Apple-2-SW/emailler
1
0
Fork 0
mirror of https://github.com/bobbimanners/emailler.git synced 2025-01-19 00:29:56 +00:00
Code Issues Projects Releases Wiki Activity

Streamlined display character selection.

Browse Source 
The reverse characters of the alternate char set are place in a somewhat strange arrangement in the Apple II character ROM. This is because of backward compatibility with the standard char set. Therefore it seems more efficient and hopefully easier to understand to use a table to select them.
This commit is contained in:
Oliver Schmidt 2017-05-23 23:56:57 +02:00
parent c7b1c77367
commit 7d50e73b5b
1 changed files with 36 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

59
drivers/a2vt100.s
View File

@ -45,8 +45,6 @@ SendStr = telnet_send_string
.include "apple2.inc"
ControlFlags = $1000
; *************************************
; *
; * Zeropage
@ -1038,39 +1036,29 @@ PrnChr sta xVector ; save char
lda xVector ; restore char
; -- $80-$ff -- non-ASCII
bpl PC1
jmp PCend
; -- $20-$7f -- printable
PC1 cmp #$20
bcc PC2
jmp PCrvs
; -- $00-$1f -- control
PC2 jmp PCend ; no output
bmi PCend ; no output
; -- handle reverse mode --
PCrvs ora #$80 ; turn on high bit
ldy INVFLG
cpy #$ff ; normal character display mode?
beq PCput
cmp #$e0 ; lowercase?
bcc PCmask
and #$7f ; inverse lowercase
ldx INVFLG ; reverse mode?
bmi PC1 ; normal:$ff, reverse:$3f
tax
lda rtsc,x ; reverse to ScreenCode
jmp PCput
PCmask and INVFLG ; apply normal, inverse, flash
PC1 ora #$80 ; normal to ScreenCode
PCput ldx lbPending ; need new line?
beq PC6 ; no -> skip
beq PC2 ; no -> skip
ldx #$00 ; clear pending
stx lbPending
jsr NewLn
PC6 tax ; save char
PC2 tax ; save char
lda CH ; get crsr col
lsr ; col DIV 2
tay
txa ; restore char
bcs PC7 ; odd col?
bcs PC3 ; odd col?
bit $c055
PC7 sta (BASL),y ; char to screen
PC3 sta (BASL),y ; char to screen
bit $c054
ldy CH ; get crsr col
@ -1484,10 +1472,35 @@ ExitScr
; *************************************
; *
; * ASCII tables
; * ASCII and ScreenCode tables
; *
; *************************************
; -------------------------------------
; table reverse to ScreenCode
;
; This tabel is used to convert incoming
; reverse chars.
; -------------------------------------
rtsc;_0 _1 _2 _3 _4 _5 _6 _7 _8 _9 _a _b _c _d _e _f
; --- Control chars - should never appear --------------------------
.byt $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00 ; 0_
.byt $00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00,$00 ; 1_
; --- special chars ------------------------------------------------
.byt $20,$21,$22,$23,$24,$25,$26,$27,$28,$29,$2a,$2b,$2c,$2d,$2e,$2f ; 2_
.byt $30,$31,$32,$33,$34,$35,$36,$37,$38,$39,$3a,$3b,$3c,$3d,$3e,$3f ; 3_
; --- capital letters ----------------------------------------------
.byt $00,$01,$02,$03,$04,$05,$06,$07,$07,$09,$0a,$0b,$0c,$0d,$0e,$0f ; 4_
.byt $10,$11,$12,$13,$14,$15,$16,$17,$18,$19,$1a,$1b,$1c,$1d,$1e,$1f ; 5_
; --- lower case letters -------------------------------------------
.byt $60,$61,$62,$63,$64,$65,$66,$67,$68,$69,$6a,$6b,$6c,$6d,$6e,$6f ; 6_
.byt $70,$71,$72,$73,$74,$75,$76,$77,$78,$79,$7a,$7b,$7c,$7d,$7e,$7f ; 7_
; -------------------------------------
; table keyboard to ASCII
;