Optimizing a plot routine - Page 2

zero · 29 March 2021, 17:37

I didn't have much time to work on this lately but I have build the "speedcode":

bset d0,3920(a0)
bset d0,6970(a0)
rts

I build the code on the Amiga, not pre-calc, so I can later add some scaled versions. It all looks good and I have a table of addresses for each draw subroutine call.

Problem is how to call it from C? There is -mregparm, although I wonder if the compiler will do a decent job of keeping the variables in the right registers to avoid moving them with each call. Otherwise the overhead of stacking and unstacking the parameters will be too high.

The other option is re-write the whole loop in assembler. My original version was assembler but I was hoping to use C as much as possible.

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29 March 2021, 17:37	#21
zero Registered User Join Date: Jun 2016 Location: UK Posts: 428	I didn't have much time to work on this lately but I have build the "speedcode": bset d0,3920(a0) bset d0,6970(a0) rts I build the code on the Amiga, not pre-calc, so I can later add some scaled versions. It all looks good and I have a table of addresses for each draw subroutine call. Problem is how to call it from C? There is -mregparm, although I wonder if the compiler will do a decent job of keeping the variables in the right registers to avoid moving them with each call. Otherwise the overhead of stacking and unstacking the parameters will be too high. The other option is re-write the whole loop in assembler. My original version was assembler but I was hoping to use C as much as possible.

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