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119 lines
2.1 KiB
Go
119 lines
2.1 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 Reader struct {
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R io.Reader
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n int
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bits uint64
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}
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func (self *Reader) ReadBits64(n int) (bits uint64, err error) {
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if self.n < n {
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var b [8]byte
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var got int
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want := (n - self.n + 7) / 8
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if got, err = self.R.Read(b[:want]); err != nil {
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return
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}
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if got < want {
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err = io.EOF
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return
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}
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for i := 0; i < got; i++ {
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self.bits <<= 8
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self.bits |= uint64(b[i])
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}
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self.n += got * 8
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}
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bits = self.bits >> uint(self.n-n)
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self.bits ^= bits << uint(self.n-n)
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self.n -= n
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return
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}
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func (self *Reader) ReadBits(n int) (bits uint, err error) {
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var bits64 uint64
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if bits64, err = self.ReadBits64(n); err != nil {
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return
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}
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bits = uint(bits64)
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return
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}
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func (self *Reader) Read(p []byte) (n int, err error) {
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for n < len(p) {
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want := 8
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if len(p)-n < want {
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want = len(p) - n
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}
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var bits uint64
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if bits, err = self.ReadBits64(want * 8); err != nil {
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break
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}
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for i := 0; i < want; i++ {
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p[n+i] = byte(bits >> uint((want-i-1)*8))
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}
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n += want
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}
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return
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}
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type Writer struct {
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W io.Writer
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n int
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bits uint64
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}
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func (self *Writer) WriteBits64(bits uint64, n int) (err error) {
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if self.n+n > 64 {
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move := uint(64 - self.n)
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mask := bits >> move
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self.bits = (self.bits << move) | mask
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self.n = 64
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if err = self.FlushBits(); err != nil {
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return
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}
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n -= int(move)
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bits ^= (mask << move)
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}
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self.bits = (self.bits << uint(n)) | bits
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self.n += n
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return
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}
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func (self *Writer) WriteBits(bits uint, n int) (err error) {
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return self.WriteBits64(uint64(bits), n)
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}
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func (self *Writer) Write(p []byte) (n int, err error) {
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for n < len(p) {
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if err = self.WriteBits64(uint64(p[n]), 8); err != nil {
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return
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}
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n++
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}
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return
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}
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func (self *Writer) FlushBits() (err error) {
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if self.n > 0 {
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var b [8]byte
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bits := self.bits
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if self.n%8 != 0 {
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bits <<= uint(8 - (self.n % 8))
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}
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want := (self.n + 7) / 8
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for i := 0; i < want; i++ {
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b[i] = byte(bits >> uint((want-i-1)*8))
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}
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if _, err = self.W.Write(b[:want]); err != nil {
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return
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}
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self.n = 0
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}
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return
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}
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