1 files changed, 30 insertions, 0 deletions
diff --git a/lib/libm/exp10.c b/lib/libm/exp10.c
new file mode 100644
index 00000000..fd3747a9
--- /dev/null
+++ b/lib/libm/exp10.c
@@ -0,0 +1,30 @@
+#define _GNU_SOURCE
+#include "libm.h"
+
+#include <math.h>
+#include <stdint.h>
+
+double exp10(double x)
+{
+	static const double p10[] = { 1e-15, 1e-14, 1e-13, 1e-12, 1e-11, 1e-10,
+				      1e-9,  1e-8,  1e-7,  1e-6,  1e-5,	 1e-4,
+				      1e-3,  1e-2,  1e-1,  1,	  1e1,	 1e2,
+				      1e3,   1e4,   1e5,   1e6,	  1e7,	 1e8,
+				      1e9,   1e10,  1e11,  1e12,  1e13,	 1e14,
+				      1e15 };
+	double n, y = modf(x, &n);
+	union {
+		double f;
+		uint64_t i;
+	} u = { n };
+	/* fabs(n) < 16 without raising invalid on nan */
+	if ((u.i >> 52 & 0x7ff) < 0x3ff + 4) {
+		if (!y)
+			return p10[(int)n + 15];
+		y = exp2(3.32192809488736234787031942948939 * y);
+		return y * p10[(int)n + 15];
+	}
+	return pow(10.0, x);
+}
+
+weak_alias(exp10, pow10);