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