Browse Prior Art Database

Method for Specifying an Invalid Operation has Occurred for an Operation Implemented in Software

IP.com Disclosure Number: IPCOM000111828D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 2 page(s) / 56K

Publishing Venue

IBM

Related People

Hay, RW: AUTHOR [+3]

Abstract

Disclosed is a method for invalid operation exceptions to be reported on an architecture implementing the IEEE-754 floating-point standard, and where multiple "detail bits" are used for reporting exception type, and operations which should generate invalid operation exceptions can be implemented either in hardware or in a software routine.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 53% of the total text.

Method for Specifying an Invalid Operation has Occurred for an Operation
Implemented in Software

      Disclosed is a method for invalid operation exceptions to be
reported on an architecture implementing the IEEE-754 floating-point
standard, and where multiple "detail bits" are used for reporting
exception type, and operations which should generate invalid
operation exceptions can be implemented either in hardware or in a
software routine.

PROBLEM

      The IEEE-754 floating-point standard requires that certain
operations produce exceptions that can be detected by a user program,
either by taking a trap or setting a flag which can be queried by the
user program.  Among the required exceptions is "invalid operation",
which can be produced by any of a number of different operations.
The logical operations which can produce an invalid operation
exception can either be implemented by a single hardware instruction
or by a series of instructions in a software routine.

      Certain processors which implement the IEEE-754 standard
instead of having a single flag for the "invalid operation" exception
have a series of flags which correspond to types of invalid
operations which can be detected.  The actual state of the "invalid
operation" flag is then represented by the logical 'or' of all of the
detail flags.  Each hardware operation which can generate an invalid
operation then sets the appropriate detail flag if an exception
occurs.

      A problem arises whe...