source: azure_iot_hub/trunk/musl-1.1.18/src/math/hypotl.c@ 389

Last change on this file since 389 was 389, checked in by coas-nagasima, 5 years ago

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Line 
1#include "libm.h"
2
3#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
4long double hypotl(long double x, long double y)
5{
6 return hypot(x, y);
7}
8#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
9#if LDBL_MANT_DIG == 64
10#define SPLIT (0x1p32L+1)
11#elif LDBL_MANT_DIG == 113
12#define SPLIT (0x1p57L+1)
13#endif
14
15static void sq(long double *hi, long double *lo, long double x)
16{
17 long double xh, xl, xc;
18 xc = x*SPLIT;
19 xh = x - xc + xc;
20 xl = x - xh;
21 *hi = x*x;
22 *lo = xh*xh - *hi + 2*xh*xl + xl*xl;
23}
24
25long double hypotl(long double x, long double y)
26{
27 union ldshape ux = {x}, uy = {y};
28 int ex, ey;
29 long double hx, lx, hy, ly, z;
30
31 ux.i.se &= 0x7fff;
32 uy.i.se &= 0x7fff;
33 if (ux.i.se < uy.i.se) {
34 ex = uy.i.se;
35 ey = ux.i.se;
36 x = uy.f;
37 y = ux.f;
38 } else {
39 ex = ux.i.se;
40 ey = uy.i.se;
41 x = ux.f;
42 y = uy.f;
43 }
44
45 if (ex == 0x7fff && isinf(y))
46 return y;
47 if (ex == 0x7fff || y == 0)
48 return x;
49 if (ex - ey > LDBL_MANT_DIG)
50 return x + y;
51
52 z = 1;
53 if (ex > 0x3fff+8000) {
54 z = 0x1p10000L;
55 x *= 0x1p-10000L;
56 y *= 0x1p-10000L;
57 } else if (ey < 0x3fff-8000) {
58 z = 0x1p-10000L;
59 x *= 0x1p10000L;
60 y *= 0x1p10000L;
61 }
62 sq(&hx, &lx, x);
63 sq(&hy, &ly, y);
64 return z*sqrtl(ly+lx+hy+hx);
65}
66#endif
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