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54 lines
1.2 KiB
ArmAsm
54 lines
1.2 KiB
ArmAsm
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; 2016-02-28, Groepaz
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; 2017-06-22, Greg King
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;
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; char cpeekc (void);
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;
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.export _cpeekc
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; Get a system-specific file.
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; Note: The cbm610, and c128 targets need special
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; versions that handle RAM banking and the 80-column VDC.
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.if .def(__C16__)
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.include "plus4.inc" ; both C16 and Plus4
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.elseif .def(__C64__)
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.include "c64.inc"
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.elseif .def(__CBM510__)
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.import CURS_X: zp, SCREEN_PTR: zp
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.include "cbm510.inc"
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.elseif .def(__PET__)
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.include "pet.inc"
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.elseif .def(__VIC20__)
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.include "vic20.inc"
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.endif
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_cpeekc:
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ldy CURS_X
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lda (SCREEN_PTR),y ; get screen code
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ldx #>$0000
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and #<~$80 ; remove reverse bit
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; Convert the screen code into a PetSCII code.
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; $00 - $1F: +$40
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; $20 - $3F
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; $40 - $5f: +$20
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; $60 - $7F: +$40
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cmp #$20
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bcs @sk1 ;(bge)
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ora #$40
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rts
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@sk1: cmp #$40
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bcc @end ;(blt)
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cmp #$60
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bcc @sk2 ;(blt)
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;sec
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adc #$20 - $01
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@sk2: ;clc ; both above cmp and adc clear carry flag
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adc #$20
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@end: rts
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