Add a "fork" of musl as //fusl.

fusl/src/math/coshl.c

Index: fusl/src/math/coshl.c
diff --git a/fusl/src/math/coshl.c b/fusl/src/math/coshl.c
new file mode 100644
index 0000000000000000000000000000000000000000..06a56fe3be85d346cd98de913c091e900046a938
--- /dev/null
+++ b/fusl/src/math/coshl.c
@@ -0,0 +1,47 @@
+#include "libm.h"
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double coshl(long double x)
+{
+	return cosh(x);
+}
+#elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
+long double coshl(long double x)
+{
+	union ldshape u = {x};
+	unsigned ex = u.i.se & 0x7fff;
+	uint32_t w;
+	long double t;
+
+	/* |x| */
+	u.i.se = ex;
+	x = u.f;
+	w = u.i.m >> 32;
+
+	/* |x| < log(2) */
+	if (ex < 0x3fff-1 || (ex == 0x3fff-1 && w < 0xb17217f7)) {
+		if (ex < 0x3fff-32) {
+			FORCE_EVAL(x + 0x1p120f);
+			return 1;
+		}
+		t = expm1l(x);
+		return 1 + t*t/(2*(1+t));
+	}
+
+	/* |x| < log(LDBL_MAX) */
+	if (ex < 0x3fff+13 || (ex == 0x3fff+13 && w < 0xb17217f7)) {
+		t = expl(x);
+		return 0.5*(t + 1/t);
+	}
+
+	/* |x| > log(LDBL_MAX) or nan */
+	t = expl(0.5*x);
+	return 0.5*t*t;
+}
+#elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384
+// TODO: broken implementation to make things compile
+long double coshl(long double x)
+{
+	return cosh(x);
+}
+#endif