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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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