[Icc-mot] BSS in reverse order?

[Edward Karpicz]

Jim Fiocca wrote:

> ICC12-V7 questions:
>
> 1) In the generated map file (.mp), why are the memory addresses in the 
> BSS section (area) in the reverse order that they were allocated in the 
> program?

Does ANSI C specify the order static vars are allocated? I don't think so. 
For portability and compatibility with future ICC versions, I think you 
shouldn't assume any order of allocation.
Maybe tell us what are you trying to do? Even structs get not portable as 
soon as someone starts assuming that char is 8 bits or assuming any struct 
packing etc

struct {
  char a;
  short b;
} ...

^^ there can be a unused memory space between a and b fields, just enable 
word alignment and see. The same way there can be a unused space between 
statically allocated vars... So are you sure you need specific order of 
allocation?


>
> 2) Is there some sort of data alignment pragma?  Or other mechanism to 
> align data on a specific boundary?
>

There's a word alignment option. If you need specific address then you 
should use abs_address pragma or your custom memory area with specific start 
and end addresses. To get some every >2bytes alignment, I would use structs 
and unions of specific size and custom area to allocate only such structs.
I think you should tell us more about what you are trying to achive.


Edward

> Thanks,
> Jim
>
>
>
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