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LITERALS


Integer And Logic Literals



In verilog , to assign a value to all the bits of vector, user has to specify them explicitly.


reg[31:0] a = 32'hffffffff;


Systemverilog Adds the ability to specify unsized literal single bit values with a preceding (').'0, '1, 'X, 'x, 'Z, 'z // sets all bits to this value.


reg[31:0] a = '1;

'x is equivalent to Verilog-2001 'bx
'z is equivalent to Verilog-2001 'bz
'1 is equivalent to making an assignment of all 1's
'0 is equivalent to making an assignment of 0

Time Literals



Time is written in integer or fixed-point format, followed without a space by a time unit (fs ps ns us ms s step).


EXAMPLE
0.1ns
40ps


The time literal is interpreted as a realtime value scaled to the current time unit and rounded to the current time precision.



Array Literals



Array literals are syntactically similar to C initializers, but with the replicate operator ( {{}} ) allowed.


EXAMPLE
int n[1:2][1:3] = '{'{0,1,2},'{3{4}}};


The nesting of braces must follow the number of dimensions, unlike in C. However, replicate operators can be nested. The inner pair of braces in a replication is removed. A replication expression only operates within one dimension.


EXAMPLE:
int n[1:2][1:6] = '{2{'{3{4, 5}}}}; // same as '{'{4,5,4,5,4,5},'{4,5,4,5,4,5}}

Structure Literals



Structure literals are structure assignment patterns or pattern expressions with constant member expressions A structure literal must have a type, which may be either explicitly indicated with a prefix or implicitly indicated by an assignment-like context.


EXAMPLE
typedef struct {int a; shortreal b;} ab;
ab c;
c = '{0, 0.0}; // structure literal type determined from
// the left-hand context (c)


Nested braces should reflect the structure.
EXAMPLE
ab abarr[1:0] = '{'{1, 1.0}, '{2, 2.0}};



The C-like alternative '{1, 1.0, 2, 2.0} for the preceding example is not allowed.



EXAMPLE: default values
c = '{a:0, b:0.0};
c = '{default:0};
d = ab'{int:1, shortreal:1.0};


Index
Introduction
Data Types
Literals
Strings
Userdefined Datatypes
Enumarations
Structures And Uniouns
Typedef
Arrays
Array Methods
Dynamic Arrays
Associative Arrays
Queues
Comparison Of Arrays
Linked List
Casting
Data Declaration
Reg And Logic
Operators 1
Operators 2
Operator Precedency
Events
Control Statements
Program Block
Procedural Blocks
Fork Join
Fork Control
Subroutines
Semaphore
Mailbox
Fine Grain Process Control

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