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hash.go
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45 lines (35 loc) · 656 Bytes
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package cpio
import (
"encoding/binary"
"hash"
)
type digest struct {
sum uint32
}
// NewHash returns a new hash.Hash32 for computing SVR4 checksums.
func NewHash() hash.Hash32 {
return &digest{}
}
func (d *digest) Write(p []byte) (n int, err error) {
for _, b := range p {
d.sum += uint32(b & 0xFF)
}
return len(p), nil
}
func (d *digest) Sum(b []byte) []byte {
out := [4]byte{}
binary.LittleEndian.PutUint32(out[:], d.sum)
return append(b, out[:]...)
}
func (d *digest) Sum32() uint32 {
return d.sum
}
func (d *digest) Reset() {
d.sum = 0
}
func (d *digest) Size() int {
return 4
}
func (d *digest) BlockSize() int {
return 1
}