1 files changed, 31 insertions, 0 deletions
diff --git a/src/base/math/fmod.c b/src/base/math/fmod.c
new file mode 100644
index 0000000..d724a8c
--- /dev/null
+++ b/src/base/math/fmod.c
@@ -0,0 +1,31 @@
+#include <u.h>
+#include <base.h>
+
+/*
+ * floating-point mod function without infinity or NaN checking
+ */
+double
+math·fmod(double x, double y)
+{
+	int sign, yexp, rexp;
+	double r, yfr, rfr;
+
+	if (y == 0)
+		return x;
+	if (y < 0)
+		y = -y;
+	yfr = math·frexp(y, &yexp);
+	sign = 0;
+	if(x < 0) {
+		r = -x;
+		sign++;
+	} else
+		r = x;
+	while(r >= y) {
+		rfr = math·frexp(r, &rexp);
+		r -= math·ldexp(y, rexp - yexp - (rfr < yfr));
+	}
+	if(sign)
+		r = -r;
+	return r;
+}