void rdft(int n, int isgn, double *a)
{
void bitrv2(int n, double *a);
void cftfsub(int n, double *a);
void cftbsub(int n, double *a);
void rftfsub(int n, double *a);
void rftbsub(int n, double *a);
double xi;
if (isgn >= 0) {
if (n > 4) {
bitrv2(n, a);
cftfsub(n, a);
rftfsub(n, a);
} else if (n == 4) {
cftfsub(n, a);
}
xi = a[0] - a[1];
a[0] += a[1];
a[1] = xi;
} else {
a[1] = 0.5 * (a[0] - a[1]);
a[0] -= a[1];
if (n > 4) {
rftbsub(n, a);
bitrv2(n, a);
cftbsub(n, a);
} else if (n == 4) {
cftfsub(n, a);
}
}
}
void rdft(int n, int isgn, float *a, int *ip, float *w)
{
int j,
nw,
nc;
float xi;
void bitrv2(int n, int *ip, float *a),
cftsub(int n, float *a, float *w),
rftsub(int n, float *a, int nc, float *c);
nw = ip[0];
nc = ip[1];
if (isgn < 0) {
a[1] = 0.5 * (a[1] - a[0]);
a[0] += a[1];
for (j = 3; j <= n - 1; j += 2) {
a[j] = -a[j];
}
if (n > 4) {
rftsub(n, a, nc, w + nw);
bitrv2(n, ip + 2, a);
}
cftsub(n, a, w);
for (j = 1; j <= n - 1; j += 2) {
a[j] = -a[j];
}
}
else {
if (n > 4) {
bitrv2(n, ip + 2, a);
}
cftsub(n, a, w);
if (n > 4) {
rftsub(n, a, nc, w + nw);
}
xi = a[0] - a[1];
a[0] += a[1];
a[1] = xi;
}
}
void ddst(int n, int isgn, double *a)
{
void bitrv2(int n, double *a);
void cftfsub(int n, double *a);
void cftbsub(int n, double *a);
void rftfsub(int n, double *a);
void rftbsub(int n, double *a);
void dstsub(int n, double *a);
void dstsub4(int n, double *a);
int j;
double xr;
if (isgn < 0) {
xr = a[n - 1];
for (j = n - 2; j >= 2; j -= 2) {
a[j + 1] = -a[j] - a[j - 1];
a[j] -= a[j - 1];
}
a[1] = a[0] + xr;
a[0] -= xr;
if (n > 4) {
rftbsub(n, a);
bitrv2(n, a);
cftbsub(n, a);
} else if (n == 4) {
cftfsub(n, a);
}
}
if (n > 4) {
dstsub(n, a);
} else {
dstsub4(n, a);
}
if (isgn >= 0) {
if (n > 4) {
bitrv2(n, a);
cftfsub(n, a);
rftfsub(n, a);
} else if (n == 4) {
cftfsub(n, a);
}
xr = a[0] - a[1];
a[0] += a[1];
for (j = 2; j < n; j += 2) {
a[j - 1] = -a[j] - a[j + 1];
a[j] -= a[j + 1];
}
a[n - 1] = -xr;
}
}
void makewt(int nw, int *ip, float *w)
{
void bitrv2(int n, int *ip, float *a);
int nwh, j;
float delta, x, y;
ip[0] = nw;
ip[1] = 1;
if (nw > 2) {
nwh = nw >> 1;
delta = atan(1.0) / nwh;
w[0] = 1;
w[1] = 0;
w[nwh] = cos(delta * nwh);
w[nwh + 1] = w[nwh];
for (j = 2; j <= nwh - 2; j += 2) {
x = cos(delta * j);
y = sin(delta * j);
w[j] = x;
w[j + 1] = y;
w[nw - j] = y;
w[nw - j + 1] = x;
}
bitrv2(nw, ip + 2, w);
}
static void makewt(int nw, int *ip, double *w)
{
int j, nwh;
double delta, x, y;
if (nw > 2) {
nwh = nw >> 1;
delta = M_PI_4 / nwh;
w[0] = 1;
w[1] = 0;
w[nwh] = cos(delta * nwh);
w[nwh + 1] = w[nwh];
if (nwh > 2) {
for (j = 2; j < nwh; j += 2) {
x = cos(delta * j);
y = sin(delta * j);
w[j] = x;
w[j + 1] = y;
w[nw - j] = y;
w[nw - j + 1] = x;
}
//makebr(nw, ip);
bitrv2(nw, ip, w);
}
}
inline void makewt(int nw, int *ip, double *w) {
int j, nwh;
double delta, x, y;
ip[0] = nw;
ip[1] = 1;
if (nw > 2) {
nwh = nw >> 1;
delta = atan(1.0) / nwh;
w[0] = 1;
w[1] = 0;
w[nwh] = cos(delta * nwh);
w[nwh + 1] = w[nwh];
if (nwh > 2) {
for (j = 2; j < nwh; j += 2) {
x = cos(delta * j);
y = sin(delta * j);
w[j] = x;
w[j + 1] = y;
w[nw - j] = y;
w[nw - j + 1] = x;
}
bitrv2(nw, ip + 2, w);
}
}
void lsx_rdft_generic(int isgn, double *a, FFTcontext z)
{
double xi;
int n = z.n;
int nw = n >> 2;
if (isgn >= 0)
{
if (n > 4)
{
bitrv2(n, z.br, a);
cftfsub(n, a, z.sc);
rftfsub(n, a, nw, z.sc + nw);
}
else if (n == 4)
{
cftfsub(n, a, z.sc);
}
xi = a[0] - a[1];
a[0] += a[1];
a[1] = xi;
}
else
{
a[1] = 0.5 * (a[0] - a[1]);
a[0] -= a[1];
if (n > 4)
{
rftbsub(n, a, nw, z.sc + nw);
bitrv2(n, z.br, a);
cftbsub(n, a, z.sc);
}
else if (n == 4)
{
cftfsub(n, a, z.sc);
}
}
}
void cdft(int n, int isgn, double *a)
{
void bitrv2(int n, double *a);
void bitrv2conj(int n, double *a);
void cftfsub(int n, double *a);
void cftbsub(int n, double *a);
if (n > 4) {
if (isgn >= 0) {
bitrv2(n, a);
cftfsub(n, a);
} else {
bitrv2conj(n, a);
cftbsub(n, a);
}
} else if (n == 4) {
cftfsub(n, a);
}
}