imdct.c

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    window_ptr = imdct_window;

    /* Window and convert to real valued signal */
    for(i=0; i< 64; i++) { 
	*data_ptr++  = -buf_1[i].imag      * *window_ptr++ + *delay_ptr++ + bias;
	*data_ptr++  =  buf_1[64-i-1].real * *window_ptr++ + *delay_ptr++ + bias;
    }

    for(i=0; i< 64; i++) {
	*data_ptr++  = -buf_1[i].real      * *window_ptr++ + *delay_ptr++ + bias;
	*data_ptr++  =  buf_1[64-i-1].imag * *window_ptr++ + *delay_ptr++ + bias;
    }
	
    delay_ptr = delay;

    for(i=0; i< 64; i++) {
	*delay_ptr++ = -buf_2[i].real      * *--window_ptr;
	*delay_ptr++ =  buf_2[64-i-1].imag * *--window_ptr;
    }

    for(i=0; i< 64; i++) {
	*delay_ptr++ =  buf_2[i].imag      * *--window_ptr;
	*delay_ptr++ = -buf_2[64-i-1].real * *--window_ptr;
    }
}

void imdct_init (uint32_t mm_accel)
{
#ifdef LIBA52_MLIB
    if (mm_accel & MM_ACCEL_MLIB) {
        fprintf (stderr, "Using mlib for IMDCT transform\n");
	imdct_512 = imdct_do_512_mlib;
	imdct_256 = imdct_do_256_mlib;
    } else
#endif
    {
	int i, j, k;

	/* Twiddle factors to turn IFFT into IMDCT */
	for (i = 0; i < 128; i++) {
	    xcos1[i] = -cos ((M_PI / 2048) * (8 * i + 1));
	    xsin1[i] = -sin ((M_PI / 2048) * (8 * i + 1));
	}
#ifdef ARCH_X86
	for (i = 0; i < 128; i++) {
	    sseSinCos1c[2*i+0]= xcos1[i];
	    sseSinCos1c[2*i+1]= -xcos1[i];
	    sseSinCos1d[2*i+0]= xsin1[i];
	    sseSinCos1d[2*i+1]= xsin1[i];	
	}
#endif

	/* More twiddle factors to turn IFFT into IMDCT */
	for (i = 0; i < 64; i++) {
	    xcos2[i] = -cos ((M_PI / 1024) * (8 * i + 1));
	    xsin2[i] = -sin ((M_PI / 1024) * (8 * i + 1));
	}

	for (i = 0; i < 7; i++) {
	    j = 1 << i;
	    for (k = 0; k < j; k++) {
		w[i][k].real = cos (-M_PI * k / j);
		w[i][k].imag = sin (-M_PI * k / j);
	    }
	}
#ifdef ARCH_X86
	for (i = 1; i < 7; i++) {
	    j = 1 << i;
	    for (k = 0; k < j; k+=2) {
	    
	    	sseW[i][4*k + 0] = w[i][k+0].real;
	    	sseW[i][4*k + 1] = w[i][k+0].real;
	    	sseW[i][4*k + 2] = w[i][k+1].real;
	    	sseW[i][4*k + 3] = w[i][k+1].real;

	    	sseW[i][4*k + 4] = -w[i][k+0].imag;
	    	sseW[i][4*k + 5] = w[i][k+0].imag;
	    	sseW[i][4*k + 6] = -w[i][k+1].imag;
	    	sseW[i][4*k + 7] = w[i][k+1].imag;	    
	    	
	//we multiply more or less uninitalized numbers so we need to use exactly 0.0
		if(k==0)
		{
//			sseW[i][4*k + 0]= sseW[i][4*k + 1]= 1.0;
			sseW[i][4*k + 4]= sseW[i][4*k + 5]= 0.0;
		}
		
		if(2*k == j)
		{
			sseW[i][4*k + 0]= sseW[i][4*k + 1]= 0.0;
//			sseW[i][4*k + 4]= -(sseW[i][4*k + 5]= -1.0);
		}
	    }
	}

	for(i=0; i<128; i++)
	{
		sseWindow[2*i+0]= -imdct_window[2*i+0];
		sseWindow[2*i+1]=  imdct_window[2*i+1];	
	}
	
	for(i=0; i<64; i++)
	{
		sseWindow[256 + 2*i+0]= -imdct_window[254 - 2*i+1];
		sseWindow[256 + 2*i+1]=  imdct_window[254 - 2*i+0];
		sseWindow[384 + 2*i+0]=  imdct_window[126 - 2*i+1];
		sseWindow[384 + 2*i+1]= -imdct_window[126 - 2*i+0];
	}
#endif // arch_x86

	imdct_512 = imdct_do_512;
#ifdef ARCH_X86
	if(mm_accel & MM_ACCEL_X86_SSE)
	{
	  fprintf (stderr, "Using SSE optimized IMDCT transform\n");
	  imdct_512 = imdct_do_512_sse;
	}  
	else
	if(mm_accel & MM_ACCEL_X86_3DNOWEXT)
	{
	  fprintf (stderr, "Using 3DNowEx optimized IMDCT transform\n");
	  imdct_512 = imdct_do_512_3dnowex;
	}
	else
	if(mm_accel & MM_ACCEL_X86_3DNOW)
	{
	  fprintf (stderr, "Using 3DNow optimized IMDCT transform\n");
	  imdct_512 = imdct_do_512_3dnow;
	}
	else
#endif // arch_x86
#ifdef HAVE_ALTIVEC
        if (mm_accel & MM_ACCEL_PPC_ALTIVEC)
	{
	  fprintf(stderr, "Using AltiVec optimized IMDCT transform\n");
          imdct_512 = imdct_do_512_altivec;
	}
        else
#endif
	fprintf (stderr, "No accelerated IMDCT transform found\n");
	imdct_256 = imdct_do_256;
    }
}

static void fft_asmb(int k, complex_t *x, complex_t *wTB,
	     const complex_t *d, const complex_t *d_3)
{
  register complex_t  *x2k, *x3k, *x4k, *wB;
  register float a_r, a_i, a1_r, a1_i, u_r, u_i, v_r, v_i;

  x2k = x + 2 * k;
  x3k = x2k + 2 * k;
  x4k = x3k + 2 * k;
  wB = wTB + 2 * k;
  
  TRANSZERO(x[0],x2k[0],x3k[0],x4k[0]);
  TRANS(x[1],x2k[1],x3k[1],x4k[1],wTB[1],wB[1],d[1],d_3[1]);
  
  --k;
  for(;;) {
     TRANS(x[2],x2k[2],x3k[2],x4k[2],wTB[2],wB[2],d[2],d_3[2]);
     TRANS(x[3],x2k[3],x3k[3],x4k[3],wTB[3],wB[3],d[3],d_3[3]);
     if (!--k) break;
     x += 2;
     x2k += 2;
     x3k += 2;
     x4k += 2;
     d += 2;
     d_3 += 2;
     wTB += 2;
     wB += 2;
  }
 
}

static void fft_asmb16(complex_t *x, complex_t *wTB)
{
  register float a_r, a_i, a1_r, a1_i, u_r, u_i, v_r, v_i;
  int k = 2;

  /* transform x[0], x[8], x[4], x[12] */
  TRANSZERO(x[0],x[4],x[8],x[12]);

  /* transform x[1], x[9], x[5], x[13] */
  TRANS(x[1],x[5],x[9],x[13],wTB[1],wTB[5],delta16[1],delta16_3[1]);

  /* transform x[2], x[10], x[6], x[14] */
  TRANSHALF_16(x[2],x[6],x[10],x[14]);

  /* transform x[3], x[11], x[7], x[15] */
  TRANS(x[3],x[7],x[11],x[15],wTB[3],wTB[7],delta16[3],delta16_3[3]);

} 

static void fft_4(complex_t *x)
{
  /* delta_p = 1 here */
  /* x[k] = sum_{i=0..3} x[i] * w^{i*k}, w=e^{-2*pi/4} 
   */

  register float yt_r, yt_i, yb_r, yb_i, u_r, u_i, vi_r, vi_i;
  
  yt_r = x[0].real;
  yb_r = yt_r - x[2].real;
  yt_r += x[2].real;

  u_r = x[1].real;
  vi_i = x[3].real - u_r;
  u_r += x[3].real;
  
  u_i = x[1].imag;
  vi_r = u_i - x[3].imag;
  u_i += x[3].imag;

  yt_i = yt_r;
  yt_i += u_r;
  x[0].real = yt_i;
  yt_r -= u_r;
  x[2].real = yt_r;
  yt_i = yb_r;
  yt_i += vi_r;
  x[1].real = yt_i;
  yb_r -= vi_r;
  x[3].real = yb_r;

  yt_i = x[0].imag;
  yb_i = yt_i - x[2].imag;
  yt_i += x[2].imag;

  yt_r = yt_i;
  yt_r += u_i;
  x[0].imag = yt_r;
  yt_i -= u_i;
  x[2].imag = yt_i;
  yt_r = yb_i;
  yt_r += vi_i;
  x[1].imag = yt_r;
  yb_i -= vi_i;
  x[3].imag = yb_i;
}


static void fft_8(complex_t *x)
{
  /* delta_p = diag{1, sqrt(i)} here */
  /* x[k] = sum_{i=0..7} x[i] * w^{i*k}, w=e^{-2*pi/8} 
   */
  register float wT1_r, wT1_i, wB1_r, wB1_i, wT2_r, wT2_i, wB2_r, wB2_i;
  
  wT1_r = x[1].real;
  wT1_i = x[1].imag;
  wB1_r = x[3].real;
  wB1_i = x[3].imag;

  x[1] = x[2];
  x[2] = x[4];
  x[3] = x[6];
  fft_4(&x[0]);

  
  /* x[0] x[4] */
  wT2_r = x[5].real;
  wT2_r += x[7].real;
  wT2_r += wT1_r;
  wT2_r += wB1_r;
  wT2_i = wT2_r;
  wT2_r += x[0].real;
  wT2_i = x[0].real - wT2_i;
  x[0].real = wT2_r;
  x[4].real = wT2_i;

  wT2_i = x[5].imag;
  wT2_i += x[7].imag;
  wT2_i += wT1_i;
  wT2_i += wB1_i;
  wT2_r = wT2_i;
  wT2_r += x[0].imag;
  wT2_i = x[0].imag - wT2_i;
  x[0].imag = wT2_r;
  x[4].imag = wT2_i;
  
  /* x[2] x[6] */
  wT2_r = x[5].imag;
  wT2_r -= x[7].imag;
  wT2_r += wT1_i;
  wT2_r -= wB1_i;
  wT2_i = wT2_r;
  wT2_r += x[2].real;
  wT2_i = x[2].real - wT2_i;
  x[2].real = wT2_r;
  x[6].real = wT2_i;

  wT2_i = x[5].real;
  wT2_i -= x[7].real;
  wT2_i += wT1_r;
  wT2_i -= wB1_r;
  wT2_r = wT2_i;
  wT2_r += x[2].imag;
  wT2_i = x[2].imag - wT2_i;
  x[2].imag = wT2_i;
  x[6].imag = wT2_r;
  

  /* x[1] x[5] */
  wT2_r = wT1_r;
  wT2_r += wB1_i;
  wT2_r -= x[5].real;
  wT2_r -= x[7].imag;
  wT2_i = wT1_i;
  wT2_i -= wB1_r;
  wT2_i -= x[5].imag;
  wT2_i += x[7].real;

  wB2_r = wT2_r;
  wB2_r += wT2_i;
  wT2_i -= wT2_r;
  wB2_r *= HSQRT2;
  wT2_i *= HSQRT2;
  wT2_r = wB2_r;
  wB2_r += x[1].real;
  wT2_r =  x[1].real - wT2_r;

  wB2_i = x[5].real;
  x[1].real = wB2_r;
  x[5].real = wT2_r;

  wT2_r = wT2_i;
  wT2_r += x[1].imag;
  wT2_i = x[1].imag - wT2_i;
  wB2_r = x[5].imag;
  x[1].imag = wT2_r;
  x[5].imag = wT2_i;

  /* x[3] x[7] */
  wT1_r -= wB1_i;
  wT1_i += wB1_r;
  wB1_r = wB2_i - x[7].imag;
  wB1_i = wB2_r + x[7].real;
  wT1_r -= wB1_r;
  wT1_i -= wB1_i;
  wB1_r = wT1_r + wT1_i;
  wB1_r *= HSQRT2;
  wT1_i -= wT1_r;
  wT1_i *= HSQRT2;
  wB2_r = x[3].real;
  wB2_i = wB2_r + wT1_i;
  wB2_r -= wT1_i;
  x[3].real = wB2_i;
  x[7].real = wB2_r;
  wB2_i = x[3].imag;
  wB2_r = wB2_i + wB1_r;
  wB2_i -= wB1_r;
  x[3].imag = wB2_i;
  x[7].imag = wB2_r;
}


static void fft_128p(complex_t *a)
{
  fft_8(&a[0]); fft_4(&a[8]); fft_4(&a[12]);
  fft_asmb16(&a[0], &a[8]);
  
  fft_8(&a[16]), fft_8(&a[24]);
  fft_asmb(4, &a[0], &a[16],&delta32[0], &delta32_3[0]);

  fft_8(&a[32]); fft_4(&a[40]); fft_4(&a[44]);
  fft_asmb16(&a[32], &a[40]);

  fft_8(&a[48]); fft_4(&a[56]); fft_4(&a[60]);
  fft_asmb16(&a[48], &a[56]);

  fft_asmb(8, &a[0], &a[32],&delta64[0], &delta64_3[0]);

  fft_8(&a[64]); fft_4(&a[72]); fft_4(&a[76]);
  /* fft_16(&a[64]); */
  fft_asmb16(&a[64], &a[72]);

  fft_8(&a[80]); fft_8(&a[88]);
  
  /* fft_32(&a[64]); */
  fft_asmb(4, &a[64], &a[80],&delta32[0], &delta32_3[0]);

  fft_8(&a[96]); fft_4(&a[104]), fft_4(&a[108]);
  /* fft_16(&a[96]); */
  fft_asmb16(&a[96], &a[104]);

  fft_8(&a[112]), fft_8(&a[120]);
  /* fft_32(&a[96]); */
  fft_asmb(4, &a[96], &a[112], &delta32[0], &delta32_3[0]);
  
  /* fft_128(&a[0]); */
  fft_asmb(16, &a[0], &a[64], &delta128[0], &delta128_3[0]);
}