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Sync SetCursorRow

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michaelangel007 2016-01-10 23:36:06 -08:00
parent 9150d870df
commit 9eb9451304
1 changed files with 9 additions and 7 deletions
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@ -1135,15 +1135,16 @@ To select which row to draw at we'll pass that in the X register to our DrawChar
; PARAM: Y = column to draw at; $0 .. $27 (Columns 0 .. 39) (not modified)
; PARAM: X = row to draw at; $0 .. $17 (Rows 0 .. 23) (destroyed)
320:48 PHA
321:20 28 03 JSR CursorRow()
321:20 28 03 JSR SetCursorRow
324:68 PLA
325:4C 3B 03 JMP DrawCharCol()
; FUNC: CursorRow( row ) = $0328
; FUNC: SetCursorRow( row )
; PARAM: X = row to draw at; $0 .. $17 (Rows 0 .. 23) (not modified)
; INPUT : $E5,$E6 initial pointer to the destination screen scanline
; Note: Must start at every 8 scanlines.
; OUTPUT: $F5,$F5 working pointer to the destination screen scanline
ORG $0328
328:BD 00 64 LDA $6400,X ; HgrLo[ row ]
32B:18 CLC
32C:65 E5 ADC $E5
@ -1188,15 +1189,16 @@ Unfortunately, our usage of the X and Y registers are not intuitive. This is due
We could map the X-register to the natural column (x-axis), and the Y-register to the natural row (y-axis). Alas, we're stuck with the X=row and Y=col unless we wanted to add extra code to "swap" the two.
```assembly
; FUNC: SetCursorColRowYX() = $0379
; FUNC: SetCursorColRowYX()
; PARAM: Y = col
; PARAM: X = row
379:20 28 03 JSR CursorRow
ORG $0379
379:20 28 03 JSR SetCursorRow
37C:18 CLC
37D:98 TYA
37E:65 F5 ADC $F5
381:85 F5 STA $F5
383:60
383:60 RTS
```
Or are we stuck? Since we're using a function to calculate the destination address let's fix the order.
@ -1224,7 +1226,7 @@ And change the low byte to add `X` instead:
; PARAM: X = col
; PARAM: Y = row
; NOTES: Version 2 !
379:20 28 03 JSR CursorRow
379:20 28 03 JSR SetCursorRow
37C:18 CLC
37D:88 TXA ; changed from: TYA
37E:65 F5 ADC $F5
@ -1232,7 +1234,7 @@ And change the low byte to add `X` instead:
383:60
```
This is a little clunky but it is progress. Let's write the new SetCursorColRow() version with the CursorRow() inlined so we don't have to use a JSR.
This is a little clunky but it is progress. Let's write the new SetCursorColRow() version with the SetCursorRow() inlined so we don't have to use a JSR.
```assembly
; FUNC: SetCursorColRow( col, row )