62 lines
1.8 KiB
C
62 lines
1.8 KiB
C
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#ifndef _WASM_H_DEF
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#define _WASM_H_DEF
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#include <stdio.h>
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#include <math.h>
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struct Canvas {
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double width, height;
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double xscale, yscale;
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double xofset, yofset;
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float xt (const double x) const {
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return float (xscale * (x - xofset));
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}
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float yt (const double y) const {
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return float (height - yscale * (y - yofset));
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}
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};
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static const char * multipliers [] = {"f","p","n","μ","m","","k","M","G","T","P"};
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struct Stepping {
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double b,e,s;
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char fmtbuf [16];
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explicit Stepping (const double from, const double to) {
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double lp;
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const double z = log10 (fabs (to - from));
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const double fp = modf (z, & lp);
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if (fp < 0.30103) s = 1.0;
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else if (fp > 0.69897) s = 5.0;
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else s = 2.0;
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int ip = int (lp) - 1;
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if (z < 0.0) ip -= 1;
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s *= ::pow (10.0, double (ip));
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do {
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const int k = int (fabs(to - from) / s);
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b = round (from / s) * s;
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e = round (to / s) * s;
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if (k > 50) s *= 10.0; // prevence přeplnění osy, nevím proč, ale tohle to odstraní
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else break; // patrně log10() nedává přesně to, co bych čekal
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} while (true);
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}
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void f () {printf("stepping = %g, b = %g, e = %g\n", s, b, e);}
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char * ing (const double x, int n=0) {
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if (fabs(x) < 0.5 * s) {
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fmtbuf[n++] = ' ';
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fmtbuf[n++] = '\0';
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return fmtbuf;
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}
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if (x < 0.0) {
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fmtbuf[n++] = '-';
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return ing (-x, n);
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}
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if (x > 0.0) {
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double ip;
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const double fp = modf(log10(x), & ip);
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int pi = ip, ofs = 5 * 3;
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if (pi < -ofs) pi = -ofs;
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if (pi > 18 ) pi = 18;
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const div_t dt = div(pi + ofs, 3);
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n += snprintf (fmtbuf + n, 16 - n, "%g%s", ::pow (10.0, fp + double (dt.rem)), multipliers [dt.quot]);
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}
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return fmtbuf;
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}
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};
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#endif // _WASM_H_DEF
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