layer1.c File Reference

#include "mpg123lib_intern.h"
#include "getbits.h"
#include "debug.h"

Include dependency graph for layer1.c:

Go to the source code of this file.

Macros
#define	NEED_BITS(fr, num)
#define	MINUS_SHIFT(n)   ( (int)(((unsigned int)-1)<<(n)) )

Functions
static int	check_balloc (mpg123_handle *fr, unsigned int *balloc, unsigned int *end)
static int	I_step_one (unsigned int balloc[], unsigned int scale_index[2][SBLIMIT], mpg123_handle *fr)
static int	I_step_two (real fraction[2][SBLIMIT], unsigned int balloc[2 *SBLIMIT], unsigned int scale_index[2][SBLIMIT], mpg123_handle *fr)
int	do_layer1 (mpg123_handle *fr)

Macro Definition Documentation

MINUS_SHIFT

#define MINUS_SHIFT

(

n

)

( (int)(((unsigned int)-1)<<(n)) )

Definition at line 116 of file layer1.c.

NEED_BITS

#define NEED_BITS	(		fr,
			num
	)

Value:

    if((fr)->bits_avail < num) \
    { \
        if(NOQUIET) \
            error2("%u bits needed, %li available", num, (fr)->bits_avail); \
        return -1; \
    } \

Definition at line 37 of file layer1.c.

Function Documentation

check_balloc()

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

static

Definition at line 24 of file layer1.c.

{
    unsigned int *ba;
    for(ba=balloc; ba != end; ++ba)
    if(*ba == 15)
    {
        if(NOQUIET) error("Illegal bit allocation value.");
        return -1;
    }
 
    return 0;
}

Referenced by I_step_one().

do_layer1()

int do_layer1

(

mpg123_handle *

fr

)

Definition at line 211 of file layer1.c.

{
    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.");
        return clip;
    }
 
    for(i=0;i<SCALE_BLOCK;i++)
    {
        if(I_step_two(fraction,balloc,scale_index,fr))
        {
            if(NOQUIET)
                error("Aborting layer I decoding after step two.");
            return clip;
        }
 
        if(single != SINGLE_STEREO)
        clip += (fr->synth_mono)(fraction[single], fr);
        else
        clip += (fr->synth_stereo)(fraction[0], fraction[1], fr);
    }
 
    return clip;
}

I_step_one()

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

static

Definition at line 45 of file layer1.c.

{
    unsigned int *ba=balloc;
    unsigned int *sca = (unsigned int *) scale_index;
 
    if(fr->stereo == 2)
    {
        int i;
        int jsbound = fr->jsbound;
        unsigned int needbits = jsbound*2*4 + (SBLIMIT-jsbound)*4;
 
        NEED_BITS(fr, needbits);
        needbits = 0;
        for(i=0;i<jsbound;i++)
        {
            ba[0] = getbits_fast(fr, 4);
            ba[1] = getbits_fast(fr, 4);
            needbits += ((ba[0]?1:0)+(ba[1]?1:0))*6;
            ba+=2;
        }
        for(i=jsbound;i<SBLIMIT;i++)
        {
            *ba = getbits_fast(fr, 4);
            needbits += (*ba?1:0)*12;
            ++ba;
        }
 
        if(check_balloc(fr, balloc, ba)) return -1;
 
        ba = balloc;
        NEED_BITS(fr, needbits)
        for(i=0;i<jsbound;i++)
        {
            if ((*ba++))
                *sca++ = getbits_fast(fr, 6);
            if ((*ba++))
                *sca++ = getbits_fast(fr, 6);
        }
        for (i=jsbound;i<SBLIMIT;i++) if((*ba++))
        {
            *sca++ =  getbits_fast(fr, 6);
            *sca++ =  getbits_fast(fr, 6);
        }
    }
    else
    {
        int i;
        unsigned int needbits = SBLIMIT*4;
 
        NEED_BITS(fr, needbits)
        needbits = 0;
        for(i=0;i<SBLIMIT;i++)
        {
            *ba = getbits_fast(fr, 4);
            needbits += (*ba?1:0)*6;
            ++ba;
        }
 
        if(check_balloc(fr, balloc, ba)) return -1;
 
        ba = balloc;
        NEED_BITS(fr, needbits)
        for (i=0;i<SBLIMIT;i++)
            if ((*ba++))
                *sca++ = getbits_fast(fr, 6);
    }
 
    return 0;
}

Referenced by do_layer1().

I_step_two()

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

static

Definition at line 118 of file layer1.c.

{
    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)
    {
        unsigned int needbits = 0;
        int jsbound = fr->jsbound;
        register real *f0 = fraction[0];
        register real *f1 = fraction[1];
 
        ba = balloc;
        for(sample=smpb,i=0;i<jsbound;i++)
        {
            if((n=*ba++))
                needbits += n+1;
            if((n=*ba++))
                needbits += n+1;
        }
        for(i=jsbound;i<SBLIMIT;i++)
            if((n = *ba++))
                needbits += n+1;
        NEED_BITS(fr, needbits)
 
        ba = balloc;
        for(sample=smpb,i=0;i<jsbound;i++)
        {
            if((n = *ba++)) *sample++ = getbits(fr, n+1);
 
            if((n = *ba++)) *sample++ = getbits(fr, n+1);
        }
        for(i=jsbound;i<SBLIMIT;i++)
        if((n = *ba++))
        *sample++ = getbits(fr, n+1);
 
        ba = balloc;
        for(sample=smpb,i=0;i<jsbound;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<SBLIMIT;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
    {
        unsigned int needbits = 0;
        register real *f0 = fraction[0];
 
        ba = balloc;
        for(sample=smpb,i=0;i<SBLIMIT;i++)
            if((n = *ba++))
                needbits += n+1;
        NEED_BITS(fr, needbits);
 
        ba = balloc;
        for(sample=smpb,i=0;i<SBLIMIT;i++)
        if ((n = *ba++))
        *sample++ = getbits(fr, n+1);
 
 
        ba = balloc;
        for(sample=smpb,i=0;i<SBLIMIT;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);
    }
    return 0;
}

Referenced by do_layer1().