Command Reference    2.  Synopsys Commands         set_logic_zero



NAME
          set_logic_zero Specifies that an input port is driven
                         by logic 0.  The set_logic_one command
                         is used the same way as this command.
                         Details for both commands are provided
                         below.


SYNTAX
          int set_logic_zero port_list

          int  set_logic_one port_list


          list port_list


ARGUMENTS
          port_list      List of port names of the current
                         design.  If more than one port is
                         specified, they must be included in
                         braces ({}).


DESCRIPTION
          Specifies that input ports are driven by logic 1 or
          logic 0.  This information is used to create smaller
          designs during compile.  After optimization, a port
          connected to logic 1 or logic 0 usually does not drive
          anything inside the optimized design.  The
          set_logic_one and set_logic_zero commands can be used
          only on input ports.  Output ports can be specified as
          unused with the set_unconnected command.

          The set_logic_one command places a driven_by_logic_one
          attribute on a port.  The set_logic_zero command
          assigns a driven_by_logic_zero attribute to a port.
          You may not set a port to both logic 1 and logic 0.

          Use the remove_attribute command to remove these
          attributes.


EXAMPLES
          The following commands are issued to drive input ports
          "A" and "B" by logic 0, and input port "C" by logic 1:


                         dc_shell> set_logic_zero { A B }

                         dc_shell> set_logic_one C




V3.1      Synopsys Inc. 1988-1994. All rights reserved.     2-357

set_logic_zero       2.  Synopsys Commands      Command Reference



SEE ALSO
          find(2), get_attribute(2), remove_attribute(2),
          report(2), reset_design(2), set_unconnected(2).




















































2-358     Synopsys Inc. 1988-1994. All rights reserved.      V3.1