[Decompilation] [th01] Ellipse arc blitting

Most frequently used for complete circles, though… but who cares, as
of this commit, ReC98, as a whole, is ⅓ done!

Part of P0120, funded by Yanga.

th01/main/shape.cpp

@@ -0,0 +1,69 @@
+#include "th01/sprites/shape8x8.h"
+#include "th01/main/shape.hpp"
+
+#define shape8x8_put(shape, left, top, col) \
+	dots8x8_t sprite = sSHAPE8X8[shape]; \
+	vram_offset_t vram_offset_topleft = vram_offset_divmul(left, top); \
+	int first_bit = (left % BYTE_DOTS); \
+	if((left < 0) || (left >= RES_X) || (top < 0) || (top >= RES_Y)) { \
+		return; \
+	} \
+	grcg_put_8x8_mono(vram_offset_topleft, first_bit, sprite.rows, col);
+
+void shape8x8_diamond_put(screen_x_t left, vram_y_t top, int col)
+{
+	shape8x8_put(SHAPE8X8_DIAMOND, left, top, col);
+}
+
+void shape8x8_star_put(screen_x_t left, vram_y_t top, int col)
+{
+	shape8x8_put(SHAPE8X8_STAR, left, top, col);
+}
+
+void shape8x8_flake_put(screen_x_t left, vram_y_t top, int col)
+{
+	shape8x8_put(SHAPE8X8_FLAKE, left, top, col);
+}
+
+void shape_ellipse_arc_put(
+	screen_x_t center_x,
+	vram_y_t center_y,
+	pixel_t radius_x,
+	pixel_t radius_y,
+	int col,
+	unsigned char angle_step,
+	unsigned char angle_start,
+	unsigned char angle_end
+)
+{
+	int angle; // 16 bits to correctly work for an [angle_end] of 0xFF
+	dots8_t cache_dots = 0;
+	vram_offset_t cache_vram_offset = -1;
+
+	grcg_setcolor_rmw(col);
+
+	if(angle_start > angle_end) {
+		return;
+	}
+
+	for(angle = angle_start; angle <= angle_end; angle += angle_step) {
+		vram_offset_t vram_offset;
+		screen_x_t cur_x = polar_x(center_x, radius_x, angle);
+		vram_y_t   cur_y = polar_y(center_y, radius_y, angle);
+
+		vram_offset = vram_offset_shift(cur_x, cur_y);
+		if(cache_vram_offset != vram_offset) {
+			if(
+				(cur_x >= 0) && (cur_x < RES_X) &&
+				(cache_vram_offset >= 0) && (cache_vram_offset < PLANE_SIZE)
+			) {
+				VRAM_PUT(B, cache_vram_offset, cache_dots, 8);
+			}
+			cache_dots = ((0x80) >> (cur_x & (BYTE_DOTS - 1)));
+			cache_vram_offset = vram_offset;
+		} else {
+			cache_dots |= ((0x80) >> (cur_x & (BYTE_DOTS - 1)));
+		}
+	}
+	grcg_off();
+}

th01/main/shape8x8.hpp → th01/main/shape.hpp

@@ -3,3 +3,14 @@
 void shape8x8_diamond_put(screen_x_t left, vram_y_t top, int col);
 void shape8x8_star_put(screen_x_t left, vram_y_t top, int col);
 void shape8x8_flake_put(screen_x_t left, vram_y_t top, int col);
+
+void shape_ellipse_arc_put(
+	screen_x_t center_x,
+	vram_y_t center_y,
+	pixel_t radius_x,
+	pixel_t radius_y,
+	int col,
+	unsigned char angle_step,
+	unsigned char angle_start,
+	unsigned char angle_end
+);

th01/main_23.cpp

@@ -6,8 +6,10 @@
 #pragma option -3 -Z
 
 extern "C" {
+#include "libs/master.lib/master.h"
 #include "th01/formats/grc.cpp"
 #include "th01/hardware/grcg8x8m.cpp"
+#include "th01/math/vector.hpp"
 }
 
-#include "th01/main/shape8x8.cpp"
+#include "th01/main/shape.cpp"