void compress_file(string fn, string cfn)
{
var bits = read_bits(fn);
var bs = len(bits);
var ar = new Ar();
for (var i = 0; i < N; i++)
{
m[i] = new Model(i);
}
foreach (var bit in bits)
{
var n = predict();
ar.encode(bit, n[0], n[1]);
update(bit);
}
var cbits_queue = ar.flush();
int[] cbits = cbits_queue.ToArray();
write_bits(cfn, cbits);
var cbs = len(cbits);
WriteLine($"orig size: {format_int(bs / 8)}");
WriteLine($"comp size: {format_int(len(cbits) / 8)}");
WriteLine($"ratio: {format_float(cbs * 100.0 / bs)}%");
var bpc = cbs * 1.0 / (bs / 8);
WriteLine($"{format_float(bpc)} bpc");
var ok = check(fn, cfn, bs, cbs);
WriteLine(ok ? "ok" : "check failed");
}