Wrathchild Posted September 30, 2004 Share Posted September 30, 2004 We can improve that routine by getting rid of the Y registerEh? You've changed its functionlity? That routine was a bit pair swapper, yours is for single bits. The Combat code was: CreateFlipTable: LDX #0 @1: TXA LDY #7 @2: ASL A ROR $80 DEY BPL @2 LDA $80 STA $600,X INX BNE @1 RTS So yes, you do save on that I did think to change the bit pair version to not use the zero page temp register. CreateFlipTable: LDX #1 @1: TXA LDY #3 @2: ASL A PHP ASL A ROR FlipTable PLP ROR FlipTable DEY BPL @2 LDA FlipTable STA FlipTable,X INX BNE @1 STX FlipTable RTS Quote Link to comment Share on other sites More sharing options...
Sheddy Posted September 30, 2004 Share Posted September 30, 2004 Actually, it shouldn't work (because the bottom DEY should be DEX...right?) yep, absolutely right Nukey - thanks. How could I miss that? In such a small piece of code too! - now you know one reason why I don't normally post much (even preview is no help for some people!) this code might actually work... ldx #0 ?1 stx mirror_this ldy #8 ?2 asl mirror_this ror a dey bne ?2 sta mirror_table,x dex bne ?1 mirroring 2 bit pixels - trickier, but more interesting - I'll have to look back at some of my code on how I did that - don't think it's as elegant as these though, as it wasn't a time critical routine Quote Link to comment Share on other sites More sharing options...
Sheddy Posted September 30, 2004 Share Posted September 30, 2004 Extra byte saving and less cycles on your single bit per pixel mirror routine, Rob Doubt I would have thought of that approach. Ideal for mini-game. Quote Link to comment Share on other sites More sharing options...
+Andrew Davie Posted September 30, 2004 Share Posted September 30, 2004 6502 maniacs... i try to improve schmutzpuppe's trackball ballcode without the use of a lookup table... he used a strange (but working... ) piece of code to mirror the bitpattern of the ballsprite... of course i could use a pre generated lookup table but i am sure you could do this with some clever bit manipulations... any help here? thomas? manuel? ...or perhaps...Andrew? I assume there are 4 pairs of bits, and the bit pairs need to be reversed. Place the byte to reverse in accumulator, and repeat the following code 4 times (either inline, or loop)... ror temp rol rol temp cmp #128 ror temp ror temp asl The last 'asl' can be discarded if code is inline. This should reverse a byte's bits from ABCDEFGH to GHEFCDAB. Inline, it would take 118 cycles, 47 bytes total... ouch! Warning: untested code! Cheers A Quote Link to comment Share on other sites More sharing options...
+Andrew Davie Posted September 30, 2004 Share Posted September 30, 2004 ror temp rol rol temp cmp #128 ror temp ror temp asl If the code is inline, the first 'ror temp' can also be dropped... thus the total conversion code is ... rol rol temp cmp #128 ror temp ror temp asl ror temp rol rol temp cmp #128 ror temp ror temp asl ror temp rol rol temp cmp #128 ror temp ror temp asl ror temp rol rol temp cmp #128 ror temp ror temp Cheers A Quote Link to comment Share on other sites More sharing options...
Thomas Jentzsch Posted September 30, 2004 Share Posted September 30, 2004 If the code is inline, the first 'ror temp' can also be dropped...thus the total conversion code is ... rol rol temp cmp #128 ror temp ror temp asl ... Even shorter: asl rol temp asl ror temp ror temp Quote Link to comment Share on other sites More sharing options...
Heaven/TQA Posted September 30, 2004 Author Share Posted September 30, 2004 thanks guys... but the ballsprite is a 8bit player so not background gfx where i could use the bitpair routines...i need 8bit "swapper"... Quote Link to comment Share on other sites More sharing options...
Wrathchild Posted September 30, 2004 Share Posted September 30, 2004 typically, programmers get sidetracked all to easily Quote Link to comment Share on other sites More sharing options...
Robert M Posted October 1, 2004 Share Posted October 1, 2004 We can improve that routine by getting rid of the Y registerEh? You've changed its functionlity? Okay, my mistake, but I think you should still get rid of using Y as your loop counter and instead use a bit flag in A rotated into Carry as your loop exit test: CreateFlipTable: LDX #0 @1: LDA #$80 STX byte_0_A8 @2: ASL byte_0_A8 PHP ASL byte_0_A8 ROR A PLP ROR A BCC @2 STA FlipTable,X INX BNE @1 RTS Quote Link to comment Share on other sites More sharing options...
Thomas Jentzsch Posted October 1, 2004 Share Posted October 1, 2004 ...i need 8bit "swapper"... ABCDEFGH -> HGFEDCBA Right? Quote Link to comment Share on other sites More sharing options...
Robert M Posted October 1, 2004 Share Posted October 1, 2004 ...i need 8bit "swapper"... ABCDEFGH -> HGFEDCBA Right? Yes, that was the original request. Apparently, there is also a use in Atari 8-bit programming to be able to do this: ABCDEFGH - > GHEFCDAB For multi-colored backgrounds and such. The 2 discussions got wrapped around each other. Quote Link to comment Share on other sites More sharing options...
Heaven/TQA Posted October 1, 2004 Author Share Posted October 1, 2004 thomas, you are right, this was my intitial request... so guys, is code here in this thread doing this or is it just the bitpair flipper? Quote Link to comment Share on other sites More sharing options...
Schmutzpuppe Posted October 1, 2004 Share Posted October 1, 2004 thomas, you are right, this was my intitial request... so guys, is code here in this thread doing this or is it just the bitpair flipper? Sheddy's code will do the job. Quote Link to comment Share on other sites More sharing options...
Thomas Jentzsch Posted October 1, 2004 Share Posted October 1, 2004 thomas, you are right, this was my intitial request... Are you looking for creating a table or an on the fly solution? Or a compromise? Quote Link to comment Share on other sites More sharing options...
Schmutzpuppe Posted October 1, 2004 Share Posted October 1, 2004 thomas, you are right, this was my intitial request... Are you looking for creating a table or an on the fly solution? Or a compromise? I think it doesn't make a differnce because it should be easy to modify a "table create" code to an "on the fly" version and vice versa. If I understand it correctly the main question was about how to reflect a byte as effective as possible. Quote Link to comment Share on other sites More sharing options...
+Andrew Davie Posted October 1, 2004 Share Posted October 1, 2004 thomas, you are right, this was my intitial request... Are you looking for creating a table or an on the fly solution? Or a compromise? I think it doesn't make a differnce because it should be easy to modify a "table create" code to an "on the fly" version and vice versa. If I understand it correctly the main question was about how to reflect a byte as effective as possible. This is pretty easy: repeat the following 8 times... lsr rol temp After 8 of those, temp holds the reflected value of what was in A, and A is 0. Essentially you're rolling bits off the right side of A, and onto the left side of temp... reversing the order. Cheers A Quote Link to comment Share on other sites More sharing options...
Thomas Jentzsch Posted October 1, 2004 Share Posted October 1, 2004 This is pretty easy: repeat the following 8 times... lsr rol temp After 8 of those, temp holds the reflected value of what was in A, and A is 0. Essentially you're rolling bits off the right side of A, and onto the left side of temp... reversing the order. Yup, that's why I was asking. Doing this on the fly costs at least 7*8=56 cycles (unrolled loop) or about 10*8+5 = 85 cycles (loop). Using a table however will be significantly faster, but use a lot of memory. Combining both (e.g. using two nibble tables and OR them) will use less memory than the table approach and less time than the on the fly solution. So, whatever you choose depends on the situation. Quote Link to comment Share on other sites More sharing options...
Heaven/TQA Posted October 1, 2004 Author Share Posted October 1, 2004 thankS!!!1 i think now i got this simple task... lsr + rol. 1st i wanted to keep trackball into 4k... but now it will be a "fullprice" game hence 64k game... so for the 4k version i would like to have a small code maybe "real time solution". the levels will be now created from char-tiles full screen size... the level editor will be published to the public as i am not gonna make levels... the levels will be flashpacked and depacked every level start so the scroll engine will be now easier and more 800er like... so the only scrolling overhead will be the parallax effect but not the "genereting" tile lines each 8th frame... more to come later this weekend.... Quote Link to comment Share on other sites More sharing options...
Tezz Posted October 2, 2004 Share Posted October 2, 2004 Heaven 1st i wanted to keep trackball into 4k... but now it will be a "fullprice" game hence 64k game That's what I like to see a full fat game. the levels will be now created from char-tiles full screen size Nice the level editor will be published to the public as i am not gonna make levels... the levels will be flashpacked and depacked every level start so the scroll engine will be now easier and more 800er like... so the only scrolling overhead will be the parallax effect but not the "genereting" tile lines each 8th frame... Great stuff, very interested to see the code in all that. more to come later this weekend.... Look forward to it. Quote Link to comment Share on other sites More sharing options...
Heaven/TQA Posted October 2, 2004 Author Share Posted October 2, 2004 i am just back from 2 hours star wars battlefront on my xbox... so now i am relaxed... damned rebel separatists... dark side ruleZ! i just recieved 3 tilesets for the level gfx so now i am starting to put a demo in with the new gfx set and rewrite the scroll engine for phat levels... i still gonna need the double buffer approach as for the parallax effect... stay tuned... Quote Link to comment Share on other sites More sharing options...
Heaven/TQA Posted October 2, 2004 Author Share Posted October 2, 2004 ok... after 2 hours little coding & converting... 1) implementation of rob's mirrow code 2) dummy level genrator written in turbo basic xl 3) new scroll engine next 1st joystick routine just to get a feeling for the level size... at the moment its 5x screens tall... = 4800 bytes unpacked... the tile set is called "bubble" and was made by stefan aka retrofan... thanks mate!!! gimme more... here is the level generator... 10 REM TRACKBALL LEVEL EDITOR 20 OPEN #1,4,0,"H:BUBBLE.FNT" 30 BGET #1,$6000,1024 40 CLOSE #1 50 GRAPHICS 12+16 55 SCR=DPEEK(88) 60 POKE 756,$60 70 LEVEL=$8000 80 FOR L=0 TO 3 90 GRAPHICS 12+16 95 POKE 756,$60 100 SCR=DPEEK(88) 110 EXEC FILL 120 MOVE SCR,LEVEL,960 130 LEVEL=LEVEL+960 140 NEXT L 800 OPEN #1,8,0,"H:LEVEL.DAT" 810 BPUT #1,$8000,3840 820 CLOSE #1 999 END 1000 PROC FILL 1010 REM DRAW 10 PLATFORMS 1020 I=0 1030 REPEAT 1040 X=RAND(36) 1050 Y=RAND(23) 1060 B=RAND(30) 1070 H=RAND(8) 1075 ------------------------------ 1080 REM NOW DRAW 1090 POKE SCR+X+Y*40,1 1091 POKE SCR+X+(Y+H+1)*40,3 1100 FOR J=1 TO B 1110 POKE SCR+X+J+Y*40,6 1111 POKE SCR+X+J+(Y+H+1)*40,9 1120 NEXT J 1130 POKE SCR+X+Y*40+J,2 1131 POKE SCR+X+J+(Y+H+1)*40,4 1140 FOR J=1 TO H 1150 POKE SCR+X+(Y+J)*40,7 1155 POKE SCR+X+(Y+J)*40+B+1,8 1160 FOR A=1 TO B 1170 POKE SCR+X+A+(Y+J)*40,5 1180 NEXT A 1190 NEXT J 1200 I=I+1 1210 UNTIL I=10 1299 ENDPROC trackb4.zip Quote Link to comment Share on other sites More sharing options...
Like us on Facebook
Follow us on Twitter
AtariAge on Instagram
Watch us on YouTube
Chat on Discord
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.