,
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0xffffff5,
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0xffffff6,
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0xffffff7,
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0xffffff8,
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0xffffff9,
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0xffffffa,
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0xffffffb,
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0x14,
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0x3f8,
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0x3f9,
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0xffa,
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0x1ff9,
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0x15,
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0xf8,
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0x7fa,
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0x3fa,
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0x3fb,
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0xf9,
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0x7fb,
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0xfa,
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0x16,
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0x17,
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0x18,
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0x0,
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0x1,
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0x2,
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0x19,
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0x1a,
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0x1b,
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0x1c,
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0x1d,
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0x1e,
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0x1f,
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0x5c,
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0xfb,
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0x7ffc,
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0x20,
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0xffb,
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0x3fc,
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0x1ffa,
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0x21,
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0x5d,
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0x5e,
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0x5f,
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0x60,
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0x61,
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0x62,
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0x63,
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0x64,
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0x65,
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0x66,
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0x67,
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0x68,
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0x69,
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0x6a,
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0x6b,
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0x6c,
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0x6d,
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0x6e,
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0x6f,
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0x70,
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0x71,
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0x72,
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0xfc,
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0x73,
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0xfd,
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0x1ffb,
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0x7fff0,
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0x1ffc,
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0x3ffc,
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0x22,
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0x7ffd,
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0x3,
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0x23,
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0x4,
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0x24,
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0x5,
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0x25,
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0x26,
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0x27,
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0x6,
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0x74,
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0x75,
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0x28,
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0x29,
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0x2a,
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0x7,
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0x2b,
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0x76,
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0x2c,
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0x8,
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0x9,
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0x2d,
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0x77,
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0x78,
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0x79,
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0x7a,
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0x7b,
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0x7ffe,
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0x7fc,
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0x3ffd,
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0x1ffd,
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0xffffffc,
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0xfffe6,
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0x3fffd2,
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0xfffe7,
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0xfffe8,
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0x3fffd3,
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0x3fffd4,
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0x3fffd5,
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0x7fffd9,
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0x3fffd6,
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0x7fffda,
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0x7fffdb,
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0x7fffdc,
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0x7fffdd,
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0x7fffde,
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0xffffeb,
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0x7fffdf,
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0xffffec,
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0xffffed,
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0x3fffd7,
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0x7fffe0,
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0xffffee,
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0x7fffe1,
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0x7fffe2,
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0x7fffe3,
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0x7fffe4,
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0x1fffdc,
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0x3fffd8,
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0x7fffe5,
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0x3fffd9,
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0x7fffe6,
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0x7fffe7,
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0xffffef,
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0x3fffda,
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0x1fffdd,
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0xfffe9,
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0x3fffdb,
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0x3fffdc,
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0x7fffe8,
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0x7fffe9,
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0x1fffde,
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0x7fffea,
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0x3fffdd,
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0x3fffde,
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0xfffff0,
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0x1fffdf,
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0x3fffdf,
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0x7fffeb,
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0x7fffec,
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0x1fffe0,
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0x1fffe1,
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0x3fffe0,
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0x1fffe2,
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0x7fffed,
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0x3fffe1,
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0x7fffee,
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0x7fffef,
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0xfffea,
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0x3fffe2,
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0x3fffe3,
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0x3fffe4,
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0x7ffff0,
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0x3fffe5,
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0x3fffe6,
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0x7ffff1,
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0x3ffffe0,
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0x3ffffe1,
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0xfffeb,
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0x7fff1,
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0x3fffe7,
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0x7ffff2,
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0x3fffe8,
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0x1ffffec,
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0x3ffffe2,
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0x3ffffe3,
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0x3ffffe4,
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0x7ffffde,
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0x7ffffdf,
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0x3ffffe5,
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0xfffff1,
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0x1ffffed,
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0x7fff2,
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0x1fffe3,
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0x3ffffe6,
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0x7ffffe0,
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0x7ffffe1,
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0x3ffffe7,
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0x7ffffe2,
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0xfffff2,
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0x1fffe4,
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0x1fffe5,
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0x3ffffe8,
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0x3ffffe9,
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0xffffffd,
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0x7ffffe3,
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0x7ffffe4,
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0x7ffffe5,
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0xfffec,
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0xfffff3,
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0xfffed,
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0x1fffe6,
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0x3fffe9,
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0x1fffe7,
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0x1fffe8,
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0x7ffff3,
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0x3fffea,
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0x3fffeb,
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0x1ffffee,
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0x1ffffef,
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0xfffff4,
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0xfffff5,
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0x3ffffea,
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0x7ffff4,
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0x3ffffeb,
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0x7ffffe6,
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0x3ffffec,
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0x3ffffed,
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0x7ffffe7,
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0x7ffffe8,
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0x7ffffe9,
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0x7ffffea,
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0x7ffffeb,
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0xffffffe,
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0x7ffffec,
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0x7ffffed,
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0x7ffffee,
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0x7ffffef,
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0x7fffff0,
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0x3ffffee,
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}
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var huffmanCodeLen = [256]uint8{
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13, 23, 28, 28, 28, 28, 28, 28, 28, 24, 30, 28, 28, 30, 28, 28,
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28, 28, 28, 28, 28, 28, 30, 28, 28, 28, 28, 28, 28, 28, 28, 28,
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6, 10, 10, 12, 13, 6, 8, 11, 10, 10, 8, 11, 8, 6, 6, 6,
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5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 7, 8, 15, 6, 12, 10,
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13, 6, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
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7, 7, 7, 7, 7, 7, 7, 7, 8, 7, 8, 13, 19, 13, 14, 6,
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15, 5, 6, 5, 6, 5, 6, 6, 6, 5, 7, 7, 6, 6, 6, 5,
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6, 7, 6, 5, 5, 6, 7, 7, 7, 7, 7, 15, 11, 14, 13, 28,
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20, 22, 20, 20, 22, 22, 22, 23, 22, 23, 23, 23, 23, 23, 24, 23,
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24, 24, 22, 23, 24, 23, 23, 23, 23, 21, 22, 23, 22, 23, 23, 24,
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22, 21, 20, 22, 22, 23, 23, 21, 23, 22, 22, 24, 21, 22, 23, 23,
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21, 21, 22, 21, 23, 22, 23, 23, 20, 22, 22, 22, 23, 22, 22, 23,
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26, 26, 20, 19, 22, 23, 22, 25, 26, 26, 26, 27, 27, 26, 24, 25,
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19, 21, 26, 27, 27, 26, 27, 24, 21, 21, 26, 26, 28, 27, 27, 27,
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20, 24, 20, 21, 22, 21, 21, 23, 22, 22, 25, 25, 24, 24, 26, 23,
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26, 27, 26, 26, 27, 27, 27, 27, 27, 28, 27, 27, 27, 27, 27, 26,
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}
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