[Piglit] [PATCH 1/5] util: Wrapper to load exact hex patterns for ints

Emil Velikov emil.l.velikov at gmail.com
Fri Jul 1 15:02:59 UTC 2016

On 30 June 2016 at 10:19, Andres Gomez <agomez at igalia.com> wrote:
> On Wed, 2016-06-29 at 17:46 +0100, Emil Velikov wrote:
>> On 14 June 2016 at 22:36, Andres Gomez <agomez at igalia.com> wrote:
>> > For some cases we want to have shaders where we load an exact bit
>> > pattern into a signed int.
>> >
>> > This fixes the errno-based range validation that was broken when
>> > the
>> > integer vbo attribute parsing on 32-bit systems was recently fixed.
>> >
>> Is this because strtol{,l} requires the '-' sign to prefix the
>> negative values, while we feed it a unsigned encoded signed value ?
>> I.e. function throws an error if we give it 0x8000 0000, as it
>> expects
>> -0x7fff ffff.
>> Or is that due to sizeof(long) varying between 32 and 64bit systems ?
> I would say, both.
> As you say, for negative values we would have to pass the hex values
> as -0x7fff ffff while we want to pass the exact bit
> representation: 0x8000 0000 ...
> ... and, because of that, in order to allow it without problems in
> 32bit systems, in the previous implementation we were using strtoll,
> which was then making useless its internal validation for values inside
> the range of long.
Any chance if you can use that (or a fraction of it) as commit msg :-)

Side note: the "skip spaces and tabs" comment and the while loop is
copy pasta from other strto*_hex() functions in piglit-util.h.
Strictly speaking the strto* API uses isspace(), while "space and
tabs" refers to isblank().

Perhaps it's worth using isspace, perhaps it isn't.


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