Apple-2-SW/apple2_hgr_font_tutorial
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Added bsave commands, changed scroll up demo address

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michaelangel007 2016-01-10 18:39:47 -08:00
parent 51c260dc09
commit f90dd02144
1 changed files with 28 additions and 10 deletions
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@ -505,6 +505,9 @@ Enter in (or download [Raw Binary Font](font.bin) and with AppleWin press `F7`,
63F0:2C 1A 00 00 00 00 00 00 ; ~
63F8:00 2A 14 2A 14 2A 00 00 ;
(To save this: `BSAVE FONT.BIN,A$6000,L$400`)
### Image to Font Data (Javascript)
If you were wondering how this data was generated, you see the great thing about computers is that they can automate all the tedious and boring crap, er, calculations for us. Here's a HTML + Javascript program I wrote to convert the [image to HEX](image_2_hex.html):
@ -1327,6 +1330,8 @@ Here are all the routines we've entered in so far:
390:86 F1 A0 00 B1 F0 F0 07
398:20 10 03 C0 28 90 F5 60
(To save this: `BSAVE CODE_0300.BIN,A$300,L$A0`)
We also have a mini HGR Y address lookup table:
6400:00 80 00 80 00 80 00 80
@ -1336,6 +1341,8 @@ We also have a mini HGR Y address lookup table:
6420:00 00 01 01 02 02 03 03
6428:00 00 01 01 02 02 03 03
(To save this: `BSAVE HGR_TABLE.BIN,A$6400,L$30`)
What's left? Quite a few things actually:
* Copy the 40-Column text screen to HGR
@ -1552,7 +1559,7 @@ Hey! Homework? Yes, the only (true) way to demonstrate you understand the theo
Hope this HGR font tutorial helped you understand the inner workings of a font blitter!
Happy (Apple ][ //e //c) Hacking!
Happy (Apple ]\[ //e //c) Hacking!
Michael "AppleWin Debug Dev"
@ -1569,7 +1576,7 @@ There are many different ways to solve this depending if we want to prioritize s
We could manually unroll every loop such as this monstrosity (we trade space for speed):
Enter this:
Enter this (or download [hgr_scroll_up.bin](hgr_scroll_up.bin) or `BRUN HGR_SCROLL_UP`):
1400:A2 27
1402:BD 00 24 9D 00 20
@ -1767,25 +1774,36 @@ Enter this:
1881:CA 30 03 4C 02 14
1887:60
And let's write a little demo ...
```assembly
1380:A0 C0 LDY #C0
1382:20 00 14 .1 JSR ScrollHgrUpPixel
1385:88 DEY
1386:D0 FA BNE .1
1388:60 RTS
13F7:A0 C0 LDY #C0
13F9:20 00 14 .1 JSR ScrollHgrUpPixel
13FC:88 DEY
13FD:D0 FA BNE .1
13FF:60 RTS
```
Enter in:
1380:A0 C0 20 00 14 88 D0 FA 60
13F7:A0 C0 20 00 14 88 D0 FA 60
(To save to disk type `BSAVE HGR_SCROLL_UP.BIN,A$13F7,L$490`)
And let's try it out:
1300L
1300G
1380G
1400G
1400G
1400G
![Screenshot 21](pics/hgrfont_21.png?raw=true)
And for the finale:
13F7G
Sweet !