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gitea/vendor/github.com/couchbase/vellum/pack.go
2018-05-19 20:49:46 +08:00

56 lines
1.3 KiB
Go
Vendored

// Copyright (c) 2017 Couchbase, 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 vellum
func deltaAddr(base, trans uint64) uint64 {
// transition dest of 0 is special case
if trans == 0 {
return 0
}
return base - trans
}
const packOutMask = 1<<4 - 1
func encodePackSize(transSize, outSize int) byte {
var rv byte
rv = byte(transSize << 4)
rv |= byte(outSize)
return rv
}
func decodePackSize(pack byte) (transSize int, packSize int) {
transSize = int(pack >> 4)
packSize = int(pack & packOutMask)
return
}
const maxNumTrans = 1<<6 - 1
func encodeNumTrans(n int) byte {
if n <= maxNumTrans {
return byte(n)
}
return 0
}
func readPackedUint(data []byte) (rv uint64) {
for i := range data {
shifted := uint64(data[i]) << uint(i*8)
rv |= shifted
}
return
}