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71 lines
1.4 KiB
ArmAsm
71 lines
1.4 KiB
ArmAsm
;
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; 2016-02-28, Groepaz
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; 2017-06-26, 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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.import plot, popa
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.include "zeropage.inc"
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.include "c128.inc"
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_cpeekc:
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lda MODE
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bmi @c80
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ldy CURS_X
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lda (SCREEN_PTR),y ; get char
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@return:
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and #<~$80 ; remove reverse flag
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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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@c80:
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lda SCREEN_PTR
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ldy SCREEN_PTR+1
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clc
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adc CURS_X
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bcc @s
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iny
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; get byte from VDC mem
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@s: ldx #VDC_DATA_LO
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stx VDC_INDEX
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@L0: bit VDC_INDEX
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bpl @L0
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sta VDC_DATA
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dex
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stx VDC_INDEX
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sty VDC_DATA
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ldx #VDC_RAM_RW
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stx VDC_INDEX
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@L1: bit VDC_INDEX
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bpl @L1 ; wait for blanking
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lda VDC_DATA
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jmp @return
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