void FHT::transform(float *p)
{
if (m_num == 8)
transform8(p);
else
_transform(p, m_num, 0);
}
void FastFourierTransformation::_transform( float *p, int n, int k )
{
if(n == 8)
{
transform8( p + k );
return;
}
int i, j, ndiv2 = n / 2;
float a, *t1, *t2, *t3, *t4, *ptab, *pp;
for( i = 0, t1 = m_buf, t2 = m_buf + ndiv2, pp = &p[k]; i < ndiv2; i++ )
{
*t1++ = *pp++, *t2++ = *pp++;
}
memcpy( p + k, m_buf, sizeof( float ) * n );
_transform( p, ndiv2, k );
_transform( p, ndiv2, k + ndiv2 );
j = m_num / ndiv2 - 1;
t1 = m_buf;
t2 = t1 + ndiv2;
t3 = p + k + ndiv2;
ptab = m_tab;
pp = p + k;
a = *ptab++ * *t3++;
a += *ptab * *pp;
ptab += j;
*t1++ = *pp + a;
*t2++ = *pp++ - a;
for ( i = 1, t4 = p + k + n; i < ndiv2; i++, ptab += j )
{
a = *ptab++ * *t3++;
a += *ptab * *--t4;
*t1++ = *pp + a;
*t2++ = *pp++ - a;
}
memcpy( p + k, m_buf, sizeof(float) * n );
}
void FHT::_transform(float* p, int n, int k) {
if (n == 8) {
transform8(p + k);
return;
}
int i, j, ndiv2 = n / 2;
float a, *t1, *t2, *t3, *t4, *ptab, *pp;
for (i = 0, t1 = buf_(), t2 = buf_() + ndiv2, pp = &p[k]; i < ndiv2; i++)
*t1++ = *pp++, *t2++ = *pp++;
std::copy(buf_(), buf_() + n, p + k);
_transform(p, ndiv2, k);
_transform(p, ndiv2, k + ndiv2);
j = num_ / ndiv2 - 1;
t1 = buf_();
t2 = t1 + ndiv2;
t3 = p + k + ndiv2;
ptab = tab_();
pp = p + k;
a = *ptab++ * *t3++;
a += *ptab * *pp;
ptab += j;
*t1++ = *pp + a;
*t2++ = *pp++ - a;
for (i = 1, t4 = p + k + n; i < ndiv2; i++, ptab += j) {
a = *ptab++ * *t3++;
a += *ptab * *--t4;
*t1++ = *pp + a;
*t2++ = *pp++ - a;
}
std::copy(buf_(), buf_() + n, p + k);
}
void FHT::transform(float* p) {
if (num_ == 8)
transform8(p);
else
_transform(p, num_, 0);
}
