Class Bitreader

java/com/traneptora/jxlatte/io/Bitreader.java:9–259

import com.traneptora.jxlatte.util.MathHelper;

public class Bitreader extends InputStream {

    private InputStream in;
    private long cache = 0;
    private int cacheBits = 0;
    private long bitsRead = 0;

    public Bitreader(InputStream in) {
        this.in = in;
    }

    @Override
    public int read(byte[] buffer) throws IOException {
        return read(buffer, 0, buffer.length);
    }

    public boolean readBool() throws IOException {
        return readBits(1) != 0;
    }

    public int readU32(int c0, int u0, int c1, int u1, int c2, int u2, int c3, int u3) throws IOException {
        int choice = readBits(2);
        int[] c = new int[]{c0, c1, c2, c3};
        int[] u = new int[]{u0, u1, u2, u3};
        return c[choice] + readBits(u[choice]);
    }

    public long readU64() throws IOException {
        int index = readBits(2);
        if (index == 0)
            return 0L;
        if (index == 1)
            return 1L + readBits(4);
        if (index == 2)
            return 17L + readBits(8);
        long value = readBits(12);
        int shift = 12;
        while (readBool()) {
            if (shift == 60) {
                value |= (long)readBits(4) << shift;
                break;
            }
            value |= (long)readBits(8) << shift;
            shift += 8;
        }
        return value;
    }

    public float readF16() throws IOException {
        int bits16 = readBits(16);
        float f = MathHelper.floatFromF16(bits16);
        if (!Float.isFinite(f))
            throw new InvalidBitstreamException("Illegal infinite/NaN float16");
        return f;
    }

    public int readEnum() throws IOException {
        int constant = readU32(0, 0, 1, 0, 2, 4, 18, 6);