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42 lines
1.1 KiB
ObjectPascal
42 lines
1.1 KiB
ObjectPascal
{ %OPT=-O3 }
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{$mode objfpc} {$h+} {$typedaddress on}
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type
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pBaseType = ^BaseType;
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BaseType = uint32; // can be replaced with an arbitrary-sized array or record
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procedure Check(pstart, px: pBaseType; refIx: SizeInt; const desc: string);
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var
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ix: SizeInt;
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begin
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ix := px - pstart;
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writeln(desc, ' points at element #', ix);
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if ix = refIx then
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writeln('ok')
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else
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begin
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writeln('WRONG, must be #', refIx);
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halt(1);
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end;
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writeln;
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end;
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var
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x: array[0 .. 19] of BaseType;
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p: pBaseType;
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begin
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p := pBaseType(x);
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Check(p, p + 2, 2, 'p + 2');
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Check(p, p + 2 + 3, 5, 'p + 2 + 3');
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Check(p, p + 2 + 3 + 5, 10, 'p + 2 + 3 + 5');
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// These casts don't help.
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Check(p, pBaseType(pBaseType(p + 2) + 3) + 5, 10, 'pBaseType(pBaseType(p + 2) + 3) + 5');
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// These work, but prevent constant folding.
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Check(p, pBaseType(pointer(pBaseType(pointer(p + 2)) + 3)) + 5, 10, 'pBaseType(pointer(pBaseType(pointer(p + 2)) + 3)) + 5');
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Check(p, p + (2 + 3 + 5), 10, 'p + (2 + 3 + 5)');
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Check(p, p + 2 + 3 + 5 + 7, 17, 'p + 2 + 3 + 5 + 7');
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end.
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