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

fusl/src/math/nextafterl.c

Index: fusl/src/math/nextafterl.c
diff --git a/fusl/src/math/nextafterl.c b/fusl/src/math/nextafterl.c
new file mode 100644
index 0000000000000000000000000000000000000000..37e858fb4982a775cc4099738c539c8bd2f25d76
--- /dev/null
+++ b/fusl/src/math/nextafterl.c
@@ -0,0 +1,75 @@
+#include "libm.h"
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double nextafterl(long double x, long double y)
+{
+	return nextafter(x, y);
+}
+#elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384
+long double nextafterl(long double x, long double y)
+{
+	union ldshape ux, uy;
+
+	if (isnan(x) || isnan(y))
+		return x + y;
+	if (x == y)
+		return y;
+	ux.f = x;
+	if (x == 0) {
+		uy.f = y;
+		ux.i.m = 1;
+		ux.i.se = uy.i.se & 0x8000;
+	} else if ((x < y) == !(ux.i.se & 0x8000)) {
+		ux.i.m++;
+		if (ux.i.m << 1 == 0) {
+			ux.i.m = 1ULL << 63;
+			ux.i.se++;
+		}
+	} else {
+		if (ux.i.m << 1 == 0) {
+			ux.i.se--;
+			if (ux.i.se)
+				ux.i.m = 0;
+		}
+		ux.i.m--;
+	}
+	/* raise overflow if ux is infinite and x is finite */
+	if ((ux.i.se & 0x7fff) == 0x7fff)
+		return x + x;
+	/* raise underflow if ux is subnormal or zero */
+	if ((ux.i.se & 0x7fff) == 0)
+		FORCE_EVAL(x*x + ux.f*ux.f);
+	return ux.f;
+}
+#elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384
+long double nextafterl(long double x, long double y)
+{
+	union ldshape ux, uy;
+
+	if (isnan(x) || isnan(y))
+		return x + y;
+	if (x == y)
+		return y;
+	ux.f = x;
+	if (x == 0) {
+		uy.f = y;
+		ux.i.lo = 1;
+		ux.i.se = uy.i.se & 0x8000;
+	} else if ((x < y) == !(ux.i.se & 0x8000)) {
+		ux.i2.lo++;
+		if (ux.i2.lo == 0)
+			ux.i2.hi++;
+	} else {
+		if (ux.i2.lo == 0)
+			ux.i2.hi--;
+		ux.i2.lo--;
+	}
+	/* raise overflow if ux is infinite and x is finite */
+	if ((ux.i.se & 0x7fff) == 0x7fff)
+		return x + x;
+	/* raise underflow if ux is subnormal or zero */
+	if ((ux.i.se & 0x7fff) == 0)
+		FORCE_EVAL(x*x + ux.f*ux.f);
+	return ux.f;
+}
+#endif