On Mon, 16 Sep 2002 09:01:56 -0400 Paul Davis <[EMAIL PROTECTED]> wrote:
> i thought this was pretty insightful. vst-plugins has had a little > debate over whether or not VST should provide an integer sample > format. actually, not much of a debate. one person suggested it, > everybody else jumped on him. this post, however, is the most > detailed on why you should forget about thinking of float arithmetic > as slower than integer ... > > --;p I still use ints and fixed point because shifting and masking are faster than fdiv and fmod. As far as I know you cant do those instructions in one cycle using floats, and I use them everywhere. For my FM synth emulators I have fixed point iterators where the integer part is shifted and used as index to a sinetable and then the fractional part masked for interpolation. This amazingly beats using FSIN o my duron 850mhz, which not only starts slowing down when the float index is greater than PI/4, but also doesnt give good results because of the limited 23 bits mantisa. And yes, i tried using the fpu control register to change presicion to 32 bits. Thats why my integer code is still many times faster than my floating point code. I allways start with floating point mixers to try out approaches and then convert to fixed point to gain a very considerable speed boost. Consider also that when working with sample data you usually have it in 16 bits signed format (uses less space than a 32 bits floats) Disk space and memory usage are vital when you are writing a sampler, i'd hate it if my sample libs would take up twice as much. Also saturated adds in MMX are awesome when layering/mixing many code blocks. For now, I dont see any reason to switch to floating point for my stuff since facts show me what is faster. Juan Linietsky _______________________________________________ linux-audio-dev mailing list [EMAIL PROTECTED] http://music.columbia.edu/mailman/listinfo/linux-audio-dev
