Cfft2D - Analog Devices VISUALDSP++ 3.5 Manual

DSP Run-Time Library Reference

cfft2d

NxN point 2-D complex input FFT
Synopsis
#include <filter.h>
void cfft2d_fr16(*in, *t, *out, w[], wst, n, block_exponent,
scale_method)
const complex_fract16 *in;
complex_fract16 *t;
complex_fract16 *out;
const complex_fract16 w[];
int wst;
int n;
int *block_exponent;
int scale method;
Description
This function computes the two dimensional Fast Fourier Transform of
the complex input matrix
output matrix
The size of the input array
working buffer
FFT. The function does not impose any special memory alignment
requirements on the arrays. However, benefits in run-time performance
will be realized if the output array is allocated on an address boundary that
is a multiple of twice the FFT size.
The twiddle table is passed in the argument
twiddle factors. The function
n/2
ize the array. If the twiddle table contains more factors than needed for a
particular call on
priately; otherwise it should be 1.
4-40
/* pointer to input matrix a[n][n]
/* pointer to working buffer t[n][n] */
/* pointer to output matrix c[n][n]
/* twiddle sequence
/* twiddle factor stride
/* number of FFT points
/* block exponent of output data
/* scaling method desired 0-none,
a[n][n]
.
c[n][n]
, the output array
in
is , where
t n*n n
, then the stride factor has to be set appro-
cfft2d_fr16
VisualDSP++ 3.5 C/C++ Compiler and Library Manual
1-static, 2-dynamic
, and stores the result to the complex
out
represents the number of points in the
, which must contain at least
w
twidfft2d_fr16
, and the temporary
may be used to initial-
for ADSP-219x DSPs
*/
*/
*/
*/
*/
*/
*/