fft.hcc

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#include <stdlib.hch>
#include "pal_master.hch"

#include "audio.hch"
#include "weights_256.hch"
#include "configuration.hch"
#include "xilinxmult.hch"
#include "fft.hch"

#if HAVE_DEBUG
        #include "debug.hch"
#endif

/* Define two multi-port RAMs for FFT calculation; one for real and one for imaginary values
 * Extra block RAM settings are defined to make sure read and write actions can be performed
 * within one clock-cycle.
 * Left out extra settings on new board the clock changes TODO !!!!
 */
#if HARDWARE_MULTIPLY
mpram
{
  ram signed 18 rwrite[256];
  rom signed 18 read[256];
} real with {block = "BlockRAM"/*, westart=2.5, welength=1, rclkpos={1.5}, wclkpos={3}, clkpulselen=0.5*/};

mpram 
{
  ram signed 18 rwrite[256];
  rom signed 18 read[256];
} imaginary with {block = "BlockRAM"/*, westart=2.5, welength=1, rclkpos={1.5}, wclkpos={3}, clkpulselen=0.5*/};
#else
mpram
{
  ram signed 24 rwrite[256];
  rom signed 24 read[256];
} real with {block = "BlockRAM"/*, westart=2.5, welength=1, rclkpos={1.5}, wclkpos={3}, clkpulselen=0.5*/};

mpram 
{
  ram signed 24 rwrite[256];
  rom signed 24 read[256];
} imaginary with {block = "BlockRAM"/*, westart=2.5, welength=1, rclkpos={1.5}, wclkpos={3}, clkpulselen=0.5*/};
#endif
// multiplication factors for equalizer function
ram signed 7 eq_settings[16] = {0,2,4,7,10,13,16,19,22,26,30,35,41,48,55,63};

#if HARDWARE_MULTIPLY
#define DC_COMPONENT            0
#else
#define DC_COMPONENT            8470527
#endif

macro proc multiply(result, op_a, op_b)
{
#if HARDWARE_MULTIPLY
        xilinxmult(result, op_a, adjs(op_b,18));
#else
        result = (adjs(op_a,38))*(adjs(op_a,38));
#endif  
}




void calculate_fft(unsigned 1 select_inverse)
{
  unsigned 4 level;
  unsigned 8 point1,point2,j,f,k;
  unsigned 9 e,i;
  signed 16 weight1,weight2;
#if HARDWARE_MULTIPLY
  signed 18 p,q,r,t;
#else
  signed 24 p,q,r,t;    
#endif
  signed a,b;

#if HARDWARE_MULTIPLY
  // Macro to provide rescaling of 36-bit result of fixed point multiply
  // down to an 18-bit result. The range of bits selected depends on the 
  // number that represents the value of "1" in the trig function lookup
  // tables. (Eg. for 16384 == 1, the lowest bit selected should be [14]).
  macro expr rescale (x) = (x[35] @ x[30:14]);
#else
  //Macro to rescale the multiply result down to a 24-bit value.
  macro expr rescale (x) = ((x>>FRACBITS)<-24);
#endif

  for(level=1;level<=NUMBER_OF_COLUMNS;level++) // count all the columns
  {
        e=1<<(NUMBER_OF_COLUMNS-level+1); // number of points in each block in this column
        f=(e>>1)<-8;                      // number of butterflies in each block in this column

        for(j=1;j<=f;j++)       // count all the butterflies in each block
        {
                par
                {
                        // Weight factors for real (the same for FFT and iFFT)
                        weight1 = weight_re[((j-1)<<(level-1))<-7]; 

                        
                        // Weight factors for imaginary (opposite for FFT and iFFT)
                        weight2 = (!select_inverse) ? (weight_im[((j-1)<<(level-1))<-7]) : -(weight_im[((j-1)<<(level-1))<-7]); 

                        /* ORIGINAL CODE BELOW, MODIFIED BECAUSE OF MISMATCHING OUTPUT WITH BORLAND TESTAPP
                        weight2 = (!select_inverse) ? -(weight_im[((j-1)<<(level-1))<-7]) : weight_im[((j-1)<<(level-1))<-7]; 
                        */
                        
                        

                        for(i=0@j;i<=NUMBER_OF_POINTS;i+=e)   // count all the blocks in this column
                        {       // Butterfly calculation
                                par
                                {
                                        point1 = ((i<-8)-1);
                                        point2 = (((i<-8)+f)-1);
                                }
                                
                                par
                                {
                                        p = (real.read[point1] >> 1) + (real.rwrite[point2] >> 1);
                                        q = (imaginary.read[point1] >> 1) + (imaginary.rwrite[point2] >> 1);
                                }
                                
                                par
                                {
                                        r = (real.read[point1] >> 1) - (real.rwrite[point2] >> 1);
                                        t = (imaginary.read[point1] >> 1) - (imaginary.rwrite[point2] >> 1);
                                }               

                                multiply(a,r,weight1);
                                multiply(b,t,weight2);

                                par
                                {
                                        real.rwrite[point2] = (rescale(a-b));
                                        imaginary.rwrite[point1] = q;
                                }

                                multiply(a,t,weight1);
                                multiply(b,r,weight2);

                                par
                                {       
                                        real.rwrite[point1] = p;
                                        imaginary.rwrite[point2] = (rescale(a+b));
                                }

                        }
                }
        }
  }

  j=1;
  for(i=1;i<NUMBER_OF_POINTS;i++)
  {
        if(i<(0@j))
        {
                par
                {
                        point1=j-1;
                        point2=(i-1)<-8;
                }
                /*
                  COPYING ARRAY VALUES FROM ONE PLACE TO ANOTHER IN THE ARRAT MUST BE DONE IN 
                  2 STEPS. FIRSTLY THE VALUES ARE COPIED TO SEPARATE VARIABLES AFTER THAT THEY
                  ARE COPIED BACK TO THEIR NEW POSITION IN THE ARRAY. THIS MUST BE DONE TO 
                  PREVENT TIMING ISSUES FROM OCCURING.
                */
                par
                {
                        p = real.read[point1];
                        q = imaginary.read[point1];
                }
                par
                {
                        r = real.read[point2];
                        t = imaginary.read[point2];
                }
                par
                {
                        real.rwrite[point1] = r;        
                        imaginary.rwrite[point1] = t;
                }
                par
                {
                        real.rwrite[point2] = p;
                        imaginary.rwrite[point2] = q;
                }
        }

        k = NUMBER_OF_POINTS>>1;


        while(k<j)
        {
                j = j-k;
                k = k>>1;
        }

        j+=k;
  }

}

#if HARDWARE_MULTIPLY
void perform_fft(signed 18 *pcm_audio)
#else
void perform_fft(signed 16 *pcm_audio)
#endif
{
        unsigned 8 k;
#if HARDWARE_MULTIPLY
        signed 18 sample;
        k=0;
        sample = adjs(pcm_audio[k],18);
#else
        signed 24 sample;
        k=0;
        sample = adjs(pcm_audio[k],24);
#endif
        
        //initialize variables for the copying pipeline

        
        // copy audio data to real-array before starting FFT calculation
        // and set imaginary values to zero
        do
        {
                //Copying the array values has been pipelined to prevent parallel access to the
                //pcm_audio array. This copying procedure must be finished before another 
                //sample is read from the audio input. The time available for this loop is 
                //determined by the sampling rate of 44,1 Khz
                par
                {
                        //COPYING NEEDS TO BE DONE IN 2 STEPS, BECAUSE THE VALUE THAT NEEDS TO WRITTEN
                        //TO THE REAL-RAM NEEDS TO BE AVAILABLE ON THE START OFF THE CLOCKCYCLE.
#if HARDWARE_MULTIPLY
                        sample = adjs(pcm_audio[k+1],18);
#else
                        sample = adjs(pcm_audio[k+1],24);
#endif
                        real.rwrite[k] = sample;
                        imaginary.rwrite[k] = 0;
                        k++;
                }               
        }  while (k);

        

#if PERFORM_FFT_CALCULATION
        calculate_fft(0);
#endif


}

#if HARDWARE_MULTIPLY
void perform_ifft(signed 18 *modified_audio, unsigned 6 *ifft_info)
#else
void perform_ifft(signed 16 *modified_audio, unsigned 6 *ifft_info)
#endif
{
        unsigned 6 k;
#if HARDWARE_MULTIPLY 
        signed 18 p;
#else
        signed 24 p;
#endif
#if PERFORM_FFT_CALCULATION     
        calculate_fft(1);
#endif

        k=0;
//initialize variables for the copying pipeline
#if PERFORM_FFT_CALCULATION     
        #if HARDWARE_MULTIPLY 
                p = (real.read[(0@k)+95] << NUMBER_OF_COLUMNS);
        #else
                p = (real.read[(0@k)+95] >> NUMBER_OF_COLUMNS);
        #endif
#else
                p = (real.read[(0@k)+95]);
#endif

        do
        {
                //Copying the array values has been pipelined to prevent parallel access to the
                //pcm_audio array. This copying procedure must be finished before another 
                //sample is read from the audio input. The time available for this loop is 
                //determined by the sampling rate of 44,1 Khz
                par
                {
                        /*
                        *       Before copying the modified audio from the local real-array 
                        *       to the output array of the audio I/O component, compensate
                        *       for the FFT calculation by shifting the values. 
                        *       95 is added to start the output from the middle of the sliding
                        *       window, this is done to get a better sound quality.
                        */
#if PERFORM_FFT_CALCULATION     
        #if HARDWARE_MULTIPLY 
                        p = (real.read[(0@k)+95] << NUMBER_OF_COLUMNS);
        #else
                        p = (real.read[(0@k)+95] >> NUMBER_OF_COLUMNS);
        #endif
#else
                        p = (real.read[(0@k)+95]);
#endif
                        //Copy the modified audio from the local real array to the output array of the audio I/O component.
#if HARDWARE_MULTIPLY
                        modified_audio[k] = p ;
#else
                        modified_audio[k] = (p<-16);
#endif
                        //Fill the array for displaying the waveform, only the 6 MSB are needed.
                        ifft_info[k] = (unsigned 6)(32+(p[17:12]));             
                        k++;
                }
        } while(k);
}

void equalize_audio(audiodata_t *audiodata)
{
#if HARDWARE_MULTIPLY
  signed 18 p,q;
#else
  signed 24 p,q;
#endif
  signed 18 a;
  unsigned 8 i, mirror_i, bit, m, n;
  unsigned 7 old_value;
  unsigned 9 tmp;
  
  //macro expr equalize_bar = multiply(q,a)[29:6];
  
  macro proc equalize_bar(retval)
  {
         signed result;
         multiply(result, q,a);
#if HARDWARE_MULTIPLY
         retval = result[23:6]; //drop last 6 bit to compensate the maximum multiplication with 64 from the eq_settings array
#else
         retval = result[29:6]; //drop last 6 bit to compensate the maximum multiplication with 64 from the eq_settings array
#endif
  } 

  p = real.read[0] - DC_COMPONENT; // remove DC component for calculations
  real.rwrite[0] = p;
  
  for(i=0;i!=NUMBER_OF_FREQUENCIES;i++)   
  {  
        
                // set multiplication factor (0..64) for current frequency bar, The first frequency band must be equalized at 100% (63) since there is no DC-component taken into account.
                a = adjs(eq_settings[audiodata->equalizer_levels_ptr[i <- 7]],18);


                // multiply frequency with this factor and divide by 64 (drop 6 LSB's)
                q = real.read[i];
        equalize_bar(p);
        real.rwrite[i] = p;

        q = imaginary.read[i];
        equalize_bar(p);
        imaginary.rwrite[i] = p;

        // the upper part(128..255) of the spectrum is mirrored to the lower part; 
        // these values need to be adjusted too
        if ((i<-7)!=0) // if not in DC component bar
        {
                mirror_i = (NUMBER_OF_POINTS-1)-i+1;
                q = real.read[mirror_i];
                equalize_bar(p);
                real.rwrite[mirror_i] = p;

                q = imaginary.read[mirror_i];
                equalize_bar(p);
                imaginary.rwrite[mirror_i] = p;
        }
  }
  
  //write data to fft_info for display purposes
  for(i=0;i<NUMBER_OF_FREQUENCIES;i++)
  {
                p = real.read[i];
                q = imaginary.read[i];
#if HARDWARE_MULTIPLY
                if (p[17] == 1) p = -p; else delay;
                if (q[17] == 1) q = -q; else delay;
#else
                if (p[23] == 1) p = -p; else delay;
                if (q[23] == 1) q = -q; else delay;
#endif
        p = (p<q) ? q : p; // This is done to get the best visual frequency result
         
        if (!audiodata->display_log)
        {

                bit=126;
#if HARDWARE_MULTIPLY
                while ((p[15] == 0) && (bit != 0))
#else
                while ((p[21] == 0) && (bit != 0))
#endif
                        par
                        {
                                p = p<<1;
                                bit = bit - 18;
                        }
                old_value = audiodata->fft_info.write[0 @ (i <- 7)];
                tmp = ((0@old_value) + (0@bit))>>1;
                audiodata->fft_info.write[0 @ (i <- 7)] = (old_value <= (tmp<-7)) ? (tmp<-7) : old_value-1;
        } 
        else 
        {
                old_value = audiodata->fft_info.write[0 @ (i <- 7)];
#if HARDWARE_MULTIPLY
                audiodata->fft_info.write[0 @ (i <- 7)] = (old_value<=(unsigned)(p[15:9])) ? (unsigned)(p[15:9]) : old_value-1;
#else
                audiodata->fft_info.write[0 @ (i <- 7)] = (old_value<=(unsigned)(p[21:15])) ? (unsigned)(p[21:15]) : old_value-1;
#endif
        }
  }

  // add DC component again before inverse FFT calculation is performed

  p = real.read[0] + DC_COMPONENT; 
  real.rwrite[0] = p;
}

---