Subject: Important! Repository idea! (was: Re: [stella] Very BASIC ASM Info needed..) From: Manuel Polik <manuel.polik@xxxxxxxxxxx> Date: Thu, 08 Mar 2001 10:09:29 +0100 |
Russ Perry Jr wrote: > But you're doing that AND a lot to mask the high 6 bits, so... I'd just turn the shifting direction, then it's done with: Preloading: x10x01x00 (The first X is the carry, so it doesn't matter, too!) lda FrameCounter ror ror ror sta FrameCounter and #$03 tax ;(or tay whichever index you need) Which is 10 bytes and 16 cycles I think. But there's yet another (more hidden) advantage of the table: You don't have to preload anything, when zeroing out the machine on startup anyway. But another brilliant thought, Russ! I love thinking about such 'alternate ways for standard probs' :-) ------------------------------------------------ Besides, as a summary I'd say: For getting sequences of powers of two (0/1 v 0/1/2/3 v ...): INC FrameCounter LDA FrameCounter AND $XX TAX For getting sequences of three different values (0/1/2): LDY frameCounter LDX framecountertab,Y STX frameCounter framecountertab .byte $01,$02,$00 For getting sequences of other uneven values (0/1/2/3/4/5): dec FrameCounter bpl .skipReset lda #MAXVAL sta FrameCounter .skipReset ldx FrameCounter Is there any more ideas for these problems? Besides, I have an idea: ----------------------------------------------------------------- Maybe we should somewhere gather such 'ASM methodism' results? Brilliant thought: What if, when we have final consens about something being the 'ultimate best' solution, post it under a Non-Discussion, extra preserved topic? Let's say, when nobody comes with a better solution to this prob until monday, I'll revamp this topic with a little article and post it tagged as "[ASM WIZARDRY] #1 : Sequence Counting [Don't Reply!]". Now, it could be very easy found in the archive, with a simple query for 'ASM WIZARDRY'. One would get only the most useful results like this: "[ASM WIZARDRY] #1 : Sequence Counting [Don't Reply!]" "[ASM WIZARDRY] #2 : Cycle Optimizing [Don't Reply!]" "[ASM WIZARDRY] #3 : RAM Optimizing [Don't Reply!]" "[ASM WIZARDRY] #4 : ROM Optimizing [Don't Reply!]" "[ASM WIZARDRY] #5 : Illegal Opcodes LAX [Don't Reply!]" So, the general future way would be to write an article for building up such an "methodism repository", review it under any name and when approved by the whole list, post a tagged variant again. I'd even suggest a second series for specific 2600 topics like: "[2600 WIZARDRY] #1 : Horizontal positioning [Don't Reply!]" "[2600 WIZARDRY] #2 : NTSC/PAL conversions [Don't Reply!]" "[2600 WIZARDRY] #3 : Speeding up the kernal [Don't Reply!]" I know, most of these articles are already written and hidden somewhere, but what about dusting them of, revamping them and tag them for an easy find? Ok, there's one little drawback: When someone is pointing out to such an article saying something like "Search in the archive for [ASM WIZARDRY]" he would get all messages containing previous "Search in the archive for [ASM WIZARDRY]" pointers, since the archive doesn't provide topic only searches. But in general, what about this idea? Good/bad? Go for it? Greetings, Manuel - Archives (includes files) at http://www.biglist.com/lists/stella/archives/ Unsub & more at http://www.biglist.com/lists/stella/
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