53 lines
1.6 KiB
Plaintext
53 lines
1.6 KiB
Plaintext
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{ Turbo Overlays }
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{ Copyright (c) 1985,90 by Borland International, Inc. }
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{$F+,O+}
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program OvrDemo;
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(*
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This is a simple example of how to use the new overlay system. For
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more complete documentation, refer to the overlay chapter in the
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Programmer's Guide. Here's a quick checklist:
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1. Turn "far calls" on {$F+} (to be safe, in all overlaid units and
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the main program).
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2. Turn "Overlays allowed" on {$O+}
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3. Use Overlay unit in main program.
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4. Issue separate {$O} directives for each overlaid unit.
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5. Make sure to call OvrInit and pass the name of the .OVR file.
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6. Test OvrResult after OvrInit calls (optional).
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7. Compile to disk (cannot run in memory).
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Here are the overlay error returns for quick reference:
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const
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ovrOk = 0; { Success }
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ovrError = -1; { Overlay manager error }
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ovrNotFound = -2; { Overlay file not found }
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ovrNoMemory = -3; { Not enough memory for overlay buffer }
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ovrIOError = -4; { Overlay file I/O error }
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ovrNoEMSDriver = -5; { EMS driver not installed }
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ovrNoEMSMemory = -6; { Not enough EMS memory }
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*)
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uses
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Overlay, Crt, OvrDemo1, OvrDemo2;
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{$O OvrDemo1} { overlay 'em }
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{$O OvrDemo2}
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begin
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TextAttr := White;
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ClrScr;
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OvrInit('OVRDEMO.OVR'); { init overlay system, reserve heap space }
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if OvrResult <> 0 then
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begin
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Writeln('Overlay error: ', OvrResult);
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Halt(1);
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end;
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repeat
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Write1;
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Write2;
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until KeyPressed;
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end.
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