Sun, 15 Nov 1992 16:39:06 GMT

Related articles |
---|

Modulo n arithmetics fabre@gr.osf.org (Christian Fabre) (1992-11-06) |

Re: Modulo n arithmetics pardo@cs.washington.edu (1992-11-10) |

Re: Modulo n arithmetics drclark@daisy.uwaterloo.ca (David R. Clark) (1992-11-11) |

Re: Modulo n arithmetics dneedham@oucsace.cs.ohiou.edu (1992-11-11) |

Modulo n arithmetics wchsieh@beethoven.lcs.mit.edu (1992-11-11) |

Re: Modulo n arithmetics wendt@CS.ColoState.EDU (1992-11-15) |

Re: Modulo n arithmetics johnr@ee.uts.edu.au (1992-11-17) |

Re: Modulo n arithmetics chris@gargoyle.uchicago.edu (1992-11-19) |

Re: Modulo n arithmetics tve@crackle.CS.Berkeley.EDU (1992-11-20) |

Re: Modulo n arithmetics pcg@aber.ac.uk (1992-11-29) |

Newsgroups: | comp.compilers |

From: | wendt@CS.ColoState.EDU (alan l wendt) |

Organization: | Colorado State University, Computer Science Department |

Date: | Sun, 15 Nov 1992 16:39:06 GMT |

Followup-To: | comp.programming |

Keywords: | arithmetic |

References: | 92-11-029 92-11-043 |

Speaking of modulo-n buffering systems. This is really the wrong group

but I cannot help mentioning that the traditional head-and-tail pointer

technique for circular buffering is the wrong way to do it. The problem

is that head==tail can mean that the queue is empty or that the queue is

full, so most implementations waste a queue entry so that the queue never

really gets full.

If the algorithm maintains the queue head pointer and the queue length,

instead of head and tail, the two cases can be disambiguated easily!

Horowitz & Sahni (Fundamentals of Computer Algorithms) suggest that one

might maintain an additional boolean to disambiguate the two situations,

which I take as evidence that this idea is not widely disseminated.

Alan Wendt

--

Post a followup to this message

Return to the
comp.compilers page.

Search the
comp.compilers archives again.