static void CalcError(int r, const double ad[],
const double x[], const double y[],
int gridsize, const double Grid[],
const double D[], const double W[], double E[])
{
int i;
double A;
for (i = 0; i < gridsize; i++) {
A = ComputeA(Grid[i], r, ad, x, y);
E[i] = W[i] * (D[i] - A);
}
}
CVOID__PROTO(push_choicept, try_node_t *alt)
{
intmach_t n = alt->node_offset;
tagged_t *b0 = (tagged_t *)w->node;
node_t *b = ChoiceCharOffset(b0,n);
ComputeA(w->local_top,w->node);
w->node = b;
NewShadowregs(w->global_top);
b->trail_top = w->trail_top;
SaveGtop(b,w->global_top);
b->next_alt = alt;
b->frame = w->frame;
b->next_insn = w->next_insn;
SaveLtop(b);
n = OffsetToArity(n);
while (n>0)
ChoicePush(b0,X(--n));
if (ChoiceYounger(ChoiceOffset(w->node,CHOICEPAD),w->trail_top))
choice_overflow(Arg,CHOICEPAD);
}
void REMEZ_CreateFilter(double h[], int numtaps, int numband, double bands[],
const double des[], const double weight[], int type)
{
double *Grid, *W, *D, *E;
int i, iter, gridsize, r, *Ext;
double *taps, c;
double *x, *y, *ad;
int symmetry;
if (type == REMEZ_BANDPASS)
symmetry = POSITIVE;
else
symmetry = NEGATIVE;
r = numtaps / 2; /* number of extrema */
if ((numtaps % 2) && (symmetry == POSITIVE))
r++;
/* Predict dense grid size in advance for memory allocation
* .5 is so we round up, not truncate */
gridsize = 0;
for (i = 0; i < numband; i++) {
gridsize += (int) (2 * r * GRIDDENSITY *
(bands[2 * i + 1] - bands[2 * i]) + .5);
}
if (symmetry == NEGATIVE) {
gridsize--;
}
/* Dynamically allocate memory for arrays with proper sizes */
Grid = (double *) Util_malloc(gridsize * sizeof(double));
D = (double *) Util_malloc(gridsize * sizeof(double));
W = (double *) Util_malloc(gridsize * sizeof(double));
E = (double *) Util_malloc(gridsize * sizeof(double));
Ext = (int *) Util_malloc((r + 1) * sizeof(int));
taps = (double *) Util_malloc((r + 1) * sizeof(double));
x = (double *) Util_malloc((r + 1) * sizeof(double));
y = (double *) Util_malloc((r + 1) * sizeof(double));
ad = (double *) Util_malloc((r + 1) * sizeof(double));
/* Create dense frequency grid */
CreateDenseGrid(r, numtaps, numband, bands, des, weight,
&gridsize, Grid, D, W, symmetry);
InitialGuess(r, Ext, gridsize);
/* For Differentiator: (fix grid) */
if (type == REMEZ_DIFFERENTIATOR) {
for (i = 0; i < gridsize; i++) {
/* D[i] = D[i] * Grid[i]; */
if (D[i] > 0.0001)
W[i] = W[i] / Grid[i];
}
}
/* For odd or Negative symmetry filters, alter the
* D[] and W[] according to Parks McClellan */
if (symmetry == POSITIVE) {
if (numtaps % 2 == 0) {
for (i = 0; i < gridsize; i++) {
c = cos(Pi * Grid[i]);
D[i] /= c;
W[i] *= c;
}
}
}
else {
if (numtaps % 2) {
for (i = 0; i < gridsize; i++) {
c = sin(Pi2 * Grid[i]);
D[i] /= c;
W[i] *= c;
}
}
else {
for (i = 0; i < gridsize; i++) {
c = sin(Pi * Grid[i]);
D[i] /= c;
W[i] *= c;
}
}
}
/* Perform the Remez Exchange algorithm */
for (iter = 0; iter < MAXITERATIONS; iter++) {
CalcParms(r, Ext, Grid, D, W, ad, x, y);
CalcError(r, ad, x, y, gridsize, Grid, D, W, E);
Search(r, Ext, gridsize, E);
if (isDone(r, Ext, E))
break;
}
#ifndef ASAP
if (iter == MAXITERATIONS) {
Log_print("remez(): reached maximum iteration count. Results may be bad.");
}
#endif
CalcParms(r, Ext, Grid, D, W, ad, x, y);
/* Find the 'taps' of the filter for use with Frequency
* Sampling. If odd or Negative symmetry, fix the taps
* according to Parks McClellan */
for (i = 0; i <= numtaps / 2; i++) {
if (symmetry == POSITIVE) {
if (numtaps % 2)
c = 1;
else
c = cos(Pi * (double) i / numtaps);
}
else {
if (numtaps % 2)
c = sin(Pi2 * (double) i / numtaps);
else
c = sin(Pi * (double) i / numtaps);
}
taps[i] = ComputeA((double) i / numtaps, r, ad, x, y) * c;
}
/* Frequency sampling design with calculated taps */
FreqSample(numtaps, taps, h, symmetry);
/* Delete allocated memory */
free(Grid);
free(W);
free(D);
free(E);
free(Ext);
free(taps);
free(x);
free(y);
free(ad);
}
