Re: problem with safe-ctype.h

["Kaveh R. Ghazi" <ghazi at caip dot rutgers dot edu>]

 > From: Herman ten Brugge <Haj.Ten.Brugge@net.HCC.nl> 
 > 
 > 2000-12-14 Herman A.J. ten Brugge <Haj.Ten.Brugge@net.HCC.nl>
 > 
 >         * safe-ctype.h: Make code work on all targets and not just on
 >         targets where a char is 8 bits.
 > 
 > 
 > -#define _sch_test(c, bit) (_sch_istable[(int)(unsigned char)(c)] & (bit))
 > +#define _sch_test(c, bit) (_sch_istable[(c) & 0xff] & (bit))
 > -#define TOUPPER(c) _sch_toupper[(int)(unsigned char)(c)]
 > -#define TOLOWER(c) _sch_tolower[(int)(unsigned char)(c)]
 > +#define TOUPPER(c) _sch_toupper[(c) & 0xff]
 > +#define TOLOWER(c) _sch_tolower[(c) & 0xff]

The reason for these casts is to avoid problems when parameter `c' is
a signed char.  If you pass in something > 127 you'll get a negative
offset into the _sch_* arrays.

We used to have code to handle this in system.h before safe-ctype was
put in libiberty.  Something like:

 > #define CTYPE_CONV(CH) \
 > (sizeof(CH) == sizeof(int) ? (int)(CH) : (int)(unsigned char)(CH))

Then you'd wrap CTYPE_CONV around the `c' parameter in the ctype
definitions.

Note: CTYPE_CONV is resolved at compile-time so you don't have
multiple evaluation problems.

So e.g. if you #define TOUPPER _sch_toupper[CTYPE_CONV(c)] it should
DTRT.  You may still need to & 0xff to truncate 32-bit chars into the
right range, but CTYPE_CONV will also ensure that char 255 won't
become negative.

		--Kaveh
--
Kaveh R. Ghazi			Engagement Manager / Project Services
ghazi@caip.rutgers.edu		Qwest Internet Solutions