[Coco] Proposed change on coVDG (level1)

[Luis Antoniosi (CoCoDemus)]

hey,

One thing that drives me crazy on level1 is the velocity, or lack of, to
output on screen.
I've checked the CoVDG Write and I found a bit awkward code.
If you examine it you will see it priorizes the wrong stuff, first comes
graphic blocks, then several characters
replacements and at the very end of the compare chains you get the text.

I propose this one instead, very short and text oriented. it seems to work
good. the commented code is the old one. I do a direct
mapping of the characters except by '`' that becomes reverse apostrophe
(good for spotting the differnce).

Other good change is that this mapping is automatically applied:

| = up arrow
^ = reverse up arrow
{ = reverse [
| = reverse \
} = reverse ]
~ = reverse left arrow
_ = left arrow

What do you think ? Any reason for that old code ?

Write
* new code
cmpa #$1F
bls Dispatch
ldb <V.CFlag,u
cmpa #$40 numbers ?
bcc L0001
adda #$40
bra L00D0
L0001 cmpa #$60 lowercase ?
beq L0003 '`'
ble L00D0 uppercase
L0002 tsta
bmi L00D0 graphic blocks
suba #$60
bra L00D0 lowercase
L0003 lda #$27
bra L00D0

* old code
*  tsta
*         bmi   L00D0
*  cmpa  #$1F byte $1F?
*         bls   Dispatch branch if lower or same
*         ldb   <V.CFlag,u
*  beq   L00B0
*         cmpa  #$5E '^' ?
*         bne   L00A0
*         lda   #$00
*         bra   L00D0
*L00A0    cmpa  #$5F '_' ?
*         bne   L00A8
*         lda   #$1F
*         bra   L00D0
*L00A8    cmpa  #$60 '`' ?
*         bne   L00C0
*         lda   #$67
*         bra   L00D0
*L00B0    cmpa  #$7C '|' ?
*         bne   L00B8
*         lda   #$21
*         bra   L00D0
*L00B8    cmpa  #$7E '~' ?
*         bne   L00C0
*         lda   #$2D
*         bra   L00D0
*L00C0    cmpa  #$60 lowercase ?
*         bcs   L00C8
*         suba  #$60
*         bra   L00D0
*L00C8    cmpa  #$40 uppercase ?
*         bcs   L00CE
*         suba  #$40
*L00CE    eora  #$40

L00D0    ldx   <V.CrsrA,u get cursor address in X
         sta   ,x+ store character at address
         stx   <V.CrsrA,u update cursor address
         cmpx  <V.ScrnE,u end of screen?
         bcs   L00DF branch if not
         bsr   SScrl else if at end of screen, scroll it
L00DF    bsr   ShowCrsr ends with a CLRB/RTS anyhow