/*
 * libmad - MPEG audio decoder library
 * Copyright (C) 2000-2004 Underbit Technologies, Inc.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * $Id: layer12.c,v 1.17 2004/02/05 09:02:39 rob Exp $
 */

#ifdef HAVE_CONFIG_H
  #include "config.h"
#endif

#include "global.h"

#ifdef HAVE_LIMITS_H
  #include <limits.h>
#else
  #define CHAR_BIT 8
#endif

#include "bit.h"
#include "fixed.h"
#include "frame.h"
#include "layer12.h"
#include "stream.h"

/*
 * scalefactor table
 * used in both Layer I and Layer II decoding
 */
static const mad_fixed_t sf_table[64] = {
#include "sf_table.dat"
};

/* --- Layer I ------------------------------------------------------------- */

/* linear scaling table */
static const mad_fixed_t linear_table[14] = {
	MAD_F(0x15555555), /* 2^2  / (2^2  - 1) == 1.33333333333333 */
	MAD_F(0x12492492), /* 2^3  / (2^3  - 1) == 1.14285714285714 */
	MAD_F(0x11111111), /* 2^4  / (2^4  - 1) == 1.06666666666667 */
	MAD_F(0x10842108), /* 2^5  / (2^5  - 1) == 1.03225806451613 */
	MAD_F(0x10410410), /* 2^6  / (2^6  - 1) == 1.01587301587302 */
	MAD_F(0x10204081), /* 2^7  / (2^7  - 1) == 1.00787401574803 */
	MAD_F(0x10101010), /* 2^8  / (2^8  - 1) == 1.00392156862745 */
	MAD_F(0x10080402), /* 2^9  / (2^9  - 1) == 1.00195694716243 */
	MAD_F(0x10040100), /* 2^10 / (2^10 - 1) == 1.00097751710655 */
	MAD_F(0x10020040), /* 2^11 / (2^11 - 1) == 1.00048851978505 */
	MAD_F(0x10010010), /* 2^12 / (2^12 - 1) == 1.00024420024420 */
	MAD_F(0x10008004), /* 2^13 / (2^13 - 1) == 1.00012208521548 */
	MAD_F(0x10004001), /* 2^14 / (2^14 - 1) == 1.00006103888177 */
	MAD_F(0x10002000)  /* 2^15 / (2^15 - 1) == 1.00003051850948 */
};

/*
 * NAME:	I_sample()
 * DESCRIPTION:	decode one requantized Layer I sample from a bitstream
 */
static mad_fixed_t I_sample(struct mad_bitptr* ptr, unsigned int nb)
{
	mad_fixed_t sample;

	sample = mad_bit_read(ptr, nb);

	/* invert most significant bit, extend sign, then scale to fixed format */

	sample ^= 1 << (nb - 1);
	sample |= -(sample & (1 << (nb - 1)));

	sample <<= MAD_F_FRACBITS - (nb - 1);

	/* requantize the sample */

	/* s'' = (2^nb / (2^nb - 1)) * (s''' + 2^(-nb + 1)) */

	sample += MAD_F_ONE >> (nb - 1);

	return mad_f_mul(sample, linear_table[nb - 2]);

	/* s' = factor * s'' */
	/* (to be performed by caller) */
}

/*
 * NAME:	layer->I()
 * DESCRIPTION:	decode a single Layer I frame
 */
int mad_layer_I(struct mad_stream* stream, struct mad_frame* frame)
{
	struct mad_header* header = &frame->header;
	unsigned int	   nch, bound, ch, s, sb, nb;
	unsigned char	   allocation[2][32], scalefactor[2][32];

	nch = MAD_NCHANNELS(header);

	bound = 32;
	if (header->mode == MAD_MODE_JOINT_STEREO)
	{
		header->flags |= MAD_FLAG_I_STEREO;
		bound = 4 + header->mode_extension * 4;
	}

	/* check CRC word */

	if (header->flags & MAD_FLAG_PROTECTION)
	{
		header->crc_check = mad_bit_crc(stream->ptr, 4 * (bound * nch + (32 - bound)), header->crc_check);

		if (header->crc_check != header->crc_target && !(frame->options & MAD_OPTION_IGNORECRC))
		{
			stream->error = MAD_ERROR_BADCRC;
			return -1;
		}
	}

	/* decode bit allocations */

	for (sb = 0; sb < bound; ++sb)
	{
		for (ch = 0; ch < nch; ++ch)
		{
			nb = mad_bit_read(&stream->ptr, 4);

			if (nb == 15)
			{
				stream->error = MAD_ERROR_BADBITALLOC;
				return -1;
			}

			allocation[ch][sb] = nb ? nb + 1 : 0;
		}
	}

	for (sb = bound; sb < 32; ++sb)
	{
		nb = mad_bit_read(&stream->ptr, 4);

		if (nb == 15)
		{
			stream->error = MAD_ERROR_BADBITALLOC;
			return -1;
		}

		allocation[0][sb] = allocation[1][sb] = nb ? nb + 1 : 0;
	}

	/* decode scalefactors */

	for (sb = 0; sb < 32; ++sb)
	{
		for (ch = 0; ch < nch; ++ch)
		{
			if (allocation[ch][sb])
			{
				scalefactor[ch][sb] = mad_bit_read(&stream->ptr, 6);

#if defined(OPT_STRICT)
				/*
	 * Scalefactor index 63 does not appear in Table B.1 of
	 * ISO/IEC 11172-3. Nonetheless, other implementations accept it,
	 * so we only reject it if OPT_STRICT is defined.
	 */
				if (scalefactor[ch][sb] == 63)
				{
					stream->error = MAD_ERROR_BADSCALEFACTOR;
					return -1;
				}
#endif
			}
		}
	}

	/* decode samples */

	for (s = 0; s < 12; ++s)
	{
		for (sb = 0; sb < bound; ++sb)
		{
			for (ch = 0; ch < nch; ++ch)
			{
				nb = allocation[ch][sb];
				frame->sbsample[ch][s][sb] =
					nb ? mad_f_mul(I_sample(&stream->ptr, nb), sf_table[scalefactor[ch][sb]]) : 0;
			}
		}

		for (sb = bound; sb < 32; ++sb)
		{
			if ((nb = allocation[0][sb]))
			{
				mad_fixed_t sample;

				sample = I_sample(&stream->ptr, nb);

				for (ch = 0; ch < nch; ++ch)
				{
					frame->sbsample[ch][s][sb] = mad_f_mul(sample, sf_table[scalefactor[ch][sb]]);
				}
			}
			else
			{
				for (ch = 0; ch < nch; ++ch) frame->sbsample[ch][s][sb] = 0;
			}
		}
	}

	return 0;
}

/* --- Layer II ------------------------------------------------------------ */

/* possible quantization per subband table */
static struct
{
	unsigned int		sblimit;
	const unsigned char offsets[30];
} const sbquant_table[5] = {
	/* ISO/IEC 11172-3 Table B.2a */
	{27, {7, 7, 7, 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, /* 0 */
		  3, 3, 3, 3, 3, 3, 3, 0, 0, 0, 0}},
	/* ISO/IEC 11172-3 Table B.2b */
	{30, {7, 7, 7, 6, 6, 6, 6, 6, 6, 6, 6, 3, 3, 3, 3, 3, /* 1 */
		  3, 3, 3, 3, 3, 3, 3, 0, 0, 0, 0, 0, 0, 0}},
	/* ISO/IEC 11172-3 Table B.2c */
	{8, {5, 5, 2, 2, 2, 2, 2, 2}}, /* 2 */
	/* ISO/IEC 11172-3 Table B.2d */
	{12, {5, 5, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2}}, /* 3 */
	/* ISO/IEC 13818-3 Table B.1 */
	{30, {4, 4, 4, 4, 2, 2, 2, 2, 2, 2, 2, 1, 1, 1, 1, 1, /* 4 */
		  1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}}};

/* bit allocation table */
static struct
{
	unsigned short nbal;
	unsigned short offset;
} const bitalloc_table[8] = {
	{2, 0}, /* 0 */
	{2, 3}, /* 1 */
	{3, 3}, /* 2 */
	{3, 1}, /* 3 */
	{4, 2}, /* 4 */
	{4, 3}, /* 5 */
	{4, 4}, /* 6 */
	{4, 5}	/* 7 */
};

/* offsets into quantization class table */
static const unsigned char offset_table[6][15] = {
	{0, 1, 16},											 /* 0 */
	{0, 1, 2, 3, 4, 5, 16},								 /* 1 */
	{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14},	 /* 2 */
	{0, 1, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15}, /* 3 */
	{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 16},	 /* 4 */
	{0, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16} /* 5 */
};

/* quantization class table */
static struct quantclass
{
	unsigned short nlevels;
	unsigned char  group;
	unsigned char  bits;
	mad_fixed_t	   C;
	mad_fixed_t	   D;
} const qc_table[17] = {
#include "qc_table.dat"
};

/*
 * NAME:	II_samples()
 * DESCRIPTION:	decode three requantized Layer II samples from a bitstream
 */
static void II_samples(struct mad_bitptr* ptr, struct quantclass const* quantclass, mad_fixed_t output[3])
{
	unsigned int nb, s, sample[3];

	if ((nb = quantclass->group))
	{
		unsigned int c, nlevels;

		/* degrouping */
		c		= mad_bit_read(ptr, quantclass->bits);
		nlevels = quantclass->nlevels;

		for (s = 0; s < 3; ++s)
		{
			sample[s] = c % nlevels;
			c /= nlevels;
		}
	}
	else
	{
		nb = quantclass->bits;

		for (s = 0; s < 3; ++s) sample[s] = mad_bit_read(ptr, nb);
	}

	for (s = 0; s < 3; ++s)
	{
		mad_fixed_t requantized;

		/* invert most significant bit, extend sign, then scale to fixed format */

		requantized = sample[s] ^ (1 << (nb - 1));
		requantized |= -(requantized & (1 << (nb - 1)));

		requantized <<= MAD_F_FRACBITS - (nb - 1);

		/* requantize the sample */

		/* s'' = C * (s''' + D) */

		output[s] = mad_f_mul(requantized + quantclass->D, quantclass->C);

		/* s' = factor * s'' */
		/* (to be performed by caller) */
	}
}

/*
 * NAME:	layer->II()
 * DESCRIPTION:	decode a single Layer II frame
 */
int mad_layer_II(struct mad_stream* stream, struct mad_frame* frame)
{
	struct mad_header*	 header = &frame->header;
	struct mad_bitptr	 start;
	unsigned int		 index, sblimit, nbal, nch, bound, gr, ch, s, sb;
	const unsigned char* offsets;
	unsigned char		 allocation[2][32], scfsi[2][32], scalefactor[2][32][3];
	mad_fixed_t			 samples[3];

	nch = MAD_NCHANNELS(header);

	if (header->flags & MAD_FLAG_LSF_EXT) index = 4;
	else if (header->flags & MAD_FLAG_FREEFORMAT) goto freeformat;
	else
	{
		unsigned long bitrate_per_channel;

		bitrate_per_channel = header->bitrate;
		if (nch == 2)
		{
			bitrate_per_channel /= 2;

#if defined(OPT_STRICT)
			/*
       * ISO/IEC 11172-3 allows only single channel mode for 32, 48, 56, and
       * 80 kbps bitrates in Layer II, but some encoders ignore this
       * restriction. We enforce it if OPT_STRICT is defined.
       */
			if (bitrate_per_channel <= 28000 || bitrate_per_channel == 40000)
			{
				stream->error = MAD_ERROR_BADMODE;
				return -1;
			}
#endif
		}
		else
		{ /* nch == 1 */
			if (bitrate_per_channel > 192000)
			{
				/*
	 * ISO/IEC 11172-3 does not allow single channel mode for 224, 256,
	 * 320, or 384 kbps bitrates in Layer II.
	 */
				stream->error = MAD_ERROR_BADMODE;
				return -1;
			}
		}

		if (bitrate_per_channel <= 48000) index = (header->samplerate == 32000) ? 3 : 2;
		else if (bitrate_per_channel <= 80000) index = 0;
		else
		{
		freeformat:
			index = (header->samplerate == 48000) ? 0 : 1;
		}
	}

	sblimit = sbquant_table[index].sblimit;
	offsets = sbquant_table[index].offsets;

	bound = 32;
	if (header->mode == MAD_MODE_JOINT_STEREO)
	{
		header->flags |= MAD_FLAG_I_STEREO;
		bound = 4 + header->mode_extension * 4;
	}

	if (bound > sblimit) bound = sblimit;

	start = stream->ptr;

	/* decode bit allocations */

	for (sb = 0; sb < bound; ++sb)
	{
		nbal = bitalloc_table[offsets[sb]].nbal;

		for (ch = 0; ch < nch; ++ch) allocation[ch][sb] = mad_bit_read(&stream->ptr, nbal);
	}

	for (sb = bound; sb < sblimit; ++sb)
	{
		nbal = bitalloc_table[offsets[sb]].nbal;

		allocation[0][sb] = allocation[1][sb] = mad_bit_read(&stream->ptr, nbal);
	}

	/* decode scalefactor selection info */

	for (sb = 0; sb < sblimit; ++sb)
	{
		for (ch = 0; ch < nch; ++ch)
		{
			if (allocation[ch][sb]) scfsi[ch][sb] = mad_bit_read(&stream->ptr, 2);
		}
	}

	/* check CRC word */

	if (header->flags & MAD_FLAG_PROTECTION)
	{
		header->crc_check = mad_bit_crc(start, mad_bit_length(&start, &stream->ptr), header->crc_check);

		if (header->crc_check != header->crc_target && !(frame->options & MAD_OPTION_IGNORECRC))
		{
			stream->error = MAD_ERROR_BADCRC;
			return -1;
		}
	}

	/* decode scalefactors */

	for (sb = 0; sb < sblimit; ++sb)
	{
		for (ch = 0; ch < nch; ++ch)
		{
			if (allocation[ch][sb])
			{
				scalefactor[ch][sb][0] = mad_bit_read(&stream->ptr, 6);

				switch (scfsi[ch][sb])
				{
				case 2: scalefactor[ch][sb][2] = scalefactor[ch][sb][1] = scalefactor[ch][sb][0]; break;

				case 0:
					scalefactor[ch][sb][1] = mad_bit_read(&stream->ptr, 6);
					/* fall through */

				case 1:
				case 3: scalefactor[ch][sb][2] = mad_bit_read(&stream->ptr, 6);
				}

				if (scfsi[ch][sb] & 1) scalefactor[ch][sb][1] = scalefactor[ch][sb][scfsi[ch][sb] - 1];

#if defined(OPT_STRICT)
				/*
	 * Scalefactor index 63 does not appear in Table B.1 of
	 * ISO/IEC 11172-3. Nonetheless, other implementations accept it,
	 * so we only reject it if OPT_STRICT is defined.
	 */
				if (scalefactor[ch][sb][0] == 63 || scalefactor[ch][sb][1] == 63 || scalefactor[ch][sb][2] == 63)
				{
					stream->error = MAD_ERROR_BADSCALEFACTOR;
					return -1;
				}
#endif
			}
		}
	}

	/* decode samples */

	for (gr = 0; gr < 12; ++gr)
	{
		for (sb = 0; sb < bound; ++sb)
		{
			for (ch = 0; ch < nch; ++ch)
			{
				if ((index = allocation[ch][sb]))
				{
					index = offset_table[bitalloc_table[offsets[sb]].offset][index - 1];

					II_samples(&stream->ptr, &qc_table[index], samples);

					for (s = 0; s < 3; ++s)
					{
						frame->sbsample[ch][3 * gr + s][sb] =
							mad_f_mul(samples[s], sf_table[scalefactor[ch][sb][gr / 4]]);
					}
				}
				else
				{
					for (s = 0; s < 3; ++s) frame->sbsample[ch][3 * gr + s][sb] = 0;
				}
			}
		}

		for (sb = bound; sb < sblimit; ++sb)
		{
			if ((index = allocation[0][sb]))
			{
				index = offset_table[bitalloc_table[offsets[sb]].offset][index - 1];

				II_samples(&stream->ptr, &qc_table[index], samples);

				for (ch = 0; ch < nch; ++ch)
				{
					for (s = 0; s < 3; ++s)
					{
						frame->sbsample[ch][3 * gr + s][sb] =
							mad_f_mul(samples[s], sf_table[scalefactor[ch][sb][gr / 4]]);
					}
				}
			}
			else
			{
				for (ch = 0; ch < nch; ++ch)
				{
					for (s = 0; s < 3; ++s) frame->sbsample[ch][3 * gr + s][sb] = 0;
				}
			}
		}

		for (ch = 0; ch < nch; ++ch)
		{
			for (s = 0; s < 3; ++s)
			{
				for (sb = sblimit; sb < 32; ++sb) frame->sbsample[ch][3 * gr + s][sb] = 0;
			}
		}
	}

	return 0;
}