90 lines
1.5 KiB
Go
90 lines
1.5 KiB
Go
package bits
|
|
|
|
import (
|
|
"io"
|
|
)
|
|
|
|
type GolombBitReader struct {
|
|
R io.Reader
|
|
buf [1]byte
|
|
left byte
|
|
}
|
|
|
|
func (self *GolombBitReader) ReadBit() (res uint, err error) {
|
|
if self.left == 0 {
|
|
if _, err = self.R.Read(self.buf[:]); err != nil {
|
|
return
|
|
}
|
|
self.left = 8
|
|
}
|
|
self.left--
|
|
res = uint(self.buf[0]>>self.left) & 1
|
|
return
|
|
}
|
|
|
|
func (self *GolombBitReader) ReadBits(n int) (res uint, err error) {
|
|
for i := 0; i < n; i++ {
|
|
var bit uint
|
|
if bit, err = self.ReadBit(); err != nil {
|
|
return
|
|
}
|
|
res |= bit << uint(n-i-1)
|
|
}
|
|
return
|
|
}
|
|
|
|
func (self *GolombBitReader) ReadBits32(n uint) (r uint32, err error) {
|
|
var t uint
|
|
for i := uint(0); i < n; i++ {
|
|
t, err = self.ReadBit()
|
|
if err != nil {
|
|
return
|
|
}
|
|
r = (r << 1) | uint32(t)
|
|
}
|
|
return
|
|
}
|
|
|
|
func (self *GolombBitReader) ReadBits64(n uint) (r uint64, err error) {
|
|
var t uint
|
|
for i := uint(0); i < n; i++ {
|
|
t, err = self.ReadBit()
|
|
if err != nil {
|
|
return
|
|
}
|
|
r = (r << 1) | uint64(t)
|
|
}
|
|
return
|
|
}
|
|
|
|
func (self *GolombBitReader) ReadExponentialGolombCode() (res uint, err error) {
|
|
i := 0
|
|
for {
|
|
var bit uint
|
|
if bit, err = self.ReadBit(); err != nil {
|
|
return
|
|
}
|
|
if !(bit == 0 && i < 32) {
|
|
break
|
|
}
|
|
i++
|
|
}
|
|
if res, err = self.ReadBits(i); err != nil {
|
|
return
|
|
}
|
|
res += (1 << uint(i)) - 1
|
|
return
|
|
}
|
|
|
|
func (self *GolombBitReader) ReadSE() (res uint, err error) {
|
|
if res, err = self.ReadExponentialGolombCode(); err != nil {
|
|
return
|
|
}
|
|
if res&0x01 != 0 {
|
|
res = (res + 1) / 2
|
|
} else {
|
|
res = -res / 2
|
|
}
|
|
return
|
|
}
|