VHDL语言设计4选1多路选择器讲解学习

1、VHDL语言设计4选1多路选择器4选1多路选择器的VHDL描述要求：THEN语句和CASE语句实现4选1多路选择器，其中选择控制信号si和s0的数据类型为STD_LOGIC_VECTORs仁?O?,sO=?O?;s仁?O?,sO=?1?;s1=?1?,sO=?O?和s仁？1?,sO=?1?时,分别执行y<=a、yv=b、yv=c、yv=d。一、解法1:用IF_THEN语句实现4选1多路选择器(1)程序：LIBRARYIEEE;USEIEEE.STD_LOGIC_1164.ALL;ENTITYmux41ISPORT(a,b,c,d:INSTD_LOGIC;sO:INSTD_LOGIC;s1

2、:INSTD_LOGIC;y:OUTSTD_LOGIC);ENDENTITYmux41;ARCHITECTUREif_mux41OFmux41ISSIGNALsOs1:STD_LOGIC_VECTOR(1DOWNTO0)定义标准逻辑位矢量数据BEGINsOs1<=s1&s0;-s1相并sO,即s1与sO并置操作PROCESS(sOs1,a,b,c,d)BEGINIFsOs1="00"THENy<=a;ELSIFs0s1="01"THENy<=b;ELSIFs0s1="10"THENy<=c;ELSEy&

3、lt;=d;ENDIF;ENDPROCESS;ENDARCHITECTUREif_mux41;(2)编译的结果如下：_1LIBRARYZUSEIEEE2rTD_L0GTC_l.l石岂ALL；3 3EWTITYttittK41lS3SPORT(引46*IN5TD_LOfJIC；5 5U；INSTP_LOGIC；6 31：INSTOGIC：7 y：OUT号TdIlOGM):aEMDENTITYmux41;:ARCHITECTUREl£_mux41OFntuxaISSIGMALsOsl:STD_LOGIC_VECTOR(1DOUWTO0)；定义标准逻辑位矢虽数据BBEGINgOsKglts

4、O;s上相并即R与如并査操柞PROCESSs口slra.tocr,d)8EGINSIFsOst=J|00»THENy<=a;ISS!ELSIFsOsl=f,mrrTHENy«h;17BELSIFsOsl=M10r,THENy<=c;.ELSEy<-d;3EMbTFEHDPROCESS;EWPARCHITECTURE22编译报告:FlowStatus.Succsssfiil-!lonMiyZ32:24:40201&QuartusIIVersion90Buili13202/25/2009S5FullVersicnReisiomNamemix4iTop-

5、levelEntityNamen*ux4iFamilyFLEK1CKDeviceErF10KIQlJCa4-4TimingFinfcl用包七timlugrequirenexiteYesTot1®番iuents2/7T6(<1)TotalpinsTF阴12慕TotalmemorybiIs0/6.144(D%)二、解法2:用CASEg句实现4选1多路选择器(1)程序：LIBRARYIEEE;USEIEEE.STD_LOGIC_1164.ALL;ENTITYmux41ISPORT(a,b,c,d:INSTD_LOGIC;sO:INSTD_LOGIC;s1:INSTD_LOGIC;y:

6、OUTSTD_LOGIC);ENDENTITYmux41;ARCHITECTUREcase_mux41OFmux41ISSIGNALs0s1:STD_LOGIC_VECTOR(1DOWNTO0)定义标准逻辑位矢量数据类型BEGINs0s1<=s1&s0;-s1相并s0,即s1与s0并置操作PROCESS(s0s1,a,b,c,d)BEGINCASEs0s1IS-类似于真值表的case语句WHEN"00"=>y<=a;WHEN"01"=>y<=b;WHEN"10"=>y<=c;WHEN&

7、quot;11"=>y<=d;WHENOTHERS=>NULL;ENDCASE;ENDPROCESS;ENDcase_mux41;(2)编译结果：1 LTBRARVIEEE;2 USEIEEE,STDLOGICi151.ALL;3 jENTITYK1UK41IS4 SPORT(aftorcrd：INSTD_LOGIC；5 sn：INSTD_LCX；IC;6 51；INTTDLOGTC；7 y：OUTSTDLOGIC)；8 ENDENTITY-H1UX41；9 ARCHITECTUREcase_wux4iOFi»ld<41ISSIGNALsosl:5T

8、DLOGIC_VECTOR(1DOWNTO口心-定文标准逻辑位矢區数据类型/：BEGIN2031<=Sl£sa；_ml相并"0rWsl与兰并萱燥件HPROCESS(snslrarbrefri)BEGIM15CASEsOslIS斐馆于克值恚的c*匕语旬ieWHENf,aoif->y5a;17WHENf,0i,F=>y<-b;!WHEN"1口“三Ay<=c;19WHENrrllFTFya=d;20WHENOTHERS=AHULL；21EWD匚ASE;EMDPROCESS;ENDcase_inux41;24编译报告：Flo*StatusSucceKifvlMonfflfcy232231:5520fEQuartusIIVersion9.0Btiild13202/25/20MSTlullVersionRevi'sicinNamemux41ToplavalIntityNwnawux-41Fa