Re: [Qemu-devel] [PATCH] bswap: Don't rely on HOST_LONG_BITS

[Andreas Färber]

Am 30.01.2013 22:59, schrieb Richard Henderson:
> On 01/30/2013 01:04 PM, Stefan Weil wrote:
>>>   static inline unsigned long leul_to_cpu(unsigned long v)
>>>   {
>>> -    return le_bswap(v, HOST_LONG_BITS);
>>> +    /* In order to break an include loop between here and
>>> +       qemu-common.h, don't rely on HOST_LONG_BITS.  */
>>> +#if ULONG_MAX == UINT32_MAX
>>> +    return le_bswap(v, 32);
>>> +#elif ULONG_MAX == UINT64_MAX
>>> +    return le_bswap(v, 64);
>>> +#else
>>> +# error Unknown sizeof long
>>> +#endif
>>>   }
>>>
>>>   #undef le_bswap
>>
>> That would be wrong for 64 bit MinGW-w64 because
>> HOST_LONG_BITS is _not_ the bit size of a long value.
>>
>> See qemu-common.h for the correct definition.
> 
> I beg your pardon, but it *is* right.  HOST_LONG_BITS is set to the size
> of a host pointer, not a host long.  Which suggests that my patch is the
> *only* correct way to do this, at least for now.

IIUC on w64 ULONG_MAX == UINT32_MAX but 64 is desired for pointer.
w64 is not C99-compliant.

Andreas

-- 
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg