ch2-Unpacked array

2019-10-24

Multidimensional Unpacked Array

module tb;
  byte   stack [2][4];     // 2 rows, 4 cols
 
  initial begin
    // Assign random values to each slot of the stack
    foreach (stack[i])
          foreach (stack[i][j]) begin
            stack[i][j] = $random;
            $display ("stack[%0d][%0d] = 0x%0h", i, j, stack[i][j]);
      end
 
    // Print contents of the stack
    $display ("stack = %p", stack);
  end
endmodule

Packed + Unpacked Array

The example shown below illustrates a multidimensional packed + unpacked array.

module tb;
  bit [3:0][7:0]   stack [2][4];     // 2 rows, 4 cols
 
  initial begin
    // Assign random values to each slot of the stack
    foreach (stack[i])
          foreach (stack[i][j]) begin
            stack[i][j] = $random;
            $display ("stack[%0d][%0d] = 0x%0h", i, j, stack[i][j]);
      end
 
    // Print contents of the stack
    $display ("stack = %p", stack);
 
    // Print content of a given index
        $display("stack[0][0][2] = 0x%0h", stack[0][0][2]);
  end
endmodule
 

​ In a multidimensional declaration, the dimensions declared before the name vary more faster than the dimensions following the name.

bit   [1:4]     m_var   [1:5]      // 1:4 varies faster than 1:5 
bit         m_var2   [1:5] [1:3]    // 1:3 varies faster than 1:5
bit   [1:3] [1:7] m_var3;         // 1:7 varies faster than 1:3
 
bit   [1:3] [1:2] m_var4 [1:7] [0:2]     // 1:2 varies most rapidly, followed by 1:3, then 0:2 and then 1:7