module data_bytebit b_signed_vs_unsigned = 1;
bit b_bit_vs_logic = 1;
bit b_enum_type = 1;
bit b_struct_type = 1;// TODO-1: distinguish signed and unsigned type
initial begin: signed_vs_unsignedbyte b0;bite[7:0] b1;wait(b_signed_vs_unsigned == 1);$display("signed_vs_unsigned process block started");b0 = 'b1000_0000;$display("byte variable b0 = %d", b0);b1 = b0;$display("bit vector variable b1 = %d", b1)
end// TODO-2: distinguish bit and logic
initial initial begin: bit_vs_logicbit v1;logic v2;wait(b_bit_vs_logic == 1); $display("bit_vs_logic process block started");v2 = 'b1;$display("logic variable v2 = %d", v2);v1 = v2;$display("bit variable v1 = %d", v1);v2 = 'b0;$display("logic variable v2 = %d", v2);v1 = v2;$display("bit variable v1 = %d", v1);v2 = 'bx;$display("logic variable v2 = %d", v2);v1 = v2;$display("bit variable v1 = %d", v1);v2 = 'bz;$display("logic variable v2 = %d", v2);v1 = v2;$display("bit variable v1 = %d", v1);
end// TODO-3: enum type
initial begin: enum_typetypedef enum {IDLE, START, PROC, END} state_t;state_t st1, st2;wait(b_enum_type == 1); $display("enum_type process block started");st1 = IDLE;$display("st1 value = %0d (int)", st1);$display("st1 value = %s (string)", st1); // implicit conversion$display("st1 value = %s (string)", st1.name());st2 = state_t'(1);$display("st1 value = %0d (int)", st2);$display("st1 value = %s (string)", st2.name());
end// TODO-4: struct type
initial begin: struct_typetypedef struct {bit[7:0] addr;bit[31:0] data;bit is_write;int id;} trans_t;trans_t t1, t2, t3;wait(b_struct_type == 1); $display("struct_type process block started");t1 = '{'h10, 'h1122_3344, 'b1, 'h1000};$display("t1 data content is %p", t1);t2.addr = 'h20;t2.data = 'h5566_7788;t2.is_write = 'b0;t2.id = 'h2000;$display("t2 data content is %p", t2);t3 = t2;t3.data = 'h99AA_BBCC;t3.id = 'h3000;$display("t3 data content is %p", t3);$display("t2 data content is %p", t2);
endendmodule
字符串类型
构建字符串和字符串拼接 （一般常用$sformatf函数）
module string_type;bit b_string_format = 1;
bit b_string_builtin_function = 1;// TODO-1 understand how to formulate a new string
initial begin: string_formatstring s1, s2, s3, s4;wait(b_string_format == 1);$display("string_format process block started");s1 = "Welcome";s2 = "www.rockeric.com";s3 = {s1, " to ", s2}; // concatenation operator '{...}'$display("s3 content: %s", s3);s4 = $sformatf("%s to %s", s1, s2); // system format function$display("s4 content: %s", s4);
end// TODO-2 understand how s3 is composed with s1 and s2
initial begin: string_builtin_functionstring s1, s2, s3;int i1;wait(b_string_builtin_function == 1); $display("string_builtin_function process block started");s1 = "RockerIC is established in ";i1 = 2015;s2.itoa(i1); // integer converted to strings3 = {s1.len()+s2.len(){" "}}; // try to comment this line and check the resultfor(int i=0; i<s1.len()+s2.len(); i++) begins3[i] = i < s1.len() ? s1[i] : s2[i-s1.len()];end$display("s3 content: %s", s3);
endendmodule
数组类型
合并非合并、赋值与循环、动态数组、队列、关联数组
module array_type;bit b_unpacked_vs_packed = 1;
bit b_array_assigment_and_loop = 1;
bit b_dynamic_array = 1;
bit b_queue_use = 1;
bit b_associate_array = 1;// TODO-1 learn the difference between unpacked and packed data storage and
// assignment
initial begin: unpacked_vs_packedbit [7:0] unpacked_word [3:0];bit [3:0] [7:0] packed_word;wait(b_unpacked_vs_packed == 1); $display("unpacked_vs_packed process block started");// legal assignmentunpacked_word[0] = 10;unpacked_word[1] = 32;unpacked_word[2] = 54;unpacked_word[3] = 76;$display("unpacked_word = %p", unpacked_word);// legal assignment with '{}unpacked_word = '{76, 54, 32, 10};$display("unpacked_word = %p", unpacked_word);// legal assignmentpacked_word[0] = 10;packed_word[1] = 32;packed_word[2] = 54;packed_word[3] = 76;$display("packed_word = %p", packed_word);// legal assignment with {} but without 'packed_word = {76, 54, 32, 10};$display("packed_word = %p", packed_word);// legal assignment directly like a vector packedt_word[31:0]packed_word = (76<<24) + (54<<16) + (32<<8) + 10;$display("packed_word = %p", packed_word);// illegal assignment// packed_word = unpacked_word [X]// unpacked_word = packed_word [X]// illegal assignment between packed and unpacked arrayforeach(packed_word[i])packed_word[i] = unpacked_word[i];foreach(unpacked_word[i])unpacked_word[i] = packed_word[i];
end// TODO-2 learn the array assignment and foreach loop indexing method
initial begin: array_assigment_and_loopinteger sum [4][2]; // 8*4 size arraywait(b_array_assigment_and_loop == 1); $display("array_assigment_and_loop process block started");// concatenation and default valuesum = '{0:'{'h21, 'h43}, default:'{default:'x}};// foreach loop indexingforeach(sum[i, j]) begin$display("sum[%0d][%0d] = 'h%0x", i, j, sum[i][j]);end
end// TODO-3 learn the dynamic array basics
initial begin: dynamic_arrayint dyn1[], dyn2[];wait(b_dynamic_array == 1); $display("dynamic_array process block started");dyn1 = '{1, 2, 3, 4};$display("dyn1 = %p", dyn1);// copp method option-1dyn2 = dyn1;$display("dyn2 = %p", dyn2);$display("dyn2 size is %0d", dyn2.size());// copp method option-2dyn2 = new[dyn1.size()](dyn1);$display("dyn2 = %p", dyn2);$display("dyn2 size is %0d", dyn2.size());dyn2.delete();$display("dyn2 size is %0d", dyn2.size());
end// TODO-4: learn queue use
initial begin: queue_useint que1[$], que2[$];wait(b_queue_use == 1); $display("queue_use process block started");que1 = {10, 30, 40};$display("que1 = %p", que1);que2 = que1;$display("que2 = %p", que1);que1.insert(1, 20);$display("que1 = %p", que1);que1.delete(3); // delete que1[3]==40void'(que1.pop_front()); // pop que[0]==10$display("que1 = %p", que1);que1.delete();$display("que1 = %p", que1);
end// TODO-5 learn associate array use
initial begin: associate_arrayint id_score1[int], id_score2[int]; // key ID, value SCOREwait(b_associate_array == 1); $display("associate_array process block started");id_score1[101] = 111;id_score1[102] = 222;id_score1[103] = 333;id_score1[104] = 444;id_score1[105] = 555;// associate array copyid_score2 = id_score1;id_score2[101] = 101;id_score2[102] = 102;id_score2[103] = 103;id_score2[104] = 104;id_score2[105] = 105;foreach(id_score1[id]) begin$display("id_score1[%0d] = %0d", id, id_score1[id]);endforeach(id_score2[id]) begin$display("id_score2[%0d] = %0d", id, id_score2[id]);end
endendmodule
接口的定义与例化
接口里也可以定义方法
// TODO-1 understand how the interface is defined and instantied
// TODO-2 check how to define methods inside interface and call them internally or externally
// TODO-3 understand how to prepare transactions, drive them and monitor them
module interface_type;typedef struct {bit[7:0] addr;bit[31:0] data;bit write;int id;} trans_t;// struct print utility functionfunction void trans_print(trans_t t, string name = "trans");string s;s = $sformatf("%s struct content is as below \n", name);s = $sformatf("%s\taddr = 'h%2x \n", s, t.addr);s = $sformatf("%s\tdata = 'h%8x \n", s, t.data);s = $sformatf("%s\twrite = 'b%0b \n", s, t.write);s = $sformatf("%s\tid = 'h%8x \n", s, t.id);$display("%s", s);endfunctioninterface intf1;logic [7:0] addr;logic [31:0] data;logic write;int id;// transaction drive tasktask drive_trans(trans_t t);addr <= t.addr ;data <= t.data ;write <= t.write;id <= t.id ;endtask// transaction monitor tasktask mon_trans(output trans_t t);t.addr = addr ;t.data = data ;t.write = write;t.id = id ;endtaskendinterface// interface instantiationintf1 if1();initial begintrans_t trans_in[3], trans_mon[3];// stimulus preparationtrans_in = '{'{'h10, 'h1122_3344, 'b1, 'h1000},'{'h14, 'h5566_7788, 'b0, 'h1001},'{'h18, 'h99AA_BBCC, 'b1, 'h1002}};foreach(trans_in[i]) begin#10;// stimulus driveif1.drive_trans(trans_in[i]);trans_print(trans_in[i], $sformatf("trans_in[%0d]",i));#10;// stimulus monitorif1.mon_trans(trans_mon[i]);trans_print(trans_mon[i], $sformatf("trans_mon[%0d]",i));// transaction comparisonif(trans_in[i] === trans_mon[i])$display("trans_in[%0d] === trans_mon[%0d]", i, i);else$error("trans_in[%0d] !== trans_mon[%0d]", i, i);endendendmodule
类的封装
module class_encapsulation;bit b_object_instantiation = 1;class chnl_trans;bit[31:0] data[];int ch_id;int pkt_id;int data_nidles;int pkt_nidles;bit rsp;int obj_id;static int global_obj_id = 0;function new();global_obj_id++;obj_id = global_obj_id;endfunctionfunction chnl_trans clone();chnl_trans c = new();c.data = this.data;c.ch_id = this.ch_id;c.pkt_id = this.pkt_id;c.data_nidles = this.data_nidles;c.pkt_nidles = this.pkt_nidles;c.rsp = this.rsp;return c;endfunctionfunction string sprint();string s;s = {s, $sformatf("obj_id = %0d: \n", this.obj_id)};foreach(data[i]) s = {s, $sformatf("data[%0d] = %8x \n", i, this.data[i])};s = {s, $sformatf("ch_id = %0d: \n", this.ch_id)};s = {s, $sformatf("pkt_id = %0d: \n", this.pkt_id)};s = {s, $sformatf("data_nidles = %0d: \n", this.data_nidles)};s = {s, $sformatf("pkt_nidles = %0d: \n", this.pkt_nidles)};s = {s, $sformatf("rsp = %0d: \n", this.rsp)};return s;endfunctionendclass: chnl_trans// TODO-1 learn the object instantiation
// TODO-2 learn the handle pointting to an object
// TODO-3 learn the class function clone()/sprint()
// TODO-4 compare if t1, t2 and t3 are pointting to the same object?
// TODO-5 check if the t1 pointted object data is exactly the same with the t3
// pointted object?
// TODO-6 learn how to call STATIC member variable/function, and their
// difference with local member variable/function
initial begin: object_instantiationchnl_trans t1, t2, t3;wait(b_object_instantiation == 1); $display("b_object_instantiation process block started");t1 = new();t1.data = '{1, 2, 3, 4};t1.ch_id = 2;t1.pkt_id = 100;t2 = t1;$display("t1 object content is as below:\n%s", t1.sprint());$display("t2 object content is as below:\n%s", t2.sprint());t3 = t1.clone();$display("t3 object content is as below:\n%s", t3.sprint());$display("t1 object ID is [%0d]", t1.obj_id);$display("t2 object ID is [%0d]", t2.obj_id);$display("t3 object ID is [%0d]", t3.obj_id);$display("the latest chnl_trans object iD is [%0d]", chnl_trans::global_obj_id);
endendmodule
类的继承
module class_inheritance;bit b_member_override = 1;class trans;bit[31:0] data[];int pkt_id;int data_nidles;int pkt_nidles;bit rsp;function trans clone(trans t = null);if(t == null) t = new();t.data = data;t.pkt_id = pkt_id;t.data_nidles = data_nidles;t.pkt_nidles = pkt_nidles;t.rsp = rsp;return t;endfunctionendclassclass chnl_trans extends trans;int ch_id; // new member in child class// member function override with// same function name, arguments, and return type// TODO-1 seperately enable the clone function-1 and function-2, and check// if both of them works, and compare which is better, and why?// clone function-1function trans clone(trans t = null);chnl_trans ct;if(t == null)ct = new();elsevoid'($cast(ct, t));ct.data = data;ct.pkt_id = pkt_id;ct.data_nidles = data_nidles;ct.pkt_nidles = pkt_nidles;ct.rsp = rsp;ct.ch_id = ch_id; // new memberreturn ct;endfunction// clone function-2// function trans clone(trans t = null);// chnl_trans ct;// if(t == null)// ct = new();// else// void'($cast(ct, t));// void'(super.clone(ct));// ct.ch_id = ch_id; // new member// return ct;// endfunctionendclassinitial begin: member_overridetrans t1, t2;chnl_trans ct1, ct2;wait(b_member_override == 1); $display("b_member_override process block started");ct1 = new();ct1.pkt_id = 200;ct1.ch_id = 2;// t1 pointed to ct1's trans class data baset1 = ct1;// t2 copied ct1's trans class data baset2 = ct1.clone();void'($cast(ct2, t2));// TODO-2 why could not clone t1(->ct1) to t2?// t2 = t1.clone(); // ERROR clone call// void'($cast(ct2, t2));$display("ct1.pkt_id = %0d, ct1.ch_id = %0d", ct1.pkt_id, ct1.ch_id);// TODO-3 uncomment the statement below and consider// why t1 could not point to ct1.ch_id?// $display("ct1.pkt_id = %0d, ct1.ch_id = %0d", t1.pkt_id, t1.ch_id);$display("ct2.pkt_id = %0d, ct2.ch_id = %0d", ct2.pkt_id, ct2.ch_id);endendmodule
package的使用
package sky_pkg;class sun;typedef enum {RISE, FALL} state_e;state_e state = RISE;endclasssun apollo = new();class cloud;endclass
endpackagepackage sea_pkg;class fish;endclassclass island;string name;function new(string name = "island");this.name = name;endfunctionendclassisland hainan = new("hainan");
endpackagemodule package_usage;import sky_pkg::cloud;import sea_pkg::*;import sea_pkg::hainan;// TODO-2 why hainan could not be delcared here?// island hainan;initial begin// TODO-1 why sun type is not recognized? how to make it recognizable?// sun s;// TODO-2 why hainan could be declared here?island hainan;// TODO-3 why apollo is not recognized?// $display("sun state is %s", apollo.state);hainan = new("HAINAN");$display("hainan name is %s", hainan.name);$display("sea_pkg::hainan name is %s", sea_pkg::hainan.name);end
endmodule
随机约束
module constrained_random;bit b_system_random_func = 1;
bit b_class_randomization = 1;// TODO-1 understand how to use system random function, and its advanced
// method such as to generate unique values
initial begin: system_random_funcint unsigned rval;int unsigned gen_vals[$];wait(b_system_random_func == 1); $display("b_system_random_func process block started");// randomize 10 times, and each rand value doesnot care previous generated// valuerepeat(10) beginrval = $urandom_range(0, 9);$display("$urandom_range(0, 9) generated rand value is %0d", rval);end// Do you have other ways to generate unique number each time which should// not be duplicated with previously generate ones?repeat(10) begin$display("gen_vals queue content is %p", gen_vals);std::randomize(rval) with {foreach(gen_vals[i]) rval != gen_vals[i]; rval inside {[0:9]};};gen_vals.push_back(rval);$display("std::randomize with inline constrait generated rand value %0d", rval);end
endclass chnl_trans;rand bit[31:0] data[];rand int ch_id;rand int pkt_id;rand int data_nidles;rand int pkt_nidles;bit rsp;constraint cstr{data.size inside {[4:8]};foreach(data[i]) data[i] == 'hC000_0000 + (this.ch_id<<24) + (this.pkt_id<<8) + i;ch_id == 1;pkt_id == 1;data_nidles inside {[0:2]};pkt_nidles inside {[1:10]};};endclass// TODO-2 learn basic constraint format, class randomization method, soft
// constraint, and how to avolid constraint conflict?
initial begin: class_randomizationchnl_trans ct1, ct2;wait(b_class_randomization == 1); $display("b_class_randomization process block started");ct1 = new();// is ct1 already randomized?$display("ct1.data.size = %0d, ct1.ch_id = %0d, ct1.pkt_id = %0d", ct1.data.size(), ct1.ch_id, ct1.pkt_id);ct2 = new();// is ct2 already randomized?$display("ct2.data.size = %0d, ct2.ch_id = %0d, ct2.pkt_id = %0d", ct2.data.size(), ct2.ch_id, ct2.pkt_id);// why ct2.ch_id and ct2.pkt_id kept the same number even though it has been// randomized several times?repeat(5) beginvoid'(ct2.randomize());$display("ct2.data.size = %0d, ct2.ch_id = %0d, ct2.pkt_id = %0d", ct2.data.size(), ct2.ch_id, ct2.pkt_id);end// the randomization with inline constraint would meets randomization// failure, how to modify?// if(!ct1.randomize() with {ch_id == 2;})// $error("ct1 randomization failure!");// else// $display("ct1.data.size = %0d, ct1.ch_id = %0d, ct1.pkt_id = %0d", ct1.data.size(), ct1.ch_id, ct1.pkt_id);
endendmodule
线程的同步
module thread_sync;bit b_event_use = 0;
bit b_mailbox_use = 1;
bit b_mailbox_user_define = 1;// TODO-1.1 event does not new()
// TODO-1.2 learn event copy (direct assignment between two events)
// TODO-1.3 compare @ operator and triggered() method
initial begin: event_useevent e1, e2, e3a, e3b;wait(b_event_use == 1); $display("b_event_use process block started");e3b = e3a; // event copy, e3b and e3a are the same event->e1; // trigger e1 before @e1;->e2; // trigger e2 before e2.triggered();forkbegin @e1; $display("@%0t, @e1 finished" , $time); endbegin wait(e2.triggered()); $display("@%0t, wait(e2.triggered()) finished" , $time); endbegin @e3a; $display("@%0t, @e3a finished", $time); endbegin @e3b; $display("@%0t, @e3b finished", $time); endjoin_none#10ns;-> e3a;#10ns;-> e1; // trigger e1 again
endclass box;int id;function new(int id);this.id = id;endfunction
endclass// TODO-2 learn the parameterized mailbox and general storage method
initial begin: mailbox_usemailbox #(int) mb_id;mailbox #(box) mb_handle;box bx[5];wait(b_mailbox_use == 1); $display("b_mailbox_use process block started");// mailbox need new(N) for instantiationmb_id = new();mb_handle = new();// mailbox storageforeach(bx[i]) beginbx[i] = new(i);mb_id.put(i);mb_handle.put(bx[i]);end$display("box handles array bx content is %p", bx);// mailbox extraction$display("extracting ID and HANDLE from the TWO mailboxes");repeat(mb_id.num()) beginint id;box handle;mb_id.get(id);mb_handle.get(handle);$display("ID:%0d, HANDLE:%p", id, handle);end// check mailbox size$display("ID mailbox size is %0d", mb_id.num());$display("HANDLE mailbox size is %0d", mb_handle.num());
end// TODO-3 learn how to maximal utilize the mailbox storage with user defined
// type, we modify the 'mailbox_use' block and give a new block
// 'mailbox_user_define'
typedef struct{int id;box handle;
} mb_pair_element_t;initial begin: mailbox_user_definemailbox #(mb_pair_element_t) mb_pair;box bx[5];wait(b_mailbox_user_define == 1); $display("b_mailbox_user_define process block started");// mailbox need new(N) for instantiationmb_pair = new();// mailbox storageforeach(bx[i]) beginbx[i] = new(i);mb_pair.put('{i, bx[i]});end$display("box handles array bx content is %p", bx);// mailbox extraction$display("extracting ID and HANDLE from the ONE mailbox");repeat(mb_pair.num()) beginmb_pair_element_t pair;mb_pair.get(pair);$display("ID:%0d, HANDLE:%p", pair.id, pair.handle);end// check mailbox size$display("PAIR mailbox size is %0d", mb_pair.num);
endendmodule
线程的控制
module thread_control;bit b_fork_join = 1;
bit b_fork_join_any = 0;
bit b_fork_join_none = 0;class box;int id;function new(int id);this.id = id;endfunction
endclassbox bx[3];task automatic thread(int id = 1, int t = 10);$display("@%0t, thread id:%0d entered", $time, id);bx[id] = new(id); // allocate space#(t*1ns);bx[id] = null; // deallocate space$display("@%0t, thread id:%0d exited", $time, id);
endtask// TODO-1 learn fork-join thread exited when all sub-thread exit.
initial begin: fork_joinwait(b_fork_join == 1); $display("b_fork_join process block started");bx = '{null, null, null};$display("@%0t, fork_join_thread entered", $time);fork: fork_join_threadthread(0, 10);thread(1, 20);thread(2, 30);join$display("@%0t, fork_join_thread exited", $time);$display("@%0t, box handles array is %p", $time, bx);#10;b_fork_join = 0;b_fork_join_any = 1;
end// TODO-2.1 learn fork-join_any thread exited when just one sub-thread exites,
// but all other sub-thread are still running.
// TODO-2.2 learn disable BLOCK/fork statement, and check if the running
// sub-threads haven been disabled.
initial begin: fork_join_anywait(b_fork_join_any == 1); $display("b_fork_join_any process block started");bx = '{null, null, null};$display("@%0t, fork_join_any_thread entered", $time);fork: fork_join_any_threadthread(0, 10);thread(1, 20);thread(2, 30);join_any$display("@%0t, fork_join_any_thread exited", $time);$display("@%0t, box handles array is %p", $time, bx);disable fork_join_any_thread;$display("@%0t, disabled fork_join_any_thread", $time);#100ns;$display("@%0t, box handles array is %p", $time, bx);#10ns;b_fork_join_any = 0;b_fork_join_none = 1;
end// TODO-3.1 learn fork-join_none thread exited directly without calling any
// sub-thread, and continue executing other statements. Then the
// fork-join_none sub-threads would be still running.
// TODO-3.2 learn the wait fork statement, and check the time after it is
// satisified. The time should be the point when all fork sub-thread finished.
initial begin: fork_join_nonewait(b_fork_join_none == 1); $display("b_fork_join_none process block started");bx = '{null, null, null};$display("@%0t, fork_join_none_thread entered", $time);fork: fork_join_none_threadthread(0, 10);thread(1, 20);thread(2, 30);join_none$display("@%0t, fork_join_none_thread exited", $time);$display("@%0t, box handles array is %p", $time, bx);#15ns;$display("@%0t, box handles array is %p", $time, bx);wait fork;$display("@%0t, fork_join_none_thread's all sub-threads finished", $time);$display("@%0t, box handles array is %p", $time, bx);
endendmodule
虚方法
// This example is referred to the lec2/class_inheritance
// The purpose is to learn the convenience of virtual method
module virtual_methods;class trans;bit[31:0] data[];int pkt_id;int data_nidles;int pkt_nidles;bit rsp;virtual function trans clone(trans t = null);if(t == null) t = new();t.data = data;t.pkt_id = pkt_id;t.data_nidles = data_nidles;t.pkt_nidles = pkt_nidles;t.rsp = rsp;return t;endfunctionendclassclass chnl_trans extends trans;int ch_id; // new member in child classvirtual function trans clone(trans t = null);chnl_trans ct;if(t == null)ct = new();elsevoid'($cast(ct, t));void'(super.clone(ct));ct.ch_id = ch_id; // new memberreturn ct;endfunctionendclassinitial begintrans t1, t2;chnl_trans ct1, ct2;ct1 = new();ct1.pkt_id = 200;ct1.ch_id = 2;// t1 pointed to ct1's trans class data baset1 = ct1;$display("before cloning ct1 object");$display("ct1.pkt_id = %0d, ct1.ch_id = %0d", ct1.pkt_id, ct1.ch_id);// TODO-1 compare with lec2/class_inheritance TODO-2// why it is legal to call t1.clone() here?// TODO-2 via this example, please summarize the virtual method// conveniencet2 = t1.clone();void'($cast(ct2, t2));// TODO-3 to access ct2.ch_id, could we directly use t2.ch_id?// is it possible to add modified virtual before chnl_trans::ch_id, and// then access it by 't2.ch_id'? and why?$display("after cloning ct1 object");$display("ct1.pkt_id = %0d, ct1.ch_id = %0d", ct1.pkt_id, ct1.ch_id);$display("ct2.pkt_id = %0d, ct2.ch_id = %0d", ct2.pkt_id, ct2.ch_id);endendmodule
方法（任务与函数）
module task_and_function;bit b_function_define = 1;
bit b_task_define = 1;
bit b_inout_vs_ref = 1;function int double_f0(int a);return 2*a;
endfunctionfunction void double_f1(input int a, output int b);b = 2*a;
endfunctionfunction void double_f2(inout int a);a = 2*a;
endfunctionfunction automatic void double_f3(ref int a);a = 2*a;
endfunctiontask double_t1(input int a, output int b);b = 2*a;
endtasktask double_t2(inout int a);a = 2*a;
endtasktask automatic double_t3(ref int a);a = 2*a;
endtasktask double_t2_delay(inout int a);a = 2*a;#10ns;
endtasktask automatic double_t3_delay(ref int a);a = 2*a;#10ns;
endtask// TODO-1 lear the function definition possible ways
initial begin: function_defineint v1, v2;wait(b_function_define == 1); $display("b_function_define process block started");v1 = 10;v2 = double_f0(v1);$display("v1 = %0d, double function result is %0d", v1, v2);v1 = 10;double_f1(v1, v2);$display("v1 = %0d, double function result is %0d", v1, v2);v1 = 10;$display("v1 is %0d before calling double_f2(v1)", v1);double_f2(v1);$display("v1 is %0d (result) after calling double_f2(v1)", v1);v1 = 10;$display("v1 is %0d before calling double_f3(v1)", v1);double_f3(v1);$display("v1 is %0d (result) after calling double_f3(v1)", v1);
end// TODO-2 learn the task definition possible ways
initial begin: task_defineint v1, v2;wait(b_task_define == 1); $display("b_task_define process block started");v1 = 10;double_t1(v1, v2);$display("v1 = %0d, double task result is %0d", v1, v2);v1 = 10;$display("v1 is %0d before calling double_t2(v1)", v1);double_t2(v1);$display("v1 is %0d (result) after calling double_t2(v1)", v1);v1 = 10;$display("v1 is %0d before calling double_t3(v1)", v1);double_t3(v1);$display("v1 is %0d (result) after calling double_t3(v1)", v1);
end// TODO-3 compare the inout and ref argument between function and task use
initial begin: inout_vs_refint v1, v2;wait(b_inout_vs_ref == 1); $display("b_inout_vs_ref process block started");v1 = 10;$display("v1 is %0d before calling double_t2_delay(v1)", v1);forkdouble_t2_delay(v1);begin #5ns; $display("@%0t v1 = %0d in task call double_t2_delay(v1)", $time, v1); endjoin$display("v1 is %0d (result) after calling double_t2_delay(v1)", v1);v1 = 10;$display("v1 is %0d before calling double_t3_delay(v1)", v1);forkdouble_t3_delay(v1);begin #5ns; $display("@%0t v1 = %0d in task call double_t3_delay(v1)", $time, v1); endjoin$display("v1 is %0d (result) after calling double_t3_delay(v1)", v1);
endendmodule
