base/include/rtai_nam2num.h

Go to the documentation of this file.

/**
 * @ingroup shm
 * @ingroup lxrt
 * @ingroup tasklets
 * @file
 *
 * Conversion between characters strings and unsigned long identifiers.
 * 
 * Convert a 6 characters string to un unsigned long, and vice versa, to be used
 * as an identifier for RTAI services symmetrically available in user and kernel
 * space, e.g. @ref shm "shared memory" and @ref lxrt "LXRT and LXRT-INFORMED".
 *
 * @author Paolo Mantegazza
 *
 * @note Copyright &copy; 1999-2003 Paolo Mantegazza <mantegazza@aero.polimi.it>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#ifndef _RTAI_NAM2NUM_H
#define _RTAI_NAM2NUM_H

#include <rtai_types.h>

/**
 * Convert a 6 characters string to an unsigned long.
 *
 * Converts a 6 characters string name containing an alpha numeric
 * identifier to its corresponding unsigned long identifier.
 *
 * @param name is the name to be converted.
 *
 * Allowed characters are:
 * -  english letters (no difference between upper and lower case);
 * -  decimal digits;
 * -  underscore (_) and another character of your choice. The latter will be
 * always converted back to a $ by num2nam().
 *
 * @return the unsigned long associated with @a name.
 */
static inline unsigned long nam2num (const char *name)
{
        unsigned long retval = 0;
    int c, i;

    for (i = 0; i < 6; i++) {
        if (!(c = name[i]))
            break;
        if (c >= 'a' && c <= 'z') {
            c +=  (11 - 'a');
        } else if (c >= 'A' && c <= 'Z') {
            c += (11 - 'A');
        } else if (c >= '0' && c <= '9') {
            c -= ('0' - 1);
        } else {
            c = c == '_' ? 37 : 38;
        }
        retval = retval*39 + c;
    }
    if (i > 0)
        return retval + 2;
    else
        return 0xFFFFFFFF;
}

/**
 * Convert an unsigned long to a 6 characters string.
 *
 * @param num is the unsigned long identifier whose alphanumeric name string has
 * to be evaluated;
 * 
 * @param name is a pointer to a 6 characters buffer where the identifier will
 * be returned.
 */
static inline void num2nam (unsigned long num, char *name)
{
        int c, i, k, q; 
    if (num == 0xFFFFFFFF) {
        name[0] = 0;
        return;
    }
        i = 5; 
    num -= 2;
    while (num && i >= 0) {
        q = num/39;
        c = num - q*39;
        num = q;
        if ( c < 37) {
            name[i--] = c > 10 ? c + 'A' - 11 : c + '0' - 1;
        } else {
            name[i--] = c == 37 ? '_' : '$';
        }
    }
    for (k = 0; i < 5; k++) {
        name[k] = name[++i];
    }
    name[k] = 0;
}

#endif /* !_RTAI_NAM2NUM_H */

---