Good day to all. I had a look at the code at the Hacker's Delight website and was=20 sufficiently impressed to look for a copy. I'm in Canada and, as=20 usual, prices are higher than in the USA. However, Chapter Indigo=20 will sell me an eBook for Can $37 instead of Can $60 for the paper version. The problem with purchasing an eBook from Chapters is that it is=20 encumbered with Adobe DRM. I don't know if that means that it won't=20 work with my Sony eBook reader but I do know that I am restricted in=20 where and when I can read it. In particular, I want to be able to=20 seamlessly switch between copies on my work computer, my home=20 computer and my laptop. I have found a most likely illegal electronic copy on the web but I'd=20 rather purchase a legal copy and strip out the DRM protection. Can anyone point me in the direction as to how I might do that? Many thanks! dwayne At 12:07 PM 10/19/2012, Joe Mickley wrote: >:Mark > >Thank you for the pointer to the book. I went out this AM and bought a >copy. A little pricey, but there is a LOT >of stuff in there in additon to the divide info. I'm wading thru it right >now (lots of choices). I'll let the piclist >community know that I find out. > >Regards >Joe Mickley > >----- Original Message ----- >From: "Mark Rages" >To: "Microcontroller discussion list - Public." >Sent: Wednesday, October 17, 2012 3:42 PM >Subject: Re: [PIC] Fast 32 bit by 32 bit divide in a dsPIC30F > > > > On Wed, Oct 17, 2012 at 12:56 PM, Joe Mickley > > wrote: > >> I am using a dsPIC30F3012 (writing in ASM, not C) on a project with ve= ry > >> fast loop execution (<20 uSec in some cases) > >> and need an effecient 32 bit by 32 bit unsigned divide algorithm. The > >> dsPIC30F family has organic 16 by 16 divide > >> instruction (DIV.U and DIV.UD) and I would like to create a 32 by 32 > >> using > >> that instruction set. > >> > >> The traditional 32 by 32 divide using a shift/subtract (restoring) > >> algorithms is slow (about 400 instruction cycles nominal). It > >> should be possible to break the 32 by 32 into a set of 16 by 16 > >> operations, > >> then combine the partials back into a 32 by 32 > >> result, but I lack the knowledge of how to do or drive this. The > >> dsPIC30F > >> divide routine is fast (18 cycles, so > >> any use of itshould have a marked improvement) > >> > >> I need an unsigned divide, but could live with a signed divide as the > >> magnitude of numbers I am working with are less than > >> 2^30. Remainder or lack of is not critical. If I need it I could der= ive > >> a > >> remainder externally to the routine. > > > > This is discussed in Section 9-2 of Hacker's Delight, 2nd edition. It > > is a page and a half of C code. > > > >>From the book: "The details are surprisingly complicated." > > > > You can read the code if go to the book's page at Amazon and "search > > inside this book" for "Multiword Division". But buy the book if you > > can. > > > > -- > > Regards, > > Mark > > markrages@gmail > > -- > > http://www.piclist.com PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist > >-- >http://www.piclist.com PIC/SX FAQ & list archive >View/change your membership options at >http://mailman.mit.edu/mailman/listinfo/piclist --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .