4.3BSD - /usr/src/new/icon/lib/field.c

   1: #include "../h/rt.h"
   2: #include "../h/record.h"
   3: 
   4: /*
   5:  * x.y - access field y of record x.
   6:  */
   7: 
   8: field(nargs, arg2, arg1, arg0)
   9: int nargs;
  10: struct descrip arg2, arg1, arg0;
  11:    {
  12:    register int fnum;
  13:    register struct b_record *rp;
  14:    register struct descrip *dp;
  15:    extern int *ftab, *records;
  16: 
  17:    SetBound;
  18: 
  19:    DeRef(arg1)
  20:    /*
  21:     * x must be a record and y must be a field number.
  22:     */
  23:    if (QUAL(arg1) || TYPE(arg1) != T_RECORD)
  24:       runerr(107, &arg1);
  25:    if (QUAL(arg2) || TYPE(arg2) != T_INTEGER)
  26:       syserr("field: second operand not field number");
  27: 
  28:    /*
  29:     * Map the field number into a field number for the record x.
  30:     */
  31:    rp = (struct b_record *) BLKLOC(arg1);
  32:    fnum = ftab[INTVAL(arg2) * *records + rp->recptr->recnum - 1];
  33:    /*
  34:     * If fnum < 0, x doesn't contain the specified field.
  35:     */
  36:    if (fnum < 0)
  37:       runerr(207, &arg1);
  38: 
  39:    /*
  40:     * Return a pointer to the descriptor for the appropriate field.
  41:     */
  42:    dp = &rp->fields[fnum];
  43:    arg0.type = D_VAR + ((int *)dp - (int *)rp);
  44:    BLKLOC(arg0) = (union block *) dp;
  45:    ClearBound;
  46:    }

Defined functions