Function rInit

Singular/ipshell.cc:5620–6009

/////////////// rInit itself: INPUT: pn: ch & parameter (names), rv: variable (names) ord: ordering (all !=NULL) RETURN: currRingHdl on success NULL on error NOTE: * makes new ring to current ring, on success considers input sleftv's as read-only

// NOTE:   * makes new ring to current ring, on success
//         * considers input sleftv's as read-only
ring rInit(leftv pn, leftv rv, leftv ord)
{
  int float_len=0;
  int float_len2=0;
  ring R = NULL;
  //BOOLEAN ffChar=FALSE;

  /* ch -------------------------------------------------------*/
  // get ch of ground field

  // allocated ring
  R = (ring) omAlloc0Bin(sip_sring_bin);

  coeffs cf = NULL;

  assume( pn != NULL );
  const int P = pn->listLength();

  if (pn->Typ()==CRING_CMD)
  {
    cf=(coeffs)pn->CopyD();
    leftv pnn=pn;
    if(P>1) /*parameter*/
    {
      pnn = pnn->next;
      const int pars = pnn->listLength();
      assume( pars > 0 );
      char ** names = (char**)omAlloc0(pars * sizeof(char_ptr));

      if (rSleftvList2StringArray(pnn, names))
      {
        WerrorS("parameter expected");
        goto rInitError;
      }

      TransExtInfo extParam;

      extParam.r = rDefault( cf, pars, names); // Q/Zp [ p_1, ... p_pars ]
      for(int i=pars-1; i>=0;i--)
      {
        omFree(names[i]);
      }
      omFree(names);

      cf = nInitChar(n_transExt, &extParam);
    }
    assume( cf != NULL );
  }
  else if (pn->Typ()==INT_CMD)
  {
    int ch = (int)(long)pn->Data();
    leftv pnn=pn;

    /* parameter? -------------------------------------------------------*/
    pnn = pnn->next;

    if (pnn == NULL) // no params!?
    {