Gerhard Fiedler escreveu:
> William "Chops" Westfield wrote:
>
>   =

>> On Jun 14, 2009, at 8:21 AM, Isaac Marino Bavaresco wrote:
>>
>>     =

>>> This is basic, usually the designer must ensure only one task uses
>>> each resource (serial port, etc.) at any given time (just one task
>>> use each resource ever or using a mutex/open, close, etc.).
>>>       =

>> Which designer are YOU talking about?  I'm claiming that the designer
>> of the C18 libraries is unlikely to have taken into account all
>> possible implementations of the multitasking operating systems that
>> might run on the same software, and so the C18 library itself is VERY
>> unlikely to be "thread safe" in most of its functions.  =

>>     =

>
> AFAIK, thread safety is not part of the C standard, so whether or not a
> specific compiler or library is or is not thread-safe needs to be
> deduced from the guarantees the compiler or library gives. If they don't
> give any, this is probably not a good sign. Even if a given version is,
> this could be by accident and could be broken by any future update if
> it's not guaranteed by the designers.
>
> Gerhard
>   =


I use MPLAB-C18 with FreeRTOS in a daily basis, and most of the
MPLAB-C18 library is thread safe and re-entrant.

Several of the assembly files are explicitly documented as being re-entrant.

The only clearly non-reentrant functions are strtok (strtok.c),
strtokrampgm (stokrp.c), strtokpgmram (stokpr.c), strtokpgm (stokpgm.c)
and the busy-wait functions (Delay1KTCYx, Delay10KTCYx, Delay10TCYx,
Delay100TCYx), because they use static variables.

The math functions and built-in operations use static variables in the
section MATH_DATA, but FreeRTOS saves and restores this section in the
context switch.

The peripheral library functions must be considered non-reentrant and
the programmer must provide sinchronization using mutexes or critical
sections.

Best regards,

Isaac

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