Add fmod implementation for nolibc.

lib/std/math/math_nolibc/__fmod.c3

@@ -0,0 +1,78 @@
+module std::math::nolibc @if(env::NO_LIBC);
+
+union DoubleInternal
+{
+	double f;
+	ulong i;
+}
+
+// Based on the musl implementation
+fn double fmod(double x, double y) @extern("fmod") @weak @nostrip
+{
+	DoubleInternal ux = { .f = x };
+	DoubleInternal uy = { .f = y };
+	int ex = (int)((ux.i >> 52) & 0x7ff);
+	int ey = (int)((uy.i >> 52) & 0x7ff);
+	int sx = (int)(ux.i >> 63);
+	ulong uxi = ux.i;
+	if (uy.i << 1 == 0 || math::is_nan(y) || ex == 0x7ff) return (x * y)/(x * y);
+	if (uxi << 1 <= uy.i << 1)
+	{
+		if (uxi << 1 == uy.i << 1) return 0 * x;
+		return x;
+	}
+
+	if (!ex)
+	{
+		for (ulong i = uxi << 12; i >> 63 == 0; ex--, i <<= 1);
+		uxi <<= -ex + 1;
+	}
+	else
+	{
+		uxi &= -1UL >> 12;
+		uxi |= 1UL << 52;
+	}
+	if (!ey)
+	{
+		for (ulong i = uy.i << 12; i >> 63 == 0; ey--, i <<= 1);
+		uy.i <<= -ey + 1;
+	}
+	else
+	{
+		uy.i &= -1UL >> 12;
+		uy.i |= 1UL << 52;
+	}
+
+	/* x mod y */
+	for (; ex > ey; ex--)
+	{
+		ulong i = uxi - uy.i;
+		if (i >> 63 == 0)
+		{
+			if (i == 0) return 0 * x;
+			uxi = i;
+		}
+		uxi <<= 1;
+	}
+	ulong i = uxi - uy.i;
+	if (i >> 63 == 0)
+	{
+		if (i == 0) return 0*x;
+		uxi = i;
+	}
+	for (; uxi>>52 == 0; uxi <<= 1, ex--);
+
+	/* scale result */
+	if (ex > 0)
+	{
+		uxi -= 1UL << 52;
+		uxi |= (ulong)ex << 52;
+	}
+	else
+	{
+		uxi >>= -ex + 1;
+	}
+	uxi |= (ulong)sx << 63;
+	ux.i = uxi;
+	return ux.f;
+}

releasenotes.md

@@ -37,6 +37,7 @@
 - Similar change to `$vasplat`: `$vasplat` and `$vasplat[1..]`.
 - Add `$member.get(value)` to replace `value.$eval($member.nameof)`
 - Improve the error message when the compilation does not produce any files #1390.
+- Add `fmod` implementation for nolibc.
 
 ### Fixes