28 lines
768 B
ArmAsm
28 lines
768 B
ArmAsm
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; 2020-07-14, Groepaz
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;
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; unsigned char cpeekrevers (void);
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;
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; get inverse flag from current position, do NOT advance cursor
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.export _cpeekrevers
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.include "pce.inc"
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.include "extzp.inc"
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_cpeekrevers:
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st0 #VDC_MARR ; Memory-Address Read
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ldy SCREEN_PTR
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ldx SCREEN_PTR+1
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sty a:VDC_DATA_LO
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stx a:VDC_DATA_HI
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st0 #VDC_VRR ; VRAM Read Register
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lda a:VDC_DATA_LO ; character (bit 7 is revers bit)
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and #$80 ; get reverse bit
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asl a ; reverse bit to carry, A=0
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tax ; ldx #>$0000
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rol a ; reverse bit from carry
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rts
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