DSP_fft16x16
[Fast Fourier Transform]

Collaboration diagram for DSP_fft16x16:

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Detailed Description

void	DSP_fft16x16 (const short *restrict ptr_w, int npoints, short *restrict ptr_x, short *restrict ptr_y)

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Function Documentation

void DSP_fft16x16	(	const short *restrict	ptr_w,
		int	npoints,
		short *restrict	ptr_x,
		short *restrict	ptr_y
	)

The following code performs a mixed radix FFT for "npoints" which is either a multiple of 4 or 2. It uses logN4 - 1 stages of radix4 transform and performs either a radix2 or radix4 transform on the last stage depending on "npoints". If "npoints" is a multiple of 4 then this last stage is also a radix4 transform, otherwise it is a radix2 transform.

Parameters:

	ptr_w	= input twiddle factors
	npoints	= number of points
	ptr_x	= transformed data reversed
	ptr_y	= linear transformed data

Algorithm:

DSP_fft16x16_cn.c is the natural C equivalent of the optimized intrinsic C code without restrictions. Note that the intrinsic C code is optimized and restrictions may apply.

Assumptions:

In-place computation is not allowed.
Size of FFT, nx, must be power of 2 and 16<=nx<=65536.
The arrays for the complex input data x[], complex output data y[] and twiddle factor w[] must be double word aligned.
The input and output data are complex, with the real/imaginary components stored in adjacent locations in the array. The real components are stored at even array indices, and the imaginary components are stored at odd array indices.

Implementation Notes:

Endian Support: The code supports both big and little endian modes.
Interruptibility: The code is interruptible.

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Copyright 2014, Texas Instruments Incorporated