JTC1/SC22/WG14 N724

ISO/IEC JTC1/SC22/WG14 N724

                    Minor alteration to representations of types
                          Clive D.W. Feather


Abstract
========

N691 defines the meaning of the sign bit as being either a negation
flag or a large negative constant. At the time I was writing the
original paper I was over-generous in the latter case. This proposal
restricts implementations to the three cases of sign-and-magnitude,
twos-complement, and ones-complement.


Proposal
========

In 6.1.2.7.2 paragraph 2 (added in N691), change:

    If the sign bit is one, then the value shall be modified in
    one of the following ways:
    - the corresponding value with sign bit 0 is negated;
    - the sign bit has some value between -1 and -2**N inclusive.

to:

    If the sign bit is one, then the value shall be modified in
    one of the following ways:
    - the corresponding value with sign bit 0 is negated;
 |  - the sign bit has the value -2**N;
 |  - the sign bit has the value 1-2**N.