replacements/iconv.c questions

Hi Freddy, 

I have some questions about how tds_sys_iconv() is written.  I'm looking at it
because VS 2005 kicks out warnings for a lot of stuff related to iconv_t, and
before re-writing it, I'd like to understand why certain choices were made:

1.  Why do all the get/put functions e.g. put_utf16le() use int instead of
size_t?  inbytesleft and outbytesleft are size_t*, and il and ol are size_t, but
all the little functions take int as their length argument and many check for a
negative length.  

2.  This comment:

	 *   also we use unsigned to remove required unsigned casts

    Does that refer to warnings we would get in the get/put functions if they
took signed characters instead of unsigned?  
    
3.  Why the function pointer arrays iconv_gets and iconv_puts?  Why not a simple
switch statement instead?  The array is referenced only by tds_sys_iconv() and
a switch would be a lot clearer than bit-twiddling the iconv_t value.  

I could understand using function pointers if tds_sys_iconv_open() *set* the
pointers and tds_sys_iconv() *used* them.  As it is, though, tds_sys_iconv_open()
hacks two offsets into the iconv_t, and tds_sys_iconv() unpacks them to look up
the functions. 

Suppose we did this instead:

	In tds_sys_iconv_open():
	
		struct get_put_pair { 
			iconv_get_t get;
			iconv_put_t put; 
		};
		
		get_put_pair *cd = calloc(1, sizeof(get_put_pair));
		
		/* look up names, set members */
		
		/* ... e.g. ... */
		
		if (strcmp(enc_name, "US-ASCII") == 0)
			cd->get = get_ascii;

		/* ...  */
		
		return cd;

	In tds_sys_iconv():
	
		iconv_get_t get_func = ((struct get_put_pair*)cd)->get;
		iconv_put_t put_func = ((struct get_put_pair*)cd)->put;
	
	
	In tds_sys_iconv_close():
	
		free(cd);
	
That would be much more portable and understandable code, don't you agree?  

I don't even see why we would bother to define iconv_t as void*.  We define it
only for FreeTDS in tdsiconv.h.  It could just as easily be a get_put_pair*.

Here's to hoping SF is back online soon.  

Regards, 

--jkl