source: buchla-68k/libsm/strspn.c@ 7258c6a

/*
   ============================================================================
        strspn.c -- string scan function ala' Unix(tm)
        Version 2 -- 1987-06-12 -- D.N. Lynx Crowe

        Return the number of characters in the maximum leading segment
        of 'string' which consists solely of characters from 'charset'.
   ============================================================================
*/

int16_t strspn(int8_t *string, int8_t *charset)
{
        register int8_t *p, *q;
        register int16_t n = 0;

        for (q = string; *q != '\0'; ++q) {

                for (p = charset; *p != '\0' && *p != *q; ++p)
                        ;

                if(*p == '\0')
                        break;

                n++;
        }

        return(n);
}