layer2.cpp

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#include "mpg123.h"
#include "l2tables.h"

static int grp_3tab[32 * 3] = { 0, };   
static int grp_5tab[128 * 3] = { 0, };  
static int grp_9tab[1024 * 3] = { 0, }; 

real muls[27][64];	


/**
 *
 **/

void init_layer2(void)
{
	static double mulmul[27] = {
		0.0 , -2.0/3.0 , 2.0/3.0 ,
		2.0/7.0 , 2.0/15.0 , 2.0/31.0, 2.0/63.0 , 2.0/127.0 , 2.0/255.0 ,
		2.0/511.0 , 2.0/1023.0 , 2.0/2047.0 , 2.0/4095.0 , 2.0/8191.0 ,
		2.0/16383.0 , 2.0/32767.0 , 2.0/65535.0 ,
		-4.0/5.0 , -2.0/5.0 , 2.0/5.0, 4.0/5.0 ,
		-8.0/9.0 , -4.0/9.0 , -2.0/9.0 , 2.0/9.0 , 4.0/9.0 , 8.0/9.0 };
	static int base[3][9] = {
		{ 1 , 0, 2 , } ,
		{ 17, 18, 0 , 19, 20 , } ,
		{ 21, 1, 22, 23, 0, 24, 25, 2, 26 } };
	int i,j,k,l,len;
	real *table;
	static int tablen[3] = { 3 , 5 , 9 };
	static int *itable,*tables[3] = { grp_3tab , grp_5tab , grp_9tab };

	for(i=0;i<3;i++) {
		itable = tables[i];
		len = tablen[i];

		for(j=0;j<len;j++) {
			for(k=0;k<len;k++) {
				for(l=0;l<len;l++) {
					*itable++ = base[i][l];
					*itable++ = base[i][k];
					*itable++ = base[i][j];
				}
			}
		}
	}

	for(k=0;k<27;k++) {
		double m=mulmul[k];
		table = muls[k];
		for(j=3,i=0;i<63;i++,j--)
			*table++ = m * pow(2.0,(double) j / 3.0);
		*table++ = 0.0;
	}
}


/**
 *
 **/

static void II_step_one (unsigned int *bit_alloc,int *scale,struct frame *fr)
{
	int stereo = fr->stereo-1;
	int sblimit = fr->II_sblimit;
	int jsbound = fr->jsbound;
	int sblimit2 = fr->II_sblimit<<stereo;
	struct al_table *alloc1 = (struct al_table *) fr->alloc;
	int i;
	static unsigned int scfsi_buf[64];
	unsigned int *scfsi,*bita;
	int sc,step;

	bita = bit_alloc;

	if (stereo) {
		for (i=jsbound;i;i--,alloc1+=(1<<step)) {
			*bita++ = (char) getbits(step=alloc1->bits);
			*bita++ = (char) getbits(step);
		}

		for (i=sblimit-jsbound;i;i--,alloc1+=(1<<step)) {
			bita[0] = (char) getbits(step=alloc1->bits);
			bita[1] = bita[0];
			bita+=2;
		}

		bita = bit_alloc;
		scfsi=scfsi_buf;
		for (i=sblimit2;i;i--)
			if (*bita++)
				*scfsi++ = (char) getbits_fast(2);
		} else { /* mono */
			for (i=sblimit;i;i--,alloc1+=(1<<step))
				*bita++ = (char) getbits(step=alloc1->bits);
			bita = bit_alloc;
			scfsi=scfsi_buf;
			for (i=sblimit;i;i--)
				if (*bita++)
					*scfsi++ = (char) getbits_fast(2);
		}

		bita = bit_alloc;
		scfsi=scfsi_buf;
		for (i=sblimit2;i;i--) {
			if (*bita++) {
				switch (*scfsi++) {
				case 0: 
					*scale++ = getbits_fast(6);
					*scale++ = getbits_fast(6);
					*scale++ = getbits_fast(6);
					break;
				case 1 : 
					*scale++ = sc = getbits_fast(6);
					*scale++ = sc;
					*scale++ = getbits_fast(6);
					break;
				case 2: 
					*scale++ = sc = getbits_fast(6);
					*scale++ = sc;
					*scale++ = sc;
					break;
				case 3:
          			default:
					*scale++ = getbits_fast(6);
					*scale++ = sc = getbits_fast(6);
					*scale++ = sc;
					break;
			}
		}
        }
}


/**
 *
 **/

static void II_step_two (unsigned int *bit_alloc,real fraction[2][4][SBLIMIT],int *scale,struct frame *fr,int x1)
{
	int i,j,k,ba;
	int stereo = fr->stereo;
	int sblimit = fr->II_sblimit;
	int jsbound = fr->jsbound;
	struct al_table *alloc2,*alloc1 = (struct al_table *) fr->alloc;
	unsigned int *bita=bit_alloc;
	int d1,step;

	for (i=0;i<jsbound;i++,alloc1+=(1<<step)) {
		step = alloc1->bits;
		for (j=0;j<stereo;j++) {
			if ((ba=*bita++)) {
				k=(alloc2 = alloc1+ba)->bits;
				if( (d1=alloc2->d) < 0) {
					real cm=muls[k][scale[x1]];
					fraction[j][0][i] = ((real) ((int)getbits(k) + d1)) * cm;
					fraction[j][1][i] = ((real) ((int)getbits(k) + d1)) * cm;
					fraction[j][2][i] = ((real) ((int)getbits(k) + d1)) * cm;
				} else {
					static int *table[] = { 0,0,0,grp_3tab,0,grp_5tab,0,0,0,grp_9tab };
					unsigned int idx,*tab,m=scale[x1];
					idx = (unsigned int) getbits(k);
					tab = (unsigned int *) (table[d1] + idx + idx + idx);
					fraction[j][0][i] = muls[*tab++][m];
					fraction[j][1][i] = muls[*tab++][m];
					fraction[j][2][i] = muls[*tab][m];  
				}
				scale+=3;
			} else
				fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;
		}
	}

	for (i=jsbound;i<sblimit;i++,alloc1+=(1<<step)) {
		step = alloc1->bits;
		bita++;	

		if ((ba=*bita++)) {
			k=(alloc2 = alloc1+ba)->bits;
			if( (d1=alloc2->d) < 0) {
				real cm;
				cm=muls[k][scale[x1+3]];
				fraction[1][0][i] = (fraction[0][0][i] = (real) ((int)getbits(k) + d1) ) * cm;
				fraction[1][1][i] = (fraction[0][1][i] = (real) ((int)getbits(k) + d1) ) * cm;
				fraction[1][2][i] = (fraction[0][2][i] = (real) ((int)getbits(k) + d1) ) * cm;
				cm=muls[k][scale[x1]];
				fraction[0][0][i] *= cm; fraction[0][1][i] *= cm; fraction[0][2][i] *= cm;
			} else {
				static int *table[] = { 0,0,0,grp_3tab,0,grp_5tab,0,0,0,grp_9tab };
				unsigned int idx,*tab,m1,m2;
				m1 = scale[x1]; m2 = scale[x1+3];
				idx = (unsigned int) getbits(k);
				tab = (unsigned int *) (table[d1] + idx + idx + idx);
				fraction[0][0][i] = muls[*tab][m1]; fraction[1][0][i] = muls[*tab++][m2];
				fraction[0][1][i] = muls[*tab][m1]; fraction[1][1][i] = muls[*tab++][m2];
				fraction[0][2][i] = muls[*tab][m1]; fraction[1][2][i] = muls[*tab][m2];
			}
			scale+=6;
		} else
			fraction[0][0][i] = fraction[0][1][i] = fraction[0][2][i] = fraction[1][0][i] = fraction[1][1][i] = fraction[1][2][i] = 0.0;

	}

	for(i=sblimit;i<SBLIMIT;i++)
		for (j=0;j<stereo;j++)
			fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;
}


/**
 *
 **/

static void II_select_table(struct frame *fr)
{
	static int translate[3][2][16] =
   { { { 0,2,2,2,2,2,2,0,0,0,1,1,1,1,1,0 } ,
       { 0,2,2,0,0,0,1,1,1,1,1,1,1,1,1,0 } } ,
     { { 0,2,2,2,2,2,2,0,0,0,0,0,0,0,0,0 } ,
       { 0,2,2,0,0,0,0,0,0,0,0,0,0,0,0,0 } } ,
     { { 0,3,3,3,3,3,3,0,0,0,1,1,1,1,1,0 } ,
       { 0,3,3,0,0,0,1,1,1,1,1,1,1,1,1,0 } } };

	int table,sblim;
	static struct al_table *tables[5] =
		{ alloc_0, alloc_1, alloc_2, alloc_3 , alloc_4 };
	static int sblims[5] = { 27 , 30 , 8, 12 , 30 };

	if(fr->lsf)
		table = 4;
	else
		table = translate[fr->sampling_frequency][2-fr->stereo][fr->bitrate_index];
	sblim = sblims[table];

	fr->alloc      = tables[table];
	fr->II_sblimit = sblim;
}


/**
 *
 **/

int do_layer2 (struct frame *fr,unsigned char *pcm_sample,int *pcm_point)
{
	int clip=0;
	int i,j;
	int stereo = fr->stereo;
	real fraction[2][4][SBLIMIT]; 
	unsigned int bit_alloc[64];
	int scale[192];
	int single = fr->single;

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

	if(stereo == 1 || single == 3)
    		single = 0;

	II_step_one(bit_alloc, scale, fr);

	if(single >= 0) {
		for (i=0;i<SCALE_BLOCK;i++) {
    			II_step_two(bit_alloc,fraction,scale,fr,i>>2);
		
			for (j=0;j<3;j++)
				clip += synth_1to1_mono(fraction[0][j],pcm_sample,pcm_point);
		}
	} else {
		for (i=0;i<SCALE_BLOCK;i++) {
    			II_step_two(bit_alloc,fraction,scale,fr,i>>2);

			for (j=0;j<3;j++) {
				int p1 = *pcm_point;
				clip += synth_1to1(fraction[0][j],0,pcm_sample,&p1);
				clip += synth_1to1(fraction[1][j],1,pcm_sample,pcm_point);
			}
		}
	}

	return clip;
}