/*
* 11/19/04 1.0 moved to LGPL.
*
* 12/12/99 0.0.7 Implementation stores single bits as ints for better performance. mdm@techie.com.
*
* 02/28/99 0.0 Java Conversion by E.B, javalayer@javazoom.net
*
* Adapted from the public c code by Jeff Tsay.
*
*-----------------------------------------------------------------------
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Library General Public License as published
* by the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*----------------------------------------------------------------------
*/
package org.geogebra.desktop.sound.mp3transform;
/**
* Stores single bits as a word in the buffer. If a bit is set, the
* corresponding word in the buffer will be non-zero. If a bit is clear, the
* corresponding word is zero. Although this may seem waseful, this can be a
* factor of two quicker than packing 8 bits to a byte and extracting.
*/
public class BitReservoir {
private static final int BUFFER_SIZE = 4096 * 8;
private static final int BUFFER_SIZE_MASK = BUFFER_SIZE - 1;
private int offset, bitCount, bufferIndex;
private final int[] buffer = new int[BUFFER_SIZE];
int getBitCount() {
return bitCount;
}
int getBits(int n) {
bitCount += n;
int val = 0;
int pos = bufferIndex;
if (pos + n < BUFFER_SIZE) {
while (n-- > 0) {
val <<= 1;
val |= ((buffer[pos++] != 0) ? 1 : 0);
}
} else {
while (n-- > 0) {
val <<= 1;
val |= ((buffer[pos] != 0) ? 1 : 0);
pos = (pos + 1) & BUFFER_SIZE_MASK;
}
}
bufferIndex = pos;
return val;
}
int getOneBit() {
bitCount++;
int val = buffer[bufferIndex];
bufferIndex = (bufferIndex + 1) & BUFFER_SIZE_MASK;
return val;
}
void putByte(int val) {
int ofs = offset;
buffer[ofs++] = val & 0x80;
buffer[ofs++] = val & 0x40;
buffer[ofs++] = val & 0x20;
buffer[ofs++] = val & 0x10;
buffer[ofs++] = val & 0x08;
buffer[ofs++] = val & 0x04;
buffer[ofs++] = val & 0x02;
buffer[ofs++] = val & 0x01;
if (ofs == BUFFER_SIZE) {
offset = 0;
} else {
offset = ofs;
}
}
void rewindBits(int n) {
bitCount -= n;
bufferIndex -= n;
if (bufferIndex < 0) {
bufferIndex += BUFFER_SIZE;
}
}
void rewindBytes(int n) {
int bits = (n << 3);
bitCount -= bits;
bufferIndex -= bits;
if (bufferIndex < 0) {
bufferIndex += BUFFER_SIZE;
}
}
}