CRITICAL_SECTION alignment

[Ulrich Weigand]

Josh DuBois wrote:

>   Just as Ulrich suggested, the typedef of the CRITICAL_SECTION struct
> was inside a #pragma pack(1) block.  On the ppc, this made
> CRITICAL_SECTIONs always (or very often) get put on 2-byte boundaries. 

Aha! ;-)   I'd suggest we should try and use pack() as sparingly as
possible, e.g. by surrounding only single struct definitions with it.
Those large #pragma pack() blocks can be really confusing ...

> I didn't expect #pragma pack() to affect the alignment of types - I just
> thought it would cause structures to take up the minimum required amount
> of room.  Seems it makes both members within a structure _and_ separate
> structures get tightly packed.  Or so I gather.

This is really the same thing.  The alignment requirement of a structure
is the maximum (well, least common multiple) of the alignment requirements
of all its member.  #pragma pack(1) says that for all subsequent struct
definitions, every member's alignment requirement is artificially set to 1.
Hence, the struct's alignment requirement is also 1 ... 

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  weigand at informatik.uni-erlangen.de