Recover in VHDL

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.NUMERIC_STD.ALL;

entity RecoverExample is
end RecoverExample;

architecture Behavioral of RecoverExample is
    -- Declare a custom exception type
    type custom_exception is (no_exception, problem_exception);
    
    -- Function to simulate a panic
    function may_panic return custom_exception is
    begin
        return problem_exception;
    end function;
    
    -- Procedure to simulate recover functionality
    procedure recover(signal exception : inout custom_exception) is
    begin
        if exception /= no_exception then
            report "Recovered. Error: " & custom_exception'image(exception);
            exception <= no_exception;
        end if;
    end procedure;

begin
    process
        variable local_exception : custom_exception := no_exception;
    begin
        -- Simulate defer functionality
        local_exception := may_panic;
        recover(local_exception);
        
        -- This code will run, unlike in the original example
        report "After may_panic()";
        
        wait;
    end process;
end Behavioral;

In VHDL, we don’t have direct equivalents for panic and recover as in Go. However, we can simulate similar behavior using custom exceptions and procedures.

1. We define a custom exception type custom_exception with two possible values: no_exception and problem_exception.

2. The may_panic function simulates a panic by returning a problem_exception.

3. The recover procedure checks if an exception has occurred and reports it, simulating the recovery process.

4. In the main process, we call may_panic and immediately call recover, simulating the deferred recovery in the original Go code.

5. Unlike in the Go example, the “After may_panic()” message will be reported in this VHDL version, as VHDL doesn’t have the same concept of execution stopping at a panic point.

To run this VHDL code, you would typically use a VHDL simulator such as ModelSim or GHDL. The simulation would output something like:

# Recovered. Error: PROBLEM_EXCEPTION
# After may_panic()

Note that VHDL is typically used for hardware description and simulation, so the concepts of panic and recover don’t translate directly. This example demonstrates a way to achieve similar behavior, but in real VHDL applications, error handling would typically be implemented differently, often using assert statements or custom error handling mechanisms appropriate for the specific hardware design.