svn commit: r212064 - head/sys/boot/pc98/boot2

[Dimitry Andric]

On 2010-08-31 21:37, John Baldwin wrote:
>> -    return *(p + 0x401) * 128 * 1024 + *(u_int16_t *)(p + 0x594) * 1024 * 1024;
>> +    return *p * 128 * 1024 + *(u_int16_t *)(p + (0x594 - 0x401)) * 1024 * 1024;
>>  }
> 
> Perhaps replace '(p + 0x594 - 0x401)' with just 'PTOV(0x594)'?
> 
> I would actually find it cleaner to remove 'p' altogether perhaps:
> 
> 	return (*(u_char *)PTOV(0x401) * 128 * 1024 +
> 	    *(uint16_t *)PTOV(0x594) * 1024 * 1024);

Yes, I attempted this variation at first, but it made the code bigger,
which I wanted to avoid: it went from "11 bytes available" to "7 bytes"
available.

I tried several semantically equivalent permutations of the expression,
and the one I committed gave no increase or decrease in code size.

Apparently the code size produced by gcc is very sensitive to even
minimal changes.  For example, a lot of the PTOV() pointer dereferences
should really be qualified with 'volatile', but that even causes boot2
to become too big to fit!

If the 4 extra bytes are no problem, then I would be glad to change it
to the above expression, though.  It is certainly clearer. :)