64位计算机上的无符号128位除法 [英] Unsigned 128-bit division on 64-bit machine

问题描述

我有一个128位数字存储为2个64位数字（ Hi和 Lo）。我只需要将其除以32位数字即可。我该怎么做，使用CPU的本机64位操作？

I have a 128-bit number stored as 2 64-bit numbers ("Hi" and "Lo"). I need only to divide it by a 32-bit number. How could I do it, using the native 64-bit operations from CPU?

（请注意，我不需要任意精度库。只需要知道如何

(Please, note that I DO NOT need an arbitrary precision library. Just need to know how to make this simple division using native operations. Thank you).

推荐答案

如果您使用以下方式存储值（128位），

If you are storing the value (128-bits) using the largest possible native representation your architecture can handle (64-bits) you will have problems handling the intermediate results of the division (as you already found :) ).

但是，您的体系结构可以处理的最大本机表示形式（64位）在处理除法的中间结果时会遇到问题。您总是可以使用SMALLER表示形式。那四位数的32位呢？这样，您可以使用本机64位操作而不会出现溢出问题。

But you always can use a SMALLER representation. What about FOUR numbers of 32-bits? This way you could use the native 64-bits operations without overflow problems.

一个简单的实现（在Delphi中）可以在此处。

A simple implementation (in Delphi) can be found here.

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