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Annotation of 42BSD/ucb/lisp/franz/68k/exarith.c, revision 1.1

1.1     ! root        1: /* Copyright (c) 1982, Regents, University of California */
        !             2: struct vl      { long high; long low; };
        !             3: 
        !             4: /*
        !             5:  * $Header $
        !             6:  * exarith(mul1,mul2,add,hi,lo)
        !             7:  *
        !             8:  * (hi,lo) gets 64 bit product + sum of mul1*mul2+add;
        !             9:  * routine returns non-zero if product is bigger than 30 bits
        !            10:  */
        !            11: 
        !            12: long exarith(mul1,mul2,add,hi,lo)
        !            13: long *hi, *lo;
        !            14: register long add;
        !            15: {
        !            16:        struct vl work;
        !            17:        register long rlo;
        !            18: 
        !            19:            emul(mul1,mul2,add,&work);
        !            20:            add = work.high;
        !            21:            add <<= 2;
        !            22:            if((rlo = work.low) < 0) add += 2;
        !            23:            if(rlo & 0x40000000) add += 1;
        !            24:            *lo = rlo &0x3fffffff;
        !            25:            (*hi = add);
        !            26:            if((add==0) || (add!=-1)) return(add);
        !            27:            *lo = rlo;
        !            28:            return(0);
        !            29: }

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