Commit d26adda5 authored by Laurent Aimar's avatar Laurent Aimar
Browse files

Moved static arrays to fft context.

parent 3fb0adb3
......@@ -38,20 +38,13 @@
/******************************************************************************
* Local prototypes
*****************************************************************************/
static void fft_prepare(const sound_sample *input, float * re, float * im);
static void fft_calculate(float * re, float * im);
static void fft_prepare(const sound_sample *input, float * re, float * im,
const unsigned int *bitReverse);
static void fft_calculate(float * re, float * im,
const float *costable, const float *sintable );
static void fft_output(const float *re, const float *im, float *output);
static int reverseBits(unsigned int initial);
/* Table to speed up bit reverse copy */
static unsigned int bitReverse[FFT_BUFFER_SIZE];
/* The next two tables could be made to use less space in memory, since they
* overlap hugely, but hey. */
static float sintable[FFT_BUFFER_SIZE / 2];
static float costable[FFT_BUFFER_SIZE / 2];
/*****************************************************************************
* These functions are the ones called externally
*****************************************************************************/
......@@ -67,19 +60,19 @@ fft_state *visual_fft_init(void)
fft_state *p_state;
unsigned int i;
p_state = (fft_state *) malloc (sizeof(fft_state));
p_state = malloc( sizeof(*p_state) );
if(! p_state )
return NULL;
for(i = 0; i < FFT_BUFFER_SIZE; i++)
{
bitReverse[i] = reverseBits(i);
p_state->bitReverse[i] = reverseBits(i);
}
for(i = 0; i < FFT_BUFFER_SIZE / 2; i++)
{
float j = 2 * PI * i / FFT_BUFFER_SIZE;
costable[i] = cos(j);
sintable[i] = sin(j);
p_state->costable[i] = cos(j);
p_state->sintable[i] = sin(j);
}
return p_state;
......@@ -96,10 +89,10 @@ fft_state *visual_fft_init(void)
*/
void fft_perform(const sound_sample *input, float *output, fft_state *state) {
/* Convert data from sound format to be ready for FFT */
fft_prepare(input, state->real, state->imag);
fft_prepare(input, state->real, state->imag, state->bitReverse );
/* Do the actual FFT */
fft_calculate(state->real, state->imag);
fft_calculate(state->real, state->imag, state->costable, state->sintable);
/* Convert the FFT output into intensities */
fft_output(state->real, state->imag, output);
......@@ -119,7 +112,8 @@ void fft_close(fft_state *state) {
/*
* Prepare data to perform an FFT on
*/
static void fft_prepare(const sound_sample *input, float * re, float * im) {
static void fft_prepare( const sound_sample *input, float * re, float * im,
const unsigned int *bitReverse ) {
unsigned int i;
float *p_real = re;
float *p_imag = im;
......@@ -158,7 +152,7 @@ static void fft_output(const float * re, const float * im, float *output)
/*
* Actually perform the FFT
*/
static void fft_calculate(float * re, float * im)
static void fft_calculate(float * re, float * im, const float *costable, const float *sintable )
{
unsigned int i, j, k;
unsigned int exchanges;
......
......@@ -36,6 +36,14 @@ struct _struct_fft_state {
/* Temporary data stores to perform FFT in. */
float real[FFT_BUFFER_SIZE];
float imag[FFT_BUFFER_SIZE];
/* */
unsigned int bitReverse[FFT_BUFFER_SIZE];
/* The next two tables could be made to use less space in memory, since they
* overlap hugely, but hey. */
float sintable[FFT_BUFFER_SIZE / 2];
float costable[FFT_BUFFER_SIZE / 2];
};
/* FFT prototypes */
......
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