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108 lines
2.4 KiB
ArmAsm
108 lines
2.4 KiB
ArmAsm
;
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; Christian Groessler, June 2004
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;
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; this file provides an equivalent to the BASIC GRAPHICS function
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;
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; int __fastcall__ _graphics(unsigned char mode);
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;
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;
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.export __graphics
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.import findfreeiocb
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.import __do_oserror,__oserror
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.import fddecusage
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.import clriocb
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.import fdtoiocb
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.import newfd
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.importzp tmp1,tmp2,tmp3
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.include "atari.inc"
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.include "errno.inc"
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.code
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; set new grapics mode
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; gets new mode in A
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; returns handle or -1 on error
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; uses tmp1, tmp2, tmp3, tmp4 (in subroutines)
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.proc __graphics
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; tax
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; and #15 ; get required graphics mode
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; cmp #12
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; bcs invmode ; invalid mode
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; txa
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; and #$c0 ; invalid bits set?
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; bne invmode
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; stx tmp1
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sta tmp1 ; remember graphics mode
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parmok: jsr findfreeiocb
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beq iocbok ; we found one
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lda #<EMFILE ; "too many open files"
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seterr: jsr __mappederrno ; @@@ probably not correct to set errno here @@@
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rts ; return -1
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;invmode:ldx #>EINVAL
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; lda #<EINVAL
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; bne seterr
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iocbok: txa
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tay ; move iocb # into Y
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lda #3
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sta tmp3 ; name length + 1
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lda #<scrdev
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ldx #>scrdev
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jsr newfd
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tya
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tax
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bcs doopen ; C set: open needed
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ldx #0
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lda tmp2 ; get fd used
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jsr fdtoiocb
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tax
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doopen: txa
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;brk
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pha
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jsr clriocb
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pla
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tax
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lda #<scrdev
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sta ICBAL,x
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lda #>scrdev
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sta ICBAH,x
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lda #OPEN
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sta ICCOM,x
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lda tmp1 ; get requested graphics mode
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and #15
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sta ICAX2,x
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lda tmp1
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and #$30
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eor #$10
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ora #12
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sta ICAX1,x
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jsr CIOV
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bmi cioerr
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lda tmp2 ; get fd
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ldx #0
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stx __oserror
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rts
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cioerr: jsr fddecusage ; decrement usage counter of fd as open failed
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jmp __do_oserror
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.endproc ; __graphics
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.rodata
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scrdev: .byte "S:", 0
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