text: /* ISC license. */
  
  #include <skalibs/fmtscan.h>
  
  unsigned int ucharn_scan (char const *s, char *key, unsigned int n)
  {
    register unsigned int i = 0 ;
    for (; i < n ; i++)
    {
      unsigned char c = fmtscan_num(s[2*i], 16) ;
      if (c > 0xF) return 0 ;
      key[i] = c << 4 ;
      c = fmtscan_num(s[2*i+1], 16) ;
      if (c > 0xF) return 0 ;
      key[i] += c ;
    }
    return n << 1 ;
  }
  