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UVM TLM 2
Analysis
The analysis port is used to perform non-blocking broadcasts of transactions. It is by components like monitors/drivers to publish transactions to its subscribers, which are typically scoreboards and response/coverage collectors. For each port, more than one component can be connected. Even if a component is not connected to the port, simulation can continue, unlike put/get ports where simulation is not continued.
The uvm_analysis_port consists of a single function, write(). Subscriber component should provide an implementation of write()method. UVM provides the uvm_subscriber base component to simplify this operation, so a typical analysis component would extend uvm_subscriber and its export is analysis_export.
Lets write a example.
In the example, we will define a monitor component and a subscriber.
(S)Monitor source code:
In monitor, call the function write() pass the transaction.
class monitor extends uvm_monitor;
uvm_analysis_port #(instruction) anls_port;
function new(string name, uvm_component p = null);
super.new(name,p);
anls_port = new("anls_port", this);
endfunction
task run;
instruction inst;
inst = new();
#10ns;
inst.inst = instruction::MUL;
anls_port.write(inst);
#10ns;
inst.inst = instruction::ADD;
anls_port.write(inst);
#10ns;
inst.inst = instruction::SUB;
anls_port.write(inst);
endtask
endclass
(S)Subscriber source code:
In Subscriber, define the write() method.
class subscriber extends uvm_subscriber#(instruction);
function new(string name, uvm_component p = null);
super.new(name,p);
endfunction
function void write(instruction t);
`uvm_info(get_full_name(),
$sformatf("receiving %s",t.inst.name()), UVM_MEDIUM)
endfunction
endclass : subscriber
(S)Env source code:
class env extends uvm_env;
monitor mon;
subscriber sb,cov;
function new(string name = "env");
super.new(name);
mon = new("mon", this);
sb = new("sb", this);
cov = new("cov", this);
endfunction
function void connect();
mon.anls_port.connect(sb.analysis_export);
mon.anls_port.connect(cov.analysis_export);
endfunction
task run();
#1000;
global_stop_request();
endtask
endclass
module test;
env e;
initial begin
e = new();
run_test();
end
endmodule
(S)Download the example
uvm_tlm_3.tar
Browse the code in uvm_tlm_3.tar
(S)Command to sun the simulation
VCS Users : make vcs
Questa Users: make questa
From the below log, you see that transaction is sent to both the components cov and sb.
(S)Log
UVM_INFO subscriber.sv(18) @ 0: env.cov [env.cov] receiving MUL
UVM_INFO subscriber.sv(18) @ 0: env.sb [env.sb] receiving MUL
UVM_INFO subscriber.sv(18) @ 0: env.cov [env.cov] receiving ADD
UVM_INFO subscriber.sv(18) @ 0: env.sb [env.sb] receiving ADD
UVM_INFO subscriber.sv(18) @ 0: env.cov [env.cov] receiving SUB
UVM_INFO subscriber.sv(18) @ 0: env.sb [env.sb] receiving SUB
Tlm Fifo
Tlm_fifo provides storage of transactions between two independently running processes just like mailbox. Transactions are put into the FIFO via the put_export and fetched from the get_export.
(S)Methods
Following are the methods defined for tlm fifo.
function new(string name,
uvm_component parent = null,
int size = 1)
The size indicates the maximum size of the FIFO; a value of zero indicates no upper bound.
virtual function int size()
Returns the capacity of the FIFO. 0 indicates the FIFO capacity has no limit.
virtual function int used()
Returns the number of entries put into the FIFO.
virtual function bit is_empty()
Returns 1 when there are no entries in the FIFO, 0 otherwise.
virtual function bit is_full()
Returns 1 when the number of entries in the FIFO is equal to its size, 0 otherwise.
virtual function void flush()
Removes all entries from the FIFO, after which used returns 0 and is_empty returns 1.
Example
Lets implement a example.
In this example, we will use a tlm_fifo to connect producer and consumer.
The producer component generates the transaction and using its put_port pot() method, sends transaction out. The consumer component, to get the transaction from outside, uses get() method of get_port. These two ports are connected to tlm_fifo in the env class. In this example, producer and consumer are initiators as both components are calling the methods.
(S)Producer source code:
class producer extends uvm_component;
uvm_blocking_put_port#(int) put_port;
function new(string name, uvm_component p = null);
super.new(name,p);
put_port = new("put_port", this);
endfunction
task run;
int randval;
for(int i = 0; i < 10; i++)
begin
#10;
randval = $urandom_range(4,10);
`uvm_info("producer",
$sformatf("sending %d",randval), UVM_MEDIUM)
put_port.put(randval);
end
endtask
endclass : producer
(S)Consumer source code:
class consumer extends uvm_component;
uvm_blocking_get_port#(int) get_port;
function new(string name, uvm_component p = null);
super.new(name,p);
get_port = new("get_port", this);
endfunction
task run;
int val;
forever
begin
get_port.get(val);
`uvm_info("consumer",
$sformatf("receiving %d", val), UVM_MEDIUM)
end
endtask
endclass : consumer
(S)Env source code:
class env extends uvm_env;
producer p;
consumer c;
tlm_fifo #(int) f;
function new(string name = "env");
super.new(name);
p = new("producer", this);
c = new("consumer", this);
f = new("fifo", this);
endfunction
function void connect();
p.put_port.connect(f.put_export);
c.get_port.connect(f.get_export);
endfunction
task run();
#1000 global_stop_request();
endtask
endclass
(S)Download the example
uvm_tlm_4.tar
Browse the code in uvm_tlm_4.tar
(S)Command to sun the simulation
VCS Users : make vcs
Questa Users: make questa
(S)Log
UVM_INFO producer.sv(28) @ 10: env.producer [producer] sending 7
UVM_INFO consumer.sv(26) @ 10: env.consumer [consumer] receiving 7
UVM_INFO producer.sv(28) @ 20: env.producer [producer] sending 4
UVM_INFO consumer.sv(26) @ 20: env.consumer [consumer] receiving 4
Analysis
The analysis port is used to perform non-blocking broadcasts of transactions. It is by components like monitors/drivers to publish transactions to its subscribers, which are typically scoreboards and response/coverage collectors. For each port, more than one component can be connected. Even if a component is not connected to the port, simulation can continue, unlike put/get ports where simulation is not continued.
The uvm_analysis_port consists of a single function, write(). Subscriber component should provide an implementation of write()method. UVM provides the uvm_subscriber base component to simplify this operation, so a typical analysis component would extend uvm_subscriber and its export is analysis_export.
Lets write a example.
In the example, we will define a monitor component and a subscriber.
(S)Monitor source code:
In monitor, call the function write() pass the transaction.
class monitor extends uvm_monitor;
uvm_analysis_port #(instruction) anls_port;
function new(string name, uvm_component p = null);
super.new(name,p);
anls_port = new("anls_port", this);
endfunction
task run;
instruction inst;
inst = new();
#10ns;
inst.inst = instruction::MUL;
anls_port.write(inst);
#10ns;
inst.inst = instruction::ADD;
anls_port.write(inst);
#10ns;
inst.inst = instruction::SUB;
anls_port.write(inst);
endtask
endclass
(S)Subscriber source code:
In Subscriber, define the write() method.
class subscriber extends uvm_subscriber#(instruction);
function new(string name, uvm_component p = null);
super.new(name,p);
endfunction
function void write(instruction t);
`uvm_info(get_full_name(),
$sformatf("receiving %s",t.inst.name()), UVM_MEDIUM)
endfunction
endclass : subscriber
(S)Env source code:
class env extends uvm_env;
monitor mon;
subscriber sb,cov;
function new(string name = "env");
super.new(name);
mon = new("mon", this);
sb = new("sb", this);
cov = new("cov", this);
endfunction
function void connect();
mon.anls_port.connect(sb.analysis_export);
mon.anls_port.connect(cov.analysis_export);
endfunction
task run();
#1000;
global_stop_request();
endtask
endclass
module test;
env e;
initial begin
e = new();
run_test();
end
endmodule
(S)Download the example
uvm_tlm_3.tar
Browse the code in uvm_tlm_3.tar
(S)Command to sun the simulation
VCS Users : make vcs
Questa Users: make questa
From the below log, you see that transaction is sent to both the components cov and sb.
(S)Log
UVM_INFO subscriber.sv(18) @ 0: env.cov [env.cov] receiving MUL
UVM_INFO subscriber.sv(18) @ 0: env.sb [env.sb] receiving MUL
UVM_INFO subscriber.sv(18) @ 0: env.cov [env.cov] receiving ADD
UVM_INFO subscriber.sv(18) @ 0: env.sb [env.sb] receiving ADD
UVM_INFO subscriber.sv(18) @ 0: env.cov [env.cov] receiving SUB
UVM_INFO subscriber.sv(18) @ 0: env.sb [env.sb] receiving SUB
Tlm Fifo
Tlm_fifo provides storage of transactions between two independently running processes just like mailbox. Transactions are put into the FIFO via the put_export and fetched from the get_export.
(S)Methods
Following are the methods defined for tlm fifo.
function new(string name,
uvm_component parent = null,
int size = 1)
The size indicates the maximum size of the FIFO; a value of zero indicates no upper bound.
virtual function int size()
Returns the capacity of the FIFO. 0 indicates the FIFO capacity has no limit.
virtual function int used()
Returns the number of entries put into the FIFO.
virtual function bit is_empty()
Returns 1 when there are no entries in the FIFO, 0 otherwise.
virtual function bit is_full()
Returns 1 when the number of entries in the FIFO is equal to its size, 0 otherwise.
virtual function void flush()
Removes all entries from the FIFO, after which used returns 0 and is_empty returns 1.
Example
Lets implement a example.
In this example, we will use a tlm_fifo to connect producer and consumer.
The producer component generates the transaction and using its put_port pot() method, sends transaction out. The consumer component, to get the transaction from outside, uses get() method of get_port. These two ports are connected to tlm_fifo in the env class. In this example, producer and consumer are initiators as both components are calling the methods.
(S)Producer source code:
class producer extends uvm_component;
uvm_blocking_put_port#(int) put_port;
function new(string name, uvm_component p = null);
super.new(name,p);
put_port = new("put_port", this);
endfunction
task run;
int randval;
for(int i = 0; i < 10; i++)
begin
#10;
randval = $urandom_range(4,10);
`uvm_info("producer",
$sformatf("sending %d",randval), UVM_MEDIUM)
put_port.put(randval);
end
endtask
endclass : producer
(S)Consumer source code:
class consumer extends uvm_component;
uvm_blocking_get_port#(int) get_port;
function new(string name, uvm_component p = null);
super.new(name,p);
get_port = new("get_port", this);
endfunction
task run;
int val;
forever
begin
get_port.get(val);
`uvm_info("consumer",
$sformatf("receiving %d", val), UVM_MEDIUM)
end
endtask
endclass : consumer
(S)Env source code:
class env extends uvm_env;
producer p;
consumer c;
tlm_fifo #(int) f;
function new(string name = "env");
super.new(name);
p = new("producer", this);
c = new("consumer", this);
f = new("fifo", this);
endfunction
function void connect();
p.put_port.connect(f.put_export);
c.get_port.connect(f.get_export);
endfunction
task run();
#1000 global_stop_request();
endtask
endclass
(S)Download the example
uvm_tlm_4.tar
Browse the code in uvm_tlm_4.tar
(S)Command to sun the simulation
VCS Users : make vcs
Questa Users: make questa
(S)Log
UVM_INFO producer.sv(28) @ 10: env.producer [producer] sending 7
UVM_INFO consumer.sv(26) @ 10: env.consumer [consumer] receiving 7
UVM_INFO producer.sv(28) @ 20: env.producer [producer] sending 4
UVM_INFO consumer.sv(26) @ 20: env.consumer [consumer] receiving 4
Index
Introduction
Uvm Testbench
Uvm Reporting
Uvm Transaction
Uvm Configuration
Uvm Factory
Uvm Sequence 1
Uvm Sequence 2
Uvm Sequence 3
Uvm Sequence 4
Uvm Sequence 5
Uvm Sequence 6
Uvm Tlm 1
Uvm Tlm 2
Uvm Callback
Report a Bug or Comment on This section - Your input is what keeps Testbench.in improving with time!
Introduction
Uvm Testbench
Uvm Reporting
Uvm Transaction
Uvm Configuration
Uvm Factory
Uvm Sequence 1
Uvm Sequence 2
Uvm Sequence 3
Uvm Sequence 4
Uvm Sequence 5
Uvm Sequence 6
Uvm Tlm 1
Uvm Tlm 2
Uvm Callback
Report a Bug or Comment on This section - Your input is what keeps Testbench.in improving with time!