SV_6_Operators and expressions

摘要：SV的操作符是verilog和c语言的集合；

1. Assignment operators（赋值操作符）

=
+=
-=
*=
/=
%=
&=
|=
^=
<<=
>>=
<<<=
>>>=

赋值操作符在语义上等同于阻塞赋值，任何操作符左边的表达式只计算一次；

例子：

 1 module assignment_operator ();
 2 
 3 reg [31:0] a = 100;
 4 
 5 initial begin
 6   $display (" a         := %h",  a );  
 7   a += 4; 
 8   $display (" a += 4    := %h",  a );  
 9   a -= 4; 
10   $display (" a -= 4    := %h",  a ); 
11   a *= 4; 
12   $display (" a *= 4    := %h",  a ); 
13   a /= 4; 
14   $display (" a /= 4    := %h",  a ); 
15   a %= 17; 
16   $display (" a %s= 17    := %h", "%", a ); 
17   a &= 16'hFFFF; 
18   $display (" a &= 16'hFFFF    := %h",  a ); 
19   a |= 16'hFFFF; 
20   $display (" a |= 16'hFFFF    := %h",  a ); 
21   a ^= 16'hAAAA; 
22   $display (" a ^= 16h'AAAA    := %h",  a ); 
23   a <<= 4; 
24   $display (" a <<= 4   := %h",  a ); 
25   a >>= 4; 
26   $display (" a >>= 4   := %h",  a ); 
27   a <<<= 14; 
28   $display (" a <<<= 14  := %h",  a ); 
29   a >>>= 14; 
30   $display (" a >>>= 14  := %h",  a );
31   #1 $finish;
32 end
33 
34 endmodule
35 
36 //compile result
37     
38   a         := 00000064
39   a += 4    := 00000068
40   a -= 4    := 00000064
41   a *= 4    := 00000190
42   a /= 4    := 00000064
43   a %= 17    := 0000000f
44   a &= 16'hFFFF    := 0000000f
45   a |= 16'hFFFF    := 0000ffff
46   a ^= 16h'AAAA    := 00005555
47   a <<= 4   := 00055550
48   a >>= 4   := 00005555
49   a <<<= 14  := 15554000
50   a >>>= 14  := 00005555

2. Operations on logic and bit type

一个操作数是bit类型，另一个操作数是logic类型，则结果为logic类型；
一个操作数是int类型，另一个操作数是integer类型，则结果为integer类型；
对于操作符!= 和 == ，如果其中一个操作符包含x或者z，则返回x；

例子：

 1 module bit_logic_operator ();
 2 
 3 bit   [7:0] a = 8'b01xz_01xz;
 4 logic [7:0] b = 8'b01xz_01xz;
 5 integer     c = 32'b01xz_01xz_01xz_01xz;
 6 int         d = 32'b01xz_01xz_01xz_01xz;
 7 
 8 initial begin
 9   $display  ("Value of bit     a = %b", a);
10   $display  ("Value of logic   b = %b", b);
11   $display  ("Value of integer c = %b", c);
12   $display  ("Value of int     d = %b", d);
13   $display  (" bit + integer     = %b", a + c);
14   $display  (" logic + int       = %b", b + d);
15   a = 10;
16   b = 20;
17   c = 30;
18   d = 40;
19   $display  (" bit + logic       = %b", a + b);
20   $display  (" integer + int     = %b", c + d);
21 end
22 
23 endmodule
24 
25 //compile result
26     
27  Value of bit     a = 01000100
28  Value of logic   b = 01xz01xz
29  Value of integer c = 000000000000000001xz01xz01xz01xz
30  Value of int     d = 00000000000000000100010001000100
31   bit + integer     = xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
32   logic + int       = xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
33   bit + logic       = 00011110
34   integer + int     = 00000000000000000000000001000110

3. Wild equality and inequality

Wild equality operator （=?=）和 (!?=) 将x和z当做统配符做处理；
通配符：通配符可匹配任意0,1，z，x；

例子：

 1 module wild_equality_operator ();
 2 
 3 bit [7:0] data = 8'hFF;
 4 
 5 initial begin
 6   // Compare with wild equality
 7   if (data =?= 8'b1xxx_z1xz) begin 
 8     $display ("Data %b matches with %b", data,  8'b1xxx_z1xz);
 9   end
10   // Compare with wild non-equality
11   if (data !?= 8'b1xxx_z1x0) begin
12     $display ("Data %b does not matches with %b", data,  8'b1xxx_z1x0);
13   end
14   #1 $finish;
15 end
16 
17 endmodule
18 
19 //compile result
20     
21  Data 11111111 matches with 1xxxz1xz
22  Data 11111111 does not matches with 1xxxz1x0

4. Operator precddence and associativity

Operators	Precedence
() [] :: .	left
+ - ! ~ & ~& \| ~\| ^ ~^ ^~ ++ -- unary	right
**	left
* / %	left
+ - (binary)	left
<< >> <<< >>>	left
< <= > >= inside dist	left
== != === !== =?= !?=	left
& (binary)	left
^ ~^ ^~ (binary)	left
\| (binary)	left
&&	left
\|\|	left
? : (conditional operator)	right
>	right
= += -= *= /= %= &= ^= \|= <<= >>= <<<= >>>= := :/ <=	none
{} {{}}	concatenation

5. Concatenation

{a,b}用于连接a，b两个元素；a和b可以是表达式；
{a,b}也可以用于对数组赋值；
也可以和复制操作符配合使用，如：{a,3{b}}

例子：

 1 module  struct_expr_operator();
 2 
 3 typedef struct { 
 4   int x; 
 5   int y; 
 6 } myStruct; 
 7 
 8 myStruct s1; 
 9 int k = 1; 
10 
11 initial begin 
12   #1 s1 = '{1, 2+k}; 
13   // by position 
14   #1 $display("Value of x = %g y = %g by position", s1.x, s1.y); 
15   #1 s1 = '{x:2, y:3+k}; 
16   // by name 
17   #1 $display("Value of s1 ", s1, " by name"); 
18   #1 $finish; 
19 end
20 
21 endmodule
22 
23 //compile result
24     
25  Value of x = 1 y = 3 by position
26  Value of s1 2 4 by name

6. Streaming operators

流操作符(stream)是将位流类型按用户指定的顺序打包成一个位序列；
在左侧使用时，流操作符执行相反的操作，将位流解包到一个或多个变量中；

 1 module streaming();
 2 
 3 //-------------------------------
 4 // PACK Example
 5 //-------------------------------
 6 int j = { "A", "B", "C", "D" };
 7 
 8 bit [31:0] stream;
 9 
10 initial begin
11  $display("       PACK");
12  $display("Value of j %0x",j);
13  $monitor("@%0dns stream value is %x",$time, stream);
14  #1 stream = { << byte {j}}; 
15  #1 stream = { >> {j}} ;
16  #1 stream = { << { 8'b0011_0101 }};
17  #1 stream = { << 16 {j}}; 
18  #1 stream = { << 4 { 6'b11_0101 }};
19  #1 stream = { >> 4 { 6'b11_0101 }} ;
20  #1 stream = { << 2 { { << { 4'b1101 }} }};
21 end
22 
23 //-------------------------------
24 // UNPACK Example
25 //-------------------------------
26 int          a, b, c;
27 logic [10:0] up [3:0];
28 logic [11:1] p1, p2, p3, p4;
29 bit   [96:1] y;
30 int          j ;
31 bit   [99:0] d;
32 
33 initial begin
34   #20;
35   $display("       UNPACK");
36   // Below line should give compile error
37   //{>>{ a, b, c }} = 23'b1; 
38   {>>{ a, b, c }} = 96'b1; 
39   $display("@%0dns a %x b %x c %x",$time,a,b,c);
40   {>>{ a, b, c }} = 100'b1; 
41   $display("@%0dns a %x b %x c %x",$time,a,b,c);
42   { >> {p1, p2, p3, p4}} = up; 
43   $display("@%0dns p1 %x p2 %x p3 %x p4 %x",$time,p1,p2,p3,p4);
44   y = {>>{ a, b, c }};
45   $display("@%0dns y %x",$time,y);
46   // Below line should give compile error
47   //j = {>>{ a, b, c }};
48   d = {>>{ a, b, c }};
49   $display("@%0dns d %x",$time,d);
50 end
51 
52 endmodule
53 
54 //compile result
55     
56         PACK
57  Value of j 41424344
58  @0ns stream value is 00000000
59  @1ns stream value is 44434241
60  @2ns stream value is 41424344
61  @3ns stream value is 000000ac
62  @4ns stream value is 43444142
63  @5ns stream value is 0000004d
64  @6ns stream value is d4000000
65  @7ns stream value is 0000000e
66         UNPACK
67  @20ns a 00000000 b 00000000 c 00000001
68  @20ns a 00000000 b 00000000 c 00000000
69  @20ns p1 xxx p2 xxx p3 xxx p4 xxx
70  @20ns y 000000000000000000000000
71  @20ns d 0000000000000000000000000

7. set membership

SV支持单值和集合集成员的操作；
遍历数组进行查找；

1 //语法
2 inside_expression ::= expression inside { open_range_list }

例子:

 1 module set_member();
 2 
 3 int array [$] = {1,2,3,4,5,6,7};
 4 int check = 0;
 5 
 6 initial begin 
 7   if (check inside {array}) begin
 8     $display("check is inside array");
 9   end else begin
10     $display("check is not inside array");
11   end
12   check = 5;
13   if (check inside {array}) begin
14     $display("check is inside array");
15   end else begin
16     $display("check is not inside array");
17   end
18   check = 1;
19   // Constant range
20   if (check inside {[0:10]}) begin
21     $display("check is inside array");
22   end else begin
23     $display("check is not inside array");
24   end
25 
26 end
27 
28 endmodule
29 
30 //compile result
31     
32  check is not inside array
33  check is inside array
34  check is inside array

posted on 2021-02-27 09:46 TCJJ 阅读(234) 评论(0) 收藏举报

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SV_6_Operators and expressions

1. Assignment operators（赋值操作符）

例子：

2. Operations on logic and bit type

例子：

3. Wild equality and inequality

例子：

4. Operator precddence and associativity

5. Concatenation

例子：

6. Streaming operators

7. set membership

例子: