From 3336db962c97407f798f29db82726576796751f8 Mon Sep 17 00:00:00 2001
From: Alan Cox <alan@linux.intel.com>
Date: Sat, 30 Sep 2017 19:35:24 +0100
Subject: [PATCH] Library: add round.c to the maths library

---
 Library/libs/Makefile.z80 |  2 +-
 Library/libs/round.c      | 66 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+), 1 deletion(-)
 create mode 100644 Library/libs/round.c

diff --git a/Library/libs/Makefile.z80 b/Library/libs/Makefile.z80
index 03c3bcd8..25ab6576 100644
--- a/Library/libs/Makefile.z80
+++ b/Library/libs/Makefile.z80
@@ -81,7 +81,7 @@ SRC_LM += hypotf.c ilogbf.c j0f.c j1f.c jnf.c
 SRC_LM += ldexpf.c lgammaf.c lgammaf_r.c logf.c log2f.c log10f.c logbf.c
 SRC_LM += lrintf.c lroundf.c
 SRC_LM += modff.c nearbyintf.c nextafterf.c powf.c
-SRC_LM += remainderf.c remquof.c rintf.c
+SRC_LM += remainderf.c remquof.c rintf.c round.c
 SRC_LM += scalbnf.c scalbinf.c
 SRC_LM += sinf.c sincosf.c sinhf.c
 SRC_LM += sqrtf.c tgammaf.c
diff --git a/Library/libs/round.c b/Library/libs/round.c
new file mode 100644
index 00000000..90875660
--- /dev/null
+++ b/Library/libs/round.c
@@ -0,0 +1,66 @@
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice 
+ * is preserved.
+ * ====================================================
+ */
+
+#include "libm.h"
+
+double round(double x)
+{
+	/* Most significant word, least significant word. */
+	__int32_t msw, exponent_less_1023;
+	__uint32_t lsw;
+
+	EXTRACT_WORDS(msw, lsw, x);
+
+	/* Extract exponent field. */
+	exponent_less_1023 = ((msw & 0x7ff00000) >> 20) - 1023;
+
+	if (exponent_less_1023 < 20) {
+		if (exponent_less_1023 < 0) {
+			msw &= 0x80000000;
+			if (exponent_less_1023 == -1)
+				/* Result is +1.0 or -1.0. */
+				msw |= (1023 << 20);
+			lsw = 0;
+		} else {
+			__uint32_t exponent_mask = 0x000fffff >> exponent_less_1023;
+			if ((msw & exponent_mask) == 0 && lsw == 0)
+				/* x in an integral value. */
+				return x;
+
+			msw += 0x00080000 >> exponent_less_1023;
+			msw &= ~exponent_mask;
+			lsw = 0;
+		}
+	} else if (exponent_less_1023 > 51) {
+		if (exponent_less_1023 == 1024)
+			/* x is NaN or infinite. */
+			return x + x;
+		else
+			return x;
+	} else {
+		__uint32_t exponent_mask = 0xffffffff >> (exponent_less_1023 - 20);
+		__uint32_t tmp;
+
+		if ((lsw & exponent_mask) == 0)
+			/* x is an integral value. */
+			return x;
+
+		tmp = lsw + (1 << (51 - exponent_less_1023));
+		if (tmp < lsw)
+			msw += 1;
+		lsw = tmp;
+
+		lsw &= ~exponent_mask;
+	}
+	INSERT_WORDS(x, msw, lsw);
+
+	return x;
+}
-- 
2.34.1