MAD_F_MLA(hi, lo, X[14],  MAD_F(0x0bcbe352));  MAD_F_MLA(hi, lo, X[15], -MAD_F(0x04cfb0e2));  MAD_F_MLA(hi, lo, X[17], -MAD_F(0x0898c779));  x[20] = x[33] = MAD_F_MLZ(hi, lo) - t3;  MAD_F_ML0(hi, lo, t14, -MAD_F(0x0ec835e8));  MAD_F_MLA(hi, lo, t15,  MAD_F(0x061f78aa));  t4 = MAD_F_MLZ(hi, lo) - t7;  MAD_F_ML0(hi, lo, t12, MAD_F(0x061f78aa));  MAD_F_MLA(hi, lo, t13, MAD_F(0x0ec835e8));  x[4]  = MAD_F_MLZ(hi, lo) + t4;  x[13] = -x[4];  MAD_F_ML0(hi, lo, t8,   MAD_F(0x09bd7ca0));  MAD_F_MLA(hi, lo, t9,  -MAD_F(0x0216a2a2));  MAD_F_MLA(hi, lo, t10,  MAD_F(0x0fdcf549));  MAD_F_MLA(hi, lo, t11, -MAD_F(0x0cb19346));  x[1]  = MAD_F_MLZ(hi, lo) + t4;  x[16] = -x[1];  MAD_F_ML0(hi, lo, t8,  -MAD_F(0x0fdcf549));  MAD_F_MLA(hi, lo, t9,  -MAD_F(0x0cb19346));  MAD_F_MLA(hi, lo, t10, -MAD_F(0x09bd7ca0));  MAD_F_MLA(hi, lo, t11, -MAD_F(0x0216a2a2));  x[25] = x[28] = MAD_F_MLZ(hi, lo) + t4;  MAD_F_ML0(hi, lo, X[1],  -MAD_F(0x0fdcf549));  MAD_F_MLA(hi, lo, X[7],  -MAD_F(0x0cb19346));  MAD_F_MLA(hi, lo, X[10], -MAD_F(0x09bd7ca0));  MAD_F_MLA(hi, lo, X[16], -MAD_F(0x0216a2a2));  t5 = MAD_F_MLZ(hi, lo) - t6;  MAD_F_ML0(hi, lo, X[0],   MAD_F(0x0898c779));  MAD_F_MLA(hi, lo, X[2],   MAD_F(0x04cfb0e2));  MAD_F_MLA(hi, lo, X[3],   MAD_F(0x0bcbe352));  MAD_F_MLA(hi, lo, X[5],   MAD_F(0x00b2aa3e));  MAD_F_MLA(hi, lo, X[6],   MAD_F(0x0e313245));  MAD_F_MLA(hi, lo, X[8],  -MAD_F(0x03768962));  MAD_F_MLA(hi, lo, X[9],   MAD_F(0x0f9ee890));  MAD_F_MLA(hi, lo, X[11], -MAD_F(0x07635284));  MAD_F_MLA(hi, lo, X[12],  MAD_F(0x0ffc19fd));  MAD_F_MLA(hi, lo, X[14], -MAD_F(0x0acf37ad));  MAD_F_MLA(hi, lo, X[15],  MAD_F(0x0f426cb5));  MAD_F_MLA(hi, lo, X[17], -MAD_F(0x0d7e8807));  x[2]  = MAD_F_MLZ(hi, lo) + t5;  x[15] = -x[2];  MAD_F_ML0(hi, lo, X[0],   MAD_F(0x07635284));  MAD_F_MLA(hi, lo, X[2],   MAD_F(0x0acf37ad));  MAD_F_MLA(hi, lo, X[3],   MAD_F(0x03768962));  MAD_F_MLA(hi, lo, X[5],   MAD_F(0x0d7e8807));  MAD_F_MLA(hi, lo, X[6],  -MAD_F(0x00b2aa3e));  MAD_F_MLA(hi, lo, X[8],   MAD_F(0x0f426cb5));  MAD_F_MLA(hi, lo, X[9],  -MAD_F(0x04cfb0e2));  MAD_F_MLA(hi, lo, X[11],  MAD_F(0x0ffc19fd));  MAD_F_MLA(hi, lo, X[12], -MAD_F(0x0898c779));  MAD_F_MLA(hi, lo, X[14],  MAD_F(0x0f9ee890));  MAD_F_MLA(hi, lo, X[15], -MAD_F(0x0bcbe352));  MAD_F_MLA(hi, lo, X[17],  MAD_F(0x0e313245));  x[3]  = MAD_F_MLZ(hi, lo) + t5;  x[14] = -x[3];  MAD_F_ML0(hi, lo, X[0],  -MAD_F(0x0ffc19fd));  MAD_F_MLA(hi, lo, X[2],  -MAD_F(0x0f9ee890));  MAD_F_MLA(hi, lo, X[3],  -MAD_F(0x0f426cb5));  MAD_F_MLA(hi, lo, X[5],  -MAD_F(0x0e313245));  MAD_F_MLA(hi, lo, X[6],  -MAD_F(0x0d7e8807));  MAD_F_MLA(hi, lo, X[8],  -MAD_F(0x0bcbe352));  MAD_F_MLA(hi, lo, X[9],  -MAD_F(0x0acf37ad));  MAD_F_MLA(hi, lo, X[11], -MAD_F(0x0898c779));  MAD_F_MLA(hi, lo, X[12], -MAD_F(0x07635284));  MAD_F_MLA(hi, lo, X[14], -MAD_F(0x04cfb0e2));  MAD_F_MLA(hi, lo, X[15], -MAD_F(0x03768962));  MAD_F_MLA(hi, lo, X[17], -MAD_F(0x00b2aa3e));  x[26] = x[27] = MAD_F_MLZ(hi, lo) + t5;}#  endif/* * NAME:	III_imdct_l() * DESCRIPTION:	perform IMDCT and windowing for long blocks */staticvoid III_imdct_l(mad_fixed_t const X[18], mad_fixed_t z[36],		 unsigned int block_type){  unsigned int i;  /* IMDCT */  imdct36(X, z);  /* windowing */  switch (block_type) {  case 0:  /* normal window */# if defined(ASO_INTERLEAVE1)    {      register mad_fixed_t tmp1, tmp2;      tmp1 = window_l[0];      tmp2 = window_l[1];      for (i = 0; i < 34; i += 2) {	z[i + 0] = mad_f_mul(z[i + 0], tmp1);	tmp1 = window_l[i + 2];	z[i + 1] = mad_f_mul(z[i + 1], tmp2);	tmp2 = window_l[i + 3];      }      z[34] = mad_f_mul(z[34], tmp1);      z[35] = mad_f_mul(z[35], tmp2);    }# elif defined(ASO_INTERLEAVE2)    {      register mad_fixed_t tmp1, tmp2;      tmp1 = z[0];      tmp2 = window_l[0];      for (i = 0; i < 35; ++i) {	z[i] = mad_f_mul(tmp1, tmp2);	tmp1 = z[i + 1];	tmp2 = window_l[i + 1];      }      z[35] = mad_f_mul(tmp1, tmp2);    }# elif 1    for (i = 0; i < 36; i += 4) {      z[i + 0] = mad_f_mul(z[i + 0], window_l[i + 0]);      z[i + 1] = mad_f_mul(z[i + 1], window_l[i + 1]);      z[i + 2] = mad_f_mul(z[i + 2], window_l[i + 2]);      z[i + 3] = mad_f_mul(z[i + 3], window_l[i + 3]);    }# else    for (i =  0; i < 36; ++i) z[i] = mad_f_mul(z[i], window_l[i]);# endif    break;  case 1:  /* start block */    for (i =  0; i < 18; i += 3) {      z[i + 0] = mad_f_mul(z[i + 0], window_l[i + 0]);      z[i + 1] = mad_f_mul(z[i + 1], window_l[i + 1]);      z[i + 2] = mad_f_mul(z[i + 2], window_l[i + 2]);    }    /*  (i = 18; i < 24; ++i) z[i] unchanged */    for (i = 24; i < 30; ++i) z[i] = mad_f_mul(z[i], window_s[i - 18]);    for (i = 30; i < 36; ++i) z[i] = 0;    break;  case 3:  /* stop block */    for (i =  0; i <  6; ++i) z[i] = 0;    for (i =  6; i < 12; ++i) z[i] = mad_f_mul(z[i], window_s[i - 6]);    /*  (i = 12; i < 18; ++i) z[i] unchanged */    for (i = 18; i < 36; i += 3) {      z[i + 0] = mad_f_mul(z[i + 0], window_l[i + 0]);      z[i + 1] = mad_f_mul(z[i + 1], window_l[i + 1]);      z[i + 2] = mad_f_mul(z[i + 2], window_l[i + 2]);    }    break;  }}# endif  /* ASO_IMDCT *//* * NAME:	III_imdct_s() * DESCRIPTION:	perform IMDCT and windowing for short blocks */staticvoid III_imdct_s(mad_fixed_t const X[18], mad_fixed_t z[36]){  mad_fixed_t y[36], *yptr;  mad_fixed_t const *wptr;  int w, i;  register mad_fixed64hi_t hi;  register mad_fixed64lo_t lo;  /* IMDCT */  yptr = &y[0];  for (w = 0; w < 3; ++w) {    register mad_fixed_t const (*s)[6];    s = imdct_s;    for (i = 0; i < 3; ++i) {      MAD_F_ML0(hi, lo, X[0], (*s)[0]);      MAD_F_MLA(hi, lo, X[1], (*s)[1]);      MAD_F_MLA(hi, lo, X[2], (*s)[2]);      MAD_F_MLA(hi, lo, X[3], (*s)[3]);      MAD_F_MLA(hi, lo, X[4], (*s)[4]);      MAD_F_MLA(hi, lo, X[5], (*s)[5]);      yptr[i + 0] = MAD_F_MLZ(hi, lo);      yptr[5 - i] = -yptr[i + 0];      ++s;      MAD_F_ML0(hi, lo, X[0], (*s)[0]);      MAD_F_MLA(hi, lo, X[1], (*s)[1]);      MAD_F_MLA(hi, lo, X[2], (*s)[2]);      MAD_F_MLA(hi, lo, X[3], (*s)[3]);      MAD_F_MLA(hi, lo, X[4], (*s)[4]);      MAD_F_MLA(hi, lo, X[5], (*s)[5]);      yptr[ i + 6] = MAD_F_MLZ(hi, lo);      yptr[11 - i] = yptr[i + 6];      ++s;    }    yptr += 12;    X    += 6;  }  /* windowing, overlapping and concatenation */  yptr = &y[0];  wptr = &window_s[0];  for (i = 0; i < 6; ++i) {    z[i +  0] = 0;    z[i +  6] = mad_f_mul(yptr[ 0 + 0], wptr[0]);    MAD_F_ML0(hi, lo, yptr[ 0 + 6], wptr[6]);    MAD_F_MLA(hi, lo, yptr[12 + 0], wptr[0]);    z[i + 12] = MAD_F_MLZ(hi, lo);    MAD_F_ML0(hi, lo, yptr[12 + 6], wptr[6]);    MAD_F_MLA(hi, lo, yptr[24 + 0], wptr[0]);    z[i + 18] = MAD_F_MLZ(hi, lo);    z[i + 24] = mad_f_mul(yptr[24 + 6], wptr[6]);    z[i + 30] = 0;    ++yptr;    ++wptr;  }}/* * NAME:	III_overlap() * DESCRIPTION:	perform overlap-add of windowed IMDCT outputs */staticvoid III_overlap(mad_fixed_t const output[36], mad_fixed_t overlap[18],		 mad_fixed_t sample[18][32], unsigned int sb){  unsigned int i;# if defined(ASO_INTERLEAVE2)  {    register mad_fixed_t tmp1, tmp2;    tmp1 = overlap[0];    tmp2 = overlap[1];    for (i = 0; i < 16; i += 2) {      sample[i + 0][sb] = output[i + 0 +  0] + tmp1;      overlap[i + 0]    = output[i + 0 + 18];      tmp1 = overlap[i + 2];      sample[i + 1][sb] = output[i + 1 +  0] + tmp2;      overlap[i + 1]    = output[i + 1 + 18];      tmp2 = overlap[i + 3];    }    sample[16][sb] = output[16 +  0] + tmp1;    overlap[16]    = output[16 + 18];    sample[17][sb] = output[17 +  0] + tmp2;    overlap[17]    = output[17 + 18];  }# elif 0  for (i = 0; i < 18; i += 2) {    sample[i + 0][sb] = output[i + 0 +  0] + overlap[i + 0];    overlap[i + 0]    = output[i + 0 + 18];    sample[i + 1][sb] = output[i + 1 +  0] + overlap[i + 1];    overlap[i + 1]    = output[i + 1 + 18];  }# else  for (i = 0; i < 18; ++i) {    sample[i][sb] = output[i +  0] + overlap[i];    overlap[i]    = output[i + 18];  }# endif}/* * NAME:	III_overlap_z() * DESCRIPTION:	perform "overlap-add" of zero IMDCT outputs */static inlinevoid III_overlap_z(mad_fixed_t overlap[18],		   mad_fixed_t sample[18][32], unsigned int sb){  unsigned int i;# if defined(ASO_INTERLEAVE2)  {    register mad_fixed_t tmp1, tmp2;    tmp1 = overlap[0];    tmp2 = overlap[1];    for (i = 0; i < 16; i += 2) {      sample[i + 0][sb] = tmp1;      overlap[i + 0]    = 0;      tmp1 = overlap[i + 2];      sample[i + 1][sb] = tmp2;      overlap[i + 1]    = 0;      tmp2 = overlap[i + 3];    }    sample[16][sb] = tmp1;    overlap[16]    = 0;    sample[17][sb] = tmp2;    overlap[17]    = 0;  }# else  for (i = 0; i < 18; ++i) {    sample[i][sb] = overlap[i];    overlap[i]    = 0;  }# endif}/* * NAME:	III_freqinver() * DESCRIPTION:	perform subband frequency inversion for odd sample lines */staticvoid III_freqinver(mad_fixed_t sample[18][32], unsigned int sb){  unsigned int i;# if 1 || defined(ASO_INTERLEAVE1) || defined(ASO_INTERLEAVE2)  {    register mad_fixed_t tmp1, tmp2;    tmp1 = sample[1][sb];    tmp2 = sample[3][sb];    for (i = 1; i < 13; i += 4) {      sample[i + 0][sb] = -tmp1;      tmp1 = sample[i + 4][sb];      sample[i + 2][sb] = -tmp2;      tmp2 = sample[i + 6][sb];    }    sample[13][sb] = -tmp1;    tmp1 = sample[17][sb];    sample[15][sb] = -tmp2;    sample[17][sb] = -tmp1;  }# else  for (i = 1; i < 18; i += 2)    sample[i][sb] = -sample[i][sb];# endif}/* NAME:	III_decode() DESCRIPTION:	decode frame main_data *///被mad_layer_III（）調用static enum mad_error III_decode(struct mad_bitptr *ptr, struct mad_frame *frame, struct sideinfo *si, unsigned int nch){ struct mad_header *header = &frame->header;  unsigned int sfreqi, ngr, gr;  { unsigned int sfreq;    sfreq = header->samplerate;    if (header->flags & MAD_FLAG_MPEG_2_5_EXT)	      sfreq *= 2;    /* 48000 => 0, 44100 => 1, 32000 => 2, 24000 => 3, 22050 => 4, 16000 => 5 */    sfreqi = ((sfreq >>  7) & 0x000f) + ((sfreq >> 15) & 0x0001) - 8;    if (header->flags & MAD_FLAG_MPEG_2_5_EXT)        sfreqi += 3;  }  /* scalefactors, Huffman decoding, requantization */  ngr = (header->flags & MAD_FLAG_LSF_EXT) ? 1 : 2;  for (gr = 0; gr < ngr; ++gr)   { struct granule *granule = &si->gr[gr];    unsigned char const *sfbwidth[2];    mad_fixed_t xr[2][576];    unsigned int ch;    enum mad_error error;    for (ch = 0; ch < nch; ++ch) 	{ struct channel *channel = &granule->ch[ch];      unsigned int part2_length;      sfbwidth[ch] = sfbwidth_table[sfreqi].l;      if (channel->block_type == 2) 	  {	sfbwidth[ch] = (channel->flags & mixed_block_flag) ?	    sfbwidth_table[sfreqi].m : sfbwidth_table[sfreqi].s;      }      if (header->flags & MAD_FLAG_LSF_EXT) 	  	part2_length = III_scalefactors_lsf(ptr, channel,ch == 0 ? 0 : &si->gr[1].ch[1],header->mode_extension);      else 	  	part2_length = III_scalefactors(ptr, channel, &si->gr[0].ch[ch],gr == 0 ? 0 : si->scfsi[ch]);          error = III_huffdecode(ptr, xr[ch], channel, sfbwidth[ch], part2_length);      if (error)	return error;    }    /* joint stereo processing */    if (header->mode == MAD_MODE_JOINT_STEREO && header->mode_extension) 	{ error = III_stereo(xr, granule, header, sfbwidth[0]);      if (error)	return error;    }    /* reordering, alias reduction, IMDCT, overlap-add, frequency inversion */    for (ch = 0; ch < nch; ++ch) 	{ struct channel const *channel = &granule->ch[ch];      mad_fixed_t (*sample)[32] = &frame->sbsample[ch][18 * gr];      unsigned int sb, l, i, sblimit;      mad_fixed_t output[36];      if (channel->block_type == 2) 	  {	III_reorder(xr[ch], channel, sfbwidth[ch]);# if !defined(OPT_STRICT)	/*	 * According to ISO/IEC 11172-3, "Alias reduction is not applied for	 * granules with block_type == 2 (short block)." However, other	 * sources suggest alias reduction should indeed be performed on the	 * lower two subbands of mixed blocks. Most other implementations do	 * this, so by default we will too.	 */	if (channel->flags & mixed_block_flag)	  III_aliasreduce(xr[ch], 36);# endif      }      else	III_aliasreduce(xr[ch], 576);      l = 0;      /* subbands 0-1 */      if (channel->block_type != 2 || (channel->flags & mixed_block_flag)) 	  {	unsigned int block_type;		block_type = channel->block_type;		if (channel->flags & mixed_block_flag)	  block_type = 0;		/* long blocks */		for (sb = 0; sb < 2; ++sb, l += 18) 		{	  III_imdct_l(&xr[ch][l], output, block_type);			  III_overlap(output, (*frame->overlap)[ch][sb], sample, sb);		}      }      else 	  	/* short blocks */		for (sb = 0; sb < 2; ++sb, l += 18) 		{	III_imdct_s(&xr[ch][l], output);			III_overlap(output, (*frame->overlap)[ch][sb], sample, sb);		}      III_freqinver(sample, 1);      /* (nonzero) subbands 2-31 */      i = 576;      while (i > 36 && xr[ch][i - 1] == 0)	--i;      sblimit = 32 - (576 - i) / 18;      if (channel->block_type != 2) 	  {	/* long blocks */		for (sb = 2; sb < sblimit; ++sb, l += 18) 		{	III_imdct_l(&xr[ch][l], output, channel->block_type);			III_overlap(output, (*frame->overlap)[ch][sb], sample, sb);			if (sb & 1)    III_freqinver(sample, sb);		}      }      else 	/* short blocks */		for (sb = 2; sb < sblimit; ++sb, l += 18) 		{	III_imdct_s(&xr[ch][l], output);			III_overlap(output, (*frame->overlap)[ch][sb], sample, sb);			if (sb & 1)    III_freqinver(sample, sb);		}            /* remaining (zero) subbands */      for (sb = sblimit; sb < 32; ++sb) 	  {	III_overlap_z((*frame->overlap)[ch][sb], sample, sb);		if (sb & 1)	  III_freqinver(sample, sb);      }    }  }  return MAD_ERROR_NONE;}/* NAME:	laye