void FastMul(const BigInt &A,const BigInt &B, BigInt &C) {
ulong Len = 2;
while ( Len < A.Size + B.Size ) Len *=2;
if ( Len < 40 ) {
BigInt Atmp(A), Btmp(B);
Mul(Atmp,Btmp,C);
return;
}
ulong x;
const ushort *a=A.Coef, *b=B.Coef;
for (x = 0; x < A.Size; x++) LongNum1[x] = a[x];
for (; x < Len; x++) LongNum1[x] = 0.0;
FHT_F(LongNum1,Len);
if (a == b) {
FHTConvolution(LongNum1,LongNum1,Len);
} else {
for (x = 0; x < B.Size; x++) LongNum2[x] = b[x];
for (; x < Len; x++) LongNum2[x] = 0.0;
FHT_F(LongNum2,Len);
FHTConvolution(LongNum1,LongNum2,Len);
}
FHT_T(LongNum1,Len);
CarryNormalize(LongNum1, Len, C);
}
void RFHT_F(FFT_DATA_TYPE *Data,int Len)
/*
** Recursive Decimation in Frequency style Fast Hartley Transform
*/
{int x,Len2,Len4;
TRIG_VARS
FFT_DATA_TYPE *Left,*Right;
Len/=2;Left=&Data[0];Right=&Data[Len];
if (Len==2)
{FFT_DATA_TYPE d0=Data[0]; FFT_DATA_TYPE d1=Data[1];
FFT_DATA_TYPE d2=Data[2]; FFT_DATA_TYPE d3=Data[3];
StartTimer(FFTITime);
StartTimer(CRTLoad);
{FFT_DATA_TYPE d02; FFT_DATA_TYPE d13;
DD_Add(&d0,&d2,&d02);
DD_Add(&d1,&d3,&d13);
DD_Add(&d02,&d13,&Data[0]);
DD_Sub(&d02,&d13,&Data[1]);
}
{FFT_DATA_TYPE d02,d13;
DD_Sub(&d0,&d2,&d02);
DD_Sub(&d1,&d3,&d13);
DD_Add(&d02,&d13,&Data[2]);
DD_Sub(&d02,&d13,&Data[3]);
}
StopTimer(FFTITime);
StopTimer(CRTLoad);
return;
}
if (Len<=(CPU_CACHE/sizeof(FFT_DATA_TYPE))) {FHT_F(Data,Len*2);return;}
StartTimer(FFTITime);
{FFT_DATA_TYPE t1,t2;
t1=Left[0];t2=Right[0];
DD_Add(&t1,&t2,&Left[0]);
DD_Sub(&t1,&t2,&Right[0]);
t1=Left[Len/2];t2=Right[Len/2];
DD_Add(&t1,&t2,&Left[Len/2]);
DD_Sub(&t1,&t2,&Right[Len/2]);
}
INIT_TRIG(Len);
Len2=Len/2;
Len4=Len/4;
for (x=1;x<Len4;x++)
{
NEXT_TRIG_POW;
FHT_F2Butterfly(x,Len-x,Pow_r,Pow_i);
FHT_F2Butterfly(Len2-x,Len2+x,Pow_i,Pow_r);
}
/* Now do the two Len/4 points the loop missed */
if (Len4)
// {FFT_DATA_TYPE sq=MY_SQRT_2; /* variable allows optimizations */
// FHT_F2Butterfly(Len4,Len-Len4,sq,sq);
{
FHT_F2Butterfly(Len4,Len-Len4,Sqrt05,Sqrt05);
}
StopTimer(FFTITime);
if (Len>=2) RFHT_F(Left, Len);
if (Len>=2) RFHT_F(Right,Len);
}
