Re: [ping][patch] Fixed-point patch 2/10

[Nigel Stephens <nigel at mips dot com>]

Mark Mitchell wrote:
> Fu, Chao-Ying wrote:
>
>   
> > Ex 2: (A and B are negative. )
> > A.high = 0xffffffffffffffff and A.low = 0x8000000000000000
> > B.high = 0xffffffffffffffff and B.low = 0x0000000000000001
> > => A > B, 
> > because A.high == B.high and
> > (unsigned HOST_WIDE_INT) a.low > (unsigned HOST_WIDE_INT) b.low
> >     
>
> Yes, I see; two's complement is set up so that after masking the sign
> bit, you can do an unsigned compare.  Thank you for explaining.
>   

Since double_int is already declared with low unsigned, like this:

   typedef struct
   {
     unsigned HOST_WIDE_INT low;
     HOST_WIDE_INT high;
   } double_int;


Would it be more obvious to simply remove the casts altogether, e.g.

   double_int_scmp (double_int a, double_int b)
   {
     if (a.high < b.high)
       return -1;
     if (a.high > b.high)
       return 1;
     if (a.low < b.low)
       return -1;
     if (a.low > b.low)
       return 1;

     return 0;
   }



Nigel