/*

	layer1.c: the layer 1 decoder

	copyright 1995-2009 by the mpg123 project - free software under the terms of the LGPL 2.1

	see COPYING and AUTHORS files in distribution or http://mpg123.org

	initially written by Michael Hipp

	may have a few bugs after last optimization ... 

*/

#include "mpg123lib_intern.h"

#include "getbits.h"

#include "debug.h"

/*

	Allocation value is not allowed to be 15. Initially, libmad showed me the

	error that mpg123 used to ignore. Then, I found a quote on that in

	Shlien, S. (1994): Guide to MPEG-1 Audio Standard. 

	IEEE Transactions on Broadcasting 40, 4

	"To avoid conflicts with the synchronization code, code '1111' is defined

	to be illegal."

*/

static int check_balloc(mpg123_handle *fr, unsigned int *balloc, unsigned int *end)

{

	unsigned int *ba;

	for(ba=balloc; ba != end; ++ba)

	if(*ba == 15)

	{

		if(NOQUIET) error("Illegal bit allocation value.");

		return -1;

	}

	return 0;

}

static int I_step_one(unsigned int balloc[], unsigned int scale_index[2][SBLIMIT],mpg123_handle *fr)

{

	unsigned int *ba=balloc;

	unsigned int *sca = (unsigned int *) scale_index;

	if(fr->stereo == 2)

	{

		int i;

		int jsbound = fr->jsbound;

		for(i=0;i

		{

			*ba++ = getbits(fr, 4);

			*ba++ = getbits(fr, 4);

		}

		for(i=jsbound;i

		if(check_balloc(fr, balloc, ba)) return -1;

		ba = balloc;

		for(i=0;i

		{

			if ((*ba++))

				*sca++ = getbits(fr, 6);

			if ((*ba++))

				*sca++ = getbits(fr, 6);

		}

		for (i=jsbound;i

		if((*ba++))

		{

			*sca++ =  getbits(fr, 6);

			*sca++ =  getbits(fr, 6);

		}

	}

	else

	{

		int i;

		for(i=0;i

		if(check_balloc(fr, balloc, ba)) return -1;

		ba = balloc;

		for (i=0;i

		if ((*ba++))

		*sca++ = getbits(fr, 6);

	}

	return 0;

}

/* Something sane in place of undefined (-1)<

#define MINUS_SHIFT(n) ( (int)(((unsigned int)-1)<<(n)) )

static void I_step_two(real fraction[2][SBLIMIT],unsigned int balloc[2*SBLIMIT], unsigned int scale_index[2][SBLIMIT],mpg123_handle *fr)

{

	int i,n;

	int smpb[2*SBLIMIT]; /* values: 0-65535 */

	int *sample;

	register unsigned int *ba;

	register unsigned int *sca = (unsigned int *) scale_index;

	if(fr->stereo == 2)

	{

		int jsbound = fr->jsbound;

		register real *f0 = fraction[0];

		register real *f1 = fraction[1];

		ba = balloc;

		for(sample=smpb,i=0;i

		{

			if((n = *ba++)) *sample++ = getbits(fr, n+1);

			if((n = *ba++)) *sample++ = getbits(fr, n+1);

		}

		for(i=jsbound;i

		if((n = *ba++))

		*sample++ = getbits(fr, n+1);

		ba = balloc;

		for(sample=smpb,i=0;i

		{

			if((n=*ba++))

			*f0++ = REAL_MUL_SCALE_LAYER12(DOUBLE_TO_REAL_15(MINUS_SHIFT(n) + (*sample++) + 1), fr->muls[n+1][*sca++]);

			else *f0++ = DOUBLE_TO_REAL(0.0);

			if((n=*ba++))

			*f1++ = REAL_MUL_SCALE_LAYER12(DOUBLE_TO_REAL_15(MINUS_SHIFT(n) + (*sample++) + 1), fr->muls[n+1][*sca++]);

			else *f1++ = DOUBLE_TO_REAL(0.0);

		}

		for(i=jsbound;i

		{

			if((n=*ba++))

			{

				real samp = DOUBLE_TO_REAL_15(MINUS_SHIFT(n) + (*sample++) + 1);

				*f0++ = REAL_MUL_SCALE_LAYER12(samp, fr->muls[n+1][*sca++]);

				*f1++ = REAL_MUL_SCALE_LAYER12(samp, fr->muls[n+1][*sca++]);

			}

			else *f0++ = *f1++ = DOUBLE_TO_REAL(0.0);

		}

		for(i=fr->down_sample_sblimit;i<32;i++)

		fraction[0][i] = fraction[1][i] = 0.0;

	}

	else

	{

		register real *f0 = fraction[0];

		ba = balloc;

		for(sample=smpb,i=0;i

		if ((n = *ba++))

		*sample++ = getbits(fr, n+1);

		ba = balloc;

		for(sample=smpb,i=0;i

		{

			if((n=*ba++))

			*f0++ = REAL_MUL_SCALE_LAYER12(DOUBLE_TO_REAL_15(MINUS_SHIFT(n) + (*sample++) + 1), fr->muls[n+1][*sca++]);

			else *f0++ = DOUBLE_TO_REAL(0.0);

		}

		for(i=fr->down_sample_sblimit;i<32;i++)

		fraction[0][i] = DOUBLE_TO_REAL(0.0);

	}

}

int do_layer1(mpg123_handle *fr)

{

	int clip=0;

	int i,stereo = fr->stereo;

	unsigned int balloc[2*SBLIMIT];

	unsigned int scale_index[2][SBLIMIT];

	real (*fraction)[SBLIMIT] = fr->layer1.fraction; /* fraction[2][SBLIMIT] */

	int single = fr->single;

	fr->jsbound = (fr->mode == MPG_MD_JOINT_STEREO) ? (fr->mode_ext<<2)+4 : 32;

	if(stereo == 1 || single == SINGLE_MIX) /* I don't see mixing handled here */

	single = SINGLE_LEFT;

	if(I_step_one(balloc,scale_index,fr))

	{

		if(NOQUIET) error("Aborting layer I decoding after step one.\n");

		return clip;

	}

	for(i=0;i

	{

		I_step_two(fraction,balloc,scale_index,fr);

		if(single != SINGLE_STEREO)

		clip += (fr->synth_mono)(fraction[single], fr);

		else

		clip += (fr->synth_stereo)(fraction[0], fraction[1], fr);

	}

	return clip;

}