Cfft

Overview

Forward and inverse FFT of complex data

Discussion

Computes the forward or inverse FFT of complex data. At instantiation time (on the module name and arguments dialog) you specify whether a forward or an inverset transform should be computed. The internal hidden variable .dir controls whether a forward (= +1) or inverse (= -1) FFT is computed. The module supports multichannel signals.

Type Definition

CODE

typedef struct _ModuleCfft
{
    ModuleInstanceDescriptor instance;            // Common Audio Weaver module instance structure
    INT32 dir;                                    // Transform direction. Forward = 1. Inverse = -1
    void * hardware_specific_struct_pointer;      // This may point to a struct that varies based on the target platform
    void * fft_size_aligned_io_buffer_pointer;    // This points to a buffer which is aligned by fft size on SHARC
    void * fft_twiddle_buffer_pointer;            // This points to twiddle buffer on SHARC
} ModuleCfftClass;

Variables

Properties

Name	Type	Usage	isHidden	Default value	Range	Units
dir	int	const	0	1	-1, 1
hardware_specific_struct_pointer	void *	state	1		Unrestricted
fft_size_aligned_io_buffer_pointer	void *	state	1		Unrestricted
fft_twiddle_buffer_pointer	void *	state	1		Unrestricted

Pins

Input Pins

Name: in

Description: Complex input

Data type: float

Channel range: Unrestricted

Block size range: 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384

Sample rate range: Unrestricted

Complex support: Complex

Output Pins

Name: out

Description: Complex output

Data type: float

Scratch Pins

Channel count: 1

Block size: 5

Sample rate: 48000

MATLAB Usage

File Name: cfft_module.m

CODE

 M=cfft_module(NAME, ISFFT)
 Computes the forward or inverse FFT of complex input data.  The input
 block size must be a power of 2.  The module supports multichannel
 signals.  Arguments:
    NAME - name of the module.
    ISFFT :  1 for calculating FFT
             -1 for calculating IFFT
 ISFFT is an optional argument and is used to set the internal const
 variable 'dir'.  You can change .dir in design mode but not in tuning
 mode.