Fixed limitations in random_integer_array min/max range.

Author: LarsAsplund

vunit/vhdl/random/src/random_pkg.vhd

@@ -113,17 +113,43 @@ package body random_pkg is
     return integer_vector_ptr;
   end;
 
-  function ilog2(value : natural) return natural is
+  function ceil_log2(value : positive) return natural is
     variable res : natural := 0;
     variable pow : natural := 1;
   begin
     while pow < value loop
-      pow := pow*2;
+      pow := pow * 2;
       res := res + 1;
     end loop;
+
     return res;
   end function;
 
+  function n_bits_needed(value : integer; signed_representation : boolean) return positive is
+    variable n_bits : positive;
+  begin
+    if value > 0 then
+      if value /= integer'high then
+        n_bits := ceil_log2(value + 1);
+      else
+        n_bits := ceil_log2(value / 2 + 1) + 1;
+      end if;
+      if signed_representation then
+        n_bits := n_bits + 1;
+      end if;
+    elsif value < 0 then
+      if value /= integer'low then
+        n_bits := ceil_log2(-value) + 1;
+      else
+        n_bits := ceil_log2(-(value / 2)) + 2;
+      end if;
+    else
+      n_bits := 1;
+    end if;
+
+    return n_bits;
+  end;
+
   procedure random_integer_array(variable rnd : inout RandomPType;
                                  variable integer_array : inout integer_array_t;
                                  width : natural := 1;
@@ -137,11 +163,7 @@ package body random_pkg is
     assert min_value <= max_value report "min_value must be lower or equal to max_value";
     is_signed := min_value < 0;
 
-    if is_signed then
-      bit_width := ilog2(abs min_value) + 1;
-    else
-      bit_width := ilog2(max_value+1);
-    end if;
+    bit_width := maximum(n_bits_needed(min_value, is_signed), n_bits_needed(max_value, is_signed));
 
     deallocate(integer_array);
     integer_array := new_3d(width => width, height => height, depth => depth,

vunit/vhdl/random/test/tb_random_pkg.vhd

@@ -95,6 +95,54 @@ begin
       check_equal(integer_array.bit_width, 13);
       check_equal(integer_array.is_signed, false);
 
+      random_integer_array(rnd, integer_array, 13, min_value => 0, max_value => 0);
+      check_equal(integer_array.bit_width, 1);
+      check_equal(integer_array.is_signed, false);
+
+      random_integer_array(rnd, integer_array, 13, min_value => -2, max_value => -2);
+      check_equal(integer_array.bit_width, 2);
+      check_equal(integer_array.is_signed, true);
+
+      random_integer_array(rnd, integer_array, 13, min_value => -3, max_value => -3);
+      check_equal(integer_array.bit_width, 3);
+      check_equal(integer_array.is_signed, true);
+
+      random_integer_array(rnd, integer_array, 13, min_value => 1, max_value => 1);
+      check_equal(integer_array.bit_width, 1);
+      check_equal(integer_array.is_signed, false);
+
+      random_integer_array(rnd, integer_array, 13, min_value => 2, max_value => 2);
+      check_equal(integer_array.bit_width, 2);
+      check_equal(integer_array.is_signed, false);
+
+      random_integer_array(rnd, integer_array, 13, min_value => 0, max_value => 2);
+      check_equal(integer_array.bit_width, 2);
+      check_equal(integer_array.is_signed, false);
+
+      random_integer_array(rnd, integer_array, 13, min_value => -1, max_value => 2);
+      check_equal(integer_array.bit_width, 3);
+      check_equal(integer_array.is_signed, true);
+
+      random_integer_array(rnd, integer_array, 13, min_value => -3, max_value => 1);
+      check_equal(integer_array.bit_width, 3);
+      check_equal(integer_array.is_signed, true);
+
+      random_integer_array(rnd, integer_array, 13, min_value => 0, max_value => integer'high);
+      check_equal(integer_array.bit_width, 31);
+      check_equal(integer_array.is_signed, false);
+
+      random_integer_array(rnd, integer_array, 13, min_value => -1, max_value => integer'high);
+      check_equal(integer_array.bit_width, 32);
+      check_equal(integer_array.is_signed, true);
+
+      random_integer_array(rnd, integer_array, 13, min_value => integer'low, max_value => 0);
+      check_equal(integer_array.bit_width, 32);
+      check_equal(integer_array.is_signed, true);
+
+      random_integer_array(rnd, integer_array, 13, min_value => integer'low, max_value => integer'high);
+      check_equal(integer_array.bit_width, 32);
+      check_equal(integer_array.is_signed, true);
+
     end if;
 
     test_runner_cleanup(runner);