[music-dsp] fixed point? floating point? MAC?
kaleja at estarcion.com
Fri Jan 31 09:41:00 EST 2003
Nigel Redmon wrote:
> > What's all this talk about MACs? Isn't that made by Apple?
> To elaborate on Bram's answer, it's a single instruction that
> multiplies two number and adds them to the accumulator.
And to elaborate on your elaboration, many DSPs have a
MAC instruction with the properties you describe and
many general-purpose CPUs don't.
Besides audio DSP purposes, multiply-and-accumulate is
also key to matrix math, which means it's key to 3D math,
which makes it interesting for game platforms. The Hitachi
SH4, used in the dearly departed Sega Dreamcast game
console, had vector registers and MAC instructions. I
believe the PS2 does as well, in one of its dark and
twisty processing units, all different.
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