engine/util/big_little_endian.go

package util

//
// 注意:RTMP模式下都是大端模式
//

var LittleEndian littleEndian

// BigEndian is the big-endian implementation of ByteOrder.
var BigEndian bigEndian

// 低位字节排放在内存的低地址端,高位字节排放在内存的高地址端.
type littleEndian struct{}

// b == 0x1234, b[0] == 0x12, b[1] == 0x34
// b[0]低字节 b[1]高字节
// 内存地址 低 -> 高
// 0x34 0x12

// byte(v)低字节 b[0]内存低地址
// byte(v>>8)高字节 b[1]内存高地址

// b == 2222 2222 1111 1111
// b >> 8 -> 0000 0000 2222 2222
// b << 8 -> 1111 1111 0000 0000

func (littleEndian) Uint16(b []byte) uint16 { return uint16(b[0]) | uint16(b[1])<<8 }
func (littleEndian) Uint24(b []byte) uint32 { return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 }
func (littleEndian) Uint32(b []byte) uint32 {
	return uint32(b[0]) | uint32(b[1])<<8 | uint32(b[2])<<16 | uint32(b[3])<<24
}
func (littleEndian) Uint40(b []byte) uint64 {
	return uint64(b[0]) | uint64(b[1])<<8 |
		uint64(b[2])<<16 | uint64(b[3])<<24 | uint64(b[4])<<32
}
func (littleEndian) Uint48(b []byte) uint64 {
	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 |
		uint64(b[3])<<24 | uint64(b[4])<<32 | uint64(b[5])<<40
}
func (littleEndian) Uint64(b []byte) uint64 {
	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 |
		uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56
}

//
// Put
//

func (littleEndian) PutUint16(b []byte, v uint16) {
	b[0] = byte(v)
	b[1] = byte(v >> 8)
}
func (littleEndian) PutUint24(b []byte, v uint32) {
	b[0] = byte(v)
	b[1] = byte(v >> 8)
	b[2] = byte(v >> 16)
}
func (littleEndian) PutUint32(b []byte, v uint32) {
	b[0] = byte(v)
	b[1] = byte(v >> 8)
	b[2] = byte(v >> 16)
	b[3] = byte(v >> 24)
}
func (littleEndian) PutUint64(b []byte, v uint64) {
	b[0] = byte(v)
	b[1] = byte(v >> 8)
	b[2] = byte(v >> 16)
	b[3] = byte(v >> 24)
	b[4] = byte(v >> 32)
	b[5] = byte(v >> 40)
	b[6] = byte(v >> 48)
	b[7] = byte(v >> 56)
}

//
// To
//

func (littleEndian) ToUint16(v uint16) []byte {
	b := make([]byte, 2)
	b[0] = byte(v)
	b[1] = byte(v >> 8)
	return b
}
func (littleEndian) ToUint24(v uint32) []byte {
	b := make([]byte, 3)
	b[0] = byte(v)
	b[1] = byte(v >> 8)
	b[2] = byte(v >> 16)
	return b
}
func (littleEndian) ToUint32(v uint32) []byte {
	b := make([]byte, 4)
	b[0] = byte(v)
	b[1] = byte(v >> 8)
	b[2] = byte(v >> 16)
	b[3] = byte(v >> 24)
	return b
}
func (littleEndian) ToUint40(v uint64) []byte {
	b := make([]byte, 5)
	b[0] = byte(v)
	b[1] = byte(v >> 8)
	b[2] = byte(v >> 16)
	b[3] = byte(v >> 24)
	b[4] = byte(v >> 32)
	return b
}
func (littleEndian) ToUint48(v uint64) []byte {
	b := make([]byte, 6)
	b[0] = byte(v)
	b[1] = byte(v >> 8)
	b[2] = byte(v >> 16)
	b[3] = byte(v >> 24)
	b[4] = byte(v >> 32)
	b[5] = byte(v >> 40)
	return b
}
func (littleEndian) ToUint64(v uint64) []byte {
	b := make([]byte, 8)
	b[0] = byte(v)
	b[1] = byte(v >> 8)
	b[2] = byte(v >> 16)
	b[3] = byte(v >> 24)
	b[4] = byte(v >> 32)
	b[5] = byte(v >> 40)
	b[6] = byte(v >> 48)
	b[7] = byte(v >> 56)
	return b
}

// 高位字节排放在内存的低地址端,低位字节排放在内存的高地址端
type bigEndian struct{}

// b == 0x1234, b[0] == 0x12, b[1] == 0x34
// 内存地址 低 -> 高
// 0x12 0x34
func (bigEndian) Uint16(b []byte) uint16 { return uint16(b[1]) | uint16(b[0])<<8 }
func (bigEndian) Uint24(b []byte) uint32 { return uint32(b[2]) | uint32(b[1])<<8 | uint32(b[0])<<16 }
func (bigEndian) Uint32(b []byte) uint32 {
	return uint32(b[3]) | uint32(b[2])<<8 | uint32(b[1])<<16 | uint32(b[0])<<24
}
func (bigEndian) Uint40(b []byte) uint64 {
	return uint64(b[4]) | uint64(b[3])<<8 |
		uint64(b[2])<<16 | uint64(b[1])<<24 | uint64(b[0])<<32
}
func (bigEndian) Uint48(b []byte) uint64 {
	return uint64(b[5]) | uint64(b[4])<<8 | uint64(b[3])<<16 |
		uint64(b[2])<<24 | uint64(b[1])<<32 | uint64(b[0])<<40
}
func (bigEndian) Uint64(b []byte) uint64 {
	return 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
}

//
// Put
//

func (bigEndian) PutUint16(b []byte, v uint16) {
	b[0] = byte(v >> 8)
	b[1] = byte(v)
}
func (bigEndian) PutUint24(b []byte, v uint32) {
	b[0] = byte(v >> 16)
	b[1] = byte(v >> 8)
	b[2] = byte(v)
}
func (bigEndian) PutUint32(b []byte, v uint32) {
	b[0] = byte(v >> 24)
	b[1] = byte(v >> 16)
	b[2] = byte(v >> 8)
	b[3] = byte(v)
}
func (bigEndian) PutUint64(b []byte, v uint64) {
	b[0] = byte(v >> 56)
	b[1] = byte(v >> 48)
	b[2] = byte(v >> 40)
	b[3] = byte(v >> 32)
	b[4] = byte(v >> 24)
	b[5] = byte(v >> 16)
	b[6] = byte(v >> 8)
	b[7] = byte(v)
}

//
// To
//

func (bigEndian) ToUint16(v uint16) []byte {
	b := make([]byte, 2)
	b[0] = byte(v >> 8)
	b[1] = byte(v)
	return b
}
func (bigEndian) ToUint24(v uint32) []byte {
	b := make([]byte, 3)
	b[0] = byte(v >> 16)
	b[1] = byte(v >> 8)
	b[2] = byte(v)
	return b
}
func (bigEndian) ToUint32(v uint32) []byte {
	b := make([]byte, 4)
	b[0] = byte(v >> 24)
	b[1] = byte(v >> 16)
	b[2] = byte(v >> 8)
	b[3] = byte(v)
	return b
}
func (bigEndian) ToUint40(v uint64) []byte {
	b := make([]byte, 5)
	b[0] = byte(v >> 32)
	b[1] = byte(v >> 24)
	b[2] = byte(v >> 16)
	b[3] = byte(v >> 8)
	b[4] = byte(v)
	return b
}
func (bigEndian) ToUint48(v uint64) []byte {
	b := make([]byte, 6)
	b[0] = byte(v >> 40)
	b[1] = byte(v >> 32)
	b[2] = byte(v >> 24)
	b[3] = byte(v >> 16)
	b[4] = byte(v >> 8)
	b[5] = byte(v)
	return b
}
func (bigEndian) ToUint64(v uint64) []byte {
	b := make([]byte, 8)
	b[0] = byte(v >> 56)
	b[1] = byte(v >> 48)
	b[2] = byte(v >> 40)
	b[3] = byte(v >> 32)
	b[4] = byte(v >> 24)
	b[5] = byte(v >> 16)
	b[6] = byte(v >> 8)
	b[7] = byte(v)
	return b
}

//哥伦布解码
func GetUev(buff []byte, start int) (value int, pos int) {
	l := len(buff)
	var nZeroNum uint = 0
	for start < l*8 {
		if (buff[start/8] & (0x80 >> uint(start%8))) > 0 {
			break
		}
		nZeroNum += 1
		start += 1
	}
	dwRet := 0
	start += 1
	var i uint
	for i = 0; i < nZeroNum; i++ {
		dwRet <<= 1
		if (buff[start/8] & (0x80 >> uint(start%8))) > 0 {
			dwRet += 1
		}
		start += 1
	}
	return (1 << nZeroNum) - 1 + dwRet, start
}

func BigLittleSwap(v uint) uint {
	return (v >> 24) | ((v>>16)&0xff)<<8 | ((v>>8)&0xff)<<16 | (v&0xff)<<24
}