From jwagener@ionet.net Thu Nov 23 20:59:16 1995 Received: from ion3.ionet.net (ion3.ionet.net [204.96.200.8]) by dkuug.dk (8.6.12/8.6.12) with ESMTP id UAA06347 for ; Thu, 23 Nov 1995 20:59:14 +0100 Received: from erehwon (tsip24.ionet.net [206.28.164.33]) by ion3.ionet.net (8.6.12/8.6.12) with SMTP id NAA07434 for ; Thu, 23 Nov 1995 13:59:05 -0600 X-Mailer: InterCon TCP/Connect II 2.2.1 MIME-Version: 1.0 Message-Id: <9511231404.AA39527@erehwon> Date: Thu, 23 Nov 1995 14:04:39 -0500 From: "Jerrold L. Wagener" To: sc22wg5@dkuug.dk Subject: Liaison Report on Floating Point Exception Handling TR Content-Transfer-Encoding: Quoted-Printable Content-Type: Text/Plain; charset=ISO-8859-1 Content-Disposition: Inline X3J3/95-307r1 Liaison Report on Floating Point Exception Handling TR To: X3J3, WG5, John Reid From: X3J3/parallel References: X3J3/95-277R2, ISO/IEC JTC1/SC22/WG5 - N1149 Date: Nov 16, 1996 X3J3/95-277R2 is a draft of a replacement for section 2 of N1149. = It describes the general facilities to be provided for Floating = Point Exception Handling. The rationale and text edits in N1149 will = need to be modified to match 277R2. This facility provides: =B0 A method for detecting floating point exceptions following the IEEE approach, =B0 Procedures that allow a program to determine the level of IEEE support available on the processor, =B0 Procedures that determine if an IEEE exception has occurred, =B0 Procedures that determine whether a variable has an IEEE exceptional value, =B0 Procedures which can generate IEEE exceptional values and generate exception signals, =B0 Procedures which can test and control rounding and halting modes, =B0 Procedures which can save, restore, and reset various IEEE flags=20 and statuses, =B0 A pair of intrinsic modules which allow a processor to provide two different levels of support and a method of selecting an intrinsic module, =B0 Processor dependent support if no intrinsic module is used, =B0 A method to control inheritance of IEEE support from a used module, =B0 A minimum level of support required from processors which offer the IEEE intrinsic modules. X3J3 concurs technically with this facility in the following ways: =B0 A procedural interface to the IEEE facilities is desired, =B0 Intrinsic modules are a useful way to provide this facility, =B0 A minimum support level is necessary for portability, but full or maximum support levels cannot be portably specified for current hardware. X3J3 has technical concerns in the following areas: =B0 The procedure set may not be complete, =B0 The method of controlling inheritance of the full or subset module from a used module and the interpretation if both modules = are used, =B0 The choice of a function interface for IEEE_TEST_FLAG. Some of these concerns may reflect minor or nonexistent problems; = others may be major problems. These concerns have been raised = by individuals and subgroups with X3J3 and have not been analyzed in = detail by X3J3; the result of any such analysis may conclude there is = no problem associated with a specific item or that there are other = problems not identified. Despite this lack of detailed analysis, = X3J3 believes that this list of concerns should be addressed by = the development body for floating point exceptions.