[Vm-dev] bug on windows ioShowDisplay for bitdepth 16/8/4 (big endian)

[Eliot Miranda]

Hi Nicolai,


On Mon, May 5, 2014 at 12:06 AM, Nicolai Hess <nicolaihess at web.de> wrote:

>
> 2014-04-03 17:51 GMT+02:00 karl ramberg <karlramberg at gmail.com>:
>
>>
>> I can confirm this bug on windows Cog.
>>
>> Cheers,
>> Karl
>>
>>
>> On Thu, Apr 3, 2014 at 10:11 AM, Nicolai Hess <nicolaihess at web.de> wrote:
>>
>>>
>>> There is still something wrong with byte/word swap in windows
>>> ioShowDisplay code
>>> attached are two screenshots
>>> squeak 4.5 image with cogvm from http://files.pharo.org/vm/cogmt/win/
>>> pharo 30793 image with latest vm from
>>> http://files.pharo.org/vm/pharo/win/
>>> showing this bug after setting the Display depth to 16
>>> (Display newDepth:16)
>>>
>>> sqwin32window.c has three variants for doing the byte_swap/word_swap on
>>> bitdepths with big endian to convert to lsb
>>>
>>> This one is active and causes this error.
>>> #  if __GNUC__ >= 3
>>> #   define BYTE_SWAP(w) __asm__("bswap %0" : "=r" (w) : "r" (w))
>>> #   define WORD_SWAP(w) __asm__("roll $16, %0" : "=r" (w) : "r" (w))
>>>
>>> This one would work
>>> #  else
>>> #   define BYTE_SWAP(w) __asm__("bswap %%eax" : "=eax" (w) : "eax" (w))
>>> #   define WORD_SWAP(w) __asm__("roll $16, %%eax" : "=eax" (w) : "eax"
>>> (w))
>>>
>>> This one, of course, works too
>>> # else
>>> #  define BYTE_SWAP(w) w = (w << 24) | ((w & 0xFF00) << 8) | ((w >> 8) &
>>> 0xFF00) | (w >> 24)
>>> #  define WORD_SWAP(w) w = (( (unsigned)(w) << 16) | ((unsigned) (w) >>
>>> 16))
>>>
>>> This one is not there but would work (at least with gcc > 4.5
>>> #   define BYTE_SWAP_MY(w) __asm__("bswap %0" : "+r" (w))
>>> #   define WORD_SWAP_MY(w) __asm__("roll $16, %0" : "+r" (w))
>>>
>>> But actually I don't know assembler and/or the gcc inline code syntax, so
>>> I don't know what is wrong with the first version :)
>>>
>>> Nicolai
>>>
>>> btw, you can not test this bug with the current squeak 4.5 all in on
>>> image,
>>> as it uses a rather old vm.
>>>
>>> Third screenshot:
>>> using the latest stable pharo-vm, it looks much more wrong, as there
>>> was another(?) bug that is fixed already(?) - i don't know :)
>>>
>>>
>>>
>>>
>>
>>
>
>
> Someone else can reproduce this?
> (eliot?, nicolas? )
> It is easily fixable, I think. But I am not good at inline assembler.
> I'll open a mantis and fogbugz report.
>
> Yes, I can reproduce it.  But I've not had time to check with a pre 3.x
and a post 3.x compiler to check what the right syntax is.  I'm busy with
other stuff right now.  Hopefully I'll get to this in a coupel of weeks.
Anyone else out there who can provide the right syntax for

2.95
3.4.x
4.x

I'd be very grateful and simply integrate the fix.

-- 
best,
Eliot
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