/* rfsgetmode.c - rfsgetmode */

#include 

/*------------------------------------------------------------------------
 * rfsgetmode  -  Parse mode argument and generate integer of mode bits
 *------------------------------------------------------------------------
 */

int32   rfsgetmode (
         char   *mode                   /* String of mode characters    */
        )
{
        int32   mbits;                  /* Mode bits to return (in host */
                                        /*    byte order)               */
        char    ch;                     /* Next character in mode string*/

        mbits = 0;

        /* Mode string specifies:                                       */
        /*      r - read                                                */
        /*      w - write                                               */
        /*      o - old (file must exist)                               */
        /*      n - new (create a new file)                             */

        while ( (ch = *mode++) != NULLCH) {
                switch (ch) {

                    case 'r':   if (mbits&RF_MODE_R) {
                                        return SYSERR;
                                }
                                mbits |= RF_MODE_R;
                                continue;

                    case 'w':   if (mbits&RF_MODE_W) {
                                        return SYSERR;
                                }
                                mbits |= RF_MODE_W;
                                continue;

                    case 'o':   if (mbits&RF_MODE_O || mbits&RF_MODE_N) {
                                        return SYSERR;
                                }
                                mbits |= RF_MODE_O;
                                break;

                    case 'n':   if (mbits&RF_MODE_O || mbits&RF_MODE_N) {
                                        return SYSERR;
                                }
                                mbits |= RF_MODE_N;
                                break;

                    default:    return SYSERR;
                }
        }

        /* If neither read nor write specified, allow both */

        if ( (mbits&RF_MODE_RW) == 0 ) {
                mbits |= RF_MODE_RW;
        }
        return mbits;
}