/*
 * common.c: some common bitstream operations
 *
 * Copyright (C) 1999-2010 The L.A.M.E. project
 *
 * Initially written by Michael Hipp, see also AUTHORS and README.
 *  
 * This library 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 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library 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.
 */

/* $Id: Common.java,v 1.6 2011/08/27 18:57:09 kenchis Exp $ */

package mpg;

import mpg.MPGLib.mpstr_tag;

public class Common {

	public static final int tabsel_123[][][] = {
		   { {0,32,64,96,128,160,192,224,256,288,320,352,384,416,448,},
			     {0,32,48,56, 64, 80, 96,112,128,160,192,224,256,320,384,},
			     {0,32,40,48, 56, 64, 80, 96,112,128,160,192,224,256,320,} },

			   { {0,32,48,56,64,80,96,112,128,144,160,176,192,224,256,},
			     {0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,},
			     {0,8,16,24,32,40,48,56,64,80,96,112,128,144,160,} }
	};

	public static final int freqs[] = { 44100, 48000, 32000, 22050, 24000,
			16000, 11025, 12000, 8000 };

	public float muls[][] = new float[27][64];

	private static final int MAX_INPUT_FRAMESIZE = 4096;

	public final boolean head_check(final long head, final int check_layer) {
		/**
		 * <PRE>
		 * look for a valid header.  
		 * if check_layer > 0, then require that
		 * nLayer = check_layer.
		 * </PRE>
		 */

		/* bits 13-14 = layer 3 */
		int nLayer = (int) (4 - ((head >> 17) & 3));

		if ((head & 0xffe00000L) != 0xffe00000L) {
			/* syncword */
			return false;
		}

		if (nLayer == 4)
			return false;

		if (check_layer > 0 && nLayer != check_layer)
			return false;

		if (((head >> 12) & 0xf) == 0xf) {
			/* bits 16,17,18,19 = 1111 invalid bitrate */
			return false;
		}
		if (((head >> 10) & 0x3) == 0x3) {
			/* bits 20,21 = 11 invalid sampling freq */
			return false;
		}
		if ((head & 0x3) == 0x2)
			/* invalid emphasis */
			return false;
		return true;
	}

	/**
	 * decode a header and write the information into the frame structure
	 */
	public final int decode_header(final Frame fr, final long newhead) {

		if ((newhead & (1 << 20)) != 0) {
			fr.lsf = (newhead & (1 << 19)) != 0 ? 0x0 : 0x1;
			fr.mpeg25 = false;
		} else {
			fr.lsf = 1;
			fr.mpeg25 = true;
		}

		fr.lay = (int) (4 - ((newhead >> 17) & 3));
		if (((newhead >> 10) & 0x3) == 0x3) {
			throw new RuntimeException("Stream error");
		}
		if (fr.mpeg25) {
			fr.sampling_frequency = (int) (6 + ((newhead >> 10) & 0x3));
		} else
			fr.sampling_frequency = (int) (((newhead >> 10) & 0x3) + (fr.lsf * 3));

		fr.error_protection = ((newhead >> 16) & 0x1) == 0;

		if (fr.mpeg25) /* allow Bitrate change for 2.5 ... */
			fr.bitrate_index = (int) ((newhead >> 12) & 0xf);

		fr.bitrate_index = (int) ((newhead >> 12) & 0xf);
		fr.padding = (int) ((newhead >> 9) & 0x1);
		fr.extension = (int) ((newhead >> 8) & 0x1);
		fr.mode = (int) ((newhead >> 6) & 0x3);
		fr.mode_ext = (int) ((newhead >> 4) & 0x3);
		fr.copyright = (int) ((newhead >> 3) & 0x1);
		fr.original = (int) ((newhead >> 2) & 0x1);
		fr.emphasis = (int) (newhead & 0x3);

		fr.stereo = (fr.mode == MPG123.MPG_MD_MONO) ? 1 : 2;

		switch (fr.lay) {
		case 1:
			fr.framesize = tabsel_123[fr.lsf][0][fr.bitrate_index] * 12000;
			fr.framesize /= freqs[fr.sampling_frequency];
			fr.framesize = ((fr.framesize + fr.padding) << 2) - 4;
			fr.down_sample = 0;
			fr.down_sample_sblimit = MPG123.SBLIMIT >> (fr.down_sample);
			break;

		case 2:
			fr.framesize = tabsel_123[fr.lsf][1][fr.bitrate_index] * 144000;
			fr.framesize /= freqs[fr.sampling_frequency];
			fr.framesize += fr.padding - 4;
			fr.down_sample = 0;
			fr.down_sample_sblimit = MPG123.SBLIMIT >> (fr.down_sample);
			break;

		case 3:
			if (fr.framesize > MAX_INPUT_FRAMESIZE) {
				System.err.printf("Frame size too big.\n");
				fr.framesize = MAX_INPUT_FRAMESIZE;
				return (0);
			}

			if (fr.bitrate_index == 0)
				fr.framesize = 0;
			else {
				fr.framesize = tabsel_123[fr.lsf][2][fr.bitrate_index] * 144000;
				fr.framesize /= freqs[fr.sampling_frequency] << (fr.lsf);
				fr.framesize = fr.framesize + fr.padding - 4;
			}
			break;
		default:
			System.err.printf("Sorry, layer %d not supported\n", fr.lay);
			return (0);
		}
		/* print_header(fr); */

		return 1;
	}

	private static final String modes[] = { "Stereo", "Joint-Stereo",
			"Dual-Channel", "Single-Channel" };
	private static final String layers[] = { "Unknown", "I", "II", "III" };

	public final void print_header(final Frame fr) {

		System.err
				.printf("MPEG %s, Layer: %s, Freq: %d, mode: %s, modext: %d, BPF : %d\n",
						fr.mpeg25 ? "2.5" : (fr.lsf != 0 ? "2.0" : "1.0"),
						layers[fr.lay], freqs[fr.sampling_frequency],
						modes[fr.mode], fr.mode_ext, fr.framesize + 4);
		System.err
				.printf("Channels: %d, copyright: %s, original: %s, CRC: %s, emphasis: %d.\n",
						fr.stereo, fr.copyright != 0 ? "Yes" : "No",
						fr.original != 0 ? "Yes" : "No",
						fr.error_protection ? "Yes" : "No", fr.emphasis);
		System.err.printf("Bitrate: %d Kbits/s, Extension value: %d\n",
				tabsel_123[fr.lsf][fr.lay - 1][fr.bitrate_index], fr.extension);
	}

	public final void print_header_compact(final Frame fr) {
		System.err.printf("MPEG %s layer %s, %d kbit/s, %d Hz %s\n",
				fr.mpeg25 ? "2.5" : (fr.lsf != 0 ? "2.0" : "1.0"),
				layers[fr.lay],
				tabsel_123[fr.lsf][fr.lay - 1][fr.bitrate_index],
				freqs[fr.sampling_frequency], modes[fr.mode]);
	}

	public final int getbits(final mpstr_tag mp, final int number_of_bits) {
		long rval;

		if (number_of_bits <= 0 || null == mp.wordpointer)
			return 0;

		{
			rval = mp.wordpointer[mp.wordpointerPos + 0] & 0xff;
			rval <<= 8;
			rval |= mp.wordpointer[mp.wordpointerPos + 1] & 0xff;
			rval <<= 8;
			rval |= mp.wordpointer[mp.wordpointerPos + 2] & 0xff;
			rval <<= mp.bitindex;
			rval &= 0xffffffL;

			mp.bitindex += number_of_bits;

			rval >>= (24 - number_of_bits);

			mp.wordpointerPos += (mp.bitindex >> 3);
			mp.bitindex &= 7;
		}
		return (int) rval;
	}

	public final int getbits_fast(final mpstr_tag mp, final int number_of_bits) {
		long rval;

		{
			rval = mp.wordpointer[mp.wordpointerPos + 0] & 0xff;
			rval <<= 8;
			rval |= mp.wordpointer[mp.wordpointerPos + 1] & 0xff;
			rval <<= mp.bitindex;
			rval &= 0xffffL;
			mp.bitindex += number_of_bits;

			rval >>= (16 - number_of_bits);

			mp.wordpointerPos += (mp.bitindex >> 3);
			mp.bitindex &= 7;
		}
		return (int) rval;
	}

	public final int set_pointer(final mpstr_tag mp, final int backstep) {
		if (mp.fsizeold < 0 && backstep > 0) {
			System.err.printf("hip: Can't step back %d bytes!\n", backstep);
			return MPGLib.MP3_ERR;
		}
		byte[] bsbufold = mp.bsspace[1 - mp.bsnum];
		int bsbufoldPos = 512;
		mp.wordpointerPos -= backstep;
		if (backstep != 0)
			System.arraycopy(bsbufold, bsbufoldPos + mp.fsizeold - backstep,
					mp.wordpointer, mp.wordpointerPos, backstep);
		mp.bitindex = 0;
		return MPGLib.MP3_OK;
	}
}