cc65/libsrc/osic1p/clrscr.s

;
; void clrscr (void);
;
        .export         _clrscr
        .import         plot
        .include        "extzp.inc"
        .include        "osic1p.inc"

; Adapted from the Challenger Character Graphics
; Reference Manual, "2.3.3 MACHINE LANGUAGE SCREEN CLEAR"
; This is self-modifying code!
BANKS = VIDEORAMSIZE / $100

_clrscr:
        lda       #$20          ; ' '
        ldy       #BANKS
        ldx       #$00
staloc:
        sta       SCRNBASE,X
        inx
        bne       staloc
        inc       staloc+2
        dey
        bne       staloc
        lda       #>(SCRNBASE)  ; Load high byte
        sta       staloc+2      ; Restore base address

        lda       #$00          ; Cursor in upper left corner
        sta       CURS_X
        sta       CURS_Y
        jmp       plot          ; Set the cursor position
Implemented clrscr routine for C1P 2014-11-08 01:14:46 +01:00			`;`
			`; void clrscr (void);`
			`;`
			`.export _clrscr`
Set cursor in top left corner in clrscr() as documented in conio.h 2014-11-29 20:50:48 +01:00			`.import plot`
Include "extzp.inc" instead of using direct imports of symbols. 2015-02-12 22:12:51 +01:00			`.include "extzp.inc"`
Rename c1p target to osic1p 2015-02-03 22:42:35 +01:00			`.include "osic1p.inc"`
Implemented clrscr routine for C1P 2014-11-08 01:14:46 +01:00
			`; Adapted from the Challenger Character Graphics`
			`; Reference Manual, "2.3.3 MACHINE LANGUAGE SCREEN CLEAR"`
			`; This is self-modifying code!`
			`BANKS = VIDEORAMSIZE / $100`

Adapt to assembler coding conventions. 2014-11-16 21:57:59 +01:00			`_clrscr:`
Incorporated another round of feedback for pull request. Adjusted comment formatting in several assembler files. Removed dummy kbhit() function, as it's better to get a linker error than an implementation that does the wrong thing. 2015-02-18 18:38:42 +01:00			`lda #$20 ; ' '`
Fix formatting, replace tabs with spaces. 2015-02-08 17:35:40 +01:00			`ldy #BANKS`
			`ldx #$00`
Adapt to assembler coding conventions. 2014-11-16 21:57:59 +01:00			`staloc:`
Fix formatting, replace tabs with spaces. 2015-02-08 17:35:40 +01:00			`sta SCRNBASE,X`
			`inx`
			`bne staloc`
			`inc staloc+2`
			`dey`
			`bne staloc`
Incorporated another round of feedback for pull request. Adjusted comment formatting in several assembler files. Removed dummy kbhit() function, as it's better to get a linker error than an implementation that does the wrong thing. 2015-02-18 18:38:42 +01:00			`lda #>(SCRNBASE) ; Load high byte`
			`sta staloc+2 ; Restore base address`
Set cursor in top left corner in clrscr() as documented in conio.h 2014-11-29 20:50:48 +01:00
Incorporated another round of feedback for pull request. Adjusted comment formatting in several assembler files. Removed dummy kbhit() function, as it's better to get a linker error than an implementation that does the wrong thing. 2015-02-18 18:38:42 +01:00			`lda #$00 ; Cursor in upper left corner`
Set cursor in top left corner in clrscr() as documented in conio.h 2014-11-29 20:50:48 +01:00			`sta CURS_X`
			`sta CURS_Y`
Incorporated another round of feedback for pull request. Adjusted comment formatting in several assembler files. Removed dummy kbhit() function, as it's better to get a linker error than an implementation that does the wrong thing. 2015-02-18 18:38:42 +01:00			`jmp plot ; Set the cursor position`