4.3BSD - /usr/src/new/icon/rt/cplist.c

   1: #include "../h/rt.h"
   2: 
   3: /*
   4:  * cplist(d1,d2,i,j) - copy sublist d1[i:j] into d2.
   5:  */
   6: 
   7: cplist(d1, d2, i, j)
   8: struct descrip *d1, *d2;
   9: int i, j;
  10:    {
  11:    register struct descrip *dp;
  12:    int size, nelem;
  13:    struct b_list *lp1, *lp2;
  14:    struct b_lelem *bp1, *bp2;
  15: 
  16:    /*
  17:     * Calculate the size of the sublist and fail if it's less than 0.
  18:     *  Also round nelem up to the minimum list block size.
  19:     */
  20:    size = nelem = j - i;
  21:    if (size < 0)
  22:       fail();
  23:    if (nelem < LISTBLKSIZE)
  24:       nelem = LISTBLKSIZE;
  25: 
  26:    /*
  27:     * Get pointers to the list and list elements for the source list
  28:     *  (bp1, lp1) and the sublist (bp2, lp2).
  29:     */
  30:    hneed(sizeof(struct b_list) + sizeof(struct b_lelem) +
  31:          nelem * sizeof(struct descrip));
  32:    lp1 = (struct b_list *) BLKLOC(*d1);
  33:    bp1 = (struct b_lelem *) BLKLOC(lp1->listhead);
  34:    lp2 = (struct b_list *) alclist(size);
  35:    bp2 = (struct b_lelem *) alclstb(nelem, 0, size);
  36:    lp2->listhead.type = lp2->listtail.type = D_LELEM;
  37:    BLKLOC(lp2->listhead) = BLKLOC(lp2->listtail) = (union block *) bp2;
  38:    dp = bp2->lslots;
  39: 
  40:    /*
  41:     * Locate the block containing element i in the source list.
  42:     */
  43:    if (size > 0) {
  44:       while (i > bp1->nused) {
  45:          i -= bp1->nused;
  46:          bp1 = (struct b_lelem *) BLKLOC(bp1->listnext);
  47:          }
  48:       }
  49: 
  50:    /*
  51:     * Copy elements from the source list into the sublist, moving to
  52:     *  the next list block in the source list when all elements in a
  53:     *  block have been copied.
  54:     */
  55:    while (size > 0) {
  56:       j = bp1->first + i - 1;
  57:       if (j >= bp1->nelem)
  58:          j -= bp1->nelem;
  59:       *dp++ = bp1->lslots[j];
  60:       if (++i > bp1->nused) {
  61:          i = 1;
  62:          bp1 = (struct b_lelem *) BLKLOC(bp1->listnext);
  63:          }
  64:       size--;
  65:       }
  66: 
  67:    /*
  68:     * Fix type and location fields for the new list.
  69:     */
  70:    d2->type = D_LIST;
  71:    BLKLOC(*d2) = (union block *) lp2;
  72:    }

Defined functions