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fft.c
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#include "fft.h"
size_t size(char *__arr, size_t __size)
{
unsigned long i = 0;
while(*__arr){
i ++;
__arr++;
}
return i/__size;
}
double max(double *__arr, size_t __size)
{
double max = -__DBL_MAX__;
for(size_t j = 0; j < __size; ++j){
if(__arr[j] > max)
max = __arr[j];
}
return max;
}
unsigned long btoi(char *__src, long __size)
{
unsigned long ret = 0;
for(long i = 0; i < __size; ++i)
ret += *(__src++) << 8 * i;
return ret;
}
void *itodc(double complex *__dest, int *__src, size_t __size, uint16_t __bitsPerSample)
{
for(size_t i = 0; i < __size; ++i)
*(__dest + i) = ((double)*(__src + i) / (1 << __bitsPerSample)) + 0 * I;
return (void *)__dest;
}
void dft_uint_complex(int *__src, double complex *__dest, size_t __size, uint8_t __bitsPerSample)
{
memset(__dest, 0, __size * sizeof(double complex));
double complex temp;
for(size_t i = 0; i < __size; ++i){
temp = 0 + 0*I;
for(size_t j = 0; j < __size; ++j){
temp += ((double)*(__src + j) / (1 << __bitsPerSample) + 0 * I) * fft_coefd(i * j / __size);
}
*(__dest + i) = temp;
}
}
void dft_complex_complex(double complex *__src, double complex *__dest, size_t __size)
{
memset(__dest, 0, sizeof(double complex) * __size);
double complex temp;
for(size_t i = 0; i < __size; ++i){
temp = 0 + 0 * I;
for(size_t j = 0; j < __size; ++j)
temp += *(__src + j) * fft_coefd(i * j / __size);
*(__dest + i) = temp;
}
}
void dft_uint_double(int *__src, double *__dest, size_t __size, uint8_t __bitsPerSample)
{
memset(__dest, 0, sizeof(double) * __size);
double complex temp;
for(size_t i = 0; i < __size; ++i){
temp = 0 + 0*I;
for(size_t j = 0; j < __size; ++j){
temp += ((double)*(__src + j) / (1 << __bitsPerSample) + 0 * I) * fft_coefd(i * j / __size);
}
*(__dest + i) = 10 * log(cabs(temp));
}
}
void fft_cooley(double complex *__src, const size_t __size)
{
if (__size == 1) return;
/* add balckman - harris window */
for(size_t i = 0; i < __size; ++i)
__src[i] *= (0.35875 - 0.48829 * cos(2 * PI * i / __size) + 0.14128 * cos(4 * PI * i / __size)\
- 0.01168 * cos(6 * PI * i / __size));
double complex even[__size / 2], odd[__size / 2];
for(size_t i = 0; i < __size / 2; ++i){
even[i] = __src[2*i];
odd[i] = __src[2*i + 1];
}
// even and odd
fft_cooley(even, __size / 2);
fft_cooley(odd, __size / 2);
double complex temp = 0;
for(size_t k = 0; k < __size / 2; ++k){
temp = fft_coefd(k / __size) * odd[k];
__src[k] = even[k] + temp;
__src[k + __size / 2] = even[k] - temp;
}
}