forgejo/vendor/github.com/ulikunitz/xz/lzma/prob.go
6543 12a1f914f4
Vendor Update Go Libs (#13166)
* update github.com/alecthomas/chroma v0.8.0 -> v0.8.1

* github.com/blevesearch/bleve v1.0.10 -> v1.0.12

* editorconfig-core-go v2.1.1 -> v2.3.7

* github.com/gliderlabs/ssh v0.2.2 -> v0.3.1

* migrate editorconfig.ParseBytes to Parse

* github.com/shurcooL/vfsgen to 0d455de96546

* github.com/go-git/go-git/v5 v5.1.0 -> v5.2.0

* github.com/google/uuid v1.1.1 -> v1.1.2

* github.com/huandu/xstrings v1.3.0 -> v1.3.2

* github.com/klauspost/compress v1.10.11 -> v1.11.1

* github.com/markbates/goth v1.61.2 -> v1.65.0

* github.com/mattn/go-sqlite3 v1.14.0 -> v1.14.4

* github.com/mholt/archiver v3.3.0 -> v3.3.2

* github.com/microcosm-cc/bluemonday 4f7140c49acb -> v1.0.4

* github.com/minio/minio-go v7.0.4 -> v7.0.5

* github.com/olivere/elastic v7.0.9 -> v7.0.20

* github.com/urfave/cli v1.20.0 -> v1.22.4

* github.com/prometheus/client_golang v1.1.0 -> v1.8.0

* github.com/xanzy/go-gitlab v0.37.0 -> v0.38.1

* mvdan.cc/xurls v2.1.0 -> v2.2.0

Co-authored-by: Lauris BH <lauris@nix.lv>
2020-10-16 01:06:27 -04:00

53 lines
1.5 KiB
Go
Vendored

// Copyright 2014-2019 Ulrich Kunitz. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package lzma
// movebits defines the number of bits used for the updates of probability
// values.
const movebits = 5
// probbits defines the number of bits of a probability value.
const probbits = 11
// probInit defines 0.5 as initial value for prob values.
const probInit prob = 1 << (probbits - 1)
// Type prob represents probabilities. The type can also be used to encode and
// decode single bits.
type prob uint16
// Dec decreases the probability. The decrease is proportional to the
// probability value.
func (p *prob) dec() {
*p -= *p >> movebits
}
// Inc increases the probability. The Increase is proportional to the
// difference of 1 and the probability value.
func (p *prob) inc() {
*p += ((1 << probbits) - *p) >> movebits
}
// Computes the new bound for a given range using the probability value.
func (p prob) bound(r uint32) uint32 {
return (r >> probbits) * uint32(p)
}
// Bits returns 1. One is the number of bits that can be encoded or decoded
// with a single prob value.
func (p prob) Bits() int {
return 1
}
// Encode encodes the least-significant bit of v. Note that the p value will be
// changed.
func (p *prob) Encode(e *rangeEncoder, v uint32) error {
return e.EncodeBit(v, p)
}
// Decode decodes a single bit. Note that the p value will change.
func (p *prob) Decode(d *rangeDecoder) (v uint32, err error) {
return d.DecodeBit(p)
}