Making Color From Alpha, Hue, Saturation and Brightness

I find myself wanting to do this sometimes, so here's a bit of code (I'm sure I stole this code from somewhere else);

public static Color ColorFromAhsb(int a, float h, float s, float b) {

    if (0 > a || 255 < a) {
        throw new ArgumentOutOfRangeException(&quot;a&quot;);
    }
    if (0f > h || 360f < h) {
        throw new ArgumentOutOfRangeException(&quot;h&quot;);
    }
    if (0f > s || 1f < s) {
        throw new ArgumentOutOfRangeException(&quot;s&quot;);
    }
    if (0f > b || 1f < b) {
        throw new ArgumentOutOfRangeException(&quot;b&quot;);
    }

    if (0 == s) {
        return Color.FromArgb(a, Convert.ToInt32(b * 255),
            Convert.ToInt32(b * 255), Convert.ToInt32(b * 255));
    }

    float fMax, fMid, fMin;
    int iSextant, iMax, iMid, iMin;

    if (0.5 < b) {
        fMax = b - (b * s) + s;
        fMin = b + (b * s) - s;
    } else {
        fMax = b + (b * s);
        fMin = b - (b * s);
    }

    iSextant = (int)Math.Floor(h / 60f);
    if (300f <= h) {
        h -= 360f;
    }
    h /= 60f;
    h -= 2f * (float)Math.Floor(((iSextant + 1f) % 6f) / 2f);
    if (0 == iSextant % 2) {
        fMid = h * (fMax - fMin) + fMin;
    } else {
        fMid = fMin - h * (fMax - fMin);
    }

    iMax = Convert.ToInt32(fMax * 255);
    iMid = Convert.ToInt32(fMid * 255);
    iMin = Convert.ToInt32(fMin * 255);

    switch (iSextant) {
        case 1:
            return Color.FromArgb(a, iMid, iMax, iMin);
        case 2:
            return Color.FromArgb(a, iMin, iMax, iMid);
        case 3:
            return Color.FromArgb(a, iMin, iMid, iMax);
        case 4:
            return Color.FromArgb(a, iMid, iMin, iMax);
        case 5:
            return Color.FromArgb(a, iMax, iMin, iMid);
        default:
            return Color.FromArgb(a, iMax, iMid, iMin);
    }
}