PRIVATE: Wrapper for fast Fourier transform routines

Files
file	fnft__fft_wrapper.h
	Wraps underlying FFT library.
file	fnft__fft_wrapper_plan_t.h

Typedefs
typedef kiss_fft_cfg	fnft__fft_wrapper_plan_t
	Stores information needed by fnft__fft_wrapper_execute_plan to perform a (inverse) FFT.

Functions
static FNFT_UINT	fnft__fft_wrapper_next_fft_length (FNFT_UINT desired_length)
	Next valid number of samples for the FFT routines.
static fnft__fft_wrapper_plan_t	fnft__fft_wrapper_safe_plan_init ()
	Value to initialize plan variables.
static FNFT_INT	fnft__fft_wrapper_create_plan (fnft__fft_wrapper_plan_t *plan_ptr, FNFT_UINT fft_length, FNFT_COMPLEX *in, FNFT_COMPLEX *out, FNFT_INT is_inverse)
	Prepares a new (inverse) fast Fourier transform (FFT).
static FNFT_INT	fnft__fft_wrapper_execute_plan (fnft__fft_wrapper_plan_t plan, FNFT_COMPLEX *in, FNFT_COMPLEX *out)
	Computes a fast Fourier transform (FFT).
static FNFT_INT	fnft__fft_wrapper_destroy_plan (fnft__fft_wrapper_plan_t *plan_ptr)
	Destroys a FFT plan when it is no longer needed.
static void *	fnft__fft_wrapper_malloc (FNFT_UINT size)
	Memory allocation for the FFT wrapper.
static void	fnft__fft_wrapper_free (void *ptr)
	Memory deallocation for the FFT wrapper.

Detailed Description

Function Documentation

fnft__fft_wrapper_create_plan()

static FNFT_INT fnft__fft_wrapper_create_plan ( fnft__fft_wrapper_plan_t *  plan_ptr, FNFT_UINT  fft_length, FNFT_COMPLEX *  in, FNFT_COMPLEX *  out, FNFT_INT  is_inverse  )

inlinestatic

Prepares a new (inverse) fast Fourier transform (FFT).

Plans can be reused as long as the parameters of the FFT (fft_length and is_inverse) do not change.

Parameters

[in,out]	plan_ptr	Pointer a fnft__fft_wrapper_plan_t object. Will be changed by the routine.
[in]	fft_length	Length of the (inverse) FFT to be computed. Must be generated using fnft__fft_wrapper_next_fft_length.
[in,out]	in	Input buffer with fft_length entries. Initialize after creating the plan as it might be overwritten. Create with fnft__fft_wrapper_malloc to ensure correct alignment.
[in,out]	out	Output buffer with fft_length enties. Initialize after creating the plan as it might be overwritten. Create with fnft__fft_wrapper_malloc to ensure correct alignment.
[in]	is_inverse	-1 => forward FFT, 1 => inverse FFT. Note that the inverse FFT will not be normalized by the factor 1/fft_length.

Returns

FFT_SUCCESS or an error code.

fnft__fft_wrapper_destroy_plan()

static FNFT_INT fnft__fft_wrapper_destroy_plan ( fnft__fft_wrapper_plan_t *  plan_ptr )

inlinestatic

Destroys a FFT plan when it is no longer needed.

Frees any memory that was allocated when the plan was created, and sets the value of the plan to fnft__fft_wrapper_safe_plan_init to avoid errors when a plan is destroyed several times.

Parameters

[in]

plan_ptr

Pointer to a plan object created with fnft__fft_wrapper_create_plan

Returns

FFT_SUCCESS or an error code.

fnft__fft_wrapper_execute_plan()

static FNFT_INT fnft__fft_wrapper_execute_plan ( fnft__fft_wrapper_plan_t  plan, FNFT_COMPLEX *  in, FNFT_COMPLEX *  out  )

inlinestatic

Computes a fast Fourier transform (FFT).

Parameters

[in]	plan	Plan object created with fnft__fft_wrapper_create_plan
[in]	in	Input buffer, not neccessarily the same that was used when creating the plan. The length however has to be the same. Create with fnft__fft_wrapper_malloc to ensure correct alignment.
[out]	out	Output buffer, not neccessarily the same that was used when creating the plan. The length however has to be the same. Create with fnft__fft_wrapper_malloc to ensure correct alignment.

Returns

FFT_SUCCESS or an error code.

fnft__fft_wrapper_free()

static void fnft__fft_wrapper_free ( void *  ptr )

inlinestatic

Memory deallocation for the FFT wrapper.

Use this routine to deallocate memory that was allocated using fnft__fft_wrapper_malloc.

Parameters

[in]

ptr

Pointer to memory block that is to be freed (or NULL).

fnft__fft_wrapper_malloc()

static void * fnft__fft_wrapper_malloc ( FNFT_UINT  size )

inlinestatic

Memory allocation for the FFT wrapper.

Use this routine to allocate memory for the input and output buffers. It ensures proper alignment.

Parameters

[in]

size

Number of points to be allocated.

Returns

A pointer to the allocated buffer, or NULL if that failed.

fnft__fft_wrapper_next_fft_length()

static FNFT_UINT fnft__fft_wrapper_next_fft_length ( FNFT_UINT  desired_length )

inlinestatic

Next valid number of samples for the FFT routines.

Returns the next larger or equal valid number of samples accepted by fnft__fft_wrapper_create_plan.

Parameters

[in]

desired_length

Desired number of samples

Returns

Actual number of samples to be used.

fnft__fft_wrapper_safe_plan_init()

static fnft__fft_wrapper_plan_t fnft__fft_wrapper_safe_plan_init ( )

inlinestatic

Value to initialize plan variables.

To avoid having uninitialized plans, initialize new plans with the value returned by this function (usually, this is simply NULL).