init: dec-music 项目初始化

2026-05-23 12:55:48 +08:00
commit 21045d0aad
50 changed files with 3662 additions and 0 deletions
@@ -0,0 +1,56 @@
+package mmkv
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+)
+
+type metadata struct {
+	// added in version 0
+	crc32 uint32
+
+	// added in version 1
+	version  uint32
+	sequence uint32 // full write back count
+
+	// added in version 2
+	aesVector []byte // random iv for encryption, aes.BlockSize (16 bytes)
+
+	// added in version 3, try to reduce file corruption
+	actualSize     uint32
+	lastActualSize uint32
+	lastCRC32      uint32
+
+	//_reversed []byte // 64 bytes
+}
+
+func loadMetadata(rd io.Reader) (*metadata, error) {
+	buf := make([]byte, 0x68)
+	_, err := io.ReadFull(rd, buf)
+	if err != nil {
+		return nil, fmt.Errorf("failed to read metadata: %w", err)
+	}
+
+	m := &metadata{}
+
+	m.crc32 = binary.LittleEndian.Uint32(buf[0:4])
+	m.version = binary.LittleEndian.Uint32(buf[4:8])
+
+	if m.version >= 1 {
+		m.sequence = binary.LittleEndian.Uint32(buf[8:12])
+	}
+
+	if m.version >= 2 {
+		m.aesVector = buf[12:28]
+	}
+
+	if m.version >= 3 {
+		m.actualSize = binary.LittleEndian.Uint32(buf[28:32])
+		m.lastActualSize = binary.LittleEndian.Uint32(buf[32:36])
+		m.lastCRC32 = binary.LittleEndian.Uint32(buf[36:40])
+	}
+
+	//m._reversed = buf[40:104]
+	return m, nil
+}