1: #include "../h/rt.h"
   2: 
   3: /*
   4:  * x ** y - intersection of csets x and y or of sets x and y.
   5:  */
   6: 
   7: inter(nargs, arg2, arg1, arg0)
   8: int nargs;
   9: struct descrip arg2, arg1, arg0;
  10:    {
  11:    DclSave
  12:    register int i;
  13:    union block *bp;
  14:    int *cs1, csbuf1[CSETSIZE], *cs2, csbuf2[CSETSIZE];
  15:    extern struct b_cset *alccset();
  16: #ifdef SETS
  17:    struct descrip *dp;
  18:    struct b_set *srcp, *tstp, *dstp;
  19:    struct b_selem *sep;
  20:    extern struct b_set *alcset();
  21:    extern struct b_selem *alcselem();
  22: #endif SETS
  23: 
  24:    SetBound;
  25: #ifdef SETS
  26:    DeRef(arg1)
  27:    DeRef(arg2)
  28:    if (QUAL(arg1) || QUAL(arg2))
  29:       goto skipsets;
  30:    if (TYPE(arg1) == T_SET && TYPE(arg2) != T_SET)
  31:       runerr(119,&arg2);
  32:    if (TYPE(arg2) == T_SET && TYPE(arg1) != T_SET)
  33:       runerr(119,&arg1);
  34:    if (TYPE(arg1) == T_SET && TYPE(arg2) == T_SET) {
  35:       /*
  36:        * Both x and y are sets - do set intersection
  37:        *  get enough space for a new set the size of the smaller
  38:        *  of the two sets.
  39:        */
  40:       hneed(sizeof(struct b_set) + MIN(BLKLOC(arg1)->set.setsize,
  41:          BLKLOC(arg2)->set.setsize) * sizeof(struct b_selem));
  42:       /*
  43:        * Using the smaller of the two sets as the source
  44:        *  copy directly into the result each of its elements
  45:        *  that are also members of the other set.
  46:        */
  47:       if (BLKLOC(arg1)->set.setsize <= BLKLOC(arg2)->set.setsize) {
  48:          srcp = (struct b_set *) BLKLOC(arg1);
  49:          tstp = (struct b_set *) BLKLOC(arg2);
  50:          }
  51:       else {
  52:          srcp = (struct b_set *) BLKLOC(arg2);
  53:          tstp = (struct b_set *) BLKLOC(arg1);
  54:          }
  55:       arg0.type = D_SET;
  56:       dstp = alcset();
  57:       BLKLOC(arg0) = (union block *) dstp;
  58:       for (i = 0; i < NBUCKETS; i++) {
  59:          sep = (struct b_selem *) BLKLOC(srcp->sbucks[i]);
  60:          dp = &dstp->sbucks[i];
  61:          while (sep != NULL) {
  62:             if (locate(BLKLOC(tstp->sbucks[i]), sep)) {
  63:                dp->type = D_SELEM;
  64:                BLKLOC(*dp) = (union block *) alcselem(&sep->setmem, sep->hnum);
  65:                dp = &BLKLOC(*dp)->selem.sblink;
  66:                dstp->setsize++;
  67:                }
  68:             sep = (struct b_selem *) BLKLOC(sep->sblink);
  69:             }
  70:          }
  71:       }
  72:       else {
  73:          skipsets:
  74: #endif SETS
  75:    hneed(sizeof(struct b_cset));
  76: 
  77:    /*
  78:     * x and y must be csets.
  79:     */
  80:    if (cvcset(&arg1, &cs1, csbuf1) == NULL)
  81:       runerr(104, &arg1);
  82:    if (cvcset(&arg2, &cs2, csbuf2) == NULL)
  83:       runerr(104, &arg2);
  84: 
  85:    /*
  86:     * Allocate a new cset and in each word of it, compute the value
  87:     *  of the bitwise intersection of the corresponding words in the
  88:     *  x and y csets.
  89:     */
  90:    bp = (union block *) alccset();
  91:    for (i = 0; i < CSETSIZE; i++)
  92:       bp->cset.bits[i] = cs1[i] & cs2[i];
  93: 
  94:    arg0.type = D_CSET;
  95:    BLKLOC(arg0) = bp;
  96: #ifdef SETS
  97:    }
  98: #endif SETS
  99:    ClearBound;
 100:    }
 101: 
 102: Opblock(inter,2,"**")

Defined functions

inter defined in line 7; used 1 times
Last modified: 1984-11-18
Generated: 2016-12-26
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