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+====== Using a Timer as an Inverted Raster X-Pos Register ======
+Hi, I'm Hermit Soft. On CSDB I've shared my strongly optimized (shortened) CIA-timer using stable raster method.
+Now it's here to fill the gap in Codebase64. I hope it will be useful in "everyday's demo coding" . :)
+A short pre-description:  The first cmp$d012, bne*-3 waits till the raster-row given in the Accu. The occurence of this testing jitters in 1...7 cycles to the real starting (cycle 1) time of the rasterline, because these two commands take 4+3 cycles, and so delays detection.
+A raster row is 63 cycles long, and CPU can use all these cycles to do operations if no SPRITE or BADLINE fetches the actual raster-row.
+Also important to prevent memory page-boundaries because some commands take 1 more cycle when crossing them. Use program-start address and scan-part addresses of 256 multiplies to be clear.
+We do a second rasterrow-test (cmp $d012) after exactly 56 cycles. This 56 cycles builds up from the carefully programmed part between the first "bne" and the second "cmp $d012". If the raster-row changed, jitter made too much delay and new row started.
+In this case we jump back with second "bne" to the syncronization (first cmp$d012) and repeat this until we catch a case when the jitter doesn't make delay, and we can set our timer to it.
+The timer (re)starts with sta$dc0e,y which is the most strictly timed, to show 7...1 on $dc04 when using the d012 scan (B-part). It counts 9 steps like 8,8,7,6,5,4,3,2,1....and again and again. It runs in cycle-syncron with the raster-beam.
+===== Setting the CIA1-timerA to beam in the program beginning =====
+Accumulator can be any value, no need to set.
+<code>
+         sei           ;we don't want lost cycles by IRQ calls :)
+ sync:
+         cmp $d012     ;scan for begin rasterline (A=$11 after first return)
+         bne *-3       ;wait if not reached rasterline #$11 yet
+         ldy #8        ;the walue for cia timer fetch & for y-delay loop         2 cycles
+         sty $dc04     ;CIA Timer will count from 8,8 down to 7,6,5,4,3,2,1      4 cycles
+         dey           ;Y=Y-1 (8 iterations: 7,6,5,4,3,2,1,0)                    2 cycles*8
+         bne *-1       ;loop needed to complete the poll-delay with 39 cycles    3 cycles*7+2 cycles*1
+         sty $dc05     ;no need Hi-byte for timer at all (or it will mess up)    4 cycles
+         sta $dc0e,y   ;forced restart of the timer to value 8 (set in dc04)     5 cycles
+         lda #$11      ;value for d012 scan and for timerstart in dc0e           2 cycles
+         cmp $d012     ;check if line ended (new line) or not (same line)
+         sty $d015     ;switch off sprites, they eat cycles when fetched
+         bne sync      ;if line changed after 63 cycles, resyncronize it!
+             ....      ;the rest (this is also a stable-timed point, can be used for sg.)
+</code>
+===== Example 1: Stabilizing 7 cycle jitter when using cmp $d012 =====
+<code>
+scan:
+         ldx #$31    ;a good value that's not badline, in border and 1=white
+         cpx $d012   ;scan rasterline
+         bne *-3     ;wait until rasterline will be $31
+         lda $dc04   ;check timer A, here it jitters between 7...1
+         eor #7      ;A=7-A so jitter will be 0...6 in A
+         sta *+4     ;self-writing code, the bpl jump-address = A
+         bpl *+2     ;the jump to timer (A) dependent byte
+         cmp #$c9    ;if A=0, cmp#$c9; if A=1, cmp #$c9 again 2 cycles later
+         cmp #$c9    ;if A=2, cmp#$c9, if A=3, CMP #$EA 2 cycles later
+         bit $ea24   ;if A=4,bit$ea24; if A=5, bit $ea, if A=6, only NOP
+          ...........  anything you like, let's see a short example
+         stx $d020   ;x was 1 so border is white at the stable cycle
+         sty $d020   ;y ended in 0 in sync routine, so border black after 4 cycles
+          ...........     ;pay attention on delay before rescan rasterline, to avoid cmp$D012 again on this same rasterline in the middle.
+                           If the scan happens again in the same line, that may crash the program, because DC04 won't be usable for jumptable.
+                           (For this stx $d020, sty$d020 this is specially not problem because of the lucky timing. They're for try the routine.)
+         jmp scan    ;go to the raster again (or can go new raster)
+</code>
+===== Example 2: stabilizing a raster IRQ =====
+The first part (CIA setter) is also good for raster IRQ. The important thing is to do the "pha" (3 cycles) before "lda $dc04" in the called irq.
+<code>
+irq:
+         pha
+         lda $dc04
+         eor #7
+         sta *+4
+         bpl *+2
+         lda #$a9
+         lda #$a9
+         lda $eaa5
+         txa
+         pha
+         tya
+         pha
+         ; the rest processes in the IRQ routine
+         asl $d019
+         pla
+         tay
+         pla
+         tax
+         pla
+         rti
+</code>
+That's for now, test it, use it, or whatever you want...
+Or you can ask questions on csdb forum for this topic:
+http://noname.c64.org/csdb/forums/?roomid=11&topicid=65658