BitReserve.java

/***************************************************************************
 *  JLayerME is a JAVA library that decodes/plays/converts MPEG 1/2 Layer 3.
 *  Project Homepage: http://www.javazoom.net/javalayer/javalayerme.html.
 *  Copyright (C) JavaZOOM 1999-2005.
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *---------------------------------------------------------------------------
 */
package javazoom.jlme.decoder;

final class BitReserve {
	private final static int BUFSIZE = 4096 * 8;
	private final static int BUFSIZE_MASK = BUFSIZE - 1;
	static int offset, buf_byte_idx;
	private static final int[] buf = new int[BUFSIZE];
	static int buf_bit_idx;
	public static int totbit;

	// public int hsstell() {
	// return totbit;
	// }

	public final int hgetbits(int N) {
		totbit += N;
		val = 0;
		if (buf_byte_idx + N < BUFSIZE) {
			while (N-- > 0) {
				val <<= 1;
				val |= ((buf[buf_byte_idx++] == 0) ? 0 : 1);
			}
		} else {
			while (N-- > 0) {
				val <<= 1;
				val |= ((buf[buf_byte_idx] == 0) ? 0 : 1);
				buf_byte_idx = (buf_byte_idx + 1) & BUFSIZE_MASK;
			}
		}

		return val;
	}

	static int val;

	public final int hget1bit() {
		totbit++;
		val = buf[buf_byte_idx];
		buf_byte_idx = (buf_byte_idx + 1) & BUFSIZE_MASK;
		return val;
	}

	public final void hputbuf(int val) {
		buf[offset++] = val & 0x80;
		buf[offset++] = val & 0x40;
		buf[offset++] = val & 0x20;
		buf[offset++] = val & 0x10;
		buf[offset++] = val & 0x08;
		buf[offset++] = val & 0x04;
		buf[offset++] = val & 0x02;
		buf[offset++] = val & 0x01;
		if (offset == BUFSIZE)
			offset = 0;
	}

	public final void rewindNbits(int N) {
		totbit -= N;
		buf_byte_idx -= N;
		if (buf_byte_idx < 0) {
			buf_byte_idx += BUFSIZE;
		}
	}

	static int bits;

	public final void rewindNbytes(int N) {
		bits = (N << 3);
		totbit -= bits;
		buf_byte_idx -= bits;
		if (buf_byte_idx < 0) {
			buf_byte_idx += BUFSIZE;
		}
	}

}