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

	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);
	}
}