Ich denke mal, dass die Lösung im Handling liegt. Der Delphi Language Guide (Record Types) erklärt es so:
To ensure proper alignment of the fields in an unpacked record type, the compiler inserts an unused byte before fields with an alignment of 2, and up to three unused bytes before fields with an alignment of 4, if required. Finally, the compiler rounds the total size of the record upward to the byte boundary specified by the largest alignment of any of the fields.
If two fields share a common type specification, they are packed even if the declaration does not include the packed modifier and the record type is not declared in the {$A-} state. Thus, for example, given the following declaration
type
TMyRecord = record
A, B: Extended;
C: Extended;
end;
A and B are packed (aligned on byte boundaries) because they share the same type specification. The compiler pads the structure with unused bytes to ensure that C appears on a quadword boundary.
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