4cade/src/ui.font.lc2.a
2020-04-05 19:05:37 -04:00

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;license:MIT
;(c) 2018-2020 by 4am
;
; hi-res font drawing routines
;
; /!\ These live in LC RAM 2 and rely on the font data which is also in LC RAM 2. /!\
; Code in LC RAM 1 (which is most program code) should call the functions in ui.font
; which handle bank switching for you.
;
DrawPageInternal
; A/Y contains address of character buffer
; X contains 0-indexed left margin (HTAB)
; carry bit clear -> draw on page 1
; carry bit set -> draw on page 2
; drawing starts at VTAB 0
; each line starts at column X which was passed in (0-indexed)
; clobbers PTR
; clobbers A/X/Y
; preserves all flags, by a quirk of implementation
php
stx @leftMargin
ldx #0
stx VTAB
+ST16 PTR
@drawLine
@leftMargin=*+1
lda #$FD ; SMC
sta HTAB
ldy #0
@parseLine
lda (PTR),y
cmp #$5B ; '[' at beginning on line
bne + ; ends the parsing
tya
beq @donePage
+ cmp #$0A
beq @doneParsingLine
ldx #5
- cmp @subs_a,x
bne @nosub
lda @subs_b,x
sta (PTR),y
@nosub
dex
bpl -
iny
bne @parseLine
@doneParsingLine
sty SAVE
tya
beq @skip
ldx SAVE
+LD16 PTR
plp
php
jsr DrawBufferInternal
@skip inc SAVE ; skip carriage return
lda SAVE ; advance PTR to start of next line
clc
adc PTR
sta PTR
bcc +
inc PTR+1
+ inc VTAB ; this will print 255 lines if you give it
bne @drawLine ; 255 lines, so don't do that
@donePage
plp
rts
@subs_a
!byte $2A,$7E,$3C,$3E,$24,$25
@subs_b
!byte $10,$11,$08,$15,$0E,$0F
Draw40CharsInternal
; A/Y contains address of character buffer
; carry bit clear -> draw on page 1
; carry bit set -> draw on page 2
; $25 contains textpage line (0..23) (this is the standard VTAB address)
; drawing starts at HTAB 0
; increments VTAB
; sets HTAB to 0 on exit
; clobbers A/X/Y
jsr +
ldx #40
jsr DrawBufferInternal
inc VTAB
+ ldx #0
stx HTAB
rts
DrawCenteredStringInternal
; A/Y contains address of length-prefixed string
; carry bit clear -> draw on page 1
; carry bit set -> draw on page 2
; $25 contains textpage line (0..23) (this is the standard VTAB address)
; clobbers A/X/Y
; clobbers PTR/PTR+1
+ST16 PTR
ldy #0
php
lda #40
sec
sbc (PTR),y
lsr
sta HTAB
plp
beq +
DrawStringInternal
; A/Y contains address of length-prefixed string
; carry bit clear -> draw on page 1
; carry bit set -> draw on page 2
; $24 contains starting column (0..39) (this is the standard HTAB address)
; $25 contains textpage line (0..23) (this is the standard VTAB address)
; clobbers A/X/Y
; clobbers PTR/PTR+1
+ST16 PTR
ldy #0
+ lda (PTR),y
tax
inc PTR
bne +
inc PTR+1
+
+LD16 PTR
; /!\ execution falls through here to DrawBufferInternal
DrawBufferInternal
; A/Y contains address of character buffer
; X contains buffer length (1..40)
; carry bit clear -> draw on page 1
; carry bit set -> draw on page 2
; characters MUST have high bit off (0x00..0x7F)
; special characters (0x00..0x1F) will be drawn
; $24 contains starting column (0..39) (this is the standard HTAB address)
; $25 contains textpage line (0..23) (this is the standard VTAB address)
; all characters are drawn on the same line
; HTAB is incremented for each character
; VTAB is NOT incremented
; clobbers A/X/Y
+ST16 DBISrc+1
php
dex
lda VTAB
asl
asl
asl
; routine to calculate memory address within HGR page
; and self-modify addresses within draw loop that follows
; (routine clobbers A and Y but preserves X)
asl
tay
and #$F0
bpl @calc1
ora #$05
@calc1 bcc @calc2
ora #$0A
@calc2 asl
asl
sta @hgrlo+1
tya
and #$0E
adc #$10
asl @hgrlo+1
rol
plp
bcc +
eor #$60
clc
+
sta DBIRow0+2
adc #$04
sta DBIRow1+2
adc #$04
sta DBIRow2+2
adc #$04
sta DBIRow3+2
adc #$04
sta DBIRow4+2
adc #$04
sta DBIRow5+2
adc #$04
sta DBIRow6+2
adc #$04
sta DBIRow7+2
@hgrlo lda #$FD
clc
adc HTAB
sta DBIRow0+1
sta DBIRow1+1
sta DBIRow2+1
sta DBIRow3+1
sta DBIRow4+1
sta DBIRow5+1
sta DBIRow6+1
sta DBIRow7+1
DBILoop
DBISrc ldy $FDFD,x
lda FontDataRow0,y
DBIRow0 sta $FDFD,x
lda FontDataRow1,y
DBIRow1 sta $FDFD,x
lda FontDataRow2,y
DBIRow2 sta $FDFD,x
lda FontDataRow3,y
DBIRow3 sta $FDFD,x
lda FontDataRow4,y
DBIRow4 sta $FDFD,x
lda FontDataRow5,y
DBIRow5 sta $FDFD,x
lda FontDataRow6,y
DBIRow6 sta $FDFD,x
lda FontDataRow7,y
DBIRow7 sta $FDFD,x
inc HTAB
dex
bpl DBILoop
rts