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$cast : Dynamic Type Casting
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Dynamic type casting allows one data type to be assigned another data type. $cast is the system method which can be used for dynamic type casting. $cast can be used as task or as function. |
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Syntax |
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task $cast( singular dest_handle, singular source_handle );
or
function int $cast( singular dest_handle, singular source_handle );
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Here |
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- sourc_exp Source expressio.
- dest_var Destination variable.
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Example : Cast
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1 module cast();
2
3 typedef enum {IDLE,SFD,PREAMBLE,
4 DATA,FCS,EFD} eth_state;
5
6 eth_state fsm;
7
8 initial begin
9 #5 fsm = IDLE;
10 $display("@%0dns Current value of FSM : %s\n",
11 $time,get_name(fsm));
12 #5 fsm = SFD;
13 $display("@%0dns Current value of FSM : %s\n",
14 $time,get_name(fsm));
15 #1 $cast(fsm,1+2);
16 $display("@%0dns Current value of FSM : %s\n",
17 $time,get_name(fsm));
18 // Below line should give compile error
19 //fsm = 2 + 1;
20 end
21
22 eth_state temp;
23 eth_state temp2;
24 integer i ;
25
26 initial begin
27 #20 ;
28 for(i = 0; i <= 5; i++) begin
29 $cast(temp,i);
30 $display("Value of temp is %s",
31 get_name(temp.next()));
32 end
33 end
34
35 function string get_name;
36 input eth_state lstate;
37 case(lstate)
38 IDLE : get_name = "IDLE";
39 SFD : get_name = "SFD";
40 PREAMBLE : get_name = "PREAMBLE";
41 DATA : get_name = "DATA";
42 FCS : get_name = "FCS";
43 EFD : get_name = "EFD";
44 endcase
45 endfunction
46
47 endmodule
You could download file cast.sv here
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Simulation Output - Cast
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@5ns Current value of FSM : IDLE
@10ns Current value of FSM : SFD
@11ns Current value of FSM : DATA
Value of temp is SFD
Value of temp is PREAMBLE
Value of temp is DATA
Value of temp is FCS
Value of temp is EFD
Value of temp is IDLE
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Copyright © 1998-2014 |
Deepak Kumar Tala - All rights reserved |
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Do you have any Comment? mail me at:deepak@asic-world.com
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