20 Jun
2007
20 Jun
'07
7:02 a.m.
On 6/20/07, e.stiebler <emu at e-bbes.com> wrote:
Gordon JC Pearce wrote:
Fixed point enhanced with fast (but sometimes large) lookup tables
instead of MUL and DIV.
Another thought that occurs is, surely the
FPU-less T11 would be no
better (and in some cases not as good as) a 68000? I can see where the
F11 or J11, although expensive, might be able to handle maths-intensive
tasks rather better.
be carefull here ;-)
games etc. use a lot of fixed point instead of floating point. And the 68000 shines here with the 32 bit registers
...
Yep.
Even without 32-bit registers, there are tricks one may employ.
Twenty years ago, I had to implement a high-frequency filter in 286
assembler as part of an auto-focus routine for a vision system. It
had to be fast, and the company would not pay for a 287 co-pro. The
normal technique for a simple 3x3 kernel is to sum up all the values
in a 3x3 area and divide by 9 to get the average value, then iterate
over the entire frame. Dividing by 9 is expensive for a 286.
Dividing by 8 isn't, and produced acceptable results.
There are frequently tricks to avoid expensive math operations. Video
games use most of them.
-ethan