//
//  FFTTest.m
//  SpectogramPrototype
//
//  Created by Joshua Moerman on 24/12/13.
//  Copyright (c) 2013 Joshua Moerman. All rights reserved.
//

#import "FFTTest.h"
@import Accelerate;

@interface FFTTest () {
	FFTSetup setup;
	float * window;
	float * buffer;
}

@end

const int logN = 13;
const int N = 1 << logN;
const float scaling = 1.0 / N;

@implementation FFTTest
@synthesize acceptedSize;

- (id)init{
	if(self = [super init]){
		acceptedSize = N;
		
		// allocate structs
		setup = vDSP_create_fftsetup(logN, kFFTRadix2);
		window = calloc(N, sizeof(float));
		buffer = calloc(N, sizeof(float));
		
		assert(setup && window && buffer);
		
		// initialize bits
		vDSP_blkman_window(window, N, 0);
	}
	return self;
}

- (void)dealloc{
	free(buffer);
	free(window);
	vDSP_destroy_fftsetup(setup);
}

- (void)inPlaceFFT:(float *)data forSize:(unsigned int)n{
	assert(n == N);
	
	// Windowing
	vDSP_vmul(data, 1, window, 1, data, 1, N);
	
	// Rearrange data
	DSPSplitComplex split_buffer = { buffer, buffer + N/2 };
	vDSP_ctoz((DSPComplex *)data, 2, &split_buffer, 1, N/2);
	
	// DO IT!
	vDSP_fft_zrip(setup, &split_buffer, 1, logN, FFT_FORWARD);
	
	// Calculates magnitudes (so ignores phases)
	vDSP_zvabs(&split_buffer, 1, data, 1, N/2);
	vDSP_vsmul(data, 1, &scaling, data, 1, N/2);
	
}
@end