how does a variable to be decided it's value without it's initialize in systemverilog?

问题

Now I'm trying to digging the systemverilog as the below

denaliCdn_ahbTransaction burst1;

task sendTransfers;
      
burst1= new;       
burst1.Direction = DENALI_CDN_AHB_DIRECTION_WRITE;
burst1.FirstAddress = 32'h4020;//16416 M3 and M0 to S1
burst1.Kind = DENALI_CDN_AHB_BURSTKIND_INCR4;
burst1.Size = DENALI_CDN_AHB_TRANSFERSIZE_HALFWORD;
burst1.Data = new [8];

foreach (burst1.Data[ii])
burst1.Data[ii] = ii;

void'(activeMaster1.transAdd(burst1,0));
....
endtask

Especially, from here , how does ii be decided it's value without initialized ?

foreach (burst1.Data[ii])
burst1.Data[ii] = ii;

how does a variable to be decided it's value without it's initialize in systemverilog?

回答1:

There is a general answer and a specific answer to your question.

The general answer is that all types in System-Verilog initialise to specific values:

int    0
real   0.0
string ""
logic  1'bx

However, the specific answer to your question is that the code you specifically identify

foreach (burst1.Data[ii])
  burst1.Data[ii] = ii;

is actually performing initialisation rather than relying on it. The dynamic array burst1.data is constructed with 8 elements in the line

burst1.Data = new [8];

The line

foreach (burst1.Data[ii])

iterates over that array, looping 8 times, once for each element. The variable ii takes the value of the index of each element in the array, ie 0 to 7. The line

  burst1.Data[ii] = ii;

Sets element ii of the array to the value ii and so is initialising the array.

来源：https://stackoverflow.com/questions/47569029/how-does-a-variable-to-be-decided-its-value-without-its-initialize-in-systemve

标签

system-verilog