OSHeap_Resize Should Have R3 as Output.

[Kevin Bracey]

In message <200111032244.WAA05203 at inputplus.demon.co.uk>
          Ralph Corderoy <ralph at inputplus.demon.co.uk> wrote:

> OSLib's entry doesn't match the PRM WRT R3.
> 
>     SWI OSHeap_Resize =
>        (  NUMBER &1D,
>           ENTRY
>           (  R0 # 5 "Extends or shrinks a heap (PRM 1-375)",
>              R1 = .Ref .Data: heap,
>              R3 = .Int: size_increase
>           )
>        );
> 
>     OS_Heap 5 (SWI &1D)
> 
>     Extend or shrink heap
> 
>     On entry
>         R0 = 5 (reason code)
>         R1 = pointer to heap
>         R3 = required size change in bytes (signed integer)
> 
>     On exit
>         R0, R1 preserved
>         R3 preserved, or amount of bytes heap shrunk by if requested
>         shrink failed
> 
>     Use
>         This updates the heap size information to take account of the
>         new size. If the heap cannot shrink as far as requested -
>         because of data that has already been allocated - it will
>         shrink as far as possible, set R3 to the amount by which it
>         shrank, and return an error.
> 
> Is this a bug or a sign of my unfamiliarity with OSLib's ways.
> 

OSLib veneers won't update any return registers in the event of an error,
which is unfortunate for SWIs like OS_Heap 5 or OS_ChangeDynamicArea. I'd
imagine this is why R3 return has been omitted.

-- 
Kevin Bracey, Principal Software Engineer
Pace Micro Technology plc                     Tel: +44 (0) 1223 518566
645 Newmarket Road                            Fax: +44 (0) 1223 518526
Cambridge, CB5 8PB, United Kingdom            WWW: http://www.pace.co.uk/