bits_reader(r)
Return a bits reader that read bits from the stream reader r.
Bit streams are for reading and writing data at bit-level. As a simple example of bit encoded data, consider 16-bit color values. In 16-bit color, the red and blue components are encoded using 5-bits each, while the green component takes up 6-bit. The following program reads and writes 16-bit encoded color values:
function encode_color(rgb)
let (out = byte_array_writer(),
encoder = bits_writer(out))
{ write_bits(encoder, rgb['red], 5)
write_bits(encoder, rgb['green], 6)
write_bits(encoder, rgb['blue], 5)
bits_writer_flush(encoder)
get_output_bytes(out) }
function decode_color(color)
let (in = byte_array_reader(color),
decoder = bits_reader(in),
r = read_bits(decoder, 5),
g = read_bits(decoder, 6),
b = read_bits(decoder, 5))
#{'red: r, 'green: g, 'blue: b}
decode_color(encode_color(#{'red: 12, 'green: 51, 'blue: 20}))
// #{red: 12, green: 51, blue: 20}