Post by thread:[PIC:] square root functions in archive

Is anyone using the 24 bit or 32 bit square root functions in the archives? After struggling with the syntax, I have it working with my assembler, but I don't get the right answers. Perhaps I've bungled the conversion..... -- Bryan Mumford Mumford Micro Systems spam_OUTbryanTakeThisOuTbmumford.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

On Thu, 20 Nov 2003, Bryan Mumford wrote: > Is anyone using the 24 bit or 32 bit square root functions in the > archives? After struggling with the syntax, I have it working with my > assembler, but I don't get the right answers. Perhaps I've bungled > the conversion..... Hi Bryan, I got your messages earlier... As you know, Andy David wrote those routines and not me. However, his 32-bit routine is based upon my 16-bit routine. Also, he targeted the 17C43. A few months someone asked about a 32-bit square root routine, so like Andy I ported my 16-bit routine. I'm not sure if Andy's routine is correct or not, but I have tested mine and it certainly works for several test cases (i.e. I haven't performed a brute-forced check of all 2^32 inputs). I'm also hesitant to release the code because it has no comments at all. If you're willing to live with that then here it is: http://www.dattalo.com/technical/software/pic/sqrt_32bit.asm Scott -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam@spam@mitvma.mit.edu with SET PICList DIGEST in the body

Hi Bryan, The 24- and 32-bit routines of mine in the archive do work correctly as far as I'm aware although, like Scott, I have not tested all cases. If you need a 32-bit sqrt I recommend reading Scott's pages and developing code from that, all the sqrt code I wrote was based on Scott's code and algorithm descriptions. You might also want to have a look at John Power's work at http://www.bcpl.net/~jpower/fastsqrt.pdf. - Andy. > {Original Message removed}

I've used the square root routines out of the archive successfully. One thing to watch out for with any code out of the archive is what processor core they were written for. There are several differences in flag results between the 16 and 18 series cores. I've gotten messed up by these before. So, look for any line of code that checks a flag and look at the few instructions ahead of it. The code may count on some instruction not affecting flags while the 18 instruction does affect flags. Look especially at incf and decf instructions. Good luck! Harold {Quote hidden}> Hi Bryan, > > The 24- and 32-bit routines of mine in the archive do work correctly as > far > as I'm aware although, like Scott, I have not tested all cases. If you > need > a 32-bit sqrt I recommend reading Scott's pages and developing code from > that, all the sqrt code I wrote was based on Scott's code and algorithm > descriptions. You might also want to have a look at John Power's work at > http://www.bcpl.net/~jpower/fastsqrt.pdf. > > > - Andy. > >> {Original Message removed}