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Index > DOS > How to set display start via VESA BIOS function 0x4F07

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CandyMan



Joined: 04 Sep 2009
Posts: 301
Location: film "CandyMan" directed through Bernard Rose OR Candy Shop
CandyMan
Code:
SetDisplayStart1:
        MOV     ECX,[X]
        MOV     EDX,[Y]
        MOV     EAX,$4F07
        XOR     EBX,EBX
        INT     $10
        RET

SetDisplayStart2:
        MOV     ECX,[X]
        MOV     EDX,[Y]

        MOV     EAX,$4F07
        XOR     EBX,EBX

        IMUL    EDX,[BytesPerLine]
        IMUL    ECX,[BytesPerPixel]
        ADD     EDX,ECX
        SHR     EDX,2
        
        MOVZX   ECX,DX
        SHR     EDX,16
        
        CALL    [PtrSetDispStart] ;PM32 function 0x4F07
        RET
    

The first procedure works in all modes. However, the second procedure does not work in 8-bit mode (blinking). Should something be improved?
Post 20 Aug 2019, 19:44
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bitRAKE



Joined: 21 Jul 2003
Posts: 2796
Location: dank orb
bitRAKE
I'm sorry, don't understand this calculation:
Code:
        IMUL    EDX,BytesPerLine
        IMUL    ECX,BytesPerPixel
        ADD     EDX,ECX
        SHR     EDX,2    

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Post 20 Aug 2019, 21:51
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