Path: utzoo!utgpu!watserv1!watmath!att!linac!pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!wuarchive!uunet!overload!dillon From: dillon@overload.Berkeley.CA.US (Matthew Dillon) Newsgroups: comp.sys.amiga.tech Subject: Re: The Pure Bit... Message-ID: Date: 27 Nov 90 03:52:40 GMT References: <1990Nov22.142858.9900@canterbury.ac.nz> Lines: 39 In article <1990Nov22.142858.9900@canterbury.ac.nz> cctr120@canterbury.ac.nz (Brendon Wyber, C.S.C.) writes: >Hi, > > What exactly is the pure bit for. Many PD programs say that they have their >pure bit set and can be made resident, but what does that means since you can >set the pure bit on any file? > > If I was writing a program, what would I have to do so that I can say that it >is `legally' pure? > >Be seeing you, > >Brendon Wyber Computer Services Centre, >b.wyber@canterbury.ac.nz University of Canterbury, New Zealand. > >"Ph-nglui mglw'nafh Cthulhu R'lyeh wgah'nagl fhtagn." The pure bit tells AmigaDOS that the executable is 'residentable' .. multiple instances can be run using the same code image (i.e. shared code). The pure bit is set by the linker (specific example: Lattice's BLink and DICE's DLink) only when the executable is reentrant in this fashion. The pure bit should never be set manually, programs that are not residentable (pure bit not set) but forced resident are unreliable, even if only one instance of the program is run at a time. If you are talking about hunks, generally any program that contains a BSS or DATA hunk is *NOT* residentable and thus not usually pure. Residentable programs generally allocate their data/bss at run-time. -Matt -- Matthew Dillon dillon@Overload.Berkeley.CA.US 891 Regal Rd. uunet.uu.net!overload!dillon Berkeley, Ca. 94708 USA