reserch.vhd

VHDL编写的八位9值信号的中值输出方法

-- ********************************************  LIBRARY IEEE;
LIBRARY  ieee;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_ARITH.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
--*********************************************
ENTITY  reserch is
	PORT( 
        f_in                       :   IN   STD_LOGIC_VECTOR(7 DOWNTO 0);
        f_out                      :   OUT  STD_LOGIC_VECTOR(2 DOWNTO 0)
   		);
END reserch ;
--*********************************************
ARCHITECTURE A OF reserch IS
 BEGIN
   f_out<="000"   when f_in=0 else  --0
   "001"   when f_in=1 else         --1
   "001"   when f_in=2 else         --2
   "010"   when f_in=3 else
   "001"   when f_in=4 else
   "010"   when f_in=5 else
   "010"   when f_in=6 else
   "011"   when f_in=7 else
   "001"   when f_in=8 else
   "010"   when f_in=9 else
   "010"   when f_in=10 else
   "010"   when f_in=11 else
   "010"   when f_in=12 else
   "011"   when f_in=13 else
   "011"   when f_in=14 else
   "100"   when f_in=15 else
   "001"   when f_in=16 else
   "010"   when f_in=17 else
   "010"   when f_in=18 else
   "011"   when f_in=19 else
   "010"   when f_in=20 else
   "011"   when f_in=21 else
   "011"   when f_in=22 else
   "100"   when f_in=23 else
   "010"   when f_in=24 else
   "011"   when f_in=25 else
   "011"   when f_in=26 else
   "100"   when f_in=27 else
   "011"   when f_in=28 else
   "100"   when f_in=29 else
   "100"   when f_in=30 else
   "101"   when f_in=31 else
   "001"   when f_in=32 else
   "010"   when f_in=33 else
   "010"   when f_in=34 else
   "011"   when f_in=35 else
   "010"   when f_in=36 else
   "011"   when f_in=37 else
   "011"   when f_in=38 else
   "100"   when f_in=39 else
   "010"   when f_in=40 else
   "011"   when f_in=41 else
   "011"   when f_in=42 else
   "100"   when f_in=43 else
   "011"   when f_in=44 else
   "100"   when f_in=45 else
   "100"   when f_in=46 else
   "101"   when f_in=47 else
   "010"   when f_in=48 else
   "011"   when f_in=49 else
   "011"   when f_in=50 else
   "100"   when f_in=51 else
   "011"   when f_in=52 else
   "100"   when f_in=53 else
   "100"   when f_in=54 else
   "101"   when f_in=55 else
   "011"   when f_in=56 else
   "100"   when f_in=57 else
   "100"   when f_in=58 else
   "101"   when f_in=59 else
   "100"   when f_in=60 else
   "101"   when f_in=61 else
   "101"   when f_in=62 else
   "110"   when f_in=63 else
   "001"   when f_in=64 else
   "010"   when f_in=65 else
   "010"   when f_in=66 else
   "011"   when f_in=67 else
   "010"   when f_in=68 else
   "011"   when f_in=69 else
   "011"   when f_in=70 else
   "100"   when f_in=71 else
   "010"   when f_in=72 else
   "011"   when f_in=73 else
   "011"   when f_in=74 else
   "100"   when f_in=75 else
   "011"   when f_in=76 else
   "100"   when f_in=77 else
   "100"   when f_in=78 else
   "101"   when f_in=79 else
   "010"   when f_in=80 else
   "011"   when f_in=81 else
   "011"   when f_in=82 else
   "100"   when f_in=83 else
   "011"   when f_in=84 else
   "100"   when f_in=85 else
   "100"   when f_in=86 else
   "101"   when f_in=87 else
   "011"   when f_in=88 else
   "100"   when f_in=89 else
   "100"   when f_in=90 else
   "101"   when f_in=91 else
   "100"   when f_in=92 else
   "101"   when f_in=93 else
   "101"   when f_in=94 else
   "110"   when f_in=95 else
   "010"   when f_in=96 else
   "011"   when f_in=97 else
   "011"   when f_in=98 else
   "100"   when f_in=99 else
   "011"   when f_in=100 else
   "100"   when f_in=101 else
   "100"   when f_in=102 else
   "101"   when f_in=103 else
   "011"   when f_in=104 else
   "100"   when f_in=105 else
   "100"   when f_in=106 else
   "101"   when f_in=107 else
   "100"   when f_in=108 else
   "101"   when f_in=109 else
   "101"   when f_in=110 else
   "110"   when f_in=111 else
   "011"   when f_in=112 else
   "100"   when f_in=113 else
   "100"   when f_in=114 else
   "101"   when f_in=115 else
   "100"   when f_in=116 else
   "100"   when f_in=117 else
   "101"   when f_in=118 else
   "110"   when f_in=119 else
   "100"   when f_in=120 else
   "101"   when f_in=121 else
   "101"   when f_in=122 else
   "110"   when f_in=123 else
   "101"   when f_in=124 else
   "110"   when f_in=125 else
   "110"   when f_in=126 else
   "111"   when f_in=127 else
   "001"   when f_in=128 else
   "010"   when f_in=129 else
   "010"   when f_in=130 else
   "011"   when f_in=131 else
   "010"   when f_in=132 else
   "011"   when f_in=133 else
   "011"   when f_in=134 else
   "100"   when f_in=135 else
   "010"   when f_in=136 else
   "011"   when f_in=137 else
   "011"   when f_in=138 else
   "100"   when f_in=139 else
   "011"   when f_in=140 else
   "100"   when f_in=141 else
   "100"   when f_in=142 else
   "101"   when f_in=143 else
   "010"   when f_in=144 else
   "011"   when f_in=145 else
   "011"   when f_in=146 else
   "100"   when f_in=147 else
   "011"   when f_in=148 else
   "100"   when f_in=149 else
   "100"   when f_in=150 else
   "101"   when f_in=151 else
   "011"   when f_in=152 else
   "100"   when f_in=153 else
   "100"   when f_in=154 else
   "101"   when f_in=155 else
   "100"   when f_in=156 else
   "101"   when f_in=157 else
   "101"   when f_in=158 else
   "110"   when f_in=159 else
   "010"   when f_in=160 else
   "011"   when f_in=161 else
   "011"   when f_in=162 else
   "100"   when f_in=163 else
   "011"   when f_in=164 else
   "100"   when f_in=165 else
   "100"   when f_in=166 else
   "101"   when f_in=167 else
   "011"   when f_in=168 else
   "100"   when f_in=169 else
   "100"   when f_in=170 else
   "101"   when f_in=171 else
   "100"   when f_in=172 else
   "101"   when f_in=173 else
   "101"   when f_in=174 else
   "110"   when f_in=175 else
   "011"   when f_in=176 else
   "100"   when f_in=177 else
   "100"   when f_in=178 else
   "101"   when f_in=179 else
   "100"   when f_in=180 else
   "101"   when f_in=181 else
   "101"   when f_in=182 else
   "101"   when f_in=183 else
   "100"   when f_in=184 else
   "101"   when f_in=185 else
   "101"   when f_in=186 else
   "110"   when f_in=187 else
   "101"   when f_in=188 else
   "110"   when f_in=189 else
   "110"   when f_in=190 else
   "111"   when f_in=191 else
   "010"   when f_in=192 else
   "011"   when f_in=193 else
   "011"   when f_in=194 else
   "100"   when f_in=195 else
   "011"   when f_in=196 else
   "100"   when f_in=197 else
   "100"   when f_in=198 else
   "101"   when f_in=199 else
   "011"   when f_in=200 else
   "100"   when f_in=201 else
   "100"   when f_in=202 else
   "101"   when f_in=203 else
   "100"   when f_in=204 else
   "101"   when f_in=205 else
   "101"   when f_in=206 else
   "110"   when f_in=207 else
   "011"   when f_in=208 else
   "100"   when f_in=209 else
   "100"   when f_in=210 else
   "101"   when f_in=211 else
   "100"   when f_in=212 else
   "101"   when f_in=213 else
   "101"   when f_in=214 else
   "110"   when f_in=215 else
   "100"   when f_in=216 else
   "101"   when f_in=217 else
   "101"   when f_in=218 else
   "110"   when f_in=219 else
   "101"   when f_in=220 else
   "110"   when f_in=221 else
   "110"   when f_in=222 else
   "111"   when f_in=223 else
   "011"   when f_in=224 else
   "100"   when f_in=225 else
   "100"   when f_in=226 else
   "101"   when f_in=227 else
   "100"   when f_in=228 else
   "101"   when f_in=229 else
   "101"   when f_in=230 else
   "110"   when f_in=231 else
   "100"   when f_in=232 else
   "101"   when f_in=233 else
   "101"   when f_in=234 else
   "110"   when f_in=235 else
   "101"   when f_in=236 else
   "110"   when f_in=237 else
   "110"   when f_in=238 else
   "111"   when f_in=238 else
   "100"   when f_in=240 else
   "101"   when f_in=241 else
   "101"   when f_in=242 else
   "110"   when f_in=243 else
   "101"   when f_in=244 else
   "110"   when f_in=245 else
   "110"   when f_in=246 else
   "111"   when f_in=247 else
   "101"   when f_in=248 else
   "110"   when f_in=249 else
   "110"   when f_in=250 else
   "111"   when f_in=251 else
   "110"   when f_in=252 else
   "111"   when f_in=253 else
   "111"   when f_in=254 else
   "111"   when f_in=255 else
          "000";

END a;