[388] | 1 | #define _GNU_SOURCE
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| 2 | #include <math.h>
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| 3 | #include <stdint.h>
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| 4 | #include "libc.h"
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| 5 |
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| 6 | double exp10(double x)
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| 7 | {
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| 8 | static const double p10[] = {
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| 9 | 1e-15, 1e-14, 1e-13, 1e-12, 1e-11, 1e-10,
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| 10 | 1e-9, 1e-8, 1e-7, 1e-6, 1e-5, 1e-4, 1e-3, 1e-2, 1e-1,
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| 11 | 1, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9,
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| 12 | 1e10, 1e11, 1e12, 1e13, 1e14, 1e15
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| 13 | };
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| 14 | double n, y = modf(x, &n);
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| 15 | union {double f; uint64_t i;} u = {n};
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| 16 | /* fabs(n) < 16 without raising invalid on nan */
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| 17 | if ((u.i>>52 & 0x7ff) < 0x3ff+4) {
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| 18 | if (!y) return p10[(int)n+15];
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| 19 | y = exp2(3.32192809488736234787031942948939 * y);
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| 20 | return y * p10[(int)n+15];
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| 21 | }
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| 22 | return pow(10.0, x);
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| 23 | }
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| 24 |
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| 25 | weak_alias(exp10, pow10);
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