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Annotation of 43BSD/contrib/icon/operators/null.c, revision 1.1.1.1

1.1       root        1: #include "../h/rt.h"
                      2: 
                      3: /*
                      4:  * /x - test x for null value.
                      5:  */
                      6: 
                      7: null(nargs, arg1, arg0)
                      8: int nargs;
                      9: struct descrip arg1, arg0;
                     10:    {
                     11:    DclSave
                     12:    SetBound;
                     13: 
                     14:    /*
                     15:     * If x is null, it is returned, otherwise, the function fails.
                     16:     *  Because the pre-dereference value of x is the return value (if
                     17:     *  any), x is copied into arg0.
                     18:     */
                     19:    arg0 = arg1;
                     20:    DeRef(arg1)
                     21:    if (!NULLDESC(arg1))
                     22:       fail();
                     23:    ClearBound;
                     24:    }
                     25: 
                     26: Opblock(null,1,"/")

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