46 lines
885 B
Go
46 lines
885 B
Go
// Package varint is a variable integer encoding that works in reverse compared
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// to the stdlib binary Varint. The terminal byte in the encoding is the one
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// with the 8th bit set. This is basically like a base 128 encoding. It reads
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// forward using an io.Reader and writes forward using an io.Writer.
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package varint
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import (
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"io"
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"golang.org/x/exp/constraints"
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"lol.mleku.dev/chk"
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)
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func Encode[V constraints.Integer](w io.Writer, v V) {
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x := []byte{0}
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for {
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x[0] = byte(v) & 127
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v >>= 7
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if v == 0 {
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x[0] |= 128
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_, _ = w.Write(x)
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break
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} else {
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_, _ = w.Write(x)
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}
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}
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}
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func Decode(r io.Reader) (v uint64, err error) {
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x := []byte{0}
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v += uint64(x[0])
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var i uint64
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for {
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if _, err = r.Read(x); chk.E(err) {
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return
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}
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if x[0] >= 128 {
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v += uint64(x[0]&127) << (i * 7)
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return
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} else {
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v += uint64(x[0]) << (i * 7)
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i++
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}
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}
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}
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