Annotation of 43BSD/contrib/icon/lib/field.c, revision 1.1

1.1     ! root        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:    }

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