package bit import ( "io" ) // bit.Reader allows for bit-level reading of arbitrary source data. This is // based on the bit reader found in the standard library's bzip2 package. // https://golang.org/src/compress/bzip2/bit_reader.go type streamReader struct { src io.ByteReader // source of data n uint64 // bit buffer bits uint // number of valid bits in n err error // stored error } // ReadBits reads the given number of bits and returns them in the // least-significant part of a uint64. func (r *streamReader) ReadBits(bits uint) (n uint64) { if r.err != nil { return 0 } for bits > r.bits { b, err := r.src.ReadByte() if err != nil { r.err = err return 0 } r.n |= uint64(b) << r.bits r.bits += 8 } n = r.n & (1<>= bits r.bits -= bits return } // ReadByte reads a single byte, regardless of alignment. func (r *streamReader) ReadByte() byte { if r.bits == 0 { b, err := r.src.ReadByte() if err != nil { r.err = err return 0 } return b } return byte(r.ReadBits(8)) } // Read reads like an io.Reader, taking care of alignment internally. func (r *streamReader) Read(buf []byte) int { for i := 0; i < len(buf); i++ { b := r.ReadByte() if r.err != nil { return 0 } buf[i] = b } return len(buf) } // discards N byte of data on the reader or until EOF func (r *streamReader) DiscardBytes(n int) { for i := 0; i < n; i++ { r.ReadByte() } } func (r *streamReader) Err() error { return r.err }