Thu, 10 Feb 1994 22:36:29 GMT

Related articles |
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Frequency of integer division in source code? Peter-Lawrence.Montgomery@cwi.nl (1994-02-07) |

Re: Frequency of integer division in source code? hbaker@netcom.com (1994-02-08) |

Re: Frequency of integer division in source code? meissner@osf.org (1994-02-09) |

Re: Frequency of integer division in source code? tfj@apusapus.demon.co.uk (1994-02-10) |

Re: Frequency of integer division in source code? glew@ichips.intel.com (1994-02-11) |

Re: Frequency of integer division in source code? bazyar@netcom.com (1994-02-10) |

Re: Frequency of integer division in source code? cliffc@dawn.cs.rice.edu (1994-02-14) |

Re: Frequency of integer division in source code? chase@Think.COM (1994-02-15) |

Re: Frequency of integer division in source code? pardo@cs.washington.edu (1994-02-17) |

Newsgroups: | comp.compilers |

From: | tfj@apusapus.demon.co.uk (Trevor Jenkins) |

Keywords: | architecture, optimize |

Organization: | Don't put it down; put it away! |

References: | 94-02-058 |

Date: | Thu, 10 Feb 1994 22:36:29 GMT |

meissner@osf.org writes:

*>Another place where division (actually modulus) is used quite*

*>frequently is in calculating hash tables, which often involves modulus*

*>by a prime number constant. This of course lends itself nicely to*

*>being replaced by multiplication.*

Better yet is not to be mis-lead by Maurer's paper and to ignore his

advice by using a table whose size is a power of two. Then the integer

divide becomes an AND operation which is faster that division or

multiplication on almost all architectures.

The ``theory'' of using powers of two is explained in various papers by

Hopgood et all from the late-60/early-70s.

--

Regards, Trevor.

---------------------------------------------------------------------------

Trevor Jenkins

134 Frankland Rd, Croxley Green, RICKMANSWORTH, WD3 3AU, England

email: tfj@apusapus.demon.co.uk phone: +44 (0)923 776436 radio: G6AJG

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