1 files changed, 31 insertions, 0 deletions
diff --git a/lib/libm/rint.c b/lib/libm/rint.c
new file mode 100644
index 00000000..f1159643
--- /dev/null
+++ b/lib/libm/rint.c
@@ -0,0 +1,31 @@
+#include <float.h>
+#include <math.h>
+#include <stdint.h>
+
+#if FLT_EVAL_METHOD == 0 || FLT_EVAL_METHOD == 1
+#define EPS DBL_EPSILON
+#elif FLT_EVAL_METHOD == 2
+#define EPS LDBL_EPSILON
+#endif
+static const double_t toint = 1 / EPS;
+
+double rint(double x)
+{
+	union {
+		double f;
+		uint64_t i;
+	} u = { x };
+	int e = u.i >> 52 & 0x7ff;
+	int s = u.i >> 63;
+	double_t y;
+
+	if (e >= 0x3ff + 52)
+		return x;
+	if (s)
+		y = x - toint + toint;
+	else
+		y = x + toint - toint;
+	if (y == 0)
+		return s ? -0.0 : 0;
+	return y;
+}