usr: libc: Add math.h + musl math impl portexpt

Signed-off-by: Ian Moffett <ian@osmora.org>

1 files changed, 34 insertions, 0 deletions

diff --git a/lib/libc/src/musl-math/exp10l.c b/lib/libc/src/musl-math/exp10l.c
new file mode 100644
index 0000000..f18e554
--- /dev/null
+++ b/lib/libc/src/musl-math/exp10l.c
@@ -0,0 +1,34 @@
+#define _GNU_SOURCE
+#include <float.h>
+#include <math.h>
+//#include "libc.h"
+#include "libm.h"
+#include "weak_alias.h"
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double exp10l(long double x)
+{
+	return exp10(x);
+}
+#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
+long double exp10l(long double x)
+{
+	static const long double p10[] = {
+		1e-15L, 1e-14L, 1e-13L, 1e-12L, 1e-11L, 1e-10L,
+		1e-9L, 1e-8L, 1e-7L, 1e-6L, 1e-5L, 1e-4L, 1e-3L, 1e-2L, 1e-1L,
+		1, 1e1, 1e2, 1e3, 1e4, 1e5, 1e6, 1e7, 1e8, 1e9,
+		1e10, 1e11, 1e12, 1e13, 1e14, 1e15
+	};
+	long double n, y = modfl(x, &n);
+	union ldshape u = {n};
+	/* fabsl(n) < 16 without raising invalid on nan */
+	if ((u.i.se & 0x7fff) < 0x3fff+4) {
+		if (!y) return p10[(int)n+15];
+		y = exp2l(3.32192809488736234787031942948939L * y);
+		return y * p10[(int)n+15];
+	}
+	return powl(10.0, x);
+}
+#endif
+
+weak_alias(exp10l, pow10l);