From f3afec61bb4127439701adbc99ccbf18c13dd08e Mon Sep 17 00:00:00 2001
From: Adversing <artomixgamer@gmail.com>
Date: Thu, 23 Jan 2025 04:34:27 +0100
Subject: [PATCH] Added fmodf function #1875

---
 lib/std/math/math_nolibc/__fmod.c3 | 78 +++++++++++++++++++++++++++++-
 releasenotes.md                    |  1 +
 2 files changed, 78 insertions(+), 1 deletion(-)

diff --git a/lib/std/math/math_nolibc/__fmod.c3 b/lib/std/math/math_nolibc/__fmod.c3
index 1bc304b31..432bd0cf9 100644
--- a/lib/std/math/math_nolibc/__fmod.c3
+++ b/lib/std/math/math_nolibc/__fmod.c3
@@ -6,6 +6,12 @@ union DoubleInternal
 	ulong i;
 }
 
+union FloatInternal
+{
+	float f;
+	uint i;
+}
+
 // Based on the musl implementation
 fn double fmod(double x, double y) @extern("fmod") @weak @nostrip
 {
@@ -75,4 +81,74 @@ fn double fmod(double x, double y) @extern("fmod") @weak @nostrip
 	uxi |= (ulong)sx << 63;
 	ux.i = uxi;
 	return ux.f;
-}
\ No newline at end of file
+}
+
+fn float fmodf(float x, float y) @extern("fmodf") @weak @nostrip
+{
+	FloatInternal ux = { .f = x };
+	FloatInternal uy = { .f = y };
+	int ex = (int)((ux.i >> 23) & 0xff);
+	int ey = (int)((uy.i >> 23) & 0xff);
+	int sx = (int)(ux.i >> 31);
+	uint uxi = ux.i;
+	if (uy.i << 1 == 0 || math::is_nan(y) || ex == 0xff) 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 (uint i = uxi << 9; i >> 31 == 0; ex--, i <<= 1);
+		uxi <<= -ex + 1;
+	}
+	else
+	{
+		uxi &= -1U >> 9;
+		uxi |= 1U << 23;
+	}
+	if (!ey)
+	{
+		for (uint i = uy.i << 9; i >> 31 == 0; ey--, i <<= 1);
+		uy.i <<= -ey + 1;
+	}
+	else
+	{
+		uy.i &= -1U >> 9;
+		uy.i |= 1U << 23;
+	}
+
+	/* x mod y */
+	for (; ex > ey; ex--)
+	{
+		uint i = uxi - uy.i;
+		if (i >> 31 == 0)
+		{
+			if (i == 0) return 0 * x;
+			uxi = i;
+		}
+		uxi <<= 1;
+	}
+	uint i = uxi - uy.i;
+	if (i >> 31 == 0)
+	{
+		if (i == 0) return 0*x;
+		uxi = i;
+	}
+	for (; uxi>>23 == 0; uxi <<= 1, ex--);
+
+	/* scale result */
+	if (ex > 0)
+	{
+		uxi -= 1U << 23;
+		uxi |= (uint)ex << 23;
+	}
+	else
+	{
+		uxi >>= -ex + 1;
+	}
+	uxi |= (uint)sx << 31;
+	ux.i = uxi;
+	return ux.f;
+}
diff --git a/releasenotes.md b/releasenotes.md
index bb3e78e7c..1c20b63ce 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -45,6 +45,7 @@
 - Added channels for threads.
 - New `std::core::test` module for unit testing machinery.
 - New unit test default runner.
+- Added weakly linked `fmodf`.
 
 ## 0.6.6 Change list