Add MarshalBinary/UnmarshalBinary support (#68)

.github/workflows/go.yml

@@ -15,7 +15,7 @@ jobs:
     strategy:
       max-parallel: 4
       matrix:
-        go-version: [1.16.x, 1.15.x, 1.14.x]
+        go-version: [1.20.x, 1.19.x, 1.18.x]
         os: [ubuntu-latest, windows-latest, macos-latest]
     steps:
     - name: Set up Go ${{ matrix.go-version }}

go.mod

@@ -1,5 +1,7 @@
 module github.com/minio/sha256-simd
 
-go 1.13
+go 1.17
 
 require github.com/klauspost/cpuid/v2 v2.2.3
+
+require golang.org/x/sys v0.0.0-20220704084225-05e143d24a9e // indirect

sha256.go

@@ -19,6 +19,7 @@ package sha256
 import (
 	"crypto/sha256"
 	"encoding/binary"
+	"errors"
 	"hash"
 )
 
@@ -386,3 +387,82 @@ var _K = []uint32{
 	0xbef9a3f7,
 	0xc67178f2,
 }
+
+const (
+	magic256      = "sha\x03"
+	marshaledSize = len(magic256) + 8*4 + chunk + 8
+)
+
+func (d *digest) MarshalBinary() ([]byte, error) {
+	b := make([]byte, 0, marshaledSize)
+	b = append(b, magic256...)
+	b = appendUint32(b, d.h[0])
+	b = appendUint32(b, d.h[1])
+	b = appendUint32(b, d.h[2])
+	b = appendUint32(b, d.h[3])
+	b = appendUint32(b, d.h[4])
+	b = appendUint32(b, d.h[5])
+	b = appendUint32(b, d.h[6])
+	b = appendUint32(b, d.h[7])
+	b = append(b, d.x[:d.nx]...)
+	b = b[:len(b)+len(d.x)-d.nx] // already zero
+	b = appendUint64(b, d.len)
+	return b, nil
+}
+
+func (d *digest) UnmarshalBinary(b []byte) error {
+	if len(b) < len(magic256) || string(b[:len(magic256)]) != magic256 {
+		return errors.New("crypto/sha256: invalid hash state identifier")
+	}
+	if len(b) != marshaledSize {
+		return errors.New("crypto/sha256: invalid hash state size")
+	}
+	b = b[len(magic256):]
+	b, d.h[0] = consumeUint32(b)
+	b, d.h[1] = consumeUint32(b)
+	b, d.h[2] = consumeUint32(b)
+	b, d.h[3] = consumeUint32(b)
+	b, d.h[4] = consumeUint32(b)
+	b, d.h[5] = consumeUint32(b)
+	b, d.h[6] = consumeUint32(b)
+	b, d.h[7] = consumeUint32(b)
+	b = b[copy(d.x[:], b):]
+	b, d.len = consumeUint64(b)
+	d.nx = int(d.len % chunk)
+	return nil
+}
+
+func appendUint32(b []byte, v uint32) []byte {
+	return append(b,
+		byte(v>>24),
+		byte(v>>16),
+		byte(v>>8),
+		byte(v),
+	)
+}
+
+func appendUint64(b []byte, v uint64) []byte {
+	return append(b,
+		byte(v>>56),
+		byte(v>>48),
+		byte(v>>40),
+		byte(v>>32),
+		byte(v>>24),
+		byte(v>>16),
+		byte(v>>8),
+		byte(v),
+	)
+}
+
+func consumeUint64(b []byte) ([]byte, uint64) {
+	_ = b[7]
+	x := uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 |
+		uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56
+	return b[8:], x
+}
+
+func consumeUint32(b []byte) ([]byte, uint32) {
+	_ = b[3]
+	x := uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
+	return b[4:], x
+}