Article View: comp.sys.mac
Article #13769Re: Large (> 32K) arrays
From: David W. Berry
Date: Thu, 11 Dec 1986 14:56
Date: Thu, 11 Dec 1986 14:56
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1650 bytes
Actually, you can create arrays bigger than 32K, they just can't be in your global data. Due to the lack of memory mapping hardware on the mac, and the desire to make programs and data 100% relocatable, global data is accessed with a negative index off of a5. Since the 68000 can't handle anything other than 16 bit offsets real easily you can';t yet have a global data space larger than 32K. If someone where to write some really slick code you could still do it, it would be kinda troublesome and some of the data wouldn't be as readily accesible: move.l #offset,d0 move.l 0(a5,d0.l),d0 instead of: move.l #offset(a5),d0 Then again, apple probably limited the size of the global data area to a word thinking that nobody needs more global data than that and nobody would go to that much trouble in a compiler... If you need a large array, allocate it using NewPtr or NewHandle and go from there. -- David W. Berry dwb@well.uucp dwb@Delphi dwb@GEnie 293-0752@408.MaBell
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Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: arc1-ca.pugleaf.net!utzoo!mnetor!seismo!lll-crg!lll-lcc!well!dwb From: dwb@well.UUCP (David W. Berry) Newsgroups: comp.sys.mac Subject: Re: Large (> 32K) arrays Message-ID: <2196@well.UUCP> Date: Thu, 11-Dec-86 09:56:30 EST Article-I.D.: well.2196 Posted: Thu Dec 11 09:56:30 1986 Date-Received: Sat, 13-Dec-86 22:06:55 EST References: <164500006@uiucdcsb> <1783@batcomputer.tn.cornell.edu> Reply-To: dwb@well.UUCP (David W. Berry) Organization: Whole Earth Lectronic Link, Sausalito CA Lines: 24 Summary: Just can't be in the global data segment