Path: utzoo!utgpu!attcan!uunet!lll-winken!lll-tis!helios.ee.lbl.gov!pasteur!ames!nrl-cmf!mailrus!cornell!uw-beaver!uw-june!pardo
From: pardo@june.cs.washington.edu (David Keppel)
Newsgroups: comp.lang.misc
Subject: Re: Row/Column Major Definition and History?
Keywords: arrays, row major, column major, history, definition
Message-ID: <5632@june.cs.washington.edu>
Date: 2 Sep 88 18:41:39 GMT
References: <16512@apple.Apple.COM>
Reply-To: pardo@uw-june.UUCP (David Keppel)
Organization: U of Washington, Computer Science, Seattle
Lines: 37

malcolm@Apple.COM (Malcolm Slaney) writes:
>[ Arrays: row- and column-major.  Whuzzat? ]

Reference: _The Theory and Practice of Compiler Writing_ by Jean-Paul
Tremblay and Paul G. Sorenson.  McGraw-Hill, 1985.  pg 574.

Idea: Memory is just a 1-dimensional array.  If we want a 2-d array,
we need to make a map from the 2-d "name" (e.g., A[2,3]) to the actual
1-d location.  Row- and column-major are just slighly different ways
of doing the mapping.

Consider:

	A[4..6,2..3] of two-byte

It can be laid out starting at addres 1010 as:

	1010 <4,2>
	1012 <4,3>
	1014 <5,2>
	1016 <5,3>
	1018 <6,2>
	1020 <6,3>

or as

	1010 <4,2>
	1012 <5,2>
	1014 <6,2>
	1016 <4,3>
	1018 <5,3>
	1020 <6,3>


    ;-D on  ( Help! my my commanding officer is row-major! )  Pardo
-- 
		    pardo@cs.washington.edu
    {rutgers,cornell,ucsd,ubc-cs,tektronix}!uw-beaver!june!pardo