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//go:build amd64 && !purego
package adler32
import (
"encoding/binary"
"errors"
"hash"
"hash/adler32"
"golang.org/x/sys/cpu"
)
// Size of an Adler-32 checksum in bytes.
const Size = 4
var (
hasAVX2 = cpu.X86.HasAVX2
)
// digest represents the partial evaluation of a checksum.
// The low 16 bits are s1, the high 16 bits are s2.
type digest uint32
func (d *digest) Reset() { *d = 1 }
// New returns a new hash.Hash32 computing the Adler-32 checksum.
func New() hash.Hash32 {
if !hasAVX2 {
return adler32.New()
}
d := new(digest)
d.Reset()
return d
}
func (d *digest) MarshalBinary() ([]byte, error) {
b := make([]byte, 0, marshaledSize)
b = append(b, magic...)
b = binary.BigEndian.AppendUint32(b, uint32(*d))
return b, nil
}
func (d *digest) UnmarshalBinary(b []byte) error {
if len(b) < len(magic) || string(b[:len(magic)]) != magic {
return errors.New("hash/adler32: invalid hash state identifier")
}
if len(b) != marshaledSize {
return errors.New("hash/adler32: invalid hash state size")
}
*d = digest(binary.BigEndian.Uint32(b[len(magic):]))
return nil
}
func (d *digest) Size() int { return Size }
func (d *digest) BlockSize() int { return 4 }
func (d *digest) Write(data []byte) (nn int, err error) {
if hasAVX2 && len(data) >= 64 {
h := adler32_avx2(uint32(*d), data)
*d = digest(h)
} else {
h := update(uint32(*d), data)
*d = digest(h)
}
return len(data), nil
}
func (d *digest) Sum32() uint32 { return uint32(*d) }
func (d *digest) Sum(in []byte) []byte {
s := uint32(*d)
return append(in, byte(s>>24), byte(s>>16), byte(s>>8), byte(s))
}
// Checksum returns the Adler-32 checksum of data.
func Checksum(data []byte) uint32 {
if hasAVX2 && len(data) >= 64 {
return adler32_avx2(1, data)
}
return adler32.Checksum(data)
}
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