Dear Albert ARIBAUD,
In message 4CF7C7F4.6030803@free.fr you wrote:
Well, an u8 is as good a data type as any other. The available range of 0...255 seems more than sufficient to store the needed information, so why should I waste 4 bytes of storage when a single byte is sufficient as well?
You don't necessarily use only one byte when declaring an u8 instead of an int, because the next declaration may have alignment requirements that will cause the compiler to skip bytes after the u8. Besides, u8 is
The compiler / linker may (or may not) optimize this and collect variables of similar alignment. An "int foo;" is likely to end in .bss segment, while an "char foo;" will probably show up in .sbss - I don;t know how good or bad the current situation for ARM is, but I'm sure it is improving (look for example at all the microoptimizations done by Linaro).
not "as good a data type" as any other, it is a specific data type whereas 'int' is the native data type of the platform, supposed to be the most natural to deal with for the cpu -- 32-bit for an ARM.
Can an ARM CPU not read1s and write single bytes, too?
u8 are perfect and normal, for instance, as fields of a structure which represents byte registers, or to perform 8-bit arithmetic. Here, however, there is indeed no reason to use any specific type, so we should use the cpu's native type.
I do not share your opinion.
But this is a pretty academic topic, and I'm neither in the mood nor do I have the time for lengthy discussions. Let's stop this here.
Best regards,
Wolfgang Denk