static void fft16(FFTComplex *z)
{
FFTSample t1, t2, t3, t4, t5, t6;
fft8(z);
fft4(z+8);
fft4(z+12);
TRANSFORM_ZERO(z[0],z[4],z[8],z[12]);
TRANSFORM(z[2],z[6],z[10],z[14],sqrthalf,sqrthalf);
TRANSFORM(z[1],z[5],z[9],z[13],ff_cos_16[1],ff_cos_16[3]);
TRANSFORM(z[3],z[7],z[11],z[15],ff_cos_16[3],ff_cos_16[1]);
}
static void fft16(Complex *z) {
float t1, t2, t3, t4, t5, t6;
fft8(z);
fft4(z + 8);
fft4(z + 12);
const float * const cosTable = getCosineTable(4);
TRANSFORM_ZERO(z[0], z[4], z[8], z[12]);
TRANSFORM(z[2], z[6], z[10], z[14], sqrthalf, sqrthalf);
TRANSFORM(z[1], z[5], z[9], z[13], cosTable[1],cosTable[3]);
TRANSFORM(z[3], z[7], z[11], z[15], cosTable[3], cosTable[1]);
}
void fft16(FFTComplex *z)
{
fft8(z);
fft4(z+8);
fft4(z+12);
TRANSFORM_ZERO(z,4);
z+=2;
TRANSFORM_EQUAL(z,4);
z-=1;
TRANSFORM(z,4,cPI1_8,cPI3_8);
z+=2;
TRANSFORM(z,4,cPI3_8,cPI1_8);
}
void FFT::fft16(Complex *z) {
float t1, t2, t3, t4, t5, t6;
fft8(z);
fft4(z + 8);
fft4(z + 12);
assert(_cosTables[0]);
const float * const cosTable = _cosTables[0]->getTable();
TRANSFORM_ZERO(z[0], z[4], z[8], z[12]);
TRANSFORM(z[2], z[6], z[10], z[14], sqrthalf, sqrthalf);
TRANSFORM(z[1], z[5], z[9], z[13], cosTable[1],cosTable[3]);
TRANSFORM(z[3], z[7], z[11], z[15], cosTable[3], cosTable[1]);
}
void FFT::fft8(Complex *z) {
float t1, t2, t3, t4, t5, t6, t7, t8;
fft4(z);
BF(t1, z[5].re, z[4].re, -z[5].re);
BF(t2, z[5].im, z[4].im, -z[5].im);
BF(t3, z[7].re, z[6].re, -z[7].re);
BF(t4, z[7].im, z[6].im, -z[7].im);
BF(t8, t1, t3, t1);
BF(t7, t2, t2, t4);
BF(z[4].re, z[0].re, z[0].re, t1);
BF(z[4].im, z[0].im, z[0].im, t2);
BF(z[6].re, z[2].re, z[2].re, t7);
BF(z[6].im, z[2].im, z[2].im, t8);
TRANSFORM(z[1], z[3], z[5], z[7], sqrthalf, sqrthalf);
}
static inline void fft8(FFTComplex *z)
{
fft4(z);
FFTSample t1,t2,t3,t4,t7,t8;
BF(t1, z[5].re, z[4].re, -z[5].re);
BF(t2, z[5].im, z[4].im, -z[5].im);
BF(t3, z[7].re, z[6].re, -z[7].re);
BF(t4, z[7].im, z[6].im, -z[7].im);
BF(t8, t1, t3, t1);
BF(t7, t2, t2, t4);
BF(z[4].re, z[0].re, z[0].re, t1);
BF(z[4].im, z[0].im, z[0].im, t2);
BF(z[6].re, z[2].re, z[2].re, t7);
BF(z[6].im, z[2].im, z[2].im, t8);
z++;
TRANSFORM_EQUAL(z,2);
}
void FFT::fft(int n, int logn, Complex *z) {
switch (logn) {
case 2:
fft4(z);
break;
case 3:
fft8(z);
break;
case 4:
fft16(z);
break;
default:
fft((n / 2), logn - 1, z);
fft((n / 4), logn - 2, z + (n / 4) * 2);
fft((n / 4), logn - 2, z + (n / 4) * 3);
assert(_cosTables[logn - 4]);
if (n > 1024)
pass_big(z, _cosTables[logn - 4]->getTable(), (n / 4) / 2);
else
pass(z, _cosTables[logn - 4]->getTable(), (n / 4) / 2);
}
}
static void fft4_dispatch(FFTComplex *z)
{
fft4(z);
}
