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1 #define _GNU_SOURCE | 1 #define _GNU_SOURCE |
2 #include <math.h> | 2 #include <math.h> |
3 #include <stdint.h> | 3 #include <stdint.h> |
4 #include "libc.h" | 4 #include "libc.h" |
5 | 5 |
6 double exp10(double x) | 6 double exp10(double x) { |
7 { | 7 static const double p10[] = { |
8 » static const double p10[] = { | 8 1e-15, 1e-14, 1e-13, 1e-12, 1e-11, 1e-10, 1e-9, 1e-8, 1e-7, 1e-6, 1e-5, |
9 » » 1e-15, 1e-14, 1e-13, 1e-12, 1e-11, 1e-10, | 9 1e-4, 1e-3, 1e-2, 1e-1, 1, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, |
10 » » 1e-9, 1e-8, 1e-7, 1e-6, 1e-5, 1e-4, 1e-3, 1e-2, 1e-1, | 10 1e7, 1e8, 1e9, 1e10, 1e11, 1e12, 1e13, 1e14, 1e15}; |
11 » » 1, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9, | 11 double n, y = modf(x, &n); |
12 » » 1e10, 1e11, 1e12, 1e13, 1e14, 1e15 | 12 union { |
13 » }; | 13 double f; |
14 » double n, y = modf(x, &n); | 14 uint64_t i; |
15 » union {double f; uint64_t i;} u = {n}; | 15 } u = {n}; |
16 » /* fabs(n) < 16 without raising invalid on nan */ | 16 /* fabs(n) < 16 without raising invalid on nan */ |
17 » if ((u.i>>52 & 0x7ff) < 0x3ff+4) { | 17 if ((u.i >> 52 & 0x7ff) < 0x3ff + 4) { |
18 » » if (!y) return p10[(int)n+15]; | 18 if (!y) |
19 » » y = exp2(3.32192809488736234787031942948939 * y); | 19 return p10[(int)n + 15]; |
20 » » return y * p10[(int)n+15]; | 20 y = exp2(3.32192809488736234787031942948939 * y); |
21 » } | 21 return y * p10[(int)n + 15]; |
22 » return pow(10.0, x); | 22 } |
| 23 return pow(10.0, x); |
23 } | 24 } |
24 | 25 |
25 weak_alias(exp10, pow10); | 26 weak_alias(exp10, pow10); |
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