Post by thread:Looking for a signed addtion routine

part 0 767 bytes content-type:application/octet-stream;In http://www.piclist.com/faq was no routine that treats this problem. In AN701 you find an algorithm to calculate the integral part of an PID-control. But there Brett Duane dont proof the overflow !! Any suggestions? Martin ;********************************************** ;** name: Martin Schaefer ** ;** company: elektronik 21 GmbH, Germany ** ;** e-mail: spam_OUTschaeferTakeThisOuTelektronik21.de ** ;********************************************** <<Martin SchŠfer.vcf>> Content-Type: application/octet-stream; name="Martin SchŠfer.vcf" Content-Disposition: attachment; filename="Martin SchŠfer.vcf" Attachment converted: definition:Martin Sch=fer.vcf 1 (????/----) (0000E3F7)

At 10:49 PM 4/10/00 +0200, you wrote: >If one wants to add two numbers, this is really simple - even in 32 Bit :-) >But I'm looking for a 2th complement signed routine (8,16,24 bit). The >difficulty >there is to see an overflow. The carry-flag is not indicating an overflow >(add 0x7F and 0x7F) ! One way: 1) If the numbers have different signs, no overflow is possible, you don't need to check it. 2) If the numbers have the same sign, and the sign of the result is different, then there has been an overflow. Tres simple, non? Best regards, =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Spehro Pefhany --"it's the network..." "The Journey is the reward" .....speffKILLspam@spam@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=