Re: [ECOS] Two minor memory allocation issues

[Andrew Lunn <andrew at lunn dot ch>]

On Tue, May 16, 2006 at 11:15:02AM +0100, Andy Jackson wrote:
> I've just been experimenting with memory allocation (malloc and friends) on 
> eCos and have spotted two minor issues:
> 
> 1. A malloc request for 0x7FFFFFFF bytes succeeds and allocates a small 
> amount of memory. Reducing the request to 0x7FFFFFF0 causes it to fail as 
> expected. My guess is that this is a function of the allocation padding 
> calculation, but I haven't got time at present to investigate further.

It looks like internally dlmalloc is using cyg_int32 to represent
size. There is a macro request2size() which does arithmatic on the
size and 0x7FFFFFFF it is probably wrapping around to negative and so
it allocates the minimal amount of space. 

 
> 2. In the reference manual section 'eCos Memory Pools' on the page for 
> 'stdlib malloc Pools, the prototype for calloc is given as:
> 
> void *calloc(size_t size);

Yes, this is wrong. I will update the documentation.

     Andrew

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