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

Nicolai Hess nicolaihess at web.de
Mon May 5 07:06:01 UTC 2014


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.

regards
Nicolai
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