[Decompilation] Encode the per-component range in the RGB color template

Allowing us to then retrieve it using a function call with no run-time
cost, although we do have to be careful with the types here.
Also, is that another solution to decompilation puzzles that involve
types of number literals?

Part of P0080, funded by Ember2528 and Splashman.

ReC98.h

@@ -17,7 +17,7 @@
 #ifdef __cplusplus
 	// master.lib palettes use twice the bits per RGB component for more
 	// toning precision
-	typedef RGB<uint8_t> RGB8;
+	typedef RGB<uint8_t, 256> RGB8;
 	typedef Palette<RGB8> Palette8;
 #endif
 // ---------------------

pc98.h

@@ -25,16 +25,29 @@ typedef bool page_t;
 #pragma option -a1
 
 #ifdef __cplusplus
-	template <class ComponentType> union RGB {
+	template <class ComponentType, int Range> union RGB {
 		struct {
 			ComponentType r, g, b;
 		} c;
 		ComponentType v[3];
+
+		// Yes, we actually need this function in certain cases where code
+		// generation calls for a 0 in the ComponentType.
+		static ComponentType min() {
+			return 0;
+		}
+		static ComponentType max() {
+			return (Range - 1);
+		}
 	};
 
 	template <class RGBType> struct Palette {
 		RGBType colors[COLOR_COUNT];
 
+		static int range() {
+			return RGBType::Range;
+		}
+
 		RGBType& operator [](int col) {
 			return colors[col];
 		}
@@ -44,7 +57,7 @@ typedef bool page_t;
 	// 4,096 colors
 	typedef int8_t uint4_t;
 
-	typedef RGB<uint4_t> RGB4;
+	typedef RGB<uint4_t, 16> RGB4;
 	typedef Palette<RGB4> Palette4;
 #endif
 

th01/hardware/graph.cpp

@@ -547,7 +547,7 @@ void z_palette_fade_from(
 	unsigned int step_ms
 )
 {
-	RGB4 fadepal[COLOR_COUNT];
+	Palette4 fadepal;
 	int i;
 	int col;
 	int comp;
@@ -564,12 +564,12 @@ void z_palette_fade_from(
 			fadepal[i].c.b = z_Palettes[i].c.b;
 		}
 	}
-	for(i = 0; i < 16; i++) {
+	for(i = 0; i < fadepal.range(); i++) {
 		z_vsync_wait();
 		for(col = 0; col < COLOR_COUNT; col++) {
 			for(comp = 0; comp < sizeof(RGB4); comp++) {
 				if(fadepal[col].v[comp] != z_Palettes[col].v[comp]) {
-					fadepal[col].v[comp] +=
+					fadepal.colors[col].v[comp] +=
 						(fadepal[col].v[comp] < z_Palettes[col].v[comp])
 						?  1
 						: -1;