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// Copyright 2016, Joe Tsai. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE.md file.
//go:build gofuzz
// +build gofuzz
// This file exists to export internal implementation details for fuzz testing.
package bzip2
func ForwardBWT(buf []byte) (ptr int) {
var bwt burrowsWheelerTransform
return bwt.Encode(buf)
}
func ReverseBWT(buf []byte, ptr int) {
var bwt burrowsWheelerTransform
bwt.Decode(buf, ptr)
}
type fuzzReader struct {
Checksums Checksums
}
// updateChecksum updates Checksums.
//
// If a valid pos is provided, it appends the (pos, val) pair to the slice.
// Otherwise, it will update the last record with the new value.
func (fr *fuzzReader) updateChecksum(pos int64, val uint32) {
if pos >= 0 {
fr.Checksums = append(fr.Checksums, Checksum{pos, val})
} else {
fr.Checksums[len(fr.Checksums)-1].Value = val
}
}
type Checksum struct {
Offset int64 // Bit offset of the checksum
Value uint32 // Checksum value
}
type Checksums []Checksum
// Apply overwrites all checksum fields in d with the ones in cs.
func (cs Checksums) Apply(d []byte) []byte {
d = append([]byte(nil), d...)
for _, c := range cs {
setU32(d, c.Offset, c.Value)
}
return d
}
func setU32(d []byte, pos int64, val uint32) {
for i := uint(0); i < 32; i++ {
bpos := uint64(pos) + uint64(i)
d[bpos/8] &= ^byte(1 << (7 - bpos%8))
d[bpos/8] |= byte(val>>(31-i)) << (7 - bpos%8)
}
}
// Verify checks that all checksum fields in d matches those in cs.
func (cs Checksums) Verify(d []byte) bool {
for _, c := range cs {
if getU32(d, c.Offset) != c.Value {
return false
}
}
return true
}
func getU32(d []byte, pos int64) (val uint32) {
for i := uint(0); i < 32; i++ {
bpos := uint64(pos) + uint64(i)
val |= (uint32(d[bpos/8] >> (7 - bpos%8))) << (31 - i)
}
return val
}
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