--- layout: fc_discuss_archives title: Message 3 from Frama-C-discuss on February 2010 ---
Hello Boris, Le lun. 01 f?vr. 2010 13:29:59 CET, "Hollas Boris (CR/AEY1)" <Boris.Hollas at de.bosch.com> a ?crit : > We have applications where we do arithmetics in GF(2^32). This is easily done with unsigned integers and the standard operations +, *. However, Jessie isn't able to verify arithmetic safety because it doesn't know that we want to compute in GF(2^32). For example, nothing bad can happen in this code > You can tell Jessie to use modulo arithmetic (2^n where n depends on the C type of the result) with a pragma: #pragma JessieIntegerModel(modulo) See section 7.4 of user manual for more information about the various representations of C ints that can be used by Jessie. In modulo mode, C int operations are treated as modulo operations, so that you don't have proofs obligations related to overflows. Note however that automated theorem provers are usually quite bad at dealing with modulo arithmetic, so that you might experience some difficulties proving your specifications. Hope this helps, -- E tutto per oggi, a la prossima volta. Virgile