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54 lines
1.4 KiB
54 lines
1.4 KiB
externFP GetSelectorBase ; in KERNEL
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sBegin Data
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externD flatBase
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externW flatSel
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sEnd
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;--------------------------------------------------------------------------;
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;
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; MapFlat - convert a 16:16 pointer into a 0:32 pointer
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;
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; note this macro assumes the memory will *not* move
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; while being accessed. If this is not true call GlobalFix
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; on the memory
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;
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; INPUT:
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; ptr16 16:16 pointer to map flat.
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; ptr32 put flat pointer here.
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;
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; OUTPUT:
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; eax flat pointer (or pointer stored)
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;
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;--------------------------------------------------------------------------;
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assumes ds,Data
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assumes es,nothing
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MapFlat macro ptr16, ptr32
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; is this call safe from a 32-bit seg?
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push word ptr ptr16[2]
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db 66h,9Ah ; call <far ptr GetSelectorBase>
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dw OFFSET GetSelectorBase
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dw SEG GetSelectorBase
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ror eax,16 ; xchg HIWORD(eax) and LOWORD(eax)
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shrd eax,edx,16 ; move LOWORD(edx) to HIWORD(eax)
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movzx edx,word ptr ptr16[0] ; add pointer offset
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add eax,edx
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sub eax,[flatBase] ; make relative to base offset
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ifb <ptr32>
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mov ptr16,eax
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else
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mov ptr32,eax
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endif
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endm
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FlatDS macro
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mov ds,[flatSel]
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mov es,[flatSel]
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endm
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