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  ../images/main/bulllet_4dots_orange.gif cross

cross is used for creating permutation and combitation of state and tran bins creater in coverage group. Basically this is used for creating more deep functional coverage points.

   

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Lets assume we have

   

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  • variable a which is 1 bit wide and states are S0 and S1
  • variable b whish is also is 1 bit wide and states are M0 and M1
  • when we do cross on samples of a and b it creates S0M0, S0M1, S1M0, S1M1.
  • Basically it means when S0 occured, did M0 occured, same for other states
   

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  ../images/main/bullet_star_pink.gif Example
   

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  1 class coverage_cross {
  2   bit [1:0] value1;
  3   bit [1:0] value2;
  4   event     now;
  5 
  6   coverage_group something {
  7      sample_event = sync(ALL,now);
  8      sample value1,value2;
  9      cross MY_CROSS (value1,value2);
 10   }
 11 
 12   task update_coverage (bit [1:0] value1,bit [1:0] value2) {
 13      this.value1 = value1;
 14      this.value2 = value2;
 15      trigger(now);
 16   }
 17 }
 18 
 19 
 20 
 21 program test {
 22   coverage_cross cov = new();
 23   bit [1:0] v1; 
 24   bit [1:0] v2; 
 25   repeat (10) {
 26     v1 = random();
 27     v2 = random();
 28     printf("Value is %0d %0d\n",v1,v2);
 29     cov.update_coverage(v1,v2);
 30     delay(1);
 31   }
 32 }    
You could download file coverage_cross.vr here
   

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  ../images/main/bullet_star_pink.gif Simulation log
   

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 Value is 0 1
 Value is 3 1
 Value is 1 2
 Value is 2 3
 Value is 3 1
 Value is 2 3
 Value is 1 2
 Value is 2 0
 Value is 0 3
 Value is 2 2
   

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  ../images/main/bullet_star_pink.gif Coverage Report
   

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 Group : test::coverage_cross::something
 
 ====================================================
 Group : test::coverage_cross::something
 ====================================================
 Score   Weight  Goal    
  81.25  1       100     
 
 
 
 
 ====================================================
 
 Samples for Group : test::coverage_cross::something
 
 
 
 Variable Expected Covered Percent Goal Weight 
                                               
 Total    8        8       100.00              
                                               
 value1   4        4       100.00  100  1      
                                               
 value2   4        4       100.00  100  1      
                                               
 
 
 Crosses for Group : test::coverage_cross::something
 
 
 
 Cross    Expected Covered Percent Goal Weight 
                                               
 Total    16       7       43.75               
                                               
 MY_CROSS 16       7       43.75   100  1      
                                               
 
 
 ====================================================
 
 Summary for variable value1
 
 
                              Expected Covered Percent 
                                                       
 Automatically Generated Bins 4        4       100.00  
                                                       
 
 
 Automatically Generated Bins for value1
 
 
 Bins
 
 name    count at least  
                        
 auto[0] 2     1        
                        
 auto[1] 2     1        
                        
 auto[2] 4     1        
                        
 auto[3] 2     1        
                        
 
 
 ====================================================
 
 Summary for variable value2
 
 
                              Expected Covered Percent 
                                                       
 Automatically Generated Bins 4        4       100.00  
                                                       
 
 
 Automatically Generated Bins for value2
 
 
 Bins
 
 name    count at least  
                        
 auto[0] 1     1        
                        
 auto[1] 3     1        
                        
 auto[2] 3     1        
                        
 auto[3] 3     1        
                        
 
 
 ====================================================
 
 Summary for cross MY_CROSS
 
 
 Samples crossed: value1 value2
                                    Expected Covered Percent Missing 
                                                                     
 Automatically Generated Cross Bins 16       7       43.75   9       
                                                                     
 
 
 Automatically Generated Cross Bins for MY_CROSS
 
 
 Uncovered bins
 
 value1    value2              count at least          
                                                       
 [auto[0]] [auto[0]]           0     1        
                                              
 [auto[0]] [auto[2]]           0     1        
                                              
 [auto[1]] [auto[0] - auto[1]] --    --       (2 bins) 
                                                       
 [auto[1]] [auto[3]]           0     1        
                                              
 [auto[2]] [auto[1]]           0     1        
                                              
 [auto[3]] [auto[0]]           0     1        
                                              
 [auto[3]] [auto[2] - auto[3]] --    --       (2 bins) 
                                                       
 
 
 Covered bins
 
 value1  value2  count at least  
                                
 auto[2] auto[2] 1     1        
                                
 auto[2] auto[0] 1     1        
                                
 auto[2] auto[3] 2     1        
                                
 auto[0] auto[3] 1     1        
                                
 auto[0] auto[1] 1     1        
                                
 auto[1] auto[2] 2     1        
                                
 auto[3] auto[1] 2     1        
                                
 
 
   

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Copyright © 1998-2014

Deepak Kumar Tala - All rights reserved

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