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#include <pal_master.hch>
#include <stdlib.hch>
#include "fft.hch"
#include "weights256.hch"
#include "config.hch"
#include "debug.hch"
//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.
mpram
{
ram signed 32 rwrite[256];
rom signed 32 read[256];
} real with {block = "BlockRAM" /*block=4, westart=2.5, welength=1, rclkpos={1.5}, wclkpos={3}, clkpulselen=0.5*/};
mpram
{
ram signed 32 rwrite[256];
rom signed 32 read[256];
} imaginary with {block = "BlockRAM" /*block=6, westart=2.5, welength=1, rclkpos={1.5}, wclkpos={3}, clkpulselen=0.5*/};
// 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};
/****************************************************************
* Function: multiply *
* *
* Arguments *
* x,y signed variables *
* *
* Description *
* Just a multiplier. But by doing this in a function the *
* FPGA space needed is reduced. *
* *
* Return Values *
* The result after multiplication *
****************************************************************/
signed multiply(signed x,signed y)
{
return((adjs(x,40))*(adjs(y,40)));
}
/************************************************************************
* Function: calculate_fft *
* *
* Arguments *
* select_inverse Boolean that indicates FFT or iFFT calculation *
* *
* Description *
* This routine performs the Fast Fourier Transform for *
* calculation of the frequency spectrum *
* *
************************************************************************/
void calculate_fft(unsigned 1 select_inverse)
{
unsigned 4 level;
unsigned 8 point1, point2, k, f, j;
unsigned 9 e, i;
signed 16 weight1,weight2;
signed 32 p,q,r,t;
signed 40 a,b;
// float u,v,z,c,s,p,q,r,t,w,a;
// n=1<<NUMBER_OF_COLUMNS;//n=256 order=8
for(level=1;level<=NUMBER_OF_COLUMNS;level++)
{
e=1<<(NUMBER_OF_COLUMNS-level+1);
f=(e>>1)<-8;
for(j=1;j<=f;j++)
{
weight1 = weight_re[((1<<(level-1))*(j-1))<-7];
weight2 = (select_inverse) ? -weight_im[((1<<(level-1))*(j-1))<-7] : weight_im[((1<<(level-1))*(j-1))<-7];
for(i=0@j;i<=NUMBER_OF_POINTS;i+=e)
{
point1 = (i<-8)-1;
point2 = ((i<-8)+f)-1;
p = real.read[point1] + real.read[point2];
r = real.read[point1] - real.read[point2];
q = imaginary.read[point1] + imaginary.read[point2];
t = imaginary.read[point1] - imaginary.read[point2];
real.rwrite[point1] = p;
imaginary.rwrite[point1] = q;
a = multiply(adjs(r,40),adjs(weight1,40));
b = multiply(adjs(t,40),adjs(weight2,40));
real.rwrite[point2]=((a-b)>>FRACBITS)<-32;
a = multiply(adjs(t,40),adjs(weight1,40));
b = multiply(adjs(r,40),adjs(weight2,40));
imaginary.rwrite[point2]=((a-b)>>FRACBITS)<-32;
}
}
}
j=1;// Bit reversing start
for(i=1;i<NUMBER_OF_POINTS;i++)
{
if(i < (0@j))
{
point1 = j-1;
point2 = (i-1)<-8;
p = real.read[point1];
real.rwrite[point1] = real.read[point2];
real.rwrite[point2] = p;
q = imaginary.read[point1];
imaginary.rwrite[point1] = imaginary.read[point2];
imaginary.rwrite[point2] = q;
}
k=NUMBER_OF_POINTS>>1;
while(k<j)
{
j-=k;
k=k>>1;
}
j+=k;
}// Bit reversing end
/* if(select_inverse)
{
a=(1<<14)>>NUMBER_OF_COLUMNS;
for(k=0;k<(adju(n,8));k++)
{
real.rwrite[k]*=(0@a);
imaginary.rwrite[k]*=(0@a);
}
}*/
}
/********************************************************************/
void perform_fft(signed 16 *pcm_audio)
{
unsigned 1 select_inverse;
unsigned 8 k;
// copy audio data to real-array before starting FFT calculation
// and set imaginary values to zero
k=0;
do
par{
real.rwrite[k] = 0@pcm_audio[k];
imaginary.rwrite[k]=0;
k++;
} while (k!=0);
select_inverse=0;
calculate_fft(select_inverse);
}
/********************************************************************/
void perform_ifft(signed 16 *modified_audio/*, unsigned 6 *ifft_info*/)
{
unsigned 1 select_inverse;
unsigned 8 k;
signed 32 p;
select_inverse=1;
calculate_fft(select_inverse);
k=0;
do
{
// divide samples by number of points
p=(real.read[(k+95)]>>NUMBER_OF_COLUMNS);
// write data to output buffer & display buffer
modified_audio[k<-6]=(p<-16);
//ifft_info[k]=(unsigned)(p[15:10]);
print_string("Real[");
// print_hex_value(adju(k,16));
print_string("]: ");
print_hex_value((unsigned)real.read[k]);
print_eol();
k++;
} while(k<64);
}
/********************************************************************/
/*void equalize_audio(unsigned 4 *eq_level, unsigned 7 *fft_info)
{
signed 24 p,q;
signed 16 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];
//real.rwrite[0] = real.read[0] - DC_COMPONENT; // remove DC component for calculations
// imaginary.rwrite[0] = 0; // remove DC component
for(i=0;i<=NUMBER_OF_FREQUENCIES;i++)
{
// set multiplication factor (0..64) for current frequency bar
a = adjs(eq_settings[eq_level[i<-7]],16);
// multiply frequency with this factor and divide by 64 (drop 6 LSB's)
q = real.read[i];
real.rwrite[i] = equalize_bar;
q=imaginary.read[i];
imaginary.rwrite[i] = equalize_bar;
// 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];
real.rwrite[mirror_i] = equalize_bar;
q = imaginary.read[mirror_i];
imaginary.rwrite[mirror_i] = equalize_bar;
};
}
//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 (p[23]==1) p=-p; else delay;
if (q[23]==1) q=-q; else delay;
p = (p<q) ? q : p; // This is done to get the best visual frequency result
if (display_log)
{
bit=126;
while ((p[21]==0) && (bit!=0))
par{
p = p<<1;
bit = bit - 18;
}
old_value = fft_info[i<-7];
tmp=((0@old_value) + (0@bit))>>1;
fft_info[i<-7] = (old_value<=(tmp<-7)) ? (tmp<-7) : old_value-1;
} else {
old_value = fft_info[i<-7];
fft_info[i<-7] = (old_value<=(unsigned)(p[21:15])) ? (unsigned)(p[21:15]) : old_value-1;
}
}
// add DC component again before inverse FFT calculation is performed
//real.rwrite[0] = real.read[0] + DC_COMPONENT;
}
*/
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