From 6ab4cfb71401ebb5390deaf58bb2427b32d5c7d7 Mon Sep 17 00:00:00 2001
From: Mirko Scholz <mirko@talitha>
Date: Sat, 5 Sep 2020 10:35:45 +0200
Subject: [PATCH] extra checks for multiply

---
 src/decn/decn.c         |  6 ++++++
 src/decn/decn_tests.cpp | 13 +++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/src/decn/decn.c b/src/decn/decn.c
index ea03035..07d752e 100644
--- a/src/decn/decn.c
+++ b/src/decn/decn.c
@@ -696,6 +696,12 @@ void mult_decn(void){
 	uint8_t carry = 0;
 	uint8_t is_neg;
 	exp_t new_exponent;
+#ifdef EXTRA_CHECKS
+	if (decn_is_nan(&AccDecn) || decn_is_nan(&BDecn)) {
+		set_dec80_NaN(&AccDecn);
+		return;
+	}
+#endif
 	//initialize values
 	set_dec80_zero(&TmpDecn);
 	//normalize
diff --git a/src/decn/decn_tests.cpp b/src/decn/decn_tests.cpp
index 18a292b..b9a42bf 100644
--- a/src/decn/decn_tests.cpp
+++ b/src/decn/decn_tests.cpp
@@ -243,6 +243,19 @@ TEST_CASE("multiply"){
 	decn_to_str_complete(&AccDecn);
 	CHECK_THAT(Buf, Equals("Error")); //acc*b
 
+	//NaN
+	build_dec80("9.99", DEC80_MAX_EXP/2);
+	set_dec80_NaN(&BDecn);
+	mult_decn();
+	decn_to_str_complete(&AccDecn);
+	CHECK_THAT(Buf, Equals("Error")); //acc*b
+
+	//NaN
+	set_dec80_NaN(&AccDecn);
+	build_decn_at(&BDecn, "9.99", DEC80_MAX_EXP/2);
+	mult_decn();
+	decn_to_str_complete(&AccDecn);
+	CHECK_THAT(Buf, Equals("Error")); //acc*b
 }
 
 static void div_test(