[Cfp-interest] DFP and unary +

[Ian McIntosh]

The normal implementation of a unary + is to do nothing.  In that case any
non-canonical encodings are unchanged.

An alternate implementation is to add the value to zero.  Non-canonical
encodings would be made canonical.  I don't know of any implementations
that do that.

The wording should allow either.

This applies to BFP too, in cases like the sign of zero, and in some
non-IEEE implementations the exponent of zero.

- Ian McIntosh          IBM Canada Lab         Compiler Back End Support
and Development



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  |"Fred J. Tydeman" <tydeman at tybor.com>                                                                                                             |
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  |"cfp-interest" <cfp-interest at ucbtest.org>                                                                                                         |
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  |06/13/2013 10:22 PM                                                                                                                               |
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  |[Cfp-interest] DFP and unary +                                                                                                                    |
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  |cfp-interest-bounces at oakapple.net                                                                                                                 |
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Does a unary + operation propagate non-canonical encodings?

WG14 N1722 11.1 Operators says that Unary Arithmetic operators
in C11 follow the semantic of IEC 60559.  But, 60559 has
no mention of unary + operator.


---
Fred J. Tydeman        Tydeman Consulting
tydeman at tybor.com      Testing, numerics, programming
+1 (775) 287-5904      Vice-chair of PL22.11 (ANSI "C")
Sample C99+FPCE tests: http://www.tybor.com
Savers sleep well, investors eat well, spenders work forever.

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