User manual
mikroPascal PRO for dsPIC30/33 and PIC24
MikroElektronika
642
Bit Reverse Complex Library
mikroPascal PRO for dsPIC30/33 and PIC24 includes a Bit Reverse Complex Library for DSP engine. All routines work
with fractional Q15 format.
Library Routines
- BitReverseComplex
BitReverseComplex
Prototype
procedure BitReverseComplex(log2N: word; var ReIm: array[1024] of word);
Description This function does Complex (in-place) Bit Reverse re-organization.
Parameters - N: buffer length (must be the power of 2).
- ReIm: output sample(from FFT).
Returns Nothing.
Requires Nothing.
Example
var InputSamples: array[512] of word; ydata; // Y data is required by
FFT routine
// See datasheet for your
dsPIC to see Y data space limits.
...
// Perform FFT (DFT), 7 stages, 128 samples of complex pairs
// Twiddle factors are taken from help
FFT(8, word(@TwiddleCoeff_256), InputSamples);
// DFT butterīy algorythm bit-reverses output samples.
// We have to restore them in natural order.
BitReverseComplex(8, InputSamples);
Notes Input samples must be in Y data space.