[Decompilation] Templatize subpixels to offer both 16-bit and 8-bit variants

Yup, TH03 actually uses a 4.4 fixed-point format.

Part of P0061, funded by Touhou Patch Center.

th03/math/subpixel.hpp

@@ -7,30 +7,37 @@ inline subpixel_t to_sp(float screen_v) {
 	return static_cast<subpixel_t>(screen_v * 16.0f);
 }
 
-class Subpixel {
+template <class T> class SubpixelBase {
 public:
 	// Code generation will require direct access to v, if performing
 	// arithmetic with a local variable...
-	subpixel_t v;
+	T v;
 
 	void operator +=(float screen_v) {
-		this->v += to_sp(screen_v);
+		this->v += static_cast<T>(to_sp(screen_v));
 	}
 
 	void operator -=(float screen_v) {
-		this->v -= to_sp(screen_v);
+		this->v -= static_cast<T>(to_sp(screen_v));
 	}
 
 	void operator =(float screen_v) {
-		v = to_sp(screen_v);
+		v = static_cast<T>(to_sp(screen_v));
 	}
 };
 
-struct SPPoint {
-	Subpixel x, y;
+template <class T> struct SPPointBase {
+	T x, y;
 
 	void set(float screen_x, float screen_y) {
 		x = screen_x;
 		y = screen_y;
 	}
 };
+
+// 16-bit (Q12.4)
+typedef SubpixelBase<subpixel_t> Subpixel;
+typedef SPPointBase<Subpixel> SPPoint;
+// 8-bit (Q4.4)
+typedef SubpixelBase<char> Subpixel8;
+typedef SPPointBase<Subpixel8> SPPoint8;

th03/math/subpixel.inc

@@ -0,0 +1,4 @@
+SPPoint8 struc
+	db ?	; x
+	db ?	; y
+SPPoint8 ends