[DOC] update decimal float section in extend.texi

[Janis Johnson <janis187 at us dot ibm dot com>]

This documentation patch updates the description of decimal float
support to reference the latest draft TR.  It uses the terminology
of that draft TR, and lists areas of functionality that GCC does not
yet support.  Tested with "make info" and "make dvi"; OK for trunk?

2006-08-22  Janis Johnson  <janis187@us.ibm.com

	* doc/extend.texi (Decimal Float): Update for latest draft TR.

Index: gcc/doc/extend.texi
===================================================================
--- gcc/doc/extend.texi	(revision 116309)
+++ gcc/doc/extend.texi	(working copy)
@@ -33,7 +33,7 @@
 * Conditionals::        Omitting the middle operand of a @samp{?:} expression.
 * Long Long::		Double-word integers---@code{long long int}.
 * Complex::             Data types for complex numbers.
-* Decimal Float::	Decimal Floating Point.
+* Decimal Float::       Decimal Floating Types. 
 * Hex Floats::          Hexadecimal floating-point constants.
 * Zero Length::         Zero-length arrays.
 * Variable Length::     Arrays whose length is computed at run time.
@@ -816,8 +816,8 @@
 examine and set these two fictitious variables with your debugger.
 
 @node Decimal Float
-@section Decimal Floating Point
-@cindex decimal floating point
+@section Decimal Floating Types
+@cindex decimal floating types
 @cindex @code{_Decimal32} data type
 @cindex @code{_Decimal64} data type
 @cindex @code{_Decimal128} data type
@@ -828,26 +828,37 @@
 @cindex @code{DD} integer suffix
 @cindex @code{DL} integer suffix
 
-GNU C supports decimal floating point types in addition to the
-standard floating-point types.  This extension supports decimal
-floating-point arithmetic as defined in IEEE-754R, the proposed
-revision of IEEE-754.  The C language extension is defined in ISO/IEC
-DTR 24732, Draft 5.  Support for this functionality will change when
-it is accepted into the C standard and might change for new drafts
-of the proposal.  Calling conventions for any target might also change.
-Not all targets support decimal floating point.
+As an extension, the GNU C compiler supports decimal floating types as
+defined in the N1176 draft of ISO/IEC WDTR24732.  Support for decimal
+floating types in GCC will evolve as the draft technical report changes.
+Calling conventions for any target might also change.  Not all targets
+support decimal floating types.
 
-Support for decimal floating point includes the arithmetic operators
+GCC support of decimal float as specified by the draft technical report
+is incomplete:
+
+@itemize @bullet
+@item
+Translation time data type (TTDT) is not supported.
+
+@item
+Characteristics of decimal floating types are defined in header file
+@file{decfloat.h} rather than @file{float.h}.
+
+@item
+When the value of a decimal floating type cannot be represented in the
+integer type to which it is being converted, the result is undefined
+rather than the result value specified by the draft technical report.
+@end itemize
+
+Support for decimal floating types includes the arithmetic operators
 add, subtract, multiply, divide; unary arithmetic operators;
 relational operators; equality operators; and conversions to and from
-integer and other floating-point types.  Use a suffix @samp{df} or
+integer and other floating types.  Use a suffix @samp{df} or
 @samp{DF} in a literal constant of type @code{_Decimal32}, @samp{dd}
 or @samp{DD} for @code{_Decimal64}, and @samp{dl} or @samp{DL} for
 @code{_Decimal128}.
 
-Passing a decimal floating-point value as an argument to a function
-without a prototype is undefined.
-
 Types @code{_Decimal32}, @code{_Decimal64}, and @code{_Decimal128}
 are supported by the DWARF2 debug information format.