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bitreader.go
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bitreader.go
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package vorbis
type bitReader struct {
data []byte
position int
bitOffset uint
eof bool
}
func newBitReader(data []byte) *bitReader {
return &bitReader{data, 0, 0, false}
}
func (r *bitReader) EOF() bool {
return r.eof
}
func (r *bitReader) Read1() uint32 {
if r.position >= len(r.data) {
r.eof = true
return 0
}
var result uint32
if r.data[r.position]&(1<<r.bitOffset) != 0 {
result = 1
}
if r.bitOffset < 7 {
r.bitOffset++
} else {
r.bitOffset = 0
r.position++
}
return result
}
func (r *bitReader) read(n uint, bits uint) uint32 {
if n > bits {
panic("invalid argument")
}
var result uint32
var written uint
size := n
for n > 0 {
if r.position >= len(r.data) {
r.eof = true
return 0
}
result |= uint32(r.data[r.position]>>r.bitOffset) << written
written += 8 - r.bitOffset
if n < 8-r.bitOffset {
r.bitOffset += n
break
}
n -= 8 - r.bitOffset
r.bitOffset = 0
r.position++
}
return result &^ (0xFFFFFFFF << size)
}
func (r *bitReader) Read8(n uint) uint8 {
return uint8(r.read(n, 8))
}
func (r *bitReader) Read16(n uint) uint16 {
return uint16(r.read(n, 16))
}
func (r *bitReader) Read32(n uint) uint32 {
return uint32(r.read(n, 32))
}
func (r *bitReader) ReadBool() bool {
return r.Read8(1) == 1
}