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Difference between revisions of "Coding Conventions"
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→Endianess issues: Add link to new HOWTO covering debugging Endian Issues.
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(→Endianess issues: Add link to new HOWTO covering debugging Endian Issues.) |
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* ScummVM runs on both little endian (Windows, x86 Mac OS X, x86 Linux...) and big endian hosts (PowerPC Mac OS X, PlayStation 3 Linux...). So when writing data (think savegames) to files and reading it back again, you need to compensate for this. This is easily done by using the READ_ and WRITE_ macros from common/endian.h (like READ_LE_UINT32 or WRITE_BE_UINT16.) respectively the corresponding Stream class methods (like readUint32LE or writeUint16BE). | * ScummVM runs on both little endian (Windows, x86 Mac OS X, x86 Linux...) and big endian hosts (PowerPC Mac OS X, PlayStation 3 Linux...). So when writing data (think savegames) to files and reading it back again, you need to compensate for this. This is easily done by using the READ_ and WRITE_ macros from common/endian.h (like READ_LE_UINT32 or WRITE_BE_UINT16.) respectively the corresponding Stream class methods (like readUint32LE or writeUint16BE). | ||
* Furthermore, some games existed in multiple versions, e.g. one for Windows and one for Mac OS. In that case, you may have to detect and distinguish these versions and employ different reading calls, to compensate for endian differences in the game data files. | * Furthermore, some games existed in multiple versions, e.g. one for Windows and one for Mac OS. In that case, you may have to detect and distinguish these versions and employ different reading calls, to compensate for endian differences in the game data files. | ||
As most desktop machines are now little-endian i.e. x86, debugging any remaining endian issues without access to a big-endian desktop system is hard. [[HOWTO-Debug-Endian-Issues |HOWTO Debug Endian Issues]] details a solution to this by using a virtual machine software package to emulate a machine with a different endian CPU to the host system. | |||
== Struct packing == | == Struct packing == | ||