/*

  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 "../common/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;

}

#define NEED_BITS(fr, num) \

  if((fr)->bits_avail < num) \

  { \

    if(NOQUIET) \

      error2("%u bits needed, %li available", num, (fr)->bits_avail); \

    return -1; \

  } \

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;

    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;

}

/* Something sane in place of undefined (-1)<<n. Well, not really. */

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

static int 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)

  {

    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;

}

int INT123_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->hdr.mode == MPG_MD_JOINT_STEREO) ? (fr->hdr.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;

}