On 23 July 2014 12:55, Dmitry Poletaev <poletaev-q...@yandex.ru> wrote: > 14.07.2014, 18:59, "Peter Maydell" <peter.mayd...@linaro.org>: > >> Since softfloat's status flags are sticky ... > > What does it mean?
"Sticky" here means that the status flags accumulate the status from a sequence of operations: a softfloat function will set the flag if the relevant exception occurred, but if the exceptional condition did not happen then the flag will be left at whatever its preceding value was. So you can't just say "if the flag is set then the last operation I did set it", because it might have been set by some operation before that. (That is, once a bit gets set in the flags word it "sticks" and doesn't go away.) This matches the IEEE mandated behaviour for floating point exception flags, which is why we do it. thanks -- PMM
