New IR 2070

Attached is a new IR
2070    Support for floating point denormal numbers

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VHDL Issue Number:        2070

Language_Version          VHDL-2002
Classification            LRM Terminology, Grammar and Typographical Errors
Summary                   Support for floating point denormal numbers
Relevant_LRM_Sections     Section 7.2.7 paragraph 3 and 3.1.4 paragraph 6 conflict with one another.
Related_Issues            
Key_Words_and_Phrases     IEEE 854, 754, floating point, denormal
Authors_Name              David Bishop
Authors_Phone_Number      585-726-6788
Authors_Fax_Number        
Authors_Email_Address     dbishop@vhdl.org
Authors_Affiliation       Eastman Kodak
Authors_Address1          2400 Mt Read Blvd
Authors_Address2          Rochester NY 14650-3006
Authors_Address3          

Current Status:           Submitted

Superseded By:

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Date Submitted:           28 July 2005
Date Analyzed:
Author of Analysis:
Revision Number:          0
Date Last Revised:

Description of Problem
----------------------

In some simulators 2.0**-1025 results in 2**-1025 (a denormal 64 bit
IEEE 754 (854) floating point number.  In others, it becomes zero.
Note that this is very similar to the famous "Pentium bug", which is
now built into the IEEE 1076-2002 LRM....

In a floating point number, if the exponent is zero, by IEEE 854 the
number can become "denormal".  This is a mechanism in floating point
which allows you to express very small numbers (3.1.4 paragraph 6).
However, in 7.2.7 paragraph 6 it says "if the exponent is negative
then the result is the reciprocal of that obtained with the absolute
value of the exponent."

Proposed Resolution
-------------------

Modify section 7.2.7 to refer to IEEE 854 on how to treat an exponent.

VASG-ISAC Analysis & Rationale
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TBD

VASG-ISAC Recommendation for IEEE Std 1076-2002
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TBD

VASG-ISAC Recommendation for Future Revisions
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TBD


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