Hi Victor, Thanks very much, the document does indeed explain the issue very well. I guess it's strange to me though that we have code that can be #ifdef'd to be truncating or not. I don't think I've ever used the macro but I've seen it here and there, and my first assumption was that it truncated, but it seems one can't depend on that. I guess in practice though it doesn't really come into play, as no one's mentioned anything yet and I haven't noticed anything funny. Thanks! steven On 10/21/06, Victor Lazzarini wrote: > Steven, > > Erik's text in www.mega-nerd.com/FPcast explains > it well. > > I went and tested the two options I gave here: > lrint() + test is slower than just casting. > lrint() on its own is faster than casting, but > it rounds; if truncation is needed then we're > better off with casting. > > I am just checking the best way to make table > lookup code faster. I suppose using integer > sampling increments and indexing is the fastest, > anyway. > > Victor > > > > > Hi Victor, > > > > This is somewhat related and is a question for everyone: > > in H/sysdep.h, if USE_LRINT is enabled, does the code in > > there: > > > > 230 # define MYFLT2LONG(x) ((long) lrintf((float) > > (x))) > > > > not yield a different result than: > > > > 263 # define MYFLT2LONG(x) ((long) (x)) > > > > ? I guess I'm wondering what that code is all about. > > > > Thanks! > > steven > > > > > > On 10/21/06, Victor Lazzarini > > > wrote: A question for any int to float guru out there > > > (Erik?), which of the two truncation codes below would > > be faster? > > > > (1) > > > double a; long b; > > > b = (long) a; > > > > > > (2) > > > double a; long b; > > > b = lrint(a); > > > b = b <= a ? b : b - 1; > > > > > > (both assuming positive numbers only). > > > I suppose my question is whether b <= a, comparing > > > fixed and floating-point, involves any casting > > > that might slow down things. > > > > > > I would expect that if there is any casting it would > > > be long -> double; I suppose that does not carry > > > any penalty, or does it? > > > > > > Thanks > > > > > > Victor > > > > > > > > ---------------------------------------------------------- > > > --------------- Using Tomcat but need to do more? Need > > > to support web services, security? Get stuff done > > quickly with pre-integrated technology to make your job > > > easier Download IBM WebSphere Application Server v.1.0.1 > > > based on Apache Geronimo > > > http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 > > > _______________________________________________ > > > Csound-devel mailing list > > > Csound-devel@lists.sourceforge.net > > > > > https://lists.sourceforge.net/lists/listinfo/csound-devel > > > > > > > ---------------------------------------------------------- > > --------------- Using Tomcat but need to do more? Need to > > support web services, security? Get stuff done quickly > > with pre-integrated technology to make your job easier > > Download IBM WebSphere Application Server v.1.0.1 based on > > Apache Geronimo > > > http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 > > _______________________________________________ > > Csound-devel mailing list > > Csound-devel@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/csound-devel > > ------------------------------------------------------------------------- > Using Tomcat but need to do more? Need to support web services, security? > Get stuff done quickly with pre-integrated technology to make your job easier > Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo > http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 > _______________________________________________ > Csound-devel mailing list > Csound-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/csound-devel > ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ Csound-devel mailing list Csound-devel@lists.sourceforge.net