Answers Database FPGA Express 3.x: Expression is ambiguous (VSS-501) Record #640 Product Family: Software Product Line: Synopsys Product Part: FPGA Express Product Version: 2.1.1 Problem Title: FPGA Express 3.x: Expression is ambiguous (VSS-501) Problem Description: Urgency: Standard General Description: FPGA Express no longer requires conversion functions to convert from HEX or OCTAL values to std_logic_vectors. These functions are found in the STD_LOGIC_1164 library and the previous requirements are described in (Xilinx Solution 4376). However, the use of these conversion functions will lead to a Synopsys error when checking syntax: Error L29/C0 : #0 Error: C:/path/mydesign.vhd line 29 Expression is ambiguous. (VSS-501) This error is most frequently seen after having upgraded from FPGA Express v2.x to v3.x. Solution 1: Remove the explicit call to the conversion function. For example: dout <= to_stdlogicvector(X"F0"); should be edited to simply: dout <= (X"F0"); The parenthesis are optional, but are okay to leave in. This will allow users to globally search and replace the offending conversion function. "To_X01" is another such conversion. End of Record #640 - Last Modified: 03/17/99 13:46

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