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(nasm.info)Section 8.2.2

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8.2.2. Finding Your Local Data Items
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   Having got the GOT, you can then use it to obtain the addresses of
your data items. Most variables will reside in the sections you have
declared; they can be accessed using the `..gotoff' special `WRT' type.
The way this works is like this:

             lea     eax,[ebx+myvar wrt ..gotoff]

   The expression `myvar wrt ..gotoff' is calculated, when the shared
library is linked, to be the offset to the local variable `myvar' from
the beginning of the GOT. Therefore, adding it to `EBX' as above will
place the real address of `myvar' in `EAX'.

   If you declare variables as `GLOBAL' without specifying a size for
them, they are shared between code modules in the library, but do not
get exported from the library to the program that loaded it. They will
still be in your ordinary data and BSS sections, so you can access them
in the same way as local variables, using the above `..gotoff'
mechanism.

   Note that due to a peculiarity of the way BSD `a.out' format handles
this relocation type, there must be at least one non-local symbol in the
same section as the address you're trying to access.