It really blew my mind when Paul Davis <[EMAIL PROTECTED]> said: > >I have recently written a paper titled "Faster Floating Point to Integer Conve > >rsions" > >which can be read here: > > > > http://mega-nerd.com/FPcast/ > > nice work. but i have a question: your timings how that lrintf and > lrint basically take nearly twice as long as the optimal asm macro. if > you're writing a program in which float<->int conversion is a > significant issue, why would you move from the cast solution (which is > obviously bad) to one thats only half as good as it could be?
This is a gcc optimisation issue which I don't have the guts to tackle :-). > many other platforms (e.g. MIPS) do float<->int phenomenally well just > via a cast. it seems to me that it would be "cleverer" to define a > portable solution, if you're going to be willing to use autoconf, that > defines FLOAT_TO_INT, but make it platform specific and possibly a > no-op if the platform's cast does the job properly. > > did you consider this? I did, but lrint/lrint is a nicer solution because its already in the C99 standard and hence more portable. The macro has problems like possible macro side effects and being too ugly. Erik -- +-----------------------------------------------------------+ Erik de Castro Lopo [EMAIL PROTECTED] (Yes it's valid) +-----------------------------------------------------------+ Java : A language from the C family of languages. It has all the bad features of C++ but without the most powerful feature of C, pointers.
