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

fusl/src/math/fmodl.c

Index: fusl/src/math/fmodl.c
diff --git a/fusl/src/math/fmodl.c b/fusl/src/math/fmodl.c
new file mode 100644
index 0000000000000000000000000000000000000000..9f5b87393dcad9ffcd44876d7b76120563a3e85f
--- /dev/null
+++ b/fusl/src/math/fmodl.c
@@ -0,0 +1,105 @@
+#include "libm.h"
+
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double fmodl(long double x, long double y)
+{
+	return fmod(x, y);
+}
+#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384
+long double fmodl(long double x, long double y)
+{
+	union ldshape ux = {x}, uy = {y};
+	int ex = ux.i.se & 0x7fff;
+	int ey = uy.i.se & 0x7fff;
+	int sx = ux.i.se & 0x8000;
+
+	if (y == 0 || isnan(y) || ex == 0x7fff)
+		return (x*y)/(x*y);
+	ux.i.se = ex;
+	uy.i.se = ey;
+	if (ux.f <= uy.f) {
+		if (ux.f == uy.f)
+			return 0*x;
+		return x;
+	}
+
+	/* normalize x and y */
+	if (!ex) {
+		ux.f *= 0x1p120f;
+		ex = ux.i.se - 120;
+	}
+	if (!ey) {
+		uy.f *= 0x1p120f;
+		ey = uy.i.se - 120;
+	}
+
+	/* x mod y */
+#if LDBL_MANT_DIG == 64
+	uint64_t i, mx, my;
+	mx = ux.i.m;
+	my = uy.i.m;
+	for (; ex > ey; ex--) {
+		i = mx - my;
+		if (mx >= my) {
+			if (i == 0)
+				return 0*x;
+			mx = 2*i;
+		} else if (2*mx < mx) {
+			mx = 2*mx - my;
+		} else {
+			mx = 2*mx;
+		}
+	}
+	i = mx - my;
+	if (mx >= my) {
+		if (i == 0)
+			return 0*x;
+		mx = i;
+	}
+	for (; mx >> 63 == 0; mx *= 2, ex--);
+	ux.i.m = mx;
+#elif LDBL_MANT_DIG == 113
+	uint64_t hi, lo, xhi, xlo, yhi, ylo;
+	xhi = (ux.i2.hi & -1ULL>>16) | 1ULL<<48;
+	yhi = (uy.i2.hi & -1ULL>>16) | 1ULL<<48;
+	xlo = ux.i2.lo;
+	ylo = uy.i2.lo;
+	for (; ex > ey; ex--) {
+		hi = xhi - yhi;
+		lo = xlo - ylo;
+		if (xlo < ylo)
+			hi -= 1;
+		if (hi >> 63 == 0) {
+			if ((hi|lo) == 0)
+				return 0*x;
+			xhi = 2*hi + (lo>>63);
+			xlo = 2*lo;
+		} else {
+			xhi = 2*xhi + (xlo>>63);
+			xlo = 2*xlo;
+		}
+	}
+	hi = xhi - yhi;
+	lo = xlo - ylo;
+	if (xlo < ylo)
+		hi -= 1;
+	if (hi >> 63 == 0) {
+		if ((hi|lo) == 0)
+			return 0*x;
+		xhi = hi;
+		xlo = lo;
+	}
+	for (; xhi >> 48 == 0; xhi = 2*xhi + (xlo>>63), xlo = 2*xlo, ex--);
+	ux.i2.hi = xhi;
+	ux.i2.lo = xlo;
+#endif
+
+	/* scale result */
+	if (ex <= 0) {
+		ux.i.se = (ex+120)|sx;
+		ux.f *= 0x1p-120f;
+	} else
+		ux.i.se = ex|sx;
+	return ux.f;
+}
+#endif