Apple-2-SW/apple2_hgr_font_tutorial
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Fix spelling and bad end assembly tag

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michaelangel007 2016-01-13 21:40:24 -08:00
parent 0c754dded2
commit 60588911f3
1 changed files with 4 additions and 3 deletions
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@ -1290,7 +1290,7 @@ That might look like something like this:
STA _LoadFont+2
```
Hmm, that seems like an **aweul lot of work** just for some `bit-shuffling`!! For one thing we're doing a shift and `stuvw` is not taking advantage of it. Can we not we make use of the fact that we will eventually be doing `AND #1F` and `AND #E0` ?
Hmm, that seems like an **awful lot of work** just for some `bit-shuffling`!! For one thing we're doing a shift and `stuvw` is not taking advantage of it. Can we not we make use of the fact that we will eventually be doing `AND #1F` and `AND #E0` ?
The **lateral** thinking is to _use partial results_.
@ -1328,7 +1328,8 @@ Let's code this up:
0346:2A ROL ; C=s A=%00000PQR and 1 last ROL to get R
0347:69 60 ADC #>Font ; += FontHi; Carry=0 since s=0 from above
0349:8D 54 03 STA _LoadFont+2; AddressHi = FontHi + (c/32)
``` ; intentional fall into _DrawChar1 @ $034C
; intentional fall into _DrawChar1 @ $034C
```
Since we'll re-use our existing font drawing code `_DrawChar1` at $034C it is always a good idea to document why there is no `RTS` at the end.
@ -1336,7 +1337,7 @@ Here is a comparison between the original and final version:
Original Final
Bytes 23 18
Cycles ? ?
Cycles ? TODO ? TODO
Much better!!!