robert@464: /*
robert@464:  ____  _____ _        _    
robert@464: | __ )| ____| |      / \   
robert@464: |  _ \|  _| | |     / _ \  
robert@464: | |_) | |___| |___ / ___ \ 
robert@464: |____/|_____|_____/_/   \_\
robert@464: 
robert@464: The platform for ultra-low latency audio and sensor processing
robert@464: 
robert@464: http://bela.io
robert@464: 
robert@464: A project of the Augmented Instruments Laboratory within the
robert@464: Centre for Digital Music at Queen Mary University of London.
robert@464: http://www.eecs.qmul.ac.uk/~andrewm
robert@464: 
robert@464: (c) 2016 Augmented Instruments Laboratory: Andrew McPherson,
robert@464:   Astrid Bin, Liam Donovan, Christian Heinrichs, Robert Jack,
robert@464:   Giulio Moro, Laurel Pardue, Victor Zappi. All rights reserved.
robert@464: 
robert@464: The Bela software is distributed under the GNU Lesser General Public License
robert@464: (LGPL 3.0), available here: https://www.gnu.org/licenses/lgpl-3.0.txt
robert@464: */
robert@464: 
robert@464: 
robert@464: #include <Bela.h>
robert@464: #include <rtdk.h>
robert@464: #include <ne10/NE10.h>					// neon library
robert@464: #include <cmath>
robert@464: 
robert@464: int gFFTSize;
robert@464: 
robert@464: int gReadPointer = 0;
robert@464: int gWritePointer = 0;
robert@464: 
robert@464: // FFT vars
robert@464: static ne10_fft_cpx_float32_t* timeDomainIn;
robert@464: static ne10_fft_cpx_float32_t* timeDomainOut;
robert@464: static ne10_fft_cpx_float32_t* frequencyDomain;
robert@464: static ne10_fft_cfg_float32_t cfg;
robert@464: 
robert@464: bool setup(BelaContext *context, void *userData)
robert@464: {
robert@464: 	// Retrieve a parameter passed in from the initAudio() call
robert@464: 	gFFTSize = *(int *)userData;
robert@464: 
robert@464: 	timeDomainIn = (ne10_fft_cpx_float32_t*) NE10_MALLOC (gFFTSize * sizeof (ne10_fft_cpx_float32_t));
robert@464: 	timeDomainOut = (ne10_fft_cpx_float32_t*) NE10_MALLOC (gFFTSize * sizeof (ne10_fft_cpx_float32_t));
robert@464: 	frequencyDomain = (ne10_fft_cpx_float32_t*) NE10_MALLOC (gFFTSize * sizeof (ne10_fft_cpx_float32_t));
robert@464: 	cfg = ne10_fft_alloc_c2c_float32_neon (gFFTSize);
robert@464: 
robert@464: 	memset(timeDomainOut, 0, gFFTSize * sizeof (ne10_fft_cpx_float32_t));
robert@464: 
robert@464: 	return true;
robert@464: }
robert@464: 
robert@464: void render(BelaContext *context, void *userData)
robert@464: {
robert@464: 	for(unsigned int n = 0; n < context->audioFrames; n++) {
robert@464: 		timeDomainIn[gReadPointer].r = (ne10_float32_t) ((context->audioIn[n*context->audioChannels] +
robert@464: 															context->audioIn[n*context->audioChannels+1]) * 0.5);
robert@464: 		timeDomainIn[gReadPointer].i = 0;
robert@464: 
robert@464: 		if(++gReadPointer >= gFFTSize)
robert@464: 		{
robert@464: 			//FFT
robert@464: 			ne10_fft_c2c_1d_float32_neon (frequencyDomain, timeDomainIn, cfg, 0);
robert@464: 
robert@464: 			//Do frequency domain stuff
robert@464: 
robert@464: 			//IFFT
robert@464: 			ne10_fft_c2c_1d_float32_neon (timeDomainOut, frequencyDomain, cfg, 1);
robert@464: 
robert@464: 			gReadPointer = 0;
robert@464: 			gWritePointer = 0;
robert@464: 		}
robert@464: 
robert@464: 		for(unsigned int channel = 0; channel < context->audioChannels; channel++)
robert@464: 			context->audioOut[n * context->audioChannels + channel] = (float) timeDomainOut[gWritePointer].r;
robert@464: 		gWritePointer++;
robert@464: 	}
robert@464: }
robert@464: 
robert@464: void cleanup(BelaContext *context, void *userData)
robert@464: {
robert@464: 	NE10_FREE(timeDomainIn);
robert@464: 	NE10_FREE(timeDomainOut);
robert@464: 	NE10_FREE(frequencyDomain);
robert@464: 	NE10_FREE(cfg);
robert@464: }
robert@464: 
robert@464: 
robert@464: /**
robert@500: \example FFT-audio-in/render.cpp
robert@464: 
robert@464: Fast Fourier Transform
robert@464: ----------------------
robert@464: 
robert@464: This sketch performs an FFT (Fast Fourier Transform) on incoming audio. It uses 
robert@464: the NE10 library, included at the top of the file.
robert@464: 
robert@464: Read the documentation on the NE10 library [here](http://projectne10.github.io/Ne10/doc/annotated.html).
robert@464: 
robert@464: The variables `timeDomainIn`, `timeDomainOut` and `frequencyDomain` are 
robert@464: variables of the struct `ne10_fft_cpx_float32_t` [http://projectne10.github.io/Ne10/doc/structne10__fft__cpx__float32__t.html](http://projectne10.github.io/Ne10/doc/structne10__fft__cpx__float32__t.html). 
robert@464: These are declared at the top of the file, and memory is allocated 
robert@464: for them in `setup()`.
robert@464: 
robert@464: In `render()` a `for` loop performs the FFT which is performed on each sample, 
robert@464: and the resulting output is placed on each channel.
robert@464: */