Initial commit

Libs/NanoBlaze/hdl/branchStack_RTL.vhd

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+ARCHITECTURE RTL OF branchStack IS
+
+  subtype progCounterType is unsigned(progCounter'range);
+  type progCounterArrayType is array (0 to 2**stackPointerBitNb) of progCounterType;
+  signal progCounterArray : progCounterArrayType;
+
+  signal writePointer : unsigned(stackPointerBitNb-1 downto 0);
+  signal readPointer  : unsigned(stackPointerBitNb-1 downto 0);
+
+BEGIN
+  ------------------------------------------------------------------------------
+                                                               -- stack pointers
+  updateStackPointer: process(reset, clock)
+  begin
+    if reset = '1' then
+      writePointer <= (others => '0');
+    elsif rising_edge(clock) then
+      if storePC = '1' then
+        writePointer <= writePointer + 1;
+      elsif prevPC = '1' then
+        writePointer <= writePointer - 1;
+      end if;
+    end if;
+  end process updateStackPointer;
+
+  readPointer <= writePointer - 1;
+
+  ------------------------------------------------------------------------------
+                                                       -- program counters stack
+  updateStack: process(reset, clock)
+  begin
+    if rising_edge(clock) then
+      if storePc = '1' then
+        progCounterArray(to_integer(writePointer)) <= progCounter;
+      end if;
+      storedProgCounter <= progCounterArray(to_integer(readPointer));
+    end if;
+  end process updateStack;
+
+END ARCHITECTURE RTL;