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Forums > CSDb Entries > Release id #172238 : Waves 16k
2018-12-09 10:09
Heaven
Account closed

Registered: Jul 2008
Posts: 102
Release id #172238 : Waves 16k

<Post edited by moderator on 11/12-2018 15:33>

                    ldx #0                  ;top = 0
                                            ;we use Xreg as top
loop_fractal_line   cpx #0
                    bpl @+                  ;if x<0 go to drawing
                    jmp exit_fractal_line
@                   lda sx2,x               ;dx = abs(sx2-sx1)
                    sec
                    sbc sx1,x
                    bcs @+
                    eor #$FF
                    adc #1
@                   cmp #2                  ;if dx<2 skip to plot point
                    bcs subdiv_fractal_line
                    ldy sx1,x
                    lda sy1,x
                    sta heights,y
                    dex
                    bne loop_fractal_line
                    beq loop_fractal_line
subdiv_fractal_line lsr                     ;ed = dx/4
                    lsr
                    sta edge_displacement
                    
                    lda sx2,x               ;sx2 = int((sx1+sx2)/2)
                    sta sx2+1,x             ;use it to copy to top+1
                    clc
                    adc sx1,x
                    lsr
                    sta sx2,x
                    sta sx1+1,x             ;copy to top+1 also
                    
                    lda sy2,x               ;sy2 = int((sy1+sy2)/2)
                    sta sy2+1,x             ;use it to copy to top+1
                    clc
                    adc sy1,x
                    lsr
                    sta sy2,x
                    
                    lda st2,x               ;st2 = st1+st2
                    sta st2+1,x             ;use it to copy to top+1
                    clc
                    adc st1,x
                    sta st2,x
                    sta st1+1,x             ;copy to top+1 also
                    
                    bvs @+                  ;if v<>0 skip displacement
                    bmi n_equal_1
                    lda sy2,x               ;n == 0
                    clc                     ;sy2 += ed
                    adc edge_displacement
                    sta sy2,x
                    jmp @+
n_equal_1           lda sy2,x               ;n == 1
                    sec                     ;sy2 -= ed
                    sbc edge_displacement
                    sta sy2,x

@                                           ;Copy new Y to top+1
                    lda sy2,x
                    sta sy1+1,x
                    
                    inx                     ;top += 1
                    jmp loop_fractal_line
exit_fractal_line

2018-12-09 14:56
chatGPZ

Registered: Dec 2001
Posts: 11088
that would be so much better with a 'code' tag =D
2018-12-11 09:29
Bitbreaker

Registered: Oct 2002
Posts: 498
So much precious cycles waster with sec/clc and no illegal spotted :-(
2018-12-11 11:01
Heaven
Account closed

Registered: Jul 2008
Posts: 102
@Bitbreaker...

yeah... ;)

we Atarians do not use illegals often due to 65816 boards :D.

no honestly. Axis teached me last week first time AXS e.g. so first time I used any illegal was LAX in Arsantica 3 and the Voxel... :D
2018-12-11 12:12
Bitbreaker

Registered: Oct 2002
Posts: 498
All the lsr could be replaced with an asr #$fe and thus carry will stay clear and clc can be dropped, and i see even more potential :-) (sta sy2,x being stored and loaded again just on the next step, a comparision would suffice on the abs function, and that would save a sec)
2018-12-11 15:05
Cruzer

Registered: Dec 2001
Posts: 1048
What
    Groepaz
           said
2018-12-11 15:33
iAN CooG

Registered: May 2002
Posts: 3128
I edited the 1st post to reformat it with the code tags
2018-12-11 15:40
Heaven
Account closed

Registered: Jul 2008
Posts: 102
@bitbreaker

ah thx. I guess I will revisit the fractal core. :D

btw. if you wonder what ST1 and ST2 is. It's what Carpenter calls "node tag values" and those represent the characteristics of the line (e.h. "mountain" or "cloud" etc).

so... say fractline(0,100,4 to 319,100,4) will be different to fractline(0,100,20 to 319,100,4). Even Tag1 4 and Tag2 5 should be different.

http://old.siggraph.org/publications/rarities/carpenter-1980sup..
2018-12-11 15:52
Heaven
Account closed

Registered: Jul 2008
Posts: 102
Quote: All the lsr could be replaced with an asr #$fe and thus carry will stay clear and clc can be dropped, and i see even more potential :-) (sta sy2,x being stored and loaded again just on the next step, a comparision would suffice on the abs function, and that would save a sec)

another idea was exchange x reg with y reg as I moved the height array into ZP... just saw in c64debugger that STA height,y is $00xx....
2018-12-11 16:15
Bitbreaker

Registered: Oct 2002
Posts: 498
If things happen linearly one could also push bytes to stack instead of storing and read them back with lda $0100,y
Interrupts should not matter, as they add bytes at the bottom end. X gets interesting as index then again as tsx fethes the proper position in stack for indexed reads again.
2018-12-11 16:20
Bitbreaker

Registered: Oct 2002
Posts: 498
the cpx #0 can also be omitted, as this point is eitehr reached after ldx, dex, inx that all set the minus-flag anyway, also

                    bne loop_fractal_line
                    beq loop_fractal_line


can be replaced by a jmp
 
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