Re: [PATCH] hw/display/artist: Fix bug in coordinate extraction in artist_vram_read()

[Helge Deller <deller@gmx.de>]

On 5/25/21 5:53 AM, Philippe Mathieu-Daudé wrote:
> Hi Helge,

Hi Plilippe,

> On 5/24/21 10:23 PM, Helge Deller wrote:
>> The CDE desktop on HP-UX 10 shows wrongly rendered pixels when the local screen
>> menu is closed. This bug was introduced by commit c7050f3f167b
>> ("hw/display/artist: Refactor x/y coordination extraction") which converted the
>> coordinate extraction in artist_vram_read() to use the ADDR_TO_X and ADDR_TO_Y
>> macros, but forgot to right-shift the address by 2 as it was done before.
>
> OK, but there is a similar issue in artist_vram_write(), right?

Similar code: Yes.
Issue: Maybe.
I applied the same patch in artist_vram_write() and it didn't showed any
negative (or positive) effects.
So, I'll resend my patch with artist_vram_write() adjusted as well.

Thanks!
Helge


>> Signed-off-by: Helge Deller <deller@gmx.de>
>> Fixes: c7050f3f167b ("hw/display/artist: Refactor x/y coordination extraction")
>> Cc: Philippe Mathieu-Daudé <f4bug@amsat.org>
>> Cc: Richard Henderson <richard.henderson@linaro.org>
>> Cc: Sven Schnelle <svens@stackframe.org>
>> Cc: qemu-stable@nongnu.org
>>
>> diff --git a/hw/display/artist.c b/hw/display/artist.c
>> index ed0e637f25..34efd3a565 100644
>> --- a/hw/display/artist.c
>> +++ b/hw/display/artist.c
>> @@ -1233,8 +1233,8 @@ static uint64_t artist_vram_read(void *opaque, hwaddr addr, unsigned size)
>>           return 0;
>>       }
>>
>> -    posy = ADDR_TO_Y(addr);
>> -    posx = ADDR_TO_X(addr);
>> +    posy = ADDR_TO_Y(addr >> 2);
>> +    posx = ADDR_TO_X(addr >> 2);
>>
>>       if (posy > buf->height || posx > buf->width) {
>>           return 0;
>>