Apple-2-SW/apple2_hgr_font_tutorial
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Fix EQU alignment

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Michaelangel007 2016-01-27 15:57:04 -08:00
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@ -1,6 +1,6 @@
#Apple ]\[ //e HGR Font 6502 Assembly Language Tutorial #Apple ]\[ //e HGR Font 6502 Assembly Language Tutorial
Revision: 56, Jan 27, 2016. Revision: 57, Jan 27, 2016.
# Table of Contents # Table of Contents
@ -696,12 +696,12 @@ How did I know to use $0400 when going to the next line? One quirk of the HGR s
Before we can start a simple `DrawChar(char c)` function, we also first need to assign some zero page memory locations for our static and temporary variables, our 16-bit address of where want to draw to. Since we also have our font data, we need a symbol for that too. Before we can start a simple `DrawChar(char c)` function, we also first need to assign some zero page memory locations for our static and temporary variables, our 16-bit address of where want to draw to. Since we also have our font data, we need a symbol for that too.
```assembly ```assembly
HgrLo EQU $E5 ; Low byte Pointer to screen destination HgrLo EQU $E5 ; Low byte Pointer to screen destination
HgrHi EQU $E6 ; High byte Pointer to screen destination HgrHi EQU $E6 ; High byte Pointer to screen destination
TmpLo EQU $F5 ; Low byte Working pointer to screen byte TmpLo EQU $F5 ; Low byte Working pointer to screen byte
TmpHi EQU $F6 ; High byte Working pointer to screen byte TmpHi EQU $F6 ; High byte Working pointer to screen byte
Font EQU $6000 Font EQU $6000
``` ```
Here's the disassembly of our (hard-coded) DrawChar() program: Here's the disassembly of our (hard-coded) DrawChar() program:
@ -1008,7 +1008,7 @@ Wait, you say! There IS a way to solve this problem -- and it doesn't take later
Listing 4a: Listing 4a:
```assembly ```assembly
TopHi EQU $FD TopHi EQU $FD
ORG $034C ORG $034C
034C: _DrawChar1 034C: _DrawChar1
@ -1960,22 +1960,22 @@ Now that we have the basic print char working lets extend it to print a C-style
Listing 12: Listing 12:
```assembly ```assembly
String EQU $F0 String EQU $F0
; FUNC: DrawString( *text ) ; FUNC: DrawString( *text )
; PARAM: X = High byte of string address ; PARAM: X = High byte of string address
; PARAM: Y = Low byte of string address ; PARAM: Y = Low byte of string address
037E: ORG $037E 037E: ORG $037E
037E: DrawString 037E: DrawString
037E:84 F0 STY String+0 037E:84 F0 STY String+0
0380:86 F1 STX String+1 0380:86 F1 STX String+1
0382:A0 00 LDY #0 0382:A0 00 LDY #0
0384:B1 F0 .1 LDA (String),Y 0384:B1 F0 .1 LDA (String),Y
0386:F0 07 BEQ .2 ; null byte? Done 0386:F0 07 BEQ .2 ; null byte? Done
0388:20 10 03 JSR DrawChar ; or DrawCharCol for speed 0388:20 10 03 JSR DrawChar ; or DrawCharCol for speed
038B:C0 28 CPY #40 ; col < 40? 038B:C0 28 CPY #40 ; col < 40?
038D:90 F5 BCC .1 038D:90 F5 BCC .1
038F:60 .2 RTS 038F:60 .2 RTS
``` ```
<hr> <hr>
**AppleWin**: **AppleWin**:
@ -2123,9 +2123,9 @@ And here is the assembly:
; DATA: ; DATA:
; $6000.$63FF Font 7x8 Data ; $6000.$63FF Font 7x8 Data
; $6400.$642F HgrLoY, HgrHiY table for every 8 scanlines ; $6400.$642F HgrLoY, HgrHiY table for every 8 scanlines
1300: Txt EQU $F7 1300: Txt EQU $F7
ORG $1300 ORG $1300
1300: CopyTextToHgr 1300: CopyTextToHgr
1300:A9 00 LDA #0 1300:A9 00 LDA #0
1302:85 F3 STA row 1302:85 F3 STA row
1304:85 E5 STA $E5 1304:85 E5 STA $E5
@ -2656,9 +2656,9 @@ However each HGR "text" line takes 8 scanlines (since our font cell is 7x8).
We could code this up as: We could code this up as:
```assembly ```assembly
Src EQU $F8 Src EQU $F8
Dst EQU $FA Dst EQU $FA
Tmp EQU $FC Tmp EQU $FC
; NOTE: Requires $E6 to be initialized with $20 or $40 for graphics page ; NOTE: Requires $E6 to be initialized with $20 or $40 for graphics page