Enumerations types are same as that found in other programming language and same as found in C language. Enumerated data types provide the capability to abstractly declare strongly typed variables without either a data type or data value and later add the required data type and value for designs that require more definition.

Enumerated data types also can be easily referenced or displayed using the enumerated names as opposed to the enumerated values. Unlike typedef, enumerated types needs to be declared first before using them. In the absence of a data type declaration, the default data type shall be int.

Syntax

• enum [ enum_base_type ] { enum_name_declaration { , enum_name_declaration } }
• enum_base_type ::= integer_atom_type [ signing ] | integer_vector_type [ signing ] [ packed_dimension ] | type_identifier [ packed_dimension ]
• enum_name_declaration ::= enum_identifier [ [ integral_number [ : integral_number ] ] ] [ = constant_expression ]

  1 module enum_data();
  2 
  3 enum integer {IDLE=0, GNT0=1, GNT1=2} state;
  4 enum {RED,GREEN,ORANGE} color;
  5 enum {BRONZE=4, SILVER, GOLD} medal;
  6 
  7 // a=0, b=7, c=8
  8 enum {a, b=7, c} alphabet;
  9 // Width declaration
 10 enum bit [3:0] {bronze='h1, silver, gold='h5} newMedal;
 11 // Using enum in typedef
 12 typedef enum { red, green, blue, yellow, white, black } Colors;
 13 
 14 Colors Lcolors;
 15 
 16 initial begin
 17   state = IDLE;
 18   color = RED;
 19   medal = BRONZE;
 20   alphabet = c;
 21   newMedal = silver;
 22   Lcolors = yellow;
 23   $display (" state = %0d", state);
 24   $display (" color = %s", color.name());
 25   $display (" medal = %s", medal.name());
 26   $display (" alphabet = %s", alphabet.name());
 27   $display (" newMedal = %s", newMedal.name());
 28   $display (" Lcolors = %s", Lcolors.name());
 29 end
 30 
 31 endmodule

  state = 0
  color = RED
  medal = BRONZE
  alphabet = c
  newMedal = silver
  Lcolors = yellow

Copyright © 1998-2014

Deepak Kumar Tala - All rights reserved

Do you have any Comment? mail me at:deepak@asic-world.com