Returning a char from a C-language function

I have a small problem when trying to make a C-language function to return one character. The code is very simple and that's what's making it so strange.

Datum val_ibool(PG_FUNCTION_ARGS)
{
iBool *input = (iBool *) PG_GETARG_POINTER(0);

PG_RETURN_CHAR(input->value);
}

input is a structure containing a character as value. I also tried this, but it didn't work:

Datum val_ibool(PG_FUNCTION_ARGS)
{
char test = 'a';

PG_RETURN_CHAR(test);
}

On the other side I have this:

CREATE FUNCTION val(ibool)
RETURNS char
AS '/home/ivan/Desktop/diplomski/trunk/C/modbms', 'val_ibool'
LANGUAGE C STRICT;

Any advice?

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