电子设计自动化四讲.ppt

* * * * * * * * * * * * 电子与通信工程系 * 条件信号赋值语句的格式为： 目标信号＜＝表达式1 WHEN 条件1 ELSE 表达式2 WHEN 条件2 ELSE 表达式3 WHEN 条件3 ELSE ┆ 表达式n WHEN 条件n ELSE 表达式n+1； （2）条件信号赋值语句 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 电子与通信工程系 * library ieee; use ieee.std_logic_1164.all; entity mux4 is port(a0,a1,a2,a3:in std_logic; s: in std_logic_vector(1 downto 0); y: out std_logic); end mux4; architecture dataflow of mux4 is begin y=a0 when s=“00” else a1 when s=“01” else a2 when s=“10” else a3; end dataflow; Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 电子与通信工程系 * RTL Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 电子与通信工程系 * library ieee; use ieee.std_logic_1164.all; entity encoder_1 is port(a,b,c,d,e,f,g,h:in std_logic; codeout: out std_logic_vector(2 downto 0)); end encoder_1; architecture behavioral of encoder_1 is begin codeout=111 when h=1 else 110 when g=1 else 101 when f=1 else 100 when e=1 else 011 when d=1 else 010 when c=1 else 001 when b=1 else 000 when a=1 else ZZZ; end behavioral; IF语句 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 电子与通信工程系 * Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 电子与通信工程系 * 选择型信号赋值语句的格式为： WITH 表达式 SELECT 目标信号＜＝表达式1 WHEN 条件1, 表达式2 WHEN 条件2, 表达式3 WHEN