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Difference between revisions of "Coding Conventions"
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Do *not* assume that structs are stored in a certain way in memory -- the layout of a struct in memory can vary a lot between platforms, and on most modern systems it will almost never be "packed". If you absolutely must use packed structs, do not just use some #pragma or __attribute__ (as that is not portable either). Instead, do the following: | Do *not* assume that structs are stored in a certain way in memory -- the layout of a struct in memory can vary a lot between platforms, and on most modern systems it will almost never be "packed". If you absolutely must use packed structs, do not just use some #pragma or __attribute__ (as that is not portable either). Instead, do the following: | ||
* Before the struct(s) you need to be packed, insert | * Before the struct(s) you need to be packed, insert | ||
<source lang="cpp"> | |||
#include "common/pack-start.h" // START STRUCT PACKING | #include "common/pack-start.h" // START STRUCT PACKING | ||
</source> | |||
* After the struct(s) you need to be packed, insert | * After the struct(s) you need to be packed, insert | ||
<source lang="cpp"> | |||
#include "common/pack-end.h" // END STRUCT PACKING | #include "common/pack-end.h" // END STRUCT PACKING | ||
</source> | |||
* At the "end" of each struct you need to be packed, insert the following between the closing } and the ; after it: | * At the "end" of each struct you need to be packed, insert the following between the closing } and the ; after it: | ||
<source lang="cpp"> | |||
PACKED_STRUCT | PACKED_STRUCT | ||
</source> | |||
You may want to look at some files which already do that, e.g. look at <code>engines/scumm/boxes.cpp</code> | You may want to look at some files which already do that, e.g. look at <code>engines/scumm/boxes.cpp</code> | ||