Re: avoiding copy - Luajit FFI

[Fabio Kaminski <fabiokaminski@...>]

nice tip.. indeed it work..  thanks to point that out

> ffi.cdef [[
>> void * malloc(size_t size);
>> void free(void *);
>> ]]
> n = ffi.C.malloc(10)

> ncaddr = ffi.cast('uintptr_t', nc)
> =ncaddr
23003152ULL

> nc = ffi.cast('uint8_t *', n)
> ncaddr = ffi.cast('uintptr_t', nc)
> =ncaddr
23003152ULL





On Tue, Jun 7, 2011 at 3:28 PM, Duncan Cross <duncan.cross@gmail.com> wrote:
> On Tue, Jun 7, 2011 at 7:03 PM, Fabio Kaminski <fabiokaminski@gmail.com> wrote:
>> but cast from void * to char * give me a new address (pointing to
>> somewhere else) and not the same pointer:
>
> This is incorrect. What you are seeing here, when you print the
> pointer, is not the value of the pointer itself but of the FFI cdata
> object that has been allocated to house it.
>
> If you want to see the numeric value of a pointer, try
> tonumber(ffi.cast('intptr_t', ptr)).
>
> -Duncan
>
>