vcgencmd is a command line utility that can get various pieces of information from the VideoCore GPU on the Raspberry Pi. This is for the command get_throttled part of that.

get_throttled.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;

public class Program
{
    public static void Main()
    {
        var parsableOutput = "0x3000F";
        var parsedInt = Convert.ToInt32(parsableOutput, 16);

        var bitArray = new BitArray(new int[] { parsedInt });

        var top = new StringBuilder();
        var bottom = new StringBuilder();

        for (int i = 0; i < bitArray.Count; i++)
        {
            top.Append(i.ToString().PadLeft(3));
            bottom.Append(string.Concat("  ", bitArray[i] ? '1' : '0'));
        }

        Console.WriteLine(top.ToString());
        Console.WriteLine(bottom.ToString());

        Console.WriteLine();

        var tStatus = new ThrottledStatus(parsedInt);
        Console.WriteLine(tStatus);

        Console.WriteLine();

        TestThrottledStatus();
    }

    public static void TestThrottledStatus()
    {
        var testCases = new Dictionary<string, List<bool>> {
                { "0x0", new List<bool> { false, false, false, false, false, false, false, false } },
                { "0x1", new List<bool> {  true, false, false, false, false, false, false, false } },
                { "0x2", new List<bool> { false,  true, false, false, false, false, false, false } },
                { "0x3", new List<bool> {  true,  true, false, false, false, false, false, false } },
                { "0x4", new List<bool> { false, false,  true, false, false, false, false, false } },
                { "0x5", new List<bool> {  true, false,  true, false, false, false, false, false } },
                { "0x6", new List<bool> { false,  true,  true, false, false, false, false, false } },
                { "0x7", new List<bool> {  true,  true,  true, false, false, false, false, false } },
                { "0x8", new List<bool> { false, false, false,  true, false, false, false, false } },
                { "0x9", new List<bool> {  true, false, false,  true, false, false, false, false } },
                { "0xA", new List<bool> { false,  true, false,  true, false, false, false, false } },
                { "0xB", new List<bool> {  true,  true, false,  true, false, false, false, false } },
                { "0xC", new List<bool> { false, false,  true,  true, false, false, false, false } },
                { "0xD", new List<bool> {  true, false,  true,  true, false, false, false, false } },
                { "0xE", new List<bool> { false,  true,  true,  true, false, false, false, false } },
                { "0xF", new List<bool> {  true,  true,  true,  true, false, false, false, false } },
            { "0x10000", new List<bool> { false, false, false, false,  true, false, false, false } },
            { "0x20000", new List<bool> { false, false, false, false, false,  true, false, false } },
            { "0x30000", new List<bool> { false, false, false, false,  true,  true, false, false } },
            { "0x40000", new List<bool> { false, false, false, false, false, false,  true, false } },
            { "0x50000", new List<bool> { false, false, false, false,  true, false,  true, false } },
            { "0x60000", new List<bool> { false, false, false, false, false,  true,  true, false } },
            { "0x70000", new List<bool> { false, false, false, false,  true,  true,  true, false } },
            { "0x80000", new List<bool> { false, false, false, false, false, false, false,  true } },
            { "0x90000", new List<bool> { false, false, false, false,  true, false, false,  true } },
            { "0xA0000", new List<bool> { false, false, false, false, false,  true, false,  true } },
            { "0xB0000", new List<bool> { false, false, false, false,  true,  true, false,  true } },
            { "0xC0000", new List<bool> { false, false, false, false, false, false,  true,  true } },
            { "0xD0000", new List<bool> { false, false, false, false,  true, false,  true,  true } },
            { "0xE0000", new List<bool> { false, false, false, false, false,  true,  true,  true } },
            { "0xF0000", new List<bool> { false, false, false, false,  true,  true,  true,  true } },
            { "0xF000F", new List<bool> {  true,  true,  true,  true,  true,  true,  true,  true } },
        };

        foreach(var test in testCases)
        {
            var parsedInt = Convert.ToInt32(test.Key, 16);
            var testThrottledStatus = new ThrottledStatus(parsedInt);

            if (test.Value[0] != testThrottledStatus.UnderVoltageDetected ||
                test.Value[1] != testThrottledStatus.ArmFrequencyCapped ||
                test.Value[2] != testThrottledStatus.CurrentlyThrottled ||
                test.Value[3] != testThrottledStatus.SoftTempLimitActive ||
                test.Value[4] != testThrottledStatus.UnderVoltageHasOccured ||
                test.Value[5] != testThrottledStatus.ArmFrequencyCappingHasOccured ||
                test.Value[6] != testThrottledStatus.ThrottlingHasOccured ||
                test.Value[7] != testThrottledStatus.SoftTempLimitHasOccured) {
                throw new Exception("Something brokey");
            }
        }
    }
}

public class ThrottledStatus
{
    public bool UnderVoltageDetected { get; }

    public bool ArmFrequencyCapped { get; }

    public bool CurrentlyThrottled { get; }

    public bool SoftTempLimitActive { get; }

    public bool UnderVoltageHasOccured { get; }

    public bool ArmFrequencyCappingHasOccured { get; }

    public bool ThrottlingHasOccured { get; }

    public bool SoftTempLimitHasOccured { get; }

    public ThrottledStatus(int data)
    {
        var bitArray = new BitArray(new int[] { data });

        UnderVoltageDetected = bitArray[0];
        ArmFrequencyCapped = bitArray[1];
        CurrentlyThrottled = bitArray[2];
        SoftTempLimitActive = bitArray[3];

        UnderVoltageHasOccured = bitArray[16];
        ArmFrequencyCappingHasOccured = bitArray[17];
        ThrottlingHasOccured = bitArray[18];
        SoftTempLimitHasOccured = bitArray[19];
    }

    public override string ToString()
    {
        var output = new List<string>();

        if (UnderVoltageDetected) output.Add("UnderVoltageDetected");
        if (ArmFrequencyCapped) output.Add("ArmFrequencyCapped");
        if (CurrentlyThrottled) output.Add("CurrentlyThrottled");
        if (SoftTempLimitActive) output.Add("SoftTempLimitActive");

        if (UnderVoltageHasOccured) output.Add("UnderVoltageHasOccured");
        if (ArmFrequencyCappingHasOccured) output.Add("ArmFrequencyCappingHasOccured");
        if (ThrottlingHasOccured) output.Add("ThrottlingHasOccured");
        if (SoftTempLimitHasOccured) output.Add("SoftTempLimitHasOccured");

        return string.Join("\n", output);
    }
}