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// Copyright 2015 The Vanadium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// A test for crc64window.
package crc64window_test
import "hash/crc64"
import "math/rand"
import "testing"
import "v.io/syncbase/x/ref/services/syncbase/localblobstore/crc64window"
// A test for the example given in the package's specification.
func TestCRC64WindowExample(t *testing.T) {
w := crc64window.New(crc64.ECMA, 3)
w.Advance(0x17)
w.Advance(0x92)
w.Advance(0x04)
rolling := w.Advance(0x28) // Rolls 0x17 out, and 0x28 in.
nonRolling := crc64.Update(0, crc64.MakeTable(crc64.ECMA), []byte{0x92, 0x04, 0x28})
if rolling != nonRolling {
t.Errorf("crc64window: rolling(0x92, 0x04, 0x28)==%x nonRolling(0x92, 0x04, 0x28)==%x\n", rolling, nonRolling)
}
}
func TestCRC64Window(t *testing.T) {
winSize := 16
iterations := 1000
w := crc64window.New(crc64.ECMA, winSize)
table := crc64.MakeTable(crc64.ECMA)
block := make([]byte, winSize-1+iterations)
for i := 0; i != len(block); i++ {
block[i] = byte(rand.Int31n(256))
}
i := 0
for ; i != winSize-1; i++ {
w.Advance(block[i])
}
for ; i != len(block); i++ {
expect := crc64.Update(0, table, block[i+1-winSize:i+1])
got := w.Advance(block[i])
if expect != got {
t.Errorf("crc64window: i %d winSize %d got %x, expect %x\n", i, winSize, got, expect)
}
}
}