SV_4_Data Type1

摘要：System Verilog 增加了新的数据类型，也对已有的数据类型进行了优化，以提高模拟器运行时的内存使用率；

• shortint and longint data types;
• shortreal (real was already defined in verilog) data type;
• string, handle and class data type; 
• logic ,bit, and byte data type;
• user defined types typedef;
• struct, union, and class types;
• void data type;
• null data type;
• arrays, queue, associative, dynamatic array;

1. integer data type

2 值的integer类型

• bit : User defined vector types.
• byte : 8-bit signed integer, can be used for storing ASCII charater.
• shortint : 16-bit signed integer.
• int : 32-bit signed integer.
• longint : 64-bit signed integer.

 4 值的integer类型

• logic : User defined vector types.
• reg : User defined vector types.
• wire : User defined vector types.
• integer : 32-bit signed integer.
• time : 64-bit unsigned integer.

数值符号性可以声明为有符号或者无符号；

默认情况下： 

signed：byte, shortint, int, longint, 

unsigned：bit, reg, logic, wire 

一个关于integer type的简单例子

module data_types();

bit       data_1bit;
byte      data_8bit;
shortint  data_16bit;
int       data_32bit;
longint   data_64bit;
integer   data_integer;

bit       unsigned data_1bit_unsigned;
byte      unsigned data_8bit_unsigned;
shortint  unsigned data_16bit_unsigned;
int       unsigned data_32bit_unsigned;
longint   unsigned data_64bit_unsigned;
integer   unsigned data_integer_unsigned;

initial begin
   data_1bit   = {32{4'b1111}};
   data_8bit   = {32{4'b1111}};
   data_16bit  = {32{4'b1111}};
   data_32bit  = {32{4'b1111}};
   data_64bit  = {32{4'b1111}};
   data_integer= {32{4'b1111}};
   $display("data_1bit    = %0d",data_1bit);
   $display("data_8bit    = %0d",data_8bit);
   $display("data_16bit   = %0d",data_16bit);
   $display("data_32bit   = %0d",data_32bit);
   $display("data_64bit   = %0d",data_64bit);
   $display("data_integer = %0d",data_integer);
   data_1bit   = {32{4'bzx01}};
   data_8bit   = {32{4'bzx01}};
   data_16bit  = {32{4'bzx01}};
   data_32bit  = {32{4'bzx01}};
   data_64bit  = {32{4'bzx01}};
   data_integer= {32{4'bzx01}};
   $display("data_1bit    = %b",data_1bit);
   $display("data_8bit    = %b",data_8bit);
   $display("data_16bit   = %b",data_16bit);
   $display("data_32bit   = %b",data_32bit);
   $display("data_64bit   = %b",data_64bit);
   $display("data_integer = %b",data_integer);
   data_1bit_unsigned   = {32{4'b1111}};
   data_8bit_unsigned   = {32{4'b1111}};
   data_16bit_unsigned  = {32{4'b1111}};
   data_32bit_unsigned  = {32{4'b1111}};
   data_64bit_unsigned  = {32{4'b1111}};
   data_integer_unsigned  = {32{4'b1111}};
   $display("data_1bit_unsigned  = %d",data_1bit_unsigned);
   $display("data_8bit_unsigned  = %d",data_8bit_unsigned);
   $display("data_16bit_unsigned = %d",data_16bit_unsigned);
   $display("data_32bit_unsigned = %d",data_32bit_unsigned);
   $display("data_64bit_unsigned = %d",data_64bit_unsigned);
   $display("data_integer_unsigned = %d",data_integer_unsigned);
   data_1bit_unsigned   = {32{4'bzx01}};
   data_8bit_unsigned   = {32{4'bzx01}};
   data_16bit_unsigned  = {32{4'bzx01}};
   data_32bit_unsigned  = {32{4'bzx01}};
   data_64bit_unsigned  = {32{4'bzx01}};
   data_integer_unsigned  = {32{4'bzx01}};
   $display("data_1bit_unsigned  = %b",data_1bit_unsigned);
   $display("data_8bit_unsigned  = %b",data_8bit_unsigned);
   $display("data_16bit_unsigned = %b",data_16bit_unsigned);
   $display("data_32bit_unsigned = %b",data_32bit_unsigned);
   $display("data_64bit_unsigned = %b",data_64bit_unsigned);
   $display("data_integer_unsigned = %b",data_integer_unsigned);
   #1 $finish;
end

endmodule

//compile result
 data_1bit    = 1
 data_8bit    = -1
 data_16bit   = -1
 data_32bit   = -1
 data_64bit   = -1
 data_integer = -1
 data_1bit    = 1
 data_8bit    = 00010001
 data_16bit   = 0001000100010001
 data_32bit   = 00010001000100010001000100010001
 data_64bit   = 0001000100010001000100010001000
    100010001000100010001000100010001
 data_integer = zx01zx01zx01zx01zx01zx01zx01zx01
 data_1bit_unsigned  = 1
 data_8bit_unsigned  = 255
 data_16bit_unsigned = 65535
 data_32bit_unsigned = 4294967295
 data_64bit_unsigned = 18446744073709551615
 data_integer_unsigned = 4294967295
 data_1bit_unsigned  = 1
 data_8bit_unsigned  = 00010001
 data_16bit_unsigned = 0001000100010001
 data_32bit_unsigned = 00010001000100010001000100010001
 data_64bit_unsigned = 0001000100010001000100010001000
                                   100010001000100010001000100010001
 data_integer_unsigned = zx01zx01zx01zx01zx01zx01zx01zx01

2. void and null data value 

• void 定义一个返回值为空的函数；
• null 用于将一个变量与空值进行比较，详细将在class 部分讨论；

3. handle data type

用于存储指针，在OOP（object orientation programming）和DPI（direct programming interface）中使用。

4. string data type

string operations

String	Description
Str1 == Str2	Equality. 检查两个字符串是否相等。如果它们相等，则结果为1，否则为0。两个字符串都可以是string类型的。或者其中一个可以是字符串文字。如果两个操作对象都是字符串文字，则等同于verilog中integer类型的相等操作符。允许使用特殊值“”。
Str1 != Str2	Inequality. == 的逻辑否定
<,>,<=,=>	Comparison. 如果对应的条件为真，且判断相等，则输出为1，条件支持嵌入式操作。
{Str1,Str2,...,Strn}	Concatenation. 每个被操作元素都可以是字符串类型或者字符文字类型；当有一个元素是字符串类型时，所有其他都会被转换为字符串类型，当所有元素都是字符串文字类型时，其也会被转换为字符串类型；总之该操作带有一个隐式的转换，输出都是字符串类型。
{multiplier{Str}}	Replication. Str 每个被操作元素都可以是字符串类型或者字符文字类型，该操作带有一个隐式的转换，输出都是字符串类型。
Str.method(...)	The dot (.) operator is used to invoke a specified method on strings.
Str[index]	Indexing. 返回一个给定索引处的ASCII码，索引范围为0-（N-1)，如果索引越界，则返回0；

string tasks

Function	Description
str.len()	返回字符串的长度。
putc(int char, FILE *stream)	把一个无符号的字符写入到指定的流中，位置标识符向前移动；
getc(int char,FILE *stream)	从指定的流中获取一个无符号的字符，位置标识符向后移动；
str.toupper()	返回字符串的大写形式
str.tolower()	返回字符串的小写形式
compare(str1,str2)	返回字符串对比结果
str1.icompare(str2)	返回不关心大小写的字符串对比结果
str.substr(start,length)	返回一个指定开始指定长度的字符串

str.atoi()	返回字符串的32进制
stratohex()	返回字符串的16进制
stratooct()	返回字符串的8进制
stratobin()	返回字符串的2进制
stratoreal()	返回字符串表示的实数
itoa(i)	返回32进制i的字符串（inverse of atohex）
hextoa()	返回16进制i的字符串 (inverse of atohex).
octtoa()	返回8进制i的字符串 (inverse of atooct).
bintoa()	返回2进制i的字符串 (inverse of atobin).
realtoa()	返回实数i的字符串 (inverse of atoreal).

一个例子

module string_ex ();

string my_string = "This is a orginal string";
string my_new_string;

initial begin
  $display ("My String = %s",my_string);
  // Assign new string of different size
  my_string = "This is new string of different length";
  $display ("My String = %s",my_string);
  // Change to uppercase and assign to new string
  my_new_string = my_string.toupper();
  $display ("My New String = %s",my_new_string);
  // Get the length of sting
  $display ("Length of new string %0d",my_new_string.len());
  // Compare variable to another variable
  if (my_string.tolower() == my_new_string.tolower()) begin
    $display("String Compare matches");
  end
  // Compare variable to variable
  if (my_string.toupper() == my_new_string) begin
    $display("String Variable Compare matches");
  end
  #1 $finish;
end

endmodule

//compile result
 My String = This is a orginal string
 My String = This is new string of different length
 My New String = THIS IS NEW STRING OF DIFFERENT LENGTH
 Length of new string 38
 String Compare matches
 String Variable Compare matches

 

5. event data type

• 基本上与verilog中的event相同，在SV中event变量之间可以赋值，相当于取别名；
• 可以被always块触发，

一个例子

 1 module events();
 2 // Declare a new event called ack
 3 event ack; 
 4 // Declare done as alias to ack 
 5 event done = ack; 
 6 // Event variable with no synchronization object
 7 event empty = null; 
 8 
 9 initial begin
10   #1 -> ack;
11   #1 -> empty;
12   #1 -> done;
13   #1 $finish;
14 end
15 
16 always @ (ack)
17 begin
18   $display("ack event emitted");
19 end
20 
21 always @ (done)
22 begin
23   $display("done event emitted");
24 end
25 //no synchronization object
26 always @ (empty)
27 begin
28   $display("empty event emitted");
29 end
30 
31 endmodule
32 
33 //compile result
34  ack event emitted
35  done event emitted
36  ack event emitted
37  done event emitted

event_code

 

6. user defined type

用户定义的类型可以在定义之前使用，前提是先被定义为空的typedef。

相关语法：

• typedef data_type type_identifier variable_dimension；
• typedef interface_instance_identifier . type_identifier；
• typedef [ enum | struct | union | class ] type_identifier；

例子：

`timescale 1ns/10ps

// Type define a struct
typedef struct {
  byte a;
  reg  b;
  shortint unsigned c;
} myStruct;

module typedef_data ();

// Full typedef here
typedef integer myinteger;

// Typedef declaration without type
typedef myinteger;
// Typedef used here
myinteger a = 10;
myStruct object = '{10,0,100};

initial begin
  $display ("a = %d", a);
  $display ("Displaying object");
  $display ("a = %b b = %b c = %h", object.a, object.b, object.c);
  #1 $finish;
end

endmodule

//compile result
 a =          10
 Displaying object
 a = 00001010 b = 0 c = 0064

 

7. enumerations types

• 枚举类型对没有数据类型或数据值的强类型变量提供了一个抽象定义；
• 还可以使用枚举变量的名字引用枚举类型的数据；
• 默认的数据类型为int。

语法：

• 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 ]

例子：

 

 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
32 
33 //compile result
34   state = 0
35   color = RED
36   medal = BRONZE
37   alphabet = c
38   newMedal = silver
39   Lcolors = yellow

module enum_data();

enum integer {IDLE=0, GNT0=1, GNT1=2} state;
enum {RED,GREEN,ORANGE} color;
enum {BRONZE=4, SILVER, GOLD} medal;

// a=0, b=7, c=8
enum {a, b=7, c} alphabet;
// Width declaration
enum bit [3:0] {bronze='h1, silver, gold='h5} newMedal;
// Using enum in typedef
typedef enum { red, green, blue, yellow, white, black } Colors;

Colors Lcolors;

initial begin
  state = IDLE;
  color = RED;
  medal = BRONZE;
  alphabet = c;
  newMedal = silver;
  Lcolors = yellow;
  $display (" state = %0d", state);
  $display (" color = %s", color.name());
  $display (" medal = %s", medal.name());
  $display (" alphabet = %s", alphabet.name());
  $display (" newMedal = %s", newMedal.name());
  $display (" Lcolors = %s", Lcolors.name());
end

endmodule

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

 

8. class type

• 类是一个包含数据以及对数据进行操作的方法的子例程集合；
• 数据（data）被称为类的属性；
• 子例程（subroutines）被称为类的方法；
• 类属性和类方法共同定义类实例或对象的内容和功能；
• 面向对象的类扩展允许动态的创建和销毁对象；
• 类实例或对象用句柄来进行传递参数；

一个例子：

module class_data();

// Class with local fields
class Packet;
  int address;
  bit [63:0] data;
  shortint crc;
endclass:Packet

// Class with task
class print;
  task print_io (input string msg);
    $display("%s",msg);
  endtask:print_io
endclass:print

// Create instance
Packet p;
print  prn;

initial begin
  // Allocate memory
  p = new();
  prn = new();
  // Assign values
  p.address = 32'hDEAD_BEAF;
  p.data = {4{16'h55AA}};
  p.crc  = 0;
  // Print all the assigned values
  $display("p.address = %d p.data = %h p.crc = %d",
    p.address, p.data, p.crc);
  prn.print_io("Test calling task inside class");
  $finish;
end

endmodule

//compile result

 p.address =  -559038801 p.data = 55aa55aa55aa55aa p.crc = 0
 Test calling task inside class

 

 

9.Casting（类型转换）

• 数据转换时使用   '  操作符；
• 要转换的表达式必须在()、[]、{}、内；

例子：

module casting_data();

int a = 0;
shortint b = 0;

initial begin
  $monitor ("%g a = %d b = %h", $time, a , b);
  #1 a = int'(2.3 * 3.3);
  #1 b = shortint'{8'hDE,8'hAD,8'hBE,8'hEF};
  #1 $finish;
end

endmodule

//compile result
 0 a =           0 b = 0000
 1 a =           8 b = 0000
 2 a =           8 b = beef