/**********************************************************************
* © 2005 Microchip Technology Inc.
*
* FileName:        main_FFTExample.c
* Dependencies:    Header (.h) files if applicable, see below
* Processor:       dsPIC30Fxxxx
* Compiler:        MPLAB® C30 v3.00 or higher
* IDE:             MPLAB® IDE v7.52 or later
* Dev. Board Used: dsPICDEM 1.1 Development Board
* Hardware Dependencies: None
*
* SOFTWARE LICENSE AGREEMENT:
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* intellectual property rights in the code accompanying this message and in all 
* derivatives hereto.  You may use this code, and any derivatives created by 
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* proprietary products.  Your acceptance and/or use of this code constitutes 
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*
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*
* REVISION HISTORY:
*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* Author            Date      Comments on this revision
*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* HV               09/30/05  First release of source file
*
*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* ADDITIONAL NOTES:
*
*
**********************************************************************/
#include <p30Fxxxx.h>
#include <dsp.h>
#include "fft.h"

/* Device configuration register macros for building the hex file */
_FOSC(CSW_FSCM_OFF & XT_PLL8);          /* XT with 8xPLL oscillator, Failsafe clock off */
_FWDT(WDT_OFF);                         /* Watchdog timer disabled */
_FBORPOR(PBOR_OFF & MCLR_EN);           /* Brown-out reset disabled, MCLR reset enabled */
_FGS(CODE_PROT_OFF);                    /* Code protect disabled */


/* Extern definitions */
extern fractcomplex sigCmpx[FFT_BLOCK_LENGTH] 		/* Typically, the input signal to an FFT  */
__attribute__ ((section (".ydata, data, ymemory"), 	/* routine is a complex array containing samples */
aligned (FFT_BLOCK_LENGTH * 2 *2)));      		/* of an input signal. For this example, */
							/* we will provide the input signal in an */
							/* array declared in Y-data space. */
/* Global Definitions */
#ifndef FFTTWIDCOEFFS_IN_PROGMEM
fractcomplex twiddleFactors[FFT_BLOCK_LENGTH/2] 	/* Declare Twiddle Factor array in X-space*/
__attribute__ ((section (".xbss, bss, xmemory"), aligned (FFT_BLOCK_LENGTH*2)));
#else
extern const fractcomplex twiddleFactors[FFT_BLOCK_LENGTH/2]	/* Twiddle Factor array in Program memory */
__attribute__ ((space(auto_psv), aligned (FFT_BLOCK_LENGTH*2)));
#endif

int	peakFrequencyBin = 0;				/* Declare post-FFT variables to compute the */
unsigned long peakFrequency = 0;			/* frequency of the largest spectral component */

int main(void)
{
	int i = 0;
	fractional *p_real = &sigCmpx[0].real ;
	fractcomplex *p_cmpx = &sigCmpx[0] ;


#ifndef FFTTWIDCOEFFS_IN_PROGMEM					/* Generate TwiddleFactor Coefficients */
	TwidFactorInit (LOG2_BLOCK_LENGTH, &twiddleFactors[0], 0);	/* We need to do this only once at start-up */
#endif

	for ( i = 0; i < FFT_BLOCK_LENGTH; i++ )/* The FFT function requires input data */
	{					/* to be in the fractional fixed-point range [-0.5, +0.5]*/
		*p_real = *p_real >>1 ;		/* So, we shift all data samples by 1 bit to the right. */
		*p_real++;			/* Should you desire to optimize this process, perform */
	}					/* data scaling when first obtaining the time samples */
						/* Or within the BitReverseComplex function source code */

	p_real = &sigCmpx[(FFT_BLOCK_LENGTH/2)-1].real ;	/* Set up pointers to convert real array */
	p_cmpx = &sigCmpx[FFT_BLOCK_LENGTH-1] ; /* to a complex array. The input array initially has all */
						/* the real input samples followed by a series of zeros */


	for ( i = FFT_BLOCK_LENGTH; i > 0; i-- ) /* Convert the Real input sample array */
	{					/* to a Complex input sample array  */
		(*p_cmpx).real = (*p_real--);	/* We will simpy zero out the imaginary  */
		(*p_cmpx--).imag = 0x0000;	/* part of each data sample */
	}

	/* Perform FFT operation */
#ifndef FFTTWIDCOEFFS_IN_PROGMEM
	FFTComplexIP (LOG2_BLOCK_LENGTH, &sigCmpx[0], &twiddleFactors[0], COEFFS_IN_DATA);
#else
	FFTComplexIP (LOG2_BLOCK_LENGTH, &sigCmpx[0], (fractcomplex *) __builtin_psvoffset(&twiddleFactors[0]), (int) __builtin_psvpage(&twiddleFactors[0]));
#endif

	/* Store output samples in bit-reversed order of their addresses */
	BitReverseComplex (LOG2_BLOCK_LENGTH, &sigCmpx[0]);

	/* Compute the square magnitude of the complex FFT output array so we have a Real output vetor */
	SquareMagnitudeCplx(FFT_BLOCK_LENGTH, &sigCmpx[0], &sigCmpx[0].real);

	/* Find the frequency Bin ( = index into the SigCmpx[] array) that has the largest energy*/
	/* i.e., the largest spectral component */
	VectorMax(FFT_BLOCK_LENGTH/2, &sigCmpx[0].real, &peakFrequencyBin);

	/* Compute the frequency (in Hz) of the largest spectral component */
	peakFrequency = peakFrequencyBin*(SAMPLING_RATE/FFT_BLOCK_LENGTH);

        while (1);	/* Place a breakpoint here and observe the watch window variables */
}