On Wed, May 13 2015, Daniel Wagner <daniel.wag...@bmw-carit.de> wrote:
>
> - if (!swap_func)
> - swap_func = (size == 4 ? u32_swap : generic_swap);
> + if (!swap_func) {
> +#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
> + switch (size) {
> + case 4:
> + swap_func = u32_swap;
> + break;
> + case 8:
> + swap_func = u64_swap;
> + break;
> + }
> +#else
> + switch (size) {
> + case 4:
> + if (((unsigned long)base & 3) == 0)
> + swap_func = u32_swap;
> + break;
> + case 8:
> + if (((unsigned long)base & 7) == 0)
> + swap_func = u64_swap;
> + break;
> + }
> +#endif /* CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS */
> +
> + if (!swap_func)
> + swap_func = generic_swap;
> + }
I was more thinking of something like
static int alignment_ok(const void *base, int align)
{
return IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) ||
((unsigned long)base & (align - 1)) == 0;
}
...
if (!swap_func) {
if (size == 4 && alignment_ok(base, 4))
swap_func = u32_swap;
else if (size == 8 && alignment_ok(base, 8))
swap_func = u64_swap;
else
swap_func = generic_swap;
}
It seems to generate the same code (I usually worry about how gcc messes
up switches), so this is just a readability thing.
Rasmus
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