Apple-2-SW/apple2_hgr_font_tutorial
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Cleanup hard-coded 033B

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michaelangel007 2016-01-11 01:11:06 -08:00
parent aaba163470
commit 7ee71cafff
1 changed files with 64 additions and 55 deletions
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119
README.md
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@ -842,22 +842,23 @@ Our prefix code to setup the source address becomes:
; PARAM: A = glyph to draw
; PARAM: Y = column to draw at; $0 .. $27 (Columns 0 .. 39) (not modified)
; NOTES: X is destroyed
ORG $033B
33B:48 PHA ; push c = %PQRSTUVW to draw
33C:29 1F AND #1F ; = %000STUVW R=0, Optimization: implicit CLC
33E:0A ASL ; c * 2 %00STUVW0
33F:0A ASL ; c * 4 %0STUVW00
340:0A ASL ; c * 8 %STUVW000
341:69 00 ADC #00 ; += FontLo; Carry = 0 since R=0 from above
343:8D 55 03 STA $355 ; AddressLo = FontLo + (c*8)
346:68 PLA ; pop c = %PQRSTUVW to draw
347:29 60 AND #60 ; = %PQR00000 S=0, Optimization: implicit CLC
349:2A ROL ; = %QR000000 C=P
34A:2A ROL ; = %R000000P C=Q
34B:2A ROL ; = %000000PQ C=R
34C:2A ROL ; c / 32 = %00000PQR C=0 and one more to get R
34D:69 60 ADC #60 ; += FontHi; Carry = 0 since S=0 from above
34F:8D 56 03 STA $356 ; AddressHi = FontHi + (c/32)
ORG $033B
33B:48 DrawCharCol
33B: PHA ; push c = %PQRSTUVW to draw
33C:29 1F AND #1F ; = %000STUVW R=0, Optimization: implicit CLC
33E:0A ASL ; c * 2 %00STUVW0
33F:0A ASL ; c * 4 %0STUVW00
340:0A ASL ; c * 8 %STUVW000
341:69 00 ADC #00 ; += FontLo; Carry = 0 since R=0 from above
343:8D 55 03 STA $355 ; AddressLo = FontLo + (c*8)
346:68 PLA ; pop c = %PQRSTUVW to draw
347:29 60 AND #60 ; = %PQR00000 S=0, Optimization: implicit CLC
349:2A ROL ; = %QR000000 C=P
34A:2A ROL ; = %R000000P C=Q
34B:2A ROL ; = %000000PQ C=R
34C:2A ROL ; c / 32 = %00000PQR C=0 and one more to get R
34D:69 60 ADC #60 ; += FontHi; Carry = 0 since S=0 from above
34F:8D 56 03 STA $356 ; AddressHi = FontHi + (c/32)
```
Recall we'll re-use our existing font drawing code `_DrawChar` at $0352:
@ -881,7 +882,7 @@ Recall we'll re-use our existing font drawing code `_DrawChar` at $0352:
We just need to touch up our entry point from $0352 ScreenPtrToTempPtr() to $033B DrawCharCol():
```assembly
307:4C 3B 03 JMP $033B ; DrawCharCol()
307:4C 3B 03 JMP DrawCharCol
```
Enter in:
@ -914,34 +915,40 @@ We now have the ability to print any of the 128 ASCII characters!
Let's verify this by writing a character inspector. We'll use the arrow keys to select the glyph and ESC to exit.
```assembly
; FUNC: DemoCharInspect() = $1000
1000:A9 00 LDA #0 ; c=0
1002:85 FE STA $FE ; save which glyph to draw
1004:A9 00 .1 LDA #0 ; screen = 0x2000
1006:85 F5 STA $F5 ;
1008:A9 20 LDA #20 ;
100A:85 F6 STA $F6 ;
100C:A5 FE LDA $FE ; A = glyph c
100E:A0 00 LDY #00 ; Y = col
1010:20 3B 03 JSR $033B ; DrawCharCol()
1013:AD 00 C0 .2 LDA $C000 ; read A=key
1016:10 FB BMI .2 ; no key?
1018:8D 10 C0 STA $C010 ; debounce key
101B:C9 88 CMP #88 ; key == <-- ?
101D:D0 0A BNE .4 ;
101F:C6 FE DEC $FE ; yes, --c
1021:A5 FE .3 LDA $FE ; c &= 0x7F
; FUNC: DemoCharInspect()
KEYBOARD EQU $C000
KEYSTROBE EQU $C010
glyph EQU $FE
ORG $1000
1000: DemoCharInspect
1000:A9 00 LDA #0 ; glyph=0
1002:85 FE STA glyph ; save which glyph to draw
1004:A9 00 .1 LDA #0 ; screen = 0x2000
1006:85 F5 STA HgrLo ;
1008:A9 20 LDA #20 ;
100A:85 F6 STA HgrHi ;
100C:A5 FE LDA glyph ; A = glyph
100E:A0 00 LDY #00 ; Y = col
1010:20 3B 03 JSR DrawCharCol
1013:AD 00 C0 .2 LDA KEYBOARD ; read A=key
1016:10 FB BMI .2 ; no key?
1018:8D 10 C0 STA KEYSTROBE; debounce key
101B:C9 88 CMP #88 ; key == <-- ?
101D:D0 0A BNE .4 ;
101F:C6 FE DEC glyph ; yes, --glyph
1021:A5 FE .3 LDA glyph ; glyph &= 0x7F
1023:29 7F AND #7F
1025:85 FE STA $FE
1027:10 DB BPL .1 ; always branch, draw prev char
1029:C9 95 .4 CMP #95 ; key == --> ?
102B:D0 05 BNE .5 ;
102D:E6 FE INC $FE ; yes, ++c
1025:85 FE STA glyph
1027:10 DB BPL .1 ; always branch, draw prev char
1029:C9 95 .4 CMP #95 ; key == --> ?
102B:D0 05 BNE .5 ;
102D:E6 FE INC glyph ; yes, ++glyph
102F:18 CLC
1030:90 EF BCC .3 ; always branch, draw prev char
1032:C9 9B .5 CMP #9B ; key == ESC ?
1034:D0 DD BNE .2 ;
1036:60 RTS ; yes, exit
1030:90 EF BCC .3 ; always branch, draw prev char
1032:C9 9B .5 CMP #9B ; key == ESC ?
1034:D0 DD BNE .2 ;
1036:60 RTS ; yes, exit
```
Enter in this code:
@ -968,7 +975,7 @@ Let's fix it up to print the hex value of the current character we are inspectin
1010:20 37 10 JSR $1037
1037:48 PHA ; save c
1038:20 3B 03 JSR $033B ; DrawCharCol()
1038:20 3B 03 JSR DrawCharCol
103B:68 PLA ; restore c so we can print it in hex
; FUNC: DrawHexByte( c ) = $103C
@ -989,7 +996,7 @@ Let's fix it up to print the hex value of the current character we are inspectin
104B:20 66 03 JSR HgrToTmpPtr
104E:BD 58 10 LDA NIB2HEX,X ; nibble to ASCII
1051:C8 INY ; IncCursorCol()
1052:20 3B 03 JSR $033B ; DrawCharCol()
1052:20 3B 03 JSR DrawCharCol
1055:60 RTS
ORG $358
1058:30 31 32 33 NIB2HEX ASC "0123456789ABCDEF"
@ -1222,18 +1229,20 @@ Or are we stuck? Since we're using a function to calculate the destination addre
We'll need to change the `X` offset in SetCursorColRowXY() to `Y`;
```assembly
; FUNC: SetCursorColRow2( row ) = $033B
; FUNC: SetCursorColRow2( row ) = $0328
; PARAM: Y = row
; NOTES: Version 2 !
328:B9 00 64 LDA $6400,Y ; changed from: ,X
32B:18 CLC
32C:65 E5 ADC $E5
32E:85 F5 STA $F5
330:B9 18 64 LDA $6418,Y ; changed from: ,X
333:18 CLC
334:65 E6 ADC $E6
336:85 F6 STA $F6
338:60 RTS
328: ORG $0328
328: SetCursorColRow2
328:B9 00 64 LDA $6400,Y ; changed from: ,X
32B:18 CLC
32C:65 E5 ADC $E5
32E:85 F5 STA $F5
330:B9 18 64 LDA $6418,Y ; changed from: ,X
333:18 CLC
334:65 E6 ADC $E6
336:85 F6 STA $F6
338:60 RTS
```
And change the low byte to add `X` instead: