'assignment process
module datt ();
reg [7:0] mem;
initial begin
$monitor("ans is %b", mem);
end
initial begin
mem=0;
#10 mem=1;
#10 mem='1;
#10 $finish;
end
bit[7:0] mem2[3];
initial begin
mem2[0]='x;
mem2[1]='1;
mem2[2]=2;
foreach(mem2[i])
$display("mem2 %b", mem2[i]);
end
endmodule
output
mem2 00000000 mem2 11111111 mem2 00000010 ans is 00000000 ans is 00000001 ans is 11111111 $finish called from file "datt.v", line 11. $finish at simulation time 30
foreach, initialization assignment {}, dynamic array, queue
When using {} for initialization assignment, 'can be used for abbreviation, and constants can be described without single quotation marks.
module tcc ();
int a[10]='{10{16'hfafa}};
int b[]={1,3,4};
initial begin
a[0]=3;
a[1]=5;
b=a;
b[0]=1;
foreach(a[i])
$display("a %b",a[i]);
foreach(b[i])
$display("b %b",b[i]);
end
int c[$]='{5{11}};
int d[$]='{1,2,3,4,56};
int e[5]={1,2,3,4,5};
initial begin
c.insert(2,0);
c.insert(6,1);
// out of bound will be wrong in run time. insert in the tail is use the finall index+1
for(int i=0;i<c.size();i++)
$display("the queue value is %b",c[i]);
end
initial begin
for(int i=0;i<d.size();i++)
$display("the queue value d is %b",d[i]);
end
endmodule
output
a 00000000000000000000000000000011 a 00000000000000000000000000000101 a 00000000000000001111101011111010 a 00000000000000001111101011111010 a 00000000000000001111101011111010 a 00000000000000001111101011111010 a 00000000000000001111101011111010 a 00000000000000001111101011111010 a 00000000000000001111101011111010 a 00000000000000001111101011111010 b 00000000000000000000000000000001 b 00000000000000000000000000000101 b 00000000000000001111101011111010 b 00000000000000001111101011111010 b 00000000000000001111101011111010 b 00000000000000001111101011111010 b 00000000000000001111101011111010 b 00000000000000001111101011111010 b 00000000000000001111101011111010 b 00000000000000001111101011111010 the queue value is 00000000000000000000000000001011 the queue value is 00000000000000000000000000001011 the queue value is 00000000000000000000000000000000 the queue value is 00000000000000000000000000001011 the queue value is 00000000000000000000000000001011 the queue value is 00000000000000000000000000001011 the queue value is 00000000000000000000000000000001 the queue value d is 00000000000000000000000000000001 the queue value d is 00000000000000000000000000000010 the queue value d is 00000000000000000000000000000011 the queue value d is 00000000000000000000000000000100 the queue value d is 00000000000000000000000000111000
Associative array, itoa function
sv's syntax allows variables to be defined in initial, but it seems that they can only be defined at the beginning. Other definitions will report errors. In Verilog syntax, it is irrelevant. It must be outside initial and always.
module tdd ();
initial begin
bit [63:0] assoc1[bit[63:0]], idx=1;
int assoc2[string];
string idx2_str;
int idx2=123;
repeat (64) begin
assoc1[idx]=idx;
idx=idx<<1;
end
foreach(assoc1[i])
$display("the assoc1 is %b", assoc1[i]);
repeat (64) begin
idx2_str.itoa(idx2);
assoc2[idx2_str]=idx2;
++idx2;
end
foreach(assoc2[i])
$display("%s, the assoc2 is %b",i, assoc2[i]);
end
reg xx;
endmodule
output
1 the assoc1 is 0000000000000000000000000000000000000000000000000000000000000001 2 the assoc1 is 0000000000000000000000000000000000000000000000000000000000000010 3 the assoc1 is 0000000000000000000000000000000000000000000000000000000000000100 4 the assoc1 is 0000000000000000000000000000000000000000000000000000000000001000 5 the assoc1 is 0000000000000000000000000000000000000000000000000000000000010000 6 the assoc1 is 0000000000000000000000000000000000000000000000000000000000100000 7 the assoc1 is 0000000000000000000000000000000000000000000000000000000001000000 8 the assoc1 is 0000000000000000000000000000000000000000000000000000000010000000 9 the assoc1 is 0000000000000000000000000000000000000000000000000000000100000000 10 the assoc1 is 0000000000000000000000000000000000000000000000000000001000000000 11 the assoc1 is 0000000000000000000000000000000000000000000000000000010000000000 12 the assoc1 is 0000000000000000000000000000000000000000000000000000100000000000 13 the assoc1 is 0000000000000000000000000000000000000000000000000001000000000000 14 the assoc1 is 0000000000000000000000000000000000000000000000000010000000000000 15 the assoc1 is 0000000000000000000000000000000000000000000000000100000000000000 16 the assoc1 is 0000000000000000000000000000000000000000000000001000000000000000 17 the assoc1 is 0000000000000000000000000000000000000000000000010000000000000000 18 the assoc1 is 0000000000000000000000000000000000000000000000100000000000000000 19 the assoc1 is 0000000000000000000000000000000000000000000001000000000000000000 20 the assoc1 is 0000000000000000000000000000000000000000000010000000000000000000 21 the assoc1 is 0000000000000000000000000000000000000000000100000000000000000000 22 the assoc1 is 0000000000000000000000000000000000000000001000000000000000000000 23 the assoc1 is 0000000000000000000000000000000000000000010000000000000000000000 24 the assoc1 is 0000000000000000000000000000000000000000100000000000000000000000 25 the assoc1 is 0000000000000000000000000000000000000001000000000000000000000000 26 the assoc1 is 0000000000000000000000000000000000000010000000000000000000000000 27 the assoc1 is 0000000000000000000000000000000000000100000000000000000000000000 28 the assoc1 is 0000000000000000000000000000000000001000000000000000000000000000 29 the assoc1 is 0000000000000000000000000000000000010000000000000000000000000000 30 the assoc1 is 0000000000000000000000000000000000100000000000000000000000000000 31 the assoc1 is 0000000000000000000000000000000001000000000000000000000000000000 32 the assoc1 is 0000000000000000000000000000000010000000000000000000000000000000 33 the assoc1 is 0000000000000000000000000000000100000000000000000000000000000000 34 the assoc1 is 0000000000000000000000000000001000000000000000000000000000000000 35 the assoc1 is 0000000000000000000000000000010000000000000000000000000000000000 36 the assoc1 is 0000000000000000000000000000100000000000000000000000000000000000 37 the assoc1 is 0000000000000000000000000001000000000000000000000000000000000000 38 the assoc1 is 0000000000000000000000000010000000000000000000000000000000000000 39 the assoc1 is 0000000000000000000000000100000000000000000000000000000000000000 40 the assoc1 is 0000000000000000000000001000000000000000000000000000000000000000 41 the assoc1 is 0000000000000000000000010000000000000000000000000000000000000000 42 the assoc1 is 0000000000000000000000100000000000000000000000000000000000000000 43 the assoc1 is 0000000000000000000001000000000000000000000000000000000000000000 44 the assoc1 is 0000000000000000000010000000000000000000000000000000000000000000 45 the assoc1 is 0000000000000000000100000000000000000000000000000000000000000000 46 the assoc1 is 0000000000000000001000000000000000000000000000000000000000000000 47 the assoc1 is 0000000000000000010000000000000000000000000000000000000000000000 48 the assoc1 is 0000000000000000100000000000000000000000000000000000000000000000 49 the assoc1 is 0000000000000001000000000000000000000000000000000000000000000000 50 the assoc1 is 0000000000000010000000000000000000000000000000000000000000000000 51 the assoc1 is 0000000000000100000000000000000000000000000000000000000000000000 52 the assoc1 is 0000000000001000000000000000000000000000000000000000000000000000 53 the assoc1 is 0000000000010000000000000000000000000000000000000000000000000000 54 the assoc1 is 0000000000100000000000000000000000000000000000000000000000000000 55 the assoc1 is 0000000001000000000000000000000000000000000000000000000000000000 56 the assoc1 is 0000000010000000000000000000000000000000000000000000000000000000 57 the assoc1 is 0000000100000000000000000000000000000000000000000000000000000000 58 the assoc1 is 0000001000000000000000000000000000000000000000000000000000000000 59 the assoc1 is 0000010000000000000000000000000000000000000000000000000000000000 60 the assoc1 is 0000100000000000000000000000000000000000000000000000000000000000 61 the assoc1 is 0001000000000000000000000000000000000000000000000000000000000000 62 the assoc1 is 0010000000000000000000000000000000000000000000000000000000000000 63 the assoc1 is 0100000000000000000000000000000000000000000000000000000000000000 64 the assoc1 is 1000000000000000000000000000000000000000000000000000000000000000 65 123, the assoc2 is 00000000000000000000000001111011 66 124, the assoc2 is 00000000000000000000000001111100 67 125, the assoc2 is 00000000000000000000000001111101 68 126, the assoc2 is 00000000000000000000000001111110 69 127, the assoc2 is 00000000000000000000000001111111 70 128, the assoc2 is 00000000000000000000000010000000 71 129, the assoc2 is 00000000000000000000000010000001 72 130, the assoc2 is 00000000000000000000000010000010 73 131, the assoc2 is 00000000000000000000000010000011 74 132, the assoc2 is 00000000000000000000000010000100 75 133, the assoc2 is 00000000000000000000000010000101 76 134, the assoc2 is 00000000000000000000000010000110 77 135, the assoc2 is 00000000000000000000000010000111 78 136, the assoc2 is 00000000000000000000000010001000 79 137, the assoc2 is 00000000000000000000000010001001 80 138, the assoc2 is 00000000000000000000000010001010 81 139, the assoc2 is 00000000000000000000000010001011 82 140, the assoc2 is 00000000000000000000000010001100 83 141, the assoc2 is 00000000000000000000000010001101 84 142, the assoc2 is 00000000000000000000000010001110 85 143, the assoc2 is 00000000000000000000000010001111 86 144, the assoc2 is 00000000000000000000000010010000 87 145, the assoc2 is 00000000000000000000000010010001 88 146, the assoc2 is 00000000000000000000000010010010 89 147, the assoc2 is 00000000000000000000000010010011 90 148, the assoc2 is 00000000000000000000000010010100 91 149, the assoc2 is 00000000000000000000000010010101 92 150, the assoc2 is 00000000000000000000000010010110 93 151, the assoc2 is 00000000000000000000000010010111 94 152, the assoc2 is 00000000000000000000000010011000 95 153, the assoc2 is 00000000000000000000000010011001 96 154, the assoc2 is 00000000000000000000000010011010 97 155, the assoc2 is 00000000000000000000000010011011 98 156, the assoc2 is 00000000000000000000000010011100 99 157, the assoc2 is 00000000000000000000000010011101 100 158, the assoc2 is 00000000000000000000000010011110 101 159, the assoc2 is 00000000000000000000000010011111 102 160, the assoc2 is 00000000000000000000000010100000 103 161, the assoc2 is 00000000000000000000000010100001 104 162, the assoc2 is 00000000000000000000000010100010 105 163, the assoc2 is 00000000000000000000000010100011 106 164, the assoc2 is 00000000000000000000000010100100 107 165, the assoc2 is 00000000000000000000000010100101 108 166, the assoc2 is 00000000000000000000000010100110 109 167, the assoc2 is 00000000000000000000000010100111 110 168, the assoc2 is 00000000000000000000000010101000 111 169, the assoc2 is 00000000000000000000000010101001 112 170, the assoc2 is 00000000000000000000000010101010 113 171, the assoc2 is 00000000000000000000000010101011 114 172, the assoc2 is 00000000000000000000000010101100 115 173, the assoc2 is 00000000000000000000000010101101 116 174, the assoc2 is 00000000000000000000000010101110 117 175, the assoc2 is 00000000000000000000000010101111 118 176, the assoc2 is 00000000000000000000000010110000 119 177, the assoc2 is 00000000000000000000000010110001 120 178, the assoc2 is 00000000000000000000000010110010 121 179, the assoc2 is 00000000000000000000000010110011 122 180, the assoc2 is 00000000000000000000000010110100 123 181, the assoc2 is 00000000000000000000000010110101 124 182, the assoc2 is 00000000000000000000000010110110 125 183, the assoc2 is 00000000000000000000000010110111 126 184, the assoc2 is 00000000000000000000000010111000 127 185, the assoc2 is 00000000000000000000000010111001 128 186, the assoc2 is 00000000000000000000000010111010 129 V C S S i m u l a t i o n R e p o r t 130 Time: 0 131 CPU Time: 0.120 seconds; Data structure size: 0.0Mb
Logical judgment of merging arrays and x
module tee ();
reg [7:0] mem[7]='{7{4'b0011}};
bit [7:0] mem2[2][3]='{'{3{15}}, '{3,4,5}};
initial begin
foreach(mem[i])
begin
$display("reg mem %b", mem[i]);
end
end
initial begin
for(int i=0;i<2;i++)
for(int j=0;j<3;j++)
$display("reg mem2 %b", mem2[i][j]);
mem[0]=1;
mem[1]=2;
$display("the sum value is %d",mem.sum() with(item<3));
$display("the sum value is %d",mem.sum with((item<3) *1));
$display("logic value %b", 4'b0100>4'bxxzz);
end
endmodule
output
1 reg mem 00000011 2 reg mem 00000011 3 reg mem 00000011 4 reg mem 00000011 5 reg mem 00000011 6 reg mem 00000011 7 reg mem 00000011 8 reg mem2 00001111 9 reg mem2 00001111 10 reg mem2 00001111 11 reg mem2 00000011 12 reg mem2 00000100 13 reg mem2 00000101 14 the sum value is 0 15 the sum value is 2 16 logic value x
Structure, flow operator, merge structure
In addition, union is a union and enum is an enumeration. It is better to use typedef for definition_ s,_ u,_ e is the type suffix, indicating structure, union, enumeration, etc.
The structure can be integrated and can be used on contents such as pixels.
module tff ();
int adx[];
initial begin
adx = new[5];
end
initial begin
typedef struct{
logic valid;
logic [7:0] tags;
logic [31:0] data;
} data_word;
data_word st1='{1'b1, 2'b10, 3'b111};
//data_word st1={1'b1, 2'b10, 3'b111};
data_word a1;
a1.valid=1;
a1.tags=7'b1100_0011;
a1.data=8'hfa;
$display("a1 is %b, %b, %b", a1.valid, a1.tags, a1.data);
a1={>>{st1}};
$display("after a1 is %b, %b, %b", a1.valid, a1.tags, a1.data);
end
initial begin
typedef struct packed{
logic valid;
logic [7:0] tags;
logic [31:0] data;
} data_word2_s;
data_word2_s st={1'b1, 2'b10, 3'b111};
data_word2_s a2;
a2.valid=1;
a2.tags=7'b100_0011;
a2.data=8'hfa;
$display("a2 is %b, %b, %b", a2.valid, a2.tags, a2.data);
a2={>>{st}};
$display("after a2 is %b, %b, %b", a2.valid, a2.tags, a2.data);
end
endmodule
output
When the merge structure is output, through the data flow, the final data is crowded on the last unit.
For non merged structures, i.e. ordinary structures, the assignment constant needs to be added ', otherwise it cannot be compiled.
Add a ' before concatenation operator to convert it to a valid assignment pattern.
a1 is 1, 01000011, 00000000000000000000000011111010 after a1 is 1, 00000010, 00000000000000000000000000000111 a2 is 1, 01000011, 00000000000000000000000011111010 after a2 is 0, 00000000, 00000000000000000000000000110111
Enumeration, exponent of real number, logical or of inside, equal sign wildcard, cast cast cast, cast of n ', property, unique
The logic or of inside should be distinguished from random constraints, which are different concepts. For another example, the assign statement is a different concept at the behavior level and the data flow level. For another example, the < = statement in the behavior level is sometimes a non blocking assignment, and sometimes a logical judgment, which is a different concept.
inside: https://blog.csdn.net/qq_22742971/article/details/115466654
When property and unique are used in case statements, the former must have a valid expression, and the latter means that there must be only one matching expression. Otherwise, the compilation process generates a warning.
module tgg ();
initial begin
real a=3.1;
typedef enum{
R,G,B
} color_e;
color_e e1=R;
int c;
$display("the a is %.4f", a);
$display("the squire of a is %4.f",a**2);
$display("the squire of a is %.4f",a**2);
$display("the inside method %b",2 inside{3,4});
$display("the inside method %b",2 inside{3,2,4});
$display("the compare ans is %b ", 4'b1011==?4'bxz11);
$display("the compare ans is %b ", 4'b0011!=?4'b1x11);
$display("typeof is %s", e1);
e1++;
$display("typeof is %s %d", e1, e1);
c=e1;
$cast(e1, c);
$display("typeof is %s %d", e1, e1);
$display("other cast method : %h",int'("a"));
$display("other cast method : %h",8'(int'("a")));
end
int irq;
always_comb
priority case (10'd8)
0: irq = 4'b0001;
1: irq = 4'b0010;
0: irq = 4'b0100;
3: irq = 4'b1000;
endcase
always_comb
unique case (10'd8)
0: irq = 4'b0001;
1: irq = 4'b0010;
0: irq = 4'b0100;
3: irq = 4'b1000;
endcase
endmodule
always_ff,always_comb,always_latch
Source: https://www.cnblogs.com/zeushuang/p/7966679.html
The first is trigger (sequential logic), the second is combinational logic, and the third is combinational logic that allows latch. It is said that it will warn, but I didn't.
module thh ();
int a=1,b=2,out;
always_comb
if(a > b)
out = 1;
else
out = 0;
int c=1,d=2,out2;
always_latch
if(c > d)
out2 = 1;
reg clk;
reg en;
reg in, out3;
always_ff @(posedge clk)
if(en)
out3 <= in;
endmodule