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From: Laszlo Ersek <lersek@redhat.com>
To: edk2-devel-01 <edk2-devel@lists.01.org>
Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>,
	Liming Gao <liming.gao@intel.com>,
	Michael D Kinney <michael.d.kinney@intel.com>,
	Sean Brogan <sean.brogan@microsoft.com>
Subject: [PATCH 3/4] MdePkg/BaseSafeIntLib: clean up parentheses in MIN_INT64_MAGNITUDE
Date: Thu, 15 Feb 2018 19:36:37 +0100	[thread overview]
Message-ID: <20180215183638.18578-4-lersek@redhat.com> (raw)
In-Reply-To: <20180215183638.18578-1-lersek@redhat.com>

The definition of the MIN_INT64_MAGNITUDE macro is correct, but it's
harder to read than necessary: the sub-expression

      (( (UINT64) - (MIN_INT64 + 1) ))

is doubly parenthesized. Reusing one pair of the outer parens, rewrite the
sub-expression (without change in meaning) so that the minus sign cannot
be mistaken for subtraction:

      ( (UINT64)(- (MIN_INT64 + 1)) )

The resultant macro definition matches the following expressions in
SafeInt64Mult():

>     //
>     // Avoid negating the most negative number.
>     //
>     UnsignedMultiplicand = ((UINT64)(- (Multiplicand + 1))) + 1;

and

>     //
>     // Avoid negating the most negative number.
>     //
>     UnsignedMultiplier = ((UINT64)(- (Multiplier + 1))) + 1;

Cc: Bret Barkelew <Bret.Barkelew@microsoft.com>
Cc: Liming Gao <liming.gao@intel.com>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Sean Brogan <sean.brogan@microsoft.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
---
 MdePkg/Library/BaseSafeIntLib/SafeIntLib.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/MdePkg/Library/BaseSafeIntLib/SafeIntLib.c b/MdePkg/Library/BaseSafeIntLib/SafeIntLib.c
index 56d97cf65601..de91ffeca2a5 100644
--- a/MdePkg/Library/BaseSafeIntLib/SafeIntLib.c
+++ b/MdePkg/Library/BaseSafeIntLib/SafeIntLib.c
@@ -33,7 +33,7 @@
 //
 // Magnitude of MIN_INT64 as expressed by a UINT64 number.
 //
-#define MIN_INT64_MAGNITUDE ((((UINT64) - (MIN_INT64 + 1))) + 1)
+#define MIN_INT64_MAGNITUDE (((UINT64)(- (MIN_INT64 + 1))) + 1)
 
 //
 // Conversion functions
-- 
2.14.1.3.gb7cf6e02401b




  parent reply	other threads:[~2018-02-15 18:30 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-15 18:36 [PATCH 0/4] MdePkg/BaseSafeIntLib: fix undefined behavior in INT64 Sub/Add/Mult Laszlo Ersek
2018-02-15 18:36 ` [PATCH 1/4] MdePkg/BaseSafeIntLib: fix undefined behavior in SafeInt64Sub() Laszlo Ersek
2018-02-15 18:36 ` [PATCH 2/4] MdePkg/BaseSafeIntLib: fix undefined behavior in SafeInt64Add() Laszlo Ersek
2018-02-15 18:36 ` Laszlo Ersek [this message]
2018-02-15 18:36 ` [PATCH 4/4] MdePkg/BaseSafeIntLib: fix undefined behavior in SafeInt64Mult() Laszlo Ersek
2018-02-16 11:28 ` [PATCH 0/4] MdePkg/BaseSafeIntLib: fix undefined behavior in INT64 Sub/Add/Mult Ard Biesheuvel
2018-02-16 20:44   ` Laszlo Ersek
2018-02-16 18:11 ` Kinney, Michael D
2018-02-16 20:49   ` Laszlo Ersek
2018-02-17  3:07     ` Kinney, Michael D
2018-02-21 11:00       ` Laszlo Ersek
2018-02-21 18:10         ` Ard Biesheuvel

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