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Merge branch 'davidgiven:master' into master
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@iss000
iss000 authored Jul 17, 2024
2 parents e2916da + 265d801 commit 0661a06
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Showing 2 changed files with 352 additions and 7 deletions.
349 changes: 347 additions & 2 deletions src/arch/commodore/c64.S
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@
#include "zif.inc"
#include "cpm65.inc"
#include "driver.inc"

#include "jumptables.inc"
READST = $ffb7
SETLFS = $ffba
SETNAM = $ffbd
Expand All @@ -29,8 +29,17 @@ SECOND = $ff93
TALKSA = $ff96
CLRCHN = $ffcc
GETIN = $ffe4
CLEAR_SCREEN = $e544
MOVE_CURSOR = $e56c
SHOW_CURSOR = $cc
CURSOR_X = $d3
CURSOR_Y = $d6
STATUS = $90

SCREEN_WIDTH=40
SCREEN_HEIGHT=25
VIDEO = $0400

ZEROPAGE

.global ptr
Expand Down Expand Up @@ -82,7 +91,244 @@ zendproc
.global drvtop
drvtop: .word drv_TTY

defdriver TTY, DRVID_TTY, drvstrat_TTY, 0
defdriver SCREEN, DRVID_SCREEN, drvstrat_SCREEN, 0

; SCREEN driver strategy routine.
; Y=SCREEN opcode.
zproc drvstrat_SCREEN
jmpdispatch screen_jmptable_lo, screen_jmptable_hi

screen_jmptable_lo:
jmptablo screen_version
jmptablo screen_getsize
jmptablo screen_clear
jmptablo screen_setcursor
jmptablo screen_getcursor
jmptablo screen_putchar
jmptablo screen_putstring
jmptablo screen_getchar
jmptablo screen_showcursor
jmptablo screen_scrollup
jmptablo screen_scrolldown
jmptablo screen_cleartoeol
jmptablo screen_setstyle
screen_jmptable_hi:
jmptabhi screen_version
jmptabhi screen_getsize
jmptabhi screen_clear
jmptabhi screen_setcursor
jmptabhi screen_getcursor
jmptabhi screen_putchar
jmptabhi screen_putstring
jmptabhi screen_getchar
jmptabhi screen_showcursor
jmptabhi screen_scrollup
jmptabhi screen_scrolldown
jmptabhi screen_cleartoeol
jmptabhi screen_setstyle
zendproc

zproc screen_version
lda #0
rts
zendproc

zproc screen_getsize
; Hardcode screen size for now
lda #SCREEN_WIDTH-1
ldx #SCREEN_HEIGHT-1
rts
zendproc

zproc screen_clear
jsr CLEAR_SCREEN
rts
zendproc

zproc screen_setcursor
sta CURSOR_X
stx CURSOR_Y
jsr MOVE_CURSOR
rts
zendproc

zproc screen_getcursor
lda CURSOR_X
ldx CURSOR_Y
rts
zendproc

zproc screen_putchar
pha
lda CURSOR_Y
ldy CURSOR_X
jsr calculate_line_address
pla
jsr convert_ascii_to_screencode
sta (ptr),y
cpy #SCREEN_WIDTH-1
zif_cc
iny
zendif
sty CURSOR_X
jsr MOVE_CURSOR
clc
rts
zendproc

zproc screen_putstring
sta ptr1+0
stx ptr1+1
lda CURSOR_Y
jsr calculate_line_address
; Add cursor x-position to pointer
lda CURSOR_X
clc
adc ptr+0
sta ptr+0
zif_cs
inc ptr+1
zendif

ldy #0
zrepeat
lda (ptr1),y
zbreakif_eq
jsr convert_ascii_to_screencode
ldx CURSOR_X
cpx #SCREEN_WIDTH
; Do not linewrap
zif_cc
sta (ptr),y
inc CURSOR_X
zendif
iny
zuntil_eq
; Restore cursor to last character on line if needed
ldx CURSOR_X
cpx #SCREEN_WIDTH-1
zif_cs
dec CURSOR_X
zendif
jsr MOVE_CURSOR

clc
rts
zendproc

zproc screen_getchar
; Ignore timeout for now, just do a non-blocking read
jsr GETIN
zif_eq
sec
rts
zendif
clc
rts
zendproc

zproc screen_scrollup
ldx #0
zrepeat
txa
jsr calculate_line_address
lda ptr+0
sta ptr1+0
lda ptr+1
sta ptr1+1 ; ptr1 is dest pointer

inx
txa
jsr calculate_line_address ; ptr is source pointer

ldy #SCREEN_WIDTH-1
zrepeat
lda (ptr), y
sta (ptr1), y
dey
zuntil_mi

cpx #SCREEN_HEIGHT-1
zuntil_eq

ldy #SCREEN_WIDTH-1
lda #' '
zrepeat
sta (ptr), y
dey
zuntil_mi
rts
zendproc

zproc screen_scrolldown
ldx #SCREEN_HEIGHT-1 ; current line
zrepeat
txa
jsr calculate_line_address
lda ptr+0
sta ptr1+0
lda ptr+1
sta ptr1+1 ; ptr1 is dest pointer

dex
txa
jsr calculate_line_address ; ptr is source pointer

ldy #SCREEN_WIDTH-1
zrepeat
lda (ptr), y
sta (ptr1), y
dey
zuntil_mi

cpx #0
zuntil_eq

ldy #SCREEN_WIDTH-1
lda #' '
zrepeat
sta (ptr), y
dey
zuntil_mi
rts
zendproc

zproc screen_cleartoeol
lda CURSOR_Y
ldy CURSOR_X
jsr calculate_line_address
lda #' '
zrepeat
sta (ptr), y
iny
cpy #SCREEN_WIDTH
zuntil_eq
rts
zendproc

zproc screen_setstyle
rts
zendproc

zproc screen_showcursor
zif_eq
lda #01
sta SHOW_CURSOR
clc
rts
zendif
lda #00
sta SHOW_CURSOR
clc
rts
zendproc

defdriver TTY, DRVID_TTY, drvstrat_TTY, drv_SCREEN

; TTY driver strategy routine.
; Y=TTY opcode.
Expand Down Expand Up @@ -634,6 +880,105 @@ zproc init_system
rts
zendproc

; Sets ptr to the address of screen line A
zproc calculate_line_address
; x*40 = x*8 + x*32.
; We have 25 lines. As 25*8 will fit in a byte, we can do this easily.

asl a ; a = y*2
asl a ; a = y*4
asl a ; a = y*8
sta ptr+0 ; store y*8

; Anything more than this needs to be 16-bit arithmetic.

asl a ; = y*16
rol ptr+1

asl a ; = y*32
rol ptr+1

; Add.

clc
adc ptr+0
sta ptr+0
zif_cs
inc ptr+1
zendif
; On in screen address (0x400)
lda ptr+1
and #0b00000011
ora #>VIDEO
sta ptr+1

rts
zendproc

; Preserves X and Y.
zproc convert_ascii_to_screencode
; Flip case.

cmp #'A'
zif_cs
cmp #'Z'+1
bcc swapcase
zendif

cmp #'a'
zif_cs
cmp #'z'+1
zif_cc
swapcase:
eor #0x20
zendif
zendif

; This is from https://codebase64.org/doku.php?id=base:petscii_to_screencode&s[]=screencodes

cmp #0x20 ; if A<32 then...
bcc ddRev

cmp #0x60 ; if A<96 then...
bcc dd1

cmp #0x80 ; if A<128 then...
bcc dd2

cmp #0xa0 ; if A<160 then...
bcc dd3

cmp #0xc0 ; if A<192 then...
bcc dd4
cmp #0xff ; if A<255 then...
bcc ddRev

lda #0x7e ; A=255, then A=126
bne ddEnd

dd2:
and #0x5f ; if A=96..127 then strip bits 5 and 7
bne ddEnd
dd3:
ora #0x40 ; if A=128..159, then set bit 6
bne ddEnd
dd4:
eor #0xc0 ; if A=160..191 then flip bits 6 and 7
bne ddEnd
dd1:
and #0x3f ; if A=32..95 then strip bits 6 and 7
bpl ddEnd ; <- you could also do .byte 0x0c here
ddRev:
eor #0x80 ; flip bit 7 (reverse on when off and vice versa)
ddEnd:

rts
zendproc


loading_msg:
.byte 147, 14, 5
.ascii "cp/m-65 FOR THE cOMMODORE 64"
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