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+-------------------------------------------------------------------------------
+-- Module     : mux2to1
+-------------------------------------------------------------------------------
+-- Author     : Johann Faerber
+-- Company    : University of Applied Sciences Augsburg
+-------------------------------------------------------------------------------
+-- Description: 2-to-1 multiplexer
+--              function modelled as structure of basic logic gates
+-------------------------------------------------------------------------------
+-- Revisions  : see end of file
+-------------------------------------------------------------------------------
+LIBRARY IEEE;
+USE IEEE.std_logic_1164.ALL;
+
+ENTITY mux2to1 IS
+  PORT (a_i   : IN  std_ulogic;         -- data input a
+        b_i   : IN  std_ulogic;         -- data input b
+        sel_i : IN  std_ulogic;         -- select which input is connected to y
+        -- sel = '1': a -> y
+        -- sel = '0': b -> y
+        y_o   : OUT std_ulogic          -- data output y
+        );
+END mux2to1;
+
+ARCHITECTURE structure OF mux2to1 IS
+
+  COMPONENT invgate
+    PORT (
+      a_i : IN  std_ulogic;
+      y_o : OUT std_ulogic);
+  END COMPONENT;
+
+  COMPONENT and2gate
+    PORT (
+      a_i : IN  std_ulogic;
+      b_i : IN  std_ulogic;
+      y_o : OUT std_ulogic);
+  END COMPONENT;
+
+  COMPONENT or2gate
+    PORT (
+      a_i : IN  std_ulogic;
+      b_i : IN  std_ulogic;
+      y_o : OUT std_ulogic);
+  END COMPONENT;
+
+  SIGNAL p0, p1  : std_ulogic;
+  SIGNAL p2 : std_ulogic;
+  
+BEGIN
+
+  inv_gate_1 : invgate
+    PORT MAP (
+      a_i => sel_i,
+      y_o => p2);
+
+  and2_gate_1 : and2gate
+    PORT MAP (
+      a_i => a_i,
+      b_i => sel_i,
+      y_o => p0);
+
+  and2_gate_2 : and2gate
+    PORT MAP (
+      a_i => b_i,
+      b_i => p2,
+      y_o => p1);
+
+  or2_gate_1 : or2gate
+    PORT MAP (
+      a_i => p0,
+      b_i => p1,
+      y_o => y_o);
+
+--  inv_gate_1 : invgate PORT MAP (sel_i, p2);
+
+--  and2_gate_1 : and2gate PORT MAP (a_i, sel_i, p0);
+
+--  and2_gate_2 : and2gate PORT MAP (b_i, p2, p1);
+
+--  or2_gate_1 : or2gate PORT MAP (p0, p1, y_o);
+
+END structure;
+
+-------------------------------------------------------------------------------
+-- Revisions:
+-- ----------
+-- $Id:$
+-------------------------------------------------------------------------------
+