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#include <stdio.h>
#include <math.h>
//#define M_PI 3.1415926536897932384626
int main(int argc, char **argv)
{
FILE *f;
char tname[50], cname[10];
int n, n2, mp2, niter, bits, t;
double F, A, mul, tmul; // CORDIC gain, convergence angle, multiplication factor
printf("0)circular, 1)linear, 2)hyperbolic? ");
scanf("%d", &t);
switch (t)
{
case 0:
sprintf(cname, "%s", "");
break;
case 1:
sprintf(cname, "%s", "_LIN");
break;
case 2:
sprintf(cname, "%s", "_HYPER");
break;
}
sprintf(tname, "CORDICtable%s.c", cname);
if (NULL == (f = fopen(tname, "wt")))
{
printf("cannot write to %s\n", tname);
return 0;
}
printf("number of bits for mantissa (e.g. 30)? ");
scanf("%d", &bits);
printf("0) mul factor is 2^n (easier output scaling), or\n"
"1) 2pi is 2^n (easier implementation)\n ? ");
scanf("%d", &mp2);
printf("suggested multiplication factor ");
if (mp2 == 0)
{
tmul = (double)(1 << (bits - 3));
printf("2^%d = %f\n", bits - 3, tmul);
}
else
{
tmul = (double)(1 << (bits - 2)) / M_PI;
printf("2^%d/pi = %f\n", bits - 2, tmul);
}
printf("multiplication factor (0 for suggested)? ");
scanf("%lf", &mul);
if (mul < 0.1)
{
mul = tmul;
printf("%f\n", mul);
}
else
mp2 = -1; // custom mul factor
switch (t)
{
case 0:
for (n = 0; n < bits; n++)
if ((int)round(atan(pow(2.0, (double)(-n))) * mul) == 0)
break;
break;
case 1:
for (n = 0; n < bits; n++)
if ((int)round((pow(2.0, (double)(-n))) * mul) == 0)
break;
break;
case 2:
for (n = 1, n2 = 4; n < bits;)
{
if ((int)round(atanh(pow(2.0, (double)(-n))) * mul) == 0)
break;
if (n == n2)
n2 = 3 * n + 1;
else
n++;
}
break;
}
printf("iterations (up to %d)? ", n);
scanf("%d", &niter);
F = 1.0;
A = 0.0;
switch (t)
{
case 0:
for (n = 0; n < niter; n++)
{
F = F * sqrt(1 + pow(2.0, -2.0 * n));
A += atan(pow(2.0, (double)(-n)));
}
break;
case 1:
for (n = 0; n < niter; n++)
{
F = F * sqrt(1);
A += (pow(2.0, (double)(-n)));
}
break;
case 2:
for (n = 1, n2 = 4; n < niter;)
{
F = F * sqrt(1 - pow(2.0, -2.0 * n));
A += atanh(pow(2.0, (double)(-n)));
if (n == n2)
n2 = 3 * n + 1;
else
n++;
}
break;
}
fprintf(f, "//CORDIC%s, %d bits, %d iterations\n", cname, bits, niter);
fprintf(f, "// 1.0 = %f multiplication factor\n", mul);
switch (t)
{
case 0:
fprintf(f, "// A = %lf convergence angle "
"(limit is 1.7432866 = 99.9deg)\n",
A);
fprintf(f, "// F = %lf gain (limit is 1.64676025812107)\n", F);
fprintf(f, "// 1/F = %lf inverse gain (limit is 0.607252935008881)\n", 1.0 / F);
break;
case 1:
fprintf(f, "// A = %lf convergence angle (limit is 2)\n", A);
fprintf(f, "// F = %lf gain (limit is 1.0)\n", F);
fprintf(f, "// 1/F = %lf inverse gain (limit is 1.0)\n", 1.0 / F);
break;
case 2:
fprintf(f, "// A = %lf convergence angle "
"(limit is 1.1181730 = 64.0deg)\n",
A);
fprintf(f, "// F = %lf gain (limit is 0.82978162013890)\n", F);
fprintf(f, "// 1/F = %lf inverse gain (limit is 1.20513635844646)\n", 1.0 / F);
break;
}
fprintf(f, "// pi = %lf (3.1415926536897932384626)\n", M_PI);
fprintf(f, "\n");
fprintf(f, "#define CORDIC%s_A %f // CORDIC convergence angle A\n", cname, A);
fprintf(f, "#define CORDIC%s_F 0x%08X // CORDIC gain F\n",
cname, (int)round(mul * F));
fprintf(f, "#define CORDIC%s_1F 0x%08X // CORDIC inverse gain 1/F\n",
cname, (int)round(mul / F));
fprintf(f, "#define CORDIC%s_HALFPI 0x%08X\n", cname, (int)round(mul * (M_PI / 2.0)));
fprintf(f, "#define CORDIC%s_PI 0x%08X\n", cname, (int)round(mul * (M_PI)));
fprintf(f, "#define CORDIC%s_TWOPI 0x%08X\n", cname, (int)round(mul * (2.0 * M_PI)));
fprintf(f, "#define CORDIC%s_MUL %f // CORDIC multiplication factor M", cname, mul);
switch (mp2)
{
case 0:
fprintf(f, " = 2^%d\n", bits - 3);
break;
case 1:
fprintf(f, " = 2^%d/pi\n", bits - 2);
break;
default:
fprintf(f, "\n");
break;
}
fprintf(f, "#define CORDIC%s_MAXITER %d\n\n", cname, niter);
fprintf(f, "int CORDIC%s_ZTBL[] = {", cname);
for (n = 0; n < niter; n++)
{
if ((n % 8) == 0)
fprintf(f, "\n ");
switch (t)
{
case 0:
fprintf(f, "0x%08X", (int)round(atan(pow(2.0, (double)(-n))) * mul));
break;
case 1:
fprintf(f, "0x%08X", (int)round((pow(2.0, (double)(-n))) * mul));
break;
case 2:
n = n == 0 ? 1 : n;
fprintf(f, "0x%08X", (int)round(atanh(pow(2.0, (double)(-n))) * mul));
break;
}
if (n < (niter - 1))
fprintf(f, ", ");
else
fprintf(f, " ");
}
fprintf(f, "};\n\n");
fclose(f);
printf("table written to %s\n", tname);
return 0;
}
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