INF: Far Pointer Comparisons Don't Account for Aliases

ID Number: Q34410

5.00 5.10 6.00 6.00a 6.00ax 7.00 | 5.00 5.10 6.00 6.00a

MS-DOS | OS/2

Summary:

In Microsoft C versions 5.0, 5.1, 6.0, 6.0a, 6.0ax, and C/C++ version

7.0, the code generated to compare two far pointers for equality does

not account for the possibility of the pointers having different

segments and offsets, yet still pointing to the same location.

This is correct behavior for the compiler. Only huge pointers are

normalized. Near and far pointers that point into the same segment are

assumed to have the same segment values; any differences between them

must be in the offset.

Normalizing pointers would involve a tremendous performance penalty

under MS-DOS and would be impossible under OS/2 because of the

protected-mode addressing scheme.

Additional reference words: 5.00 5.10 6.00 6.00a 6.00ax 7.00