* gdb.texinfo (C and C++): Add Decimal Floating Point format

	subsubsection.
	(Decimal Floating Point format): New subsubsection.

2 files changed, 29 insertions, 0 deletions

diff --git a/gdb/doc/ChangeLog b/gdb/doc/ChangeLog
index 0d73a27..f1ca784 100644
--- a/gdb/doc/ChangeLog
+++ b/gdb/doc/ChangeLog
@@ -1,3 +1,9 @@
+2008-01-07  Thiago Jung Bauermann  <bauerman@br.ibm.com>
+
+	* gdb.texinfo (C and C++): Add Decimal Floating Point format
+	subsubsection.
+	(Decimal Floating Point format): New subsubsection.
+
 2008-01-05  Pedro Alves  <pedro@codesourcery.com>
 
 	* gdb.texinfo (File Options): Remove mention of the attempt to
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 808b675..da05dcc 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -9136,6 +9136,7 @@ gcc.info, Using the @sc{gnu} Compiler Collection (GCC)}.
 * C Checks::                    C and C@t{++} type and range checks
 * Debugging C::                 @value{GDBN} and C
 * Debugging C Plus Plus::       @value{GDBN} features for C@t{++}
+* Decimal Floating Point::      Numbers in Decimal Floating Point format
 @end menu
 
 @node C Operators
@@ -9604,6 +9605,28 @@ available choices, or to finish the type list for you.
 @xref{Completion,, Command Completion}, for details on how to do this.
 @end table
 
+@node Decimal Floating Point
+@subsubsection Decimal Floating Point format
+@cindex decimal floating point format
+
+@value{GDBN} can examine, set and perform computations with numbers in
+decimal floating point format, which in the C language correspond to the
+@code{_Decimal32}, @code{_Decimal64} and @code{_Decimal128} types as
+specified by the extension to support decimal floating-point arithmetic.
+
+There are two encodings in use, depending on the architecture: BID (Binary
+Integer Decimal) for x86 and x86-64, and DPD (Densely Packed Decimal) for
+PowerPC. @value{GDBN} will use the appropriate encoding for the configured
+target.
+
+Because of a limitation in @file{libdecnumber}, the library used by @value{GDBN}
+to manipulate decimal floating point numbers, it is not possible to convert
+(using a cast, for example) integers wider than 32-bit to decimal float.
+
+In addition, in order to imitate @value{GDBN}'s behaviour with binary floating
+point computations, error checking in decimal float operations ignores
+underflow, overflow and divide by zero exceptions.
+
 @node Objective-C
 @subsection Objective-C