vmm_atomic_gen is basically a macro like vmm_channel, which basically builds a simple for loop to randomize the vmm_data and push into vmm_channel. The for loop varibale is controlled by a integer variable stop_after_n_insts.

vmm_atomic_gen is extended from vmm_xactor, and has all the cool features of vmm_xactor. To be able to use a vmm_atomic_gen, following things are need at minimum.

• vmm_data : Need to have perfect control of all the controlling variables to generate both normal and error traffic.
• instance : Create a instance of vmm_atomic_gen and set stop_after_n_insts
• start_sim: Call the start_xactor

Note :If you are new to VMM, constraint randomization, coverage convergence, Then I suggest stay away from atomic generators. It's so easy to mess things up :-)

This is modified version of notify example

   1 `include "vmm.sv"
   2 
   3 // Note : This is not exact representation of AHB data class
   4 // All data class needs to extend from vmm_data
   5 class ahb_data extends vmm_data;
   6   vmm_log log;
   7   // Declare all the fields
   8   rand bit [31:0] addr;
   9   rand bit [31:0] data [16];
  10   rand bit [3:0]  beats;
  11 
  12   // Make sure all variables have init value 
  13   function new(vmm_log log = null);
  14     int i;
  15     super.new(log);
  16     this.log  = log;
  17     this.addr       = 0;
  18     for (i = 0; i < 16; i ++) begin
  19       this.data[1] = 0;
  20     end
  21     this.beats     = 1;
  22   endfunction
  23   virtual function vmm_data copy(vmm_data to = null);
  24      ahb_data cpy;
  25      int i;
  26      if (to == null) begin
  27        cpy = new (log);
  28      end else begin
  29        if ( ! ($cast(cpy,to))) begin
  30          `vmm_fatal(log,"Object is not of type ahb_data");
  31        end
  32      end
  33     cpy.addr = this.addr;
  34     for (i = 0; i < 16; i ++) begin
  35       cpy.data[i] = this.data[1];
  36     end
  37     copy         = cpy;
  38   endfunction
  39 
  40 
  41   // Print message
  42   function void display(string prefix = "");
  43     if (is_valid()) begin
  44      `vmm_debug(log,$psprintf("%s",psdisplay(prefix)));
  45     end else begin
  46      `vmm_error(log,$psprintf("%s",psdisplay(prefix)));
  47     end
  48   endfunction
  49 
  50   // Return the string members and their values
  51   virtual function string psdisplay(string prefix = "");
  52     string msg;
  53     int i;
  54     msg = $psprintf("   %s\n", prefix);
  55     msg = $psprintf("%s ADDRESS       : 32'h%x\n",msg,addr);
  56     msg = $psprintf("%s BEATS         : %0d\n",msg,beats);
  57 
  58     for (i = 0; i < beats; i++) begin
  59       msg = $psprintf("%s DATA[%2d]      : 32'h%x\n",msg,i,data[i]);
  60     end
  61     psdisplay = msg;
  62   endfunction
  63 endclass
  64 
  65 // We need to add below line to construct vmm_channel for object ahb_data
  66 `vmm_channel(ahb_data)
  67 `vmm_atomic_gen(ahb_data,"ATOMIC GEN")
  68 
  69 // This class sinks transactions
  70 class sink extends vmm_xactor;
  71   ahb_data_channel fifo;
  72   vmm_log log;
  73   
  74   function new(vmm_log log, string name, ahb_data_channel fifo);
  75     super.new(name,name);
  76     this.log = log;
  77     this.fifo = fifo;
  78   endfunction
  79 
  80   virtual task main();
  81      ahb_data d;
  82      super.main();
  83      while (1) begin
  84        wait_if_stopped_or_empty(fifo);
  85        fifo.get(d);
  86        // Indicate we are processing the object
  87        d.notify.indicate(vmm_data::STARTED);
  88         #10 ;
  89        // Indicate we done with processing the object
  90        $display("Indicating done processing");
  91        d.notify.indicate(vmm_data::ENDED);
  92      end
  93   endtask
  94 endclass
  95 
  96 program test();
  97   vmm_log log = new("test","ahb_data");
  98   ahb_data_channel fifo = new ("CHANNEL","FIFO");
  99   // Call new with pointer to channel
 100   ahb_data_atomic_gen src = new("SOURCE",-1,fifo);
 101   sink   snk  = new(log,"SINK",fifo);
 102 
 103   initial begin
 104      // Set number of transactions to generate
 105      src.stop_after_n_insts = 2;
 106      snk.start_xactor();
 107      src.start_xactor();
 108      // Wait for source to start 
 109      src.notify.wait_for(vmm_xactor::XACTOR_BUSY); 
 110      $display("Came out of SOURCE START");
 111      // Wait for source to end
 112      src.notify.wait_for(ahb_data_atomic_gen::DONE);
 113      $display("Came out of SOURCE DONE");
 114       #100 ;
 115   end
 116 endprogram

 Trace[INTERNAL] on ATOMIC GEN Atomic Generator(SOURCE) at                    0:
     Started
 Debug[INTERNAL] on CHANNEL(FIFO) at                    0:
     New instance added to channel @-1 (level 1 of 1/0)
            
      ADDRESS       : 32'h1ff126c2
      BEATS         : 1
      DATA[ 0]      : 32'hf5ece2b5
     
 Trace[INTERNAL] on SINK(SINK) at                    0:
     Started
 Debug[INTERNAL] on CHANNEL(FIFO) at                    0:
     New instance removed from channel @0 (level 0 of 1/0)
            
      ADDRESS       : 32'h1ff126c2
      BEATS         : 1
      DATA[ 0]      : 32'hf5ece2b5
     
 Came out of SOURCE START
 Debug[INTERNAL] on CHANNEL(FIFO) at                    0:
     New instance added to channel @-1 (level 1 of 1/0)
            
      ADDRESS       : 32'h535836f8
      BEATS         : 1
      DATA[ 0]      : 32'h9746fa0b
     
 Indicating done processing
 Debug[INTERNAL] on CHANNEL(FIFO) at                   10:
     New instance removed from channel @0 (level 0 of 1/0)
            
      ADDRESS       : 32'h535836f8
      BEATS         : 1
      DATA[ 0]      : 32'h9746fa0b
     
 Came out of SOURCE DONE
 Indicating done processing
 Trace[INTERNAL] on SINK(SINK) at                   20:

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Deepak Kumar Tala - All rights reserved

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