cleaner & greener (was Re: A patch for RTEMS4.10.0 PowerPC heap space initialization)

[Sebastian Huber]

On 05/12/2011 01:10 PM, Peter Dufault wrote:
> 
> On May 12, 2011, at 6:10 , Sebastian Huber wrote:
> 
>> No, uintptr_t is the type used by the heap code.  We work here with addresses
>> and not sizes of single objects.
> 
> I had to look up the definition of uintptr_t.  At least according to Wikipedia it's C99 and is defined as:
> 
> ====
> Integers wide enough to hold pointers
> intptr_t and uintptr_t is a signed and unsigned integer which are guaranteed to hold the value of a pointer. These two types are optional.

To fulfill this we need sizeof(void *) <= sizeof(uintptr_t).

> 
> "The limits of these types are defined with the following macros:
> 
> 	• INTPTR_MIN is the minimum value (−32,767 [−215 + 1] or less) of intptr_t.
> 	• INTPTR_MAX is the maximum value (32,767 [215 − 1] or greater) of intptr_t.
> 	• UINTPTR_MAX is the maximum value (65,535 [216 − 1] or greater) of uintptr_t.
> ====

These are the portable limits and thus restricted to 16 bits.

[...]
> void
> bsp_get_work_area(
>     address_type       *work_area_begin,
>     address_size_type  *work_area_size,
>     address_type       *heap_begin,
>     address_size_type  *heap_size,
>     address_size_type  *sbrk_amount);
> 
> However: 
> 1. When would address_type not be void *?

Never, I think.

> 2. When would address_size_type not be size_t?

On some systems you may have sizeof(size_t) < sizeof(void *)?  I don't know an
example.

-- 
Sebastian Huber, embedded brains GmbH

Address : Obere Lagerstr. 30, D-82178 Puchheim, Germany
Phone   : +49 89 18 90 80 79-6
Fax     : +49 89 18 90 80 79-9
E-Mail  : sebastian.huber at embedded-brains.de
PGP     : Public key available on request.

Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.