// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bzip2

import (
	
	
)

// bitReader wraps an io.Reader and provides the ability to read values,
// bit-by-bit, from it. Its Read* methods don't return the usual error
// because the error handling was verbose. Instead, any error is kept and can
// be checked afterwards.
type bitReader struct {
	r    io.ByteReader
	n    uint64
	bits uint
	err  error
}

// newBitReader returns a new bitReader reading from r. If r is not
// already an io.ByteReader, it will be converted via a bufio.Reader.
func newBitReader( io.Reader) bitReader {
	,  := .(io.ByteReader)
	if ! {
		 = bufio.NewReader()
	}
	return bitReader{r: }
}

// ReadBits64 reads the given number of bits and returns them in the
// least-significant part of a uint64. In the event of an error, it returns 0
// and the error can be obtained by calling Err().
func ( *bitReader) ( uint) ( uint64) {
	for  > .bits {
		,  := .r.ReadByte()
		if  == io.EOF {
			 = io.ErrUnexpectedEOF
		}
		if  != nil {
			.err = 
			return 0
		}
		.n <<= 8
		.n |= uint64()
		.bits += 8
	}

	// br.n looks like this (assuming that br.bits = 14 and bits = 6):
	// Bit: 111111
	//      5432109876543210
	//
	//         (6 bits, the desired output)
	//        |-----|
	//        V     V
	//      0101101101001110
	//        ^            ^
	//        |------------|
	//           br.bits (num valid bits)
	//
	// This the next line right shifts the desired bits into the
	// least-significant places and masks off anything above.
	 = (.n >> (.bits - )) & ((1 << ) - 1)
	.bits -= 
	return
}

func ( *bitReader) ( uint) ( int) {
	 := .ReadBits64()
	return int()
}

func ( *bitReader) () bool {
	 := .ReadBits(1)
	return  != 0
}

func ( *bitReader) () error {
	return .err
}