Fix undefined behavior in sign conversion.

mpruett · Aug 30, 2016 · b62c902 · b62c902 · mschwendt · Nov 8, 2016
1 parent 82f9131
commit b62c902
Show file tree

Hide file tree

Showing 2 changed files with 7 additions and 1 deletion.
diff --git a/ChangeLog b/ChangeLog
@@ -1,3 +1,8 @@
+2016-08-29  Michael Pruett <michael@68k.org>
+
+	* libaudiofile/modules/SimpleModule.h:
+	Fix undefined behavior in sign conversion.
+
 2016-07-05  Joerg Krause <joerg.krause@embedded.rocks>
 
 	* audiofile.pc.in:

diff --git a/libaudiofile/modules/SimpleModule.h b/libaudiofile/modules/SimpleModule.h
@@ -123,7 +123,8 @@ struct signConverter
 	typedef typename IntTypes<Format>::UnsignedType UnsignedType;
 
 	static const int kScaleBits = (Format + 1) * CHAR_BIT - 1;
-	static const int kMinSignedValue = -1 << kScaleBits;
+	static const int kMaxSignedValue = (((1 << (kScaleBits - 1)) - 1) << 1) + 1;
+	static const int kMinSignedValue = -kMaxSignedValue - 1;
 
 	struct signedToUnsigned : public std::unary_function<SignedType, UnsignedType>
 	{