library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

entity Stack is
    Port (
        push    : in STD_LOGIC;               -- Signal to push data onto the stack
        pop     : in STD_LOGIC;               -- Signal to pop data from the stack
        data_in : in STD_LOGIC_VECTOR(7 downto 0);  -- Input data to be pushed onto the stack
        data_out: out STD_LOGIC_VECTOR(7 downto 0)  -- Data popped from the stack
    );
end Stack;

architecture Behavioral of Stack is
    type Stack_Type is array (0 to 7) of STD_LOGIC_VECTOR(7 downto 0);
    signal stack_memory : Stack_Type;
    signal stack_pointer: STD_LOGIC_VECTOR(2 downto 0) := "000";  -- Initial stack pointer

begin
    process (push, pop, data_in)
    begin
        if push = '1' then
            if stack_pointer = "111" then
                -- Stack is full, no more pushing allowed
                report "Stack Overflow";
            else
                stack_memory(to_integer(unsigned(stack_pointer))) <= data_in;
                stack_pointer <= stack_pointer + 1;
            end if;
        elsif pop = '1' then
            if stack_pointer = "000" then
                -- Stack is empty, no more popping allowed
                report "Stack Underflow";
            else
                stack_pointer <= stack_pointer - 1;
            end if;
        end if;
    end process;

    data_out <= stack_memory(to_integer(unsigned(stack_pointer)));  -- Output the data from the stack
end Behavioral;