static inline size_t FastReverseBits(size_t i, size_t NumBits)
{
if (NumBits <= MaxFastBits)
return gFFTBitTable[NumBits - 1][i];
else
return ReverseBits(i, NumBits);
}
int main()
{
int value = 11;
printf("Entered value:%d\n", value);
printf("swap:%d\n",ReverseBits(value));
}
// Get the actual bit values for a tree of bit depths.
static void ConvertBitDepthsToSymbols(HuffmanTreeCode* const tree) {
// 0 bit-depth means that the symbol does not exist.
int i;
int len;
uint32_t next_code[MAX_ALLOWED_CODE_LENGTH + 1];
int depth_count[MAX_ALLOWED_CODE_LENGTH + 1] = { 0 };
assert(tree != NULL);
len = tree->num_symbols;
for (i = 0; i < len; ++i) {
const int code_length = tree->code_lengths[i];
assert(code_length <= MAX_ALLOWED_CODE_LENGTH);
++depth_count[code_length];
}
depth_count[0] = 0; // ignore unused symbol
next_code[0] = 0;
{
uint32_t code = 0;
for (i = 1; i <= MAX_ALLOWED_CODE_LENGTH; ++i) {
code = (code + depth_count[i - 1]) << 1;
next_code[i] = code;
}
}
for (i = 0; i < len; ++i) {
const int code_length = tree->code_lengths[i];
tree->codes[i] = ReverseBits(code_length, next_code[code_length]++);
}
}
inline int FastReverseBits(int i, int NumBits)
{
if (NumBits <= MaxFastBits)
return gFFTBitTable[NumBits - 1][i];
else
return ReverseBits(i, NumBits);
}
void InitFFT()
{
gFFTBitTable.reinit(MaxFastBits);
size_t len = 2;
for (size_t b = 1; b <= MaxFastBits; b++) {
auto &array = gFFTBitTable[b - 1];
array.reinit(len);
for (size_t i = 0; i < len; i++)
array[i] = ReverseBits(i, b);
len <<= 1;
}
}
void InitFFT()
{
gFFTBitTable = new int *[MaxFastBits];
int len = 2;
for (int b = 1; b <= MaxFastBits; b++) {
gFFTBitTable[b - 1] = new int[len];
for (int i = 0; i < len; i++)
gFFTBitTable[b - 1][i] = ReverseBits(i, b);
len <<= 1;
}
}
BOOL RplDirStatus( VOID) {
USHORT network_type;
(VOID)memset((PVOID)&Ccb, '\0', sizeof(Ccb));
Ccb.uchDlcCommand = LLC_DIR_STATUS;
Ccb.u.pParameterTable = (PLLC_PARMS)&DirStatusParms;
if ( !EtherAcsLan()) {
return( FALSE);
}
network_type = DirStatusParms.usAdapterType;
if ( network_type != RPL_ADAPTER_ETHERNET) {
PRINTF(( "network_type=0x%x\n", network_type));
return( FALSE);
}
ReverseBits( DirStatusParms.auchNodeAddress);
return( TRUE);
}
SymbEncodingTable::SymbEncodingTable( unsigned int rate_numer,
unsigned int rate_denom,
unsigned int *inp_polys)
{
// rate_numer is the number of input bits processed each cycle
// rate_denom is the number of output bits generated each cycle
// polys points to a set of rate_numer*rate_denom polynomials
// the polynomial pointed to by polys[i][j] operates on
// the i-th input subsequence and contributes to the
// j-th output subsequence
unsigned int j;
unsigned int out_val;
int composite;
int *polys;
int num_active_bits;
polys = new int[rate_numer];
composite = 0;
for(j=0; j<rate_denom; j++)
{
composite |= inp_polys[j];
}
num_active_bits = ActiveBitCount(composite);
for( j=0; j<rate_denom; j++)
{
polys[j] = ReverseBits(inp_polys[j], num_active_bits);
cout << "P[" << j << "] = " << polys[j] << endl;
}
//---------------------------
Table_Len = 1<<num_active_bits;
Out_Table = new int[Table_Len];
for(int n=0; n<Table_Len; n++)
{
out_val=0;
for(unsigned int out_num=0; out_num<rate_denom; out_num++)
{
out_val <<= 1;
out_val |= xor(n&polys[out_num]);
}
Out_Table[n] = out_val;
}
}
void InitFFT()
{
// gFFTBitTable = new int *[MaxFastBits];
//use malloc for 16 byte alignment
gFFTBitTable = (int**) malloc(MaxFastBits * sizeof(int*));
int len = 2;
for (int b = 1; b <= MaxFastBits; b++) {
// gFFTBitTable[b - 1] = new int[len];
gFFTBitTable[b - 1] = (int*) malloc(len * sizeof(int));
for (int i = 0; i < len; i++)
gFFTBitTable[b - 1][i] = ReverseBits(i, b);
len <<= 1;
}
}
void cDriverSED1520::Set8Pixels (int x, int y, unsigned char data)
{
if (x >= width || y >= height)
return;
if (!config->upsideDown)
{
// normal orientation
LCD[x / 8][y] = LCD[x / 8][y] | data;
}
else
{
// upside down orientation
x = width - 1 - x;
y = height - 1 - y;
LCD[x / 8][y] = LCD[x / 8][y] | ReverseBits(data);
}
}
void ofxFftBasic::setup(int _bins, fftWindowType _windowType)
{
ofxFft::setup(_bins, _windowType);
gFFTBitTable = new int *[MaxFastBits];
int len = 2;
for (int b = 1; b <= MaxFastBits; b++) {
gFFTBitTable[b - 1] = new int[len];
for (int i = 0; i < len; i++)
gFFTBitTable[b - 1][i] = ReverseBits(i, b);
len <<= 1;
}
ready = true;
}
void InitFFT()
{
gFFTBitTable = (int**)calloc(MaxFastBits, sizeof(int*));
if (gFFTBitTable == NULL)
fprintf(stderr, "No se esta asignando memoria a gFFBitTable");
int len = 2;
int b = 0;
int i = 0;
for (b = 1; b <= MaxFastBits; b++) {
gFFTBitTable[b - 1] = (int*)calloc(len, sizeof(int));
if (gFFTBitTable[b - 1] == NULL)
fprintf(stderr, "No se esta asignando memoria a los elementos de gFFTBitTable");
for (i = 0; i < len; i++)
gFFTBitTable[b - 1][i] = ReverseBits(i, b);
len <<= 1;
}
}
void anim_fft_double (unsigned NofSamples,
int InverseTransform,
double *RealIn,
double *ImagIn,
double *RealOut,
double *ImagOut )
{
unsigned NofBits; /* Number of bits needed to store indices */
unsigned LSample, j, k, n;
unsigned BlockSize, BlockEnd;
double AngleNumerator = 2.0 * M_PI;
double TempReal, TempImagin; /* temp real, temp imaginary */
if ( !IsPowerOfTwo(NofSamples) ) {
PrintError(("Error in fft(): NofSamples=%u is not power of two\n", NofSamples) );
exit(1);
}
if ( InverseTransform ) AngleNumerator = -AngleNumerator;
CHECKPOINTER ( RealIn );
CHECKPOINTER ( RealOut );
CHECKPOINTER ( ImagOut );
NofBits = NumberOfBitsNeeded ( NofSamples );
/*
** Do simultaneous data copy and bit-reversal ordering into outputs...
*/
for ( LSample=0; LSample < NofSamples; LSample++ ) {
j = ReverseBits ( LSample, NofBits );
RealOut[j] = RealIn[LSample];
ImagOut[j] = (ImagIn == NULL) ? 0.0 : ImagIn[LSample];
}
/*
** Do the FFT itself...
*/
BlockEnd = 1;
for ( BlockSize = 2; BlockSize <= NofSamples; BlockSize <<= 1 ) {
double delta_angle = AngleNumerator / (double)BlockSize;
double sm2 = sin ( -2 * delta_angle );
double sm1 = sin ( -delta_angle );
double cm2 = cos ( -2 * delta_angle );
double cm1 = cos ( -delta_angle );
double w = 2 * cm1;
double ar[3], ai[3];
for ( LSample=0; LSample < NofSamples; LSample += BlockSize ) {
ar[2] = cm2;
ar[1] = cm1;
ai[2] = sm2;
ai[1] = sm1;
for ( j=LSample, n=0; n < BlockEnd; j++, n++ ) {
ar[0] = w*ar[1] - ar[2];
ar[2] = ar[1];
ar[1] = ar[0];
ai[0] = w*ai[1] - ai[2];
ai[2] = ai[1];
ai[1] = ai[0];
k = j + BlockEnd;
TempReal = ar[0]*RealOut[k] - ai[0]*ImagOut[k];
TempImagin = ar[0]*ImagOut[k] + ai[0]*RealOut[k];
RealOut[k] = RealOut[j] - TempReal;
ImagOut[k] = ImagOut[j] - TempImagin;
RealOut[j] += TempReal;
ImagOut[j] += TempImagin;
}
}
BlockEnd = BlockSize;
}
/*
** Need to normalize if inverse transform...
*/
if ( InverseTransform ) {
double denom = (double)NofSamples;
for ( LSample=0; LSample < NofSamples; LSample++ ) {
RealOut[LSample] /= denom;
ImagOut[LSample] /= denom;
}
}
}
extern void fft_float(
_UINT32 __NumSamples,
_INT32 __InverseTransform,
_IEEE32 * __RealIn,
_IEEE32 * __ImagIn,
_IEEE32 * __RealOut,
_IEEE32 * __ImagOut)
{
register _INT32 _w2c___comma;
register _UINT32 _w2c___comma0;
register _INT32 _w2c___ompv_ok_to_fork;
register _UINT64 _w2c_reg3;
register _UINT32 _w2c___comma1;
register _IEEE32 _w2c___cselect;
register _IEEE64 _w2c___comma2;
register _IEEE64 _w2c___comma3;
register _IEEE64 _w2c___comma4;
register _INT32 _w2c_trip_count;
register _INT32 _w2c___ompv_ok_to_fork0;
_IEEE64 delta_angle;
_IEEE64 denom;
_INT32 __localized_common_i;
_INT32 __localized_common_j;
_INT32 _w2c___localized_common_i0;
_IEEE64 __localized_common_ar[3LL];
_IEEE64 __localized_common_ai[3LL];
_INT32 _w2c___localized_common_j0;
_INT32 __localized_common_n;
_INT32 __ompv_gtid_s1;
/*Begin_of_nested_PU(s)*/
NumSamples = __NumSamples;
InverseTransform = __InverseTransform;
* RealIn = *__RealIn;
* ImagIn = *__ImagIn;
* RealOut = *__RealOut;
* ImagOut = *__ImagOut;
_w2c___comma = IsPowerOfTwo(NumSamples);
if(_w2c___comma == 0)
{
printf("Error in fft(): NumSamples=%u is not power of two\n", NumSamples);
exit(1);
}
if(InverseTransform != 0)
{
angle_numerator = -angle_numerator;
}
CheckPointer(RealIn, "RealIn");
CheckPointer(RealOut, "RealOut");
CheckPointer(ImagOut, "ImagOut");
_w2c___comma0 = NumberOfBitsNeeded(NumSamples);
NumBits = _w2c___comma0;
_w2c___ompv_ok_to_fork = 1;
if(_w2c___ompv_ok_to_fork)
{
_w2c___ompv_ok_to_fork = __ompc_can_fork();
}
if(_w2c___ompv_ok_to_fork)
{
__ompc_fork(0, &__omprg_fft_float_1, _w2c_reg3);
}
else
{
__ompv_gtid_s1 = __ompc_get_local_thread_num();
__ompc_serialized_parallel();
for(__localized_common_i = 0; __localized_common_i < (_INT32) NumSamples; __localized_common_i = __localized_common_i + 1)
{
_w2c___comma1 = ReverseBits((_UINT32) __localized_common_i, NumBits);
__localized_common_j = (_INT32)(_w2c___comma1);
* (RealOut + (_UINT64)((_UINT64) __localized_common_j)) = *(RealIn + (_UINT64)((_UINT64) __localized_common_i));
if((_UINT64)(ImagIn) != 0ULL)
{
_w2c___cselect = *(ImagIn + (_UINT64)((_UINT64) __localized_common_i));
}
else
{
_w2c___cselect = 0.0F;
}
* (ImagOut + (_UINT64)((_UINT64) __localized_common_j)) = _w2c___cselect;
}
__ompc_end_serialized_parallel();
}
_w2c___comma2 = log2((_IEEE64)(NumSamples));
NumIter = _U4F8TRUNC(_w2c___comma2);
m = 1;
while(NumIter >= (_UINT32) m)
{
_514 :;
_w2c___comma3 = pow(2.0, (_IEEE64)(m));
BlockSize = _U4F8TRUNC(_w2c___comma3);
_w2c___comma4 = pow(2.0, (_IEEE64)(m + -1));
BlockEnd = _U4F8TRUNC(_w2c___comma4);
delta_angle = angle_numerator / (_IEEE64)(BlockSize);
sm2 = sin(delta_angle * -2.0);
sm1 = sin(-delta_angle);
cm2 = cos(delta_angle * -2.0);
cm1 = cos(delta_angle);
w = cm1 * 2.0;
_w2c_trip_count = (((_INT32) NumSamples + (_INT32) BlockSize) + -1) / (_INT32) BlockSize;
_w2c___ompv_ok_to_fork0 = _w2c_trip_count > 1;
if(_w2c___ompv_ok_to_fork0)
{
_w2c___ompv_ok_to_fork0 = __ompc_can_fork();
}
if(_w2c___ompv_ok_to_fork0)
{
__ompc_fork(0, &__ompdo_fft_float_11, _w2c_reg3);
}
else
{
__ompv_gtid_s1 = __ompc_get_local_thread_num();
__ompc_serialized_parallel();
for(_w2c___localized_common_i0 = 0; _w2c___localized_common_i0 < (_INT32) NumSamples; _w2c___localized_common_i0 = _w2c___localized_common_i0 + (_INT32) BlockSize)
{
(__localized_common_ar)[2] = cm2;
(__localized_common_ar)[1] = cm1;
(__localized_common_ai)[2] = sm2;
(__localized_common_ai)[1] = sm1;
_w2c___localized_common_j0 = _w2c___localized_common_i0;
__localized_common_n = 0;
while((_UINT32) __localized_common_n < BlockEnd)
{
_1026 :;
(__localized_common_ar)[0] = ((__localized_common_ar)[1] * w) - (__localized_common_ar)[2];
(__localized_common_ar)[2] = (__localized_common_ar)[1];
(__localized_common_ar)[1] = (__localized_common_ar)[0];
(__localized_common_ai)[0] = ((__localized_common_ai)[1] * w) - (__localized_common_ai)[2];
(__localized_common_ai)[2] = (__localized_common_ai)[1];
(__localized_common_ai)[1] = (__localized_common_ai)[0];
k = (_INT32)((_UINT32) _w2c___localized_common_j0 + BlockEnd);
tr = ((_IEEE64)(*(RealOut + (_UINT64)((_UINT64) k))) * (__localized_common_ar)[0]) - ((_IEEE64)(*(ImagOut + (_UINT64)((_UINT64) k))) * (__localized_common_ai)[0]);
ti = ((_IEEE64)(*(RealOut + (_UINT64)((_UINT64) k))) * (__localized_common_ai)[0]) + ((_IEEE64)(*(ImagOut + (_UINT64)((_UINT64) k))) * (__localized_common_ar)[0]);
* (RealOut + (_UINT64)((_UINT64) k)) = (_IEEE32)((_IEEE64)(*(RealOut + (_UINT64)((_UINT64) _w2c___localized_common_j0))) - tr);
* (ImagOut + (_UINT64)((_UINT64) k)) = (_IEEE32)((_IEEE64)(*(ImagOut + (_UINT64)((_UINT64) _w2c___localized_common_j0))) - ti);
* (RealOut + (_UINT64)((_UINT64) _w2c___localized_common_j0)) = (_IEEE32)((_IEEE64)(*(RealOut + (_UINT64)((_UINT64) _w2c___localized_common_j0))) + tr);
* (ImagOut + (_UINT64)((_UINT64) _w2c___localized_common_j0)) = (_IEEE32)((_IEEE64)(*(ImagOut + (_UINT64)((_UINT64) _w2c___localized_common_j0))) + ti);
_w2c___localized_common_j0 = _w2c___localized_common_j0 + 1;
__localized_common_n = __localized_common_n + 1;
_770 :;
}
goto _1282;
_1282 :;
}
__ompc_end_serialized_parallel();
}
m = m + 1;
_258 :;
}
goto _1538;
_1538 :;
if(InverseTransform != 0)
{
denom = (_IEEE64)(NumSamples);
i = 0;
while(NumSamples > (_UINT32) i)
{
_2050 :;
* (RealOut + (_UINT64)((_UINT64) i)) = (_IEEE32)((_IEEE64)(*(RealOut + (_UINT64)((_UINT64) i))) / denom);
* (ImagOut + (_UINT64)((_UINT64) i)) = (_IEEE32)((_IEEE64)(*(ImagOut + (_UINT64)((_UINT64) i))) / denom);
i = i + 1;
_1794 :;
}
_2306 :;
}
return;
} /* fft_float */
/// @brief Transform
/// @param n_samples
/// @param input
/// @param output_r
/// @param output_i
/// @param inverse
///
void FFT::DoTransform (size_t n_samples,float *input,float *output_r,float *output_i,bool inverse) {
// Check if it's power of two
if (!IsPowerOfTwo(n_samples)) {
throw "FFT requires power of two input.";
}
// Inverse transform
float angle_num = 2.0f * 3.1415926535897932384626433832795f;
if (inverse) angle_num = -angle_num;
// Variables
unsigned int i, j, k, n;
float tr, ti;
// Calculate needed bits
unsigned int NumBits;
NumBits = NumberOfBitsNeeded(n_samples);
// Copy samples to output buffers
for (i=0;i<n_samples;i++) {
j = ReverseBits (i,NumBits);
output_r[j] = input[i];
output_i[j] = 0.0f;
}
unsigned int BlockEnd = 1;
unsigned int BlockSize;
for (BlockSize = 2;BlockSize<=n_samples;BlockSize<<=1) {
// Calculate variables for this iteration
float delta_angle = angle_num / (float)BlockSize;
float sm2 = sin (-2 * delta_angle);
float sm1 = sin (-delta_angle);
float cm2 = cos (-2 * delta_angle);
float cm1 = cos (-delta_angle);
float w = 2 * cm1;
float ar0, ar1, ar2, ai0, ai1, ai2;
// Apply for every sample
for(i=0;i<n_samples;i+=BlockSize) {
ar1 = cm1;
ar2 = cm2;
ai1 = sm1;
ai2 = sm2;
for (j=i,n=0;n<BlockEnd;j++,n++) {
k = j + BlockEnd;
ar0 = w*ar1 - ar2;
ai0 = w*ai1 - ai2;
ar2 = ar1;
ai2 = ai1;
ar1 = ar0;
ai1 = ai0;
tr = ar0*output_r[k] - ai0*output_i[k];
ti = ar0*output_i[k] + ai0*output_r[k];
output_r[k] = output_r[j] - tr;
output_i[k] = output_i[j] - ti;
output_r[j] += tr;
output_i[j] += ti;
}
}
// Set next block end to current size
BlockEnd = BlockSize;
}
// Divide everything by number of samples if it's an inverse transform
if (inverse) {
float denom = 1.0f/(float)n_samples;
for (i=0;i<n_samples;i++) {
output_r[i] *= denom;
output_i[i] *= denom;
}
}
}
void fft_double (unsigned int p_nSamples, bool p_bInverseTransform, double *p_lpRealIn, double *p_lpImagIn, double *p_lpRealOut, double *p_lpImagOut)
{
if(!p_lpRealIn || !p_lpRealOut || !p_lpImagOut) return;
unsigned int NumBits;
unsigned int i, j, k, n;
unsigned int BlockSize, BlockEnd;
double angle_numerator = 2.0 * PI;
double tr, ti;
if( !IsPowerOfTwo(p_nSamples) )
{
return;
}
if( p_bInverseTransform ) angle_numerator = -angle_numerator;
NumBits = NumberOfBitsNeeded ( p_nSamples );
for( i=0; i < p_nSamples; i++ )
{
j = ReverseBits ( i, NumBits );
p_lpRealOut[j] = p_lpRealIn[i];
p_lpImagOut[j] = (p_lpImagIn == NULL) ? 0.0 : p_lpImagIn[i];
}
BlockEnd = 1;
for( BlockSize = 2; BlockSize <= p_nSamples; BlockSize <<= 1 )
{
double delta_angle = angle_numerator / (double)BlockSize;
double sm2 = sin ( -2 * delta_angle );
double sm1 = sin ( -delta_angle );
double cm2 = cos ( -2 * delta_angle );
double cm1 = cos ( -delta_angle );
double w = 2 * cm1;
double ar[3], ai[3];
for( i=0; i < p_nSamples; i += BlockSize )
{
ar[2] = cm2;
ar[1] = cm1;
ai[2] = sm2;
ai[1] = sm1;
for ( j=i, n=0; n < BlockEnd; j++, n++ )
{
ar[0] = w*ar[1] - ar[2];
ar[2] = ar[1];
ar[1] = ar[0];
ai[0] = w*ai[1] - ai[2];
ai[2] = ai[1];
ai[1] = ai[0];
k = j + BlockEnd;
tr = ar[0]*p_lpRealOut[k] - ai[0]*p_lpImagOut[k];
ti = ar[0]*p_lpImagOut[k] + ai[0]*p_lpRealOut[k];
p_lpRealOut[k] = p_lpRealOut[j] - tr;
p_lpImagOut[k] = p_lpImagOut[j] - ti;
p_lpRealOut[j] += tr;
p_lpImagOut[j] += ti;
}
}
BlockEnd = BlockSize;
}
if( p_bInverseTransform )
{
double denom = (double)p_nSamples;
for ( i=0; i < p_nSamples; i++ )
{
p_lpRealOut[i] /= denom;
p_lpImagOut[i] /= denom;
}
}
}
BOOL CFourier::Fft(UINT nNumSamples, BOOL bInverse, float* pfRealIn, float* pfImagIn, float* pfRealOut, float* pfImagOut)
{
register UINT i, j, k, n;
register UINT nBlockSize;
register UINT nBlockEnd = 1;
if(!pfRealIn || !pfRealOut || !pfImagOut)
{
return FALSE;
}
if(!IsPowerOfTwo(nNumSamples))
{
return FALSE;
}
float fAngle = 2.f * PI;
if(bInverse)
{
fAngle = -fAngle;
}
// Do simultaneous data copy and bit-reversal ordering into outputs
UINT nNbBits = GetNumOfBitsNeeded(nNumSamples);
for(i = 0; i < nNumSamples; i++)
{
j = ReverseBits(i, nNbBits);
pfRealOut[j] = pfRealIn[i];
pfImagOut[j] = ((pfImagIn == NULL) ? 0.f : pfImagIn[i]);
}
register float fDelta, fAReal[3], fAImag[3];
register float fSin1, fSin2, fCos1, fCos2;
register float fTmpReal, fTmpImag, fCoef;
// Do fast fourier transform
for(nBlockSize = 2; nBlockSize <= nNumSamples; nBlockSize <<= 1)
{
fDelta = fAngle / (float)nBlockSize;
fSin1 = sinf(-fDelta);
fSin2 = sinf(-2.f * fDelta);
fCos1 = cosf(-fDelta);
fCos2 = cosf(-2.f * fDelta);
fCoef = 2.f * fCos1;
for(i = 0; i < nNumSamples; i += nBlockSize)
{
fAReal[1] = fCos1;
fAReal[2] = fCos2;
fAImag[1] = fSin1;
fAImag[2] = fSin2;
for(j = i, n = 0; n < nBlockEnd; j++, n++)
{
fAReal[0] = fCoef*fAReal[1] - fAReal[2];
fAReal[2] = fAReal[1];
fAReal[1] = fAReal[0];
fAImag[0] = fCoef*fAImag[1] - fAImag[2];
fAImag[2] = fAImag[1];
fAImag[1] = fAImag[0];
k = j + nBlockEnd;
fTmpReal = fAReal[0] * pfRealOut[k] - fAImag[0] * pfImagOut[k];
fTmpImag = fAReal[0] * pfImagOut[k] + fAImag[0] * pfRealOut[k];
pfRealOut[k] = pfRealOut[j] - fTmpReal;
pfImagOut[k] = pfImagOut[j] - fTmpImag;
pfRealOut[j] += fTmpReal;
pfImagOut[j] += fTmpImag;
}
}
nBlockEnd = nBlockSize;
}
// Need to normalize if inverse transform
if(bInverse)
{
for(i = 0; i < nNumSamples; i++)
{
pfRealOut[i] /= (float)nNumSamples;
pfImagOut[i] /= (float)nNumSamples;
}
}
return TRUE;
}
void CFft::FftDouble(unsigned int NumSamples, int InverseTransform, double *RealIn, double *ImagIn, double *RealOut, double *ImagOut)
{
double PI=3.14;
unsigned int NumBits; /* Number of bits needed to store indices */
unsigned int i, j, k, n;
unsigned int BlockSize, BlockEnd;
double angle_numerator = 2.0 * PI;
double tr, ti; /* temp real, temp imaginary */
if ( !IsPowerOfTwo(NumSamples) )
{
fprintf (
stderr,
"Error in fft(): NumSamples=%u is not power of two\n",
NumSamples );
exit(1);
}
if ( InverseTransform )
angle_numerator = -angle_numerator;
NumBits = NumberOfBitsNeeded ( NumSamples );
/*
** Do simultaneous data copy and bit-reversal ordering into outputs...
*/
for ( i=0; i < NumSamples; i++ )
{
j = ReverseBits ( i, NumBits );
RealOut[j] = RealIn[i];
ImagOut[j] = (ImagIn == NULL) ? 0.0 : ImagIn[i];
}
/*
** Do the FFT itself...
*/
BlockEnd = 1;
for ( BlockSize = 2; BlockSize <= NumSamples; BlockSize <<= 1 )
{
double delta_angle = angle_numerator / (double)BlockSize;
double sm2 = sin ( -2 * delta_angle );
double sm1 = sin ( -delta_angle );
double cm2 = cos ( -2 * delta_angle );
double cm1 = cos ( -delta_angle );
double w = 2 * cm1;
double ar[3], ai[3];
for ( i=0; i < NumSamples; i += BlockSize )
{
ar[2] = cm2;
ar[1] = cm1;
ai[2] = sm2;
ai[1] = sm1;
for ( j=i, n=0; n < BlockEnd; j++, n++ )
{
ar[0] = w*ar[1] - ar[2];
ar[2] = ar[1];
ar[1] = ar[0];
ai[0] = w*ai[1] - ai[2];
ai[2] = ai[1];
ai[1] = ai[0];
k = j + BlockEnd;
tr = ar[0]*RealOut[k] - ai[0]*ImagOut[k];
ti = ar[0]*ImagOut[k] + ai[0]*RealOut[k];
RealOut[k] = RealOut[j] - tr;
ImagOut[k] = ImagOut[j] - ti;
RealOut[j] += tr;
ImagOut[j] += ti;
}
}
BlockEnd = BlockSize;
}
/*
** Need to normalize if inverse transform...
*/
if ( InverseTransform )
{
double denom = (double)NumSamples;
for ( i=0; i < NumSamples; i++ )
{
RealOut[i] /= denom;
ImagOut[i] /= denom;
}
}
}