Avi Kivity <[EMAIL PROTECTED]> writes: | On Tue, 2005-07-05 at 20:05 +0200, Gabriel Dos Reis wrote: | > Paolo Carlin | > It is definitely a good thing to use the full bits of value | > representation if we ever want to make all "interesting" bits part of | > the hash value. For reasonable or sane representations it suffices to | > get your hand on the object representation, e.g.: | > | > const int objsize = sizeof (double); | > typedef unsigned char objrep_t[objsize]; | > double x = ....; | > objrep_t& p = reintepret_cast<objrep_t&>(x); | > // ... | > | > and let frexp and friends only for less obvious value representation. | | most architectures have different bit representations for +0.0 and -0.0, | yet the two values compare equal.
Indeed. Paolo, Michael and I have been discussing that offline. the signed zero representation is not the a serious one (say compare to having padding bits or how to handle NaNs properly) -- just compare to 0.0 and return hash value 0 before going mocking around with bytes. -- Gaby
