xtos_signal_fft_power

Computes one-sided squared-magnitude power for an unnormalized DFT, bins 0 through n/2.

On this page

Declaration

#include <xtos/signal.h>

int xtos_signal_fft_power(const double *input,
                          size_t n,
                          double *power,
                          size_t power_count);

Parameters

Parameter	Type	Description
input	const double *	Non-NULL input with at least n doubles; the implementation does not check NaN/Inf.
n	size_t	A nonzero power of two determining the FFT length.
power	double *	Non-NULL caller-allocated output with at least n/2+1 entries.
power_count	size_t	Output capacity in double elements, at least n/2+1.

Return value

Returns 0 on success and -1 on failure. power[0..n/2] is written; extra capacity is untouched.

Errors

errno	Condition
EINVAL	A pointer is NULL, n is not a nonzero power of two, or output capacity is too small.
ENOMEM	Allocation of either internal n-element temporary array failed.

Notes

The implementation calloc-allocates two n-element arrays and frees them before return; the caller still owns power.
Power is Re(X)^2+Im(X)^2 with no n or n^2 normalization, window, mean removal, or automatic factor of 2; NaN/Inf are not checked.

Example

Source

This reference describes headers and implementation at OpenXTOS commit dd313955ad57542bcd2af8827157d1bbd0cf5e83.