/
varint.go
58 lines (49 loc) · 1.39 KB
/
varint.go
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// Copyright 2022 Dolthub, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package message
import (
"encoding/binary"
)
func encodeVarints(ints []uint64, buf []byte) []byte {
return endcodeSignedDeltas(ints, buf)
}
func decodeVarints(buf []byte, ints []uint64) []uint64 {
return decodeSignedDeltas(buf, ints)
}
func maxEncodedSize(n int) int {
return (n + 1) * binary.MaxVarintLen64
}
func endcodeSignedDeltas(ints []uint64, buf []byte) []byte {
pos, prev := 0, int64(0)
for i := range ints {
curr := int64(ints[i])
delta := curr - prev
prev = curr
n := binary.PutVarint(buf[pos:], delta)
pos += n
}
return buf[:pos]
}
func decodeSignedDeltas(buf []byte, ints []uint64) []uint64 {
prev := int64(0)
for i := range ints {
delta, n := binary.Varint(buf)
buf = buf[n:]
curr := prev + delta
ints[i] = uint64(curr)
prev = curr
}
assertTrue(len(buf) == 0)
return ints
}