Unaligned access to packed structs on ppc405

Yaro Pollak yarop@altair-semi.com
Mon Jan 30 16:26:00 GMT 2006



Matthew Jones wrote:

>>From: Yaro Pollak
>>
>>Greetings,
>>I am cross-compiling on GCC 3.4.1 for the PowerPC 405,
>>which can handle unaligned accesses in hardware.
>>Whenever I am accessing members of a packed bit-struct by
>>pointer, the  compiler produces byte accesses, instead of
>>4-byte acceses. I've tried to use |-mstrict-align but to
>>no avail. Am I doing something wrong?
>>    
>>
>
>Are you sure it is the compiler? Are you looking at the generated
>assembler, or inferring this from a logic analyser? If its the
>second case, it could be the uP rather than gcc.
>
>  
>
I'm sorry I failed to mention that as well, but I am in fact looking at 
the generated assembler, vs. the assembler generated when I am accessing 
the members of the struct directly (not through a pointer).

Yaro



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