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Date: Tue, 02 Feb 1999 17:21:39 -0500
To: djgpp AT delorie DOT com
From: Paul Derbyshire <pderbysh AT usa DOT net>
Subject: Re: 64-bit integer math
In-Reply-To: <199902022009.PAA04565@envy.delorie.com>
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Reply-To: djgpp AT delorie DOT com

At 03:09 PM 2/2/99 -0500, you wrote:
>OK, I was close.  But, the 387 *can* be used as a 64-bit integer math
>unit, as it has 64-bit int load/store, and if all the numbers and
>results are 64-bit integers (i.e. be careful with division,
>multiplication, arctangents, etc), you can treat it like a 64-bit
>integer unit.
>
>It's not as fast as simulating it in the CPU though.

Really? "simulating" it? Is there no 64 bit (integer) multiply in the Intel
alu?

What is the best that an intel type chip can do for 64 bit int operations:
  Intel                                          Cyrix     AMD
  -- Pentium                                     -- 5x86?  K5?
  -- PPro              -- PPro MMX
  -- PII               -- PII MMX   --Celeron    -- 6x86   K6
  -- PIII

Also, is the 64 bit long long arithmetic provided by GCC invariably as fast
as 64 bit int arithmetic can ever be on a given platform? (Amortized,
assuming the bestpossible compile optimization -- e.g. PGCC on a Pent class
chip, with the best arch setting for the particular chip, e.g. -mamdK6.)

-- 
   .*.  "Clouds are not spheres, mountains are not cones, coastlines are not
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   `*'  straight line."    -------------------------------------------------
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_____________________ ____|________     Paul Derbyshire     pderbysh AT usa DOT net
Programmer & Humanist|ICQ: 10423848|