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[/] [qaz_libs/] [trunk/] [BFM/] [src/] [tb/] [rand_delays_c.sv] - Blame information for rev 34

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1 34 qaztronic
class rand_delays_c extends uvm_object;
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   //----------------------------------------------------------------------------------------
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   // Group: Types
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   // enum: traffic_type_e
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   // Allows for a variety of delay types
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   typedef enum {
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      FAST_AS_YOU_CAN,
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      REGULAR,
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      BURSTY
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   } traffic_type_e;
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   typedef int unsigned delay_t;
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   `uvm_object_utils_begin(rand_delays_c)
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      `uvm_field_enum(traffic_type_e, traffic_type, UVM_DEFAULT)
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      `uvm_field_int(min_delay,                     UVM_DEFAULT | UVM_DEC)
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      `uvm_field_int(max_delay,                     UVM_DEFAULT | UVM_DEC)
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      `uvm_field_int(burst_on_min,                  UVM_DEFAULT | UVM_DEC)
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      `uvm_field_int(burst_on_max,                  UVM_DEFAULT | UVM_DEC)
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      `uvm_field_int(burst_off_min,                 UVM_DEFAULT | UVM_DEC)
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      `uvm_field_int(burst_off_max,                 UVM_DEFAULT | UVM_DEC)
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      `uvm_field_int(wait_timescale,                UVM_DEFAULT | UVM_DEC)
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   `uvm_object_utils_end
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   //----------------------------------------------------------------------------------------
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   // Group: Random Fields
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   // var: traffic_type
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   rand traffic_type_e traffic_type;
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   // var: min_delay, max_delay
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   // Delays used for REGULAR traffic types
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   rand delay_t min_delay, max_delay;
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   // var: burst_on_min, burst_on_max
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   // Knobs that control the random length of bursty traffic
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   rand delay_t burst_on_min, burst_on_max;
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   // var: burst_off_min, burst_off_max
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   // Knobs that control how long a burst will be off
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   rand delay_t burst_off_min, burst_off_max;
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   // var: wait_timescale
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   // The timescale to use when wait_next_delay is called
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   time wait_timescale = 1ns;
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   //----------------------------------------------------------------------------------------
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   // Group: Local Fields
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   // var: burst_on_time
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   // When non-zero, currently burst mode is on for this many more calls
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   delay_t burst_on_time = 1;
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   //----------------------------------------------------------------------------------------
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   // Group: Constraints
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   // constraint: delay_L0_cnstr
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   // Keep min knobs <= max knobs
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   constraint delay_L0_cnstr {
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      traffic_type == REGULAR -> (min_delay <= max_delay);
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      traffic_type == BURSTY -> (burst_on_min <= burst_on_max) && (burst_off_min <= burst_off_max);
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   }
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   // constraint: delay_L1_cnstr
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   // Safe delays
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   constraint delay_L1_cnstr {
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      max_delay <= 500;
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      burst_on_max <= 500;
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      burst_off_max <= 500;
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   }
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   //----------------------------------------------------------------------------------------
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   // Group: Methods
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   ////////////////////////////////////////////
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   // func: new
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   function new(string name="rand_delay");
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      super.new(name);
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   endfunction : new
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   ////////////////////////////////////////////
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   // func: get_next_delay
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   // Return the length of the next delay
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   virtual function delay_t get_next_delay();
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      case(traffic_type)
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         FAST_AS_YOU_CAN: get_next_delay = 0;
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         REGULAR: begin
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            std::randomize(get_next_delay) with {
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               get_next_delay inside {[min_delay:max_delay]};
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            };
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         end
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         BURSTY: begin
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            if(burst_on_time) begin
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               burst_on_time -= 1;
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               get_next_delay = 0;
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            end else begin
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               std::randomize(get_next_delay) with {
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                  get_next_delay inside {[burst_off_min:burst_off_max]};
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               };
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               std::randomize(burst_on_time) with {
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                  burst_on_time inside {[burst_on_min:burst_on_max]};
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               };
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            end
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         end
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      endcase
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   endfunction : get_next_delay
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   ////////////////////////////////////////////
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   // func: wait_next_delay
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   // Wait for the next random period of time, based on the timescale provided
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   virtual task wait_next_delay();
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      delay_t delay = get_next_delay();
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      #(delay * wait_timescale);
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   endtask : wait_next_delay
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endclass : rand_delays_c

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