We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

AR# 14110

4.1i XST - A compound Boolean equation in XST will occasionally produce incorrect results


Keywords: Boolean, VHDL, equation, result, wrong, incorrect, bad, logic

Urgency: Standard

General Description:
XST may produce incorrect results when coding a "complex" Boolean expression similar to the following:

boolean_out <= not A xor B = not A xor B;


This problem is fixed in the latest 4.2i Service Pack, available at:
The first service pack containing the fix is 4.2i Service Pack 1.
AR# 14110
Date Created 03/07/2002
Last Updated 08/06/2003
Status Archive
Type General Article