mirror of
https://github.com/cc65/cc65.git
synced 2024-11-04 17:04:58 +00:00
126 lines
3.5 KiB
ArmAsm
126 lines
3.5 KiB
ArmAsm
;
|
|
; 1998-08-06, Ullrich von Bassewitz
|
|
; 2020-10-09, Greg King
|
|
;
|
|
; void cputcxy (unsigned char x, unsigned char y, char c);
|
|
; void cputc (char c);
|
|
;
|
|
|
|
.export _cputcxy, _cputc, cputdirect, putchar
|
|
.export newline, plot
|
|
.import gotoxy
|
|
.import PLOT
|
|
|
|
.scope KERNAL
|
|
.include "cbm_kernal.inc"
|
|
.endscope
|
|
|
|
.include "vic20.inc"
|
|
|
|
; VIC-20 KERNAL routines (such as PLOT) do not always leave the color RAM
|
|
; pointer CRAM_PTR pointing at the color RAM location matching the screen
|
|
; RAM pointer SCREEN_PTR. Instead they update it when they need it to be
|
|
; correct by calling UPDCRAMPTR.
|
|
;
|
|
; We make things more efficient by having conio always update CRAM_PTR when
|
|
; we move the screen pointer to avoid extra calls to ensure it's updated
|
|
; before doing screen output. (Among other things, We replace the ROM
|
|
; version of PLOT with our own in libsrc/vic20/kplot.s to ensure this
|
|
; precondition.)
|
|
;
|
|
; However, this means that CRAM_PTR may be (and is, after a cold boot)
|
|
; incorrect for us at program startup, causing cputc() not to work. We fix
|
|
; this with a constructor that ensures CRAM_PTR matches SCREEN_PTR.
|
|
;
|
|
UPDCRAMPTR := KERNAL::UPDCRAMPTR ; .constructor doesn't understand namespaces
|
|
.constructor UPDCRAMPTR
|
|
|
|
_cputcxy:
|
|
pha ; Save C
|
|
jsr gotoxy ; Set cursor, drop x and y
|
|
pla ; Restore C
|
|
|
|
; Plot a character -- also used as an internal function
|
|
|
|
_cputc: cmp #$0D ; Is it CBM '\n'?
|
|
beq newline ; Recalculate pointers
|
|
cmp #$0A ; Is it CBM '\r'?
|
|
beq cr
|
|
|
|
; Printable char. of some sort
|
|
; Convert it from PetSCII into a screen-code
|
|
|
|
cmp #$FF ; BASIC token?
|
|
bne convert
|
|
lda #$DE ; Pi symbol
|
|
convert:
|
|
tay
|
|
lsr a ; Divide by 256/8
|
|
lsr a
|
|
lsr a
|
|
lsr a
|
|
lsr a
|
|
tax ; .X = %00000xxx
|
|
tya
|
|
eor pet_to_screen,x
|
|
|
|
cputdirect:
|
|
jsr putchar ; Write the character to the screen
|
|
|
|
; Advance the cursor position
|
|
|
|
advance:
|
|
iny
|
|
cpy #XSIZE
|
|
bne L3
|
|
jsr newline ; Wrap around
|
|
|
|
cr: ldy #$00 ; Do carriage-return
|
|
L3: sty CURS_X
|
|
rts
|
|
|
|
|
|
; Move down by one full screen-line. Note: this routine doesn't scroll.
|
|
;
|
|
; (Both screen RAM and color RAM are aligned to page boundaries.
|
|
; Therefore, the lower bytes of their addresses have the same values.
|
|
; Shorten the code by taking advantage of that fact.)
|
|
|
|
newline:
|
|
clc
|
|
lda #XSIZE
|
|
adc SCREEN_PTR
|
|
sta SCREEN_PTR
|
|
sta CRAM_PTR
|
|
bcc L5
|
|
inc SCREEN_PTR+1
|
|
inc CRAM_PTR+1
|
|
L5: inc CURS_Y
|
|
rts
|
|
|
|
|
|
; Set cursor position, calculate RAM pointers
|
|
|
|
plot: ldy CURS_X
|
|
ldx CURS_Y
|
|
clc
|
|
jmp PLOT ; Set the new cursor
|
|
|
|
|
|
; Write one character to the screen without doing anything else,
|
|
; return the X position in .Y
|
|
|
|
putchar:
|
|
ora RVS ; Set revers bit
|
|
ldy CURS_X
|
|
sta (SCREEN_PTR),y ; Set char.
|
|
lda CHARCOLOR
|
|
sta (CRAM_PTR),y ; Set color
|
|
rts
|
|
|
|
|
|
.rodata
|
|
pet_to_screen:
|
|
.byte %10000000,%00000000,%01000000,%00100000 ; PetSCII -> screen-code
|
|
.byte %01000000,%11000000,%10000000,%10000000
|