OPTIMIZED ENTERPRISE ANONIX

#ifndef OMG_OPTIMIZED_CTYPE_H_
#define OMG_OPTIMIZED_CTYPE_H_

/**
 *                        __ _   _  ____  _   _ _ _  _
 *                       /  |  \| |/ __ \|  \| | | \/ /
 *                      /   |   \ | |  | |   \ | |\  /
 *                     /  . | |\  | |__| | |\  | |/  \
 *                    /__/|_|_| \_|\____/|_| \_|_|_/\_\
 *       
 *                       OPTIMIZED ANONIX INTERFACES
 *
 *  -------------------------------------------------------------------------
 *
 *  Optimized branchless ctype facilities using bitwise operations. Assumes a
 *  fixed ASCII (ANSI_X3.110-1983) code page. Functions are ISO/IEC 9899:1999
 *  (C99) compliant. Requires an ISO/IEC 9899:1999 (C99) compliant compiler.
 * 
 *  Version: 1.666alpha
 *  Bug Reports: strawberryshake [at] 1337 [dot] jp
 */
 
inline int isblank(int c) { return (c == ' ') | (c == '\t') | (c == '\v'); }
inline int iscntrl(int c) { return (c <= 0x1F) | (c == 0x7F); }
inline int isdigit(int c) { return (((unsigned int)c) - ((unsigned int)'0')) <= ((unsigned int)('9' - '0')); }
inline int isgraph(int c) { return (((unsigned int)c) - ((unsigned int)'!')) <= ((unsigned int)('~' - '!')); }
inline int islower(int c) { return (((unsigned int)c) - ((unsigned int)'a')) <= ((unsigned int)('z' - 'a')); }
inline int isprint(int c) { return (((unsigned int)c) - ((unsigned int)' ')) <= ((unsigned int)('~' - ' ')); }
inline int isupper(int c) { return (((unsigned int)c) - ((unsigned int)'A')) <= ((unsigned int)('Z' - 'A')); }
inline int isalpha(int c) { return ::hrc::islower(c) | ::hrc::isupper(c); }
inline int isalnum(int c) { return ::hrc::islower(c) | ::hrc::isupper(c) | ::hrc::isdigit(c); }
inline int ispunct(int c) { return ~(::hrc::islower(c) | ::hrc::isupper(c) | ::hrc::isdigit(c)); }
inline int isspace(int c) { return ::hrc::isblank(c) | (c == '\f') | (c == '\n') | (c == '\r'); }

inline int isxdigit(int c) {
    return ::hrc::isdigit(c) |
        ((((unsigned int)c) - ((unsigned int)'a')) <= ((unsigned int)('f' - 'a'))) |
        ((((unsigned int)c) - ((unsigned int)'A')) <= ((unsigned int)('F' - 'A')));
}

inline int tolower(int c) {
    unsigned int upper = (unsigned int)::hrc::isupper(c);
    return (int)((((~upper) + 1) & ((unsigned int)(c - 'A' + 'a'))) | ((~(upper - 1)) & ((unsigned int)c)));
}

inline int toupper(int c) {
    unsigned int lower = (unsigned int)::hrc::islower(c);
    return (int)((((~lower) + 1) & ((unsigned int)(c - 'a' + 'A'))) | ((~(lower - 1)) & ((unsigned int)c)));
}

#endif

Sorry, off to a rough start. In my haste, forgot the proper tags. Rather amateurish of a long-time /prog/rider, don't you agree? I also left in some C++ stuff. I'm actually using this in one of my private C++ libraries, but I'm placing this in the public domain with the exception that there is absolutely no warranty.

#ifndef OMG_OPTIMIZED_CTYPE_H_
#define OMG_OPTIMIZED_CTYPE_H_

/**
 *                        __ _   _  ____  _   _ _ _  _
 *                       /  |  \| |/ __ \|  \| | | \/ /
 *                      /   |   \ | |  | |   \ | |\  /
 *                     /  . | |\  | |__| | |\  | |/  \
 *                    /__/|_|_| \_|\____/|_| \_|_|_/\_\
 *       
 *                       OPTIMIZED ANONIX INTERFACES
 *
 *  -------------------------------------------------------------------------
 *
 *  Optimized branchless ctype facilities using bitwise operations. Assumes a
 *  fixed ASCII (ANSI_X3.110-1983) code page. Functions are ISO/IEC 9899:1999
 *  (C99) compliant. Requires an ISO/IEC 9899:1999 (C99) compliant compiler.
 * 
 *  Version: 1.666alpha2
 *  Bug Reports: strawberryshake [at] 1337 [dot] jp
 */
 
inline int isblank(int c) { return (c == ' ') | (c == '\t') | (c == '\v'); }
inline int iscntrl(int c) { return (c <= 0x1F) | (c == 0x7F); }
inline int isdigit(int c) { return (((unsigned int)c) - ((unsigned int)'0')) <= ((unsigned int)('9' - '0')); }
inline int isgraph(int c) { return (((unsigned int)c) - ((unsigned int)'!')) <= ((unsigned int)('~' - '!')); }
inline int islower(int c) { return (((unsigned int)c) - ((unsigned int)'a')) <= ((unsigned int)('z' - 'a')); }
inline int isprint(int c) { return (((unsigned int)c) - ((unsigned int)' ')) <= ((unsigned int)('~' - ' ')); }
inline int isupper(int c) { return (((unsigned int)c) - ((unsigned int)'A')) <= ((unsigned int)('Z' - 'A')); }
inline int isalpha(int c) { return islower(c) | isupper(c); }
inline int isalnum(int c) { return islower(c) | isupper(c) | isdigit(c); }
inline int ispunct(int c) { return ~(islower(c) | isupper(c) | isdigit(c)); }
inline int isspace(int c) { return isblank(c) | (c == '\f') | (c == '\n') | (c == '\r'); }

inline int isxdigit(int c) {
    return isdigit(c) |
        ((((unsigned int)c) - ((unsigned int)'a')) <= ((unsigned int)('f' - 'a'))) |
        ((((unsigned int)c) - ((unsigned int)'A')) <= ((unsigned int)('F' - 'A')));
}

inline int tolower(int c) {
    unsigned int upper = (unsigned int)isupper(c);
    return (int)((((~upper) + 1) & ((unsigned int)(c - 'A' + 'a'))) | ((~(upper - 1)) & ((unsigned int)c)));
}

inline int toupper(int c) {
    unsigned int lower = (unsigned int)islower(c);
    return (int)((((~lower) + 1) & ((unsigned int)(c - 'a' + 'A'))) | ((~(lower - 1)) & ((unsigned int)c)));
}

#endif