From 69f065245eab8d03300e1b64200df9616846c082 Mon Sep 17 00:00:00 2001
From: Tomasz Sowa <t.sowa@ttmath.org>
Date: Wed, 18 Aug 2010 23:31:58 +0000
Subject: [PATCH] fixed: Big::Add sometimes incorrectly rounded the last bit
 from mantissa        (when exp_offset == mantissa_size_in_bits ) the
 rounding_up was always false

git-svn-id: svn://ttmath.org/publicrep/ttmath/trunk@303 e52654a7-88a9-db11-a3e9-0013d4bc506e
---
 ttmath/ttmathbig.h  | 11 +++++------
 ttmath/ttmathuint.h |  1 +
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/ttmath/ttmathbig.h b/ttmath/ttmathbig.h
index 7b4fb4f..be1e376 100644
--- a/ttmath/ttmathbig.h
+++ b/ttmath/ttmathbig.h
@@ -819,8 +819,7 @@ private:
 	*/
 	uint AddMantissas(	Big<exp, man> & ss2,
 						bool & last_bit_set,
-						bool & rest_zero,
-						bool & rounding_up)
+						bool & rest_zero)
 	{
 	uint c = 0;
 
@@ -835,8 +834,6 @@ private:
 				last_bit_set = mantissa.Rcr(1,1);
 				c += exponent.AddOne();
 			}
-
-			rounding_up = true;
 		}
 		else
 		{
@@ -890,11 +887,13 @@ public:
 		if( ss2.IsZero() )
 			return 0;
 
-		last_bit_set = rest_zero = do_adding = do_rounding = rounding_up = false;
+		last_bit_set = rest_zero = do_adding = do_rounding = false;
+		rounding_up = (IsSign() == ss2.IsSign());
+
 		AddCheckExponents(ss2, exp_offset, last_bit_set, rest_zero, do_adding, do_rounding);
 
 		if( do_adding )
-			c += AddMantissas(ss2, last_bit_set, rest_zero, rounding_up);
+			c += AddMantissas(ss2, last_bit_set, rest_zero);
 
 		if( !round || !last_bit_set )
 			do_rounding = false;
diff --git a/ttmath/ttmathuint.h b/ttmath/ttmathuint.h
index 5041c8b..fa2ab87 100644
--- a/ttmath/ttmathuint.h
+++ b/ttmath/ttmathuint.h
@@ -1965,6 +1965,7 @@ public:
 		this algorithm is described in the following book:
 			"The art of computer programming 2" (4.3.1 page 272)
 			Donald E. Knuth 
+		!! give the description here (from the book)
 	*/
 	uint Div3(const UInt<value_size> & v, UInt<value_size> * remainder = 0)
 	{