[Reverse-engineering] [th04/th05] Bullet structure

And since everyone always cares about caps:
• TH04: 240 for the white 8×8 pellets, 220 for 16×16 sprites
• TH05: 180 for the white 8×8 pallets, 240 for 16×16 sprites

Completes P0072, funded by [Anonymous] and -Tom-.

th03/math/subpixel.hpp

@@ -43,5 +43,6 @@ template <class T> struct SPPointBase {
 typedef SubpixelBase<subpixel_t> Subpixel;
 typedef SPPointBase<Subpixel> SPPoint;
 // 8-bit (Q4.4)
+typedef SubpixelBase<unsigned char> SubpixelLength8;
 typedef SubpixelBase<char> Subpixel8;
 typedef SPPointBase<Subpixel8> SPPoint8;

th04/bullet/bullet.hpp

@@ -0,0 +1,96 @@
+/// States and modes
+/// ----------------
+#pragma option -b-
+
+#define BSS_CLOUD_FRAMES 16
+#define BMS_DECAY_FRAMES 16
+#define BMS_SLOWDOWN_BASE_SPEED 4.5f
+#define BMS_SLOWDOWN_FRAMES 32
+
+enum bullet_spawn_state_t {
+	/// Hitbox is active
+	/// ----------------
+	BSS_GRAZEABLE = 0,
+	BSS_GRAZED = 1,
+	BSS_ACTIVE = 2,
+	/// ----------------
+
+	/// Delay "cloud", no hitbox
+	/// ------------------------
+	BSS_CLOUD_BACKWARDS = 3,
+	BSS_CLOUD_FORWARDS = 4,
+	BSS_CLOUD_END = (BSS_CLOUD_FORWARDS + BSS_CLOUD_FRAMES),
+	/// ------------------------
+};
+
+enum bullet_move_state_t {
+	/// Hitbox is active
+	/// ----------------
+	// Slows down from BMS_SLOWDOWN_BASE_SPEED to [final_speed]
+	BMS_SLOWDOWN = 0,
+	// Special processing according to [special_motion]
+	BMS_SPECIAL = 1,
+	// No special processing
+	BMS_NORMAL = 2,
+	/// ----------------
+
+	/// Decay, no hitbox
+	/// ----------------
+	BMS_DECAY = 4,
+	BMS_DECAY_END = (BMS_DECAY + BMS_DECAY_FRAMES),
+	/// ----------------
+};
+
+enum bullet_special_motion_t {
+};
+
+#pragma option -b
+/// ----------------
+
+struct bullet_t {
+	char flag;
+	char age;
+	motion_t pos;
+	unsigned char from_pattern; // unused
+	int8_t unused;
+	SubpixelLength8 speed_cur;
+	unsigned char angle;
+	bullet_spawn_state_t spawn_state;
+	bullet_move_state_t move_state;
+	bullet_special_motion_t special_motion;
+	unsigned char speed_final;
+	union {
+		unsigned char slowdown_time;	// with BMS_SLOWDOWN
+		unsigned char turn_count;	// with BMS_SPECIAL
+	} ax;
+	union {
+		unsigned char slowdown_speed_delta;	// with BMS_SLOWDOWN
+		unsigned char turn_angle;	// with BMS_SPECIAL
+	} dx;
+	int patnum;
+
+#if GAME == 5
+	// Coordinates for BSM_STRAIGHT
+	SPPoint origin;
+	int distance;
+#endif
+};
+
+#define PELLET_W 8
+#define PELLET_H 8
+#define BULLET16_W 16
+#define BULLET16_H 16
+
+#if GAME == 5
+# define PELLET_COUNT 180
+# define BULLET16_COUNT 220
+#else
+# define PELLET_COUNT 240
+# define BULLET16_COUNT 200
+#endif
+
+#define BULLET_COUNT (PELLET_COUNT + BULLET16_COUNT)
+
+extern bullet_t bullets[BULLET_COUNT];
+#define pellets (&bullets[0])
+#define bullets16 (&bullets[PELLET_COUNT])

th04/bullet/bullets[bss].asm

@@ -0,0 +1,66 @@
+BSS_CLOUD_FRAMES = 16
+BMS_DECAY_FRAMES = 16
+BMS_SLOWDOWN_BASE_SPEED = (4 shl 4) + 8
+BMS_SLOWDOWN_FRAMES = 32
+
+BSS_GRAZEABLE = 0
+BSS_GRAZED = 1
+BSS_ACTIVE = 2
+BSS_CLOUD_BACKWARDS = 3
+BSS_CLOUD_FORWARDS = 4
+BSS_CLOUD_END = (BSS_CLOUD_FORWARDS + BSS_CLOUD_FRAMES)
+
+BMS_SLOWDOWN = 0
+BMS_SPECIAL = 1
+BMS_NORMAL = 2
+BMS_DECAY = 4
+BMS_DECAY_END = (BMS_DECAY + BMS_DECAY_FRAMES)
+
+bullet_t struc
+	flag	db ?
+	age	db ?
+	pos	motion_t <?>
+	from_pattern	db ?
+		db ?
+	speed_cur	db ?
+	BULLET_angle	db ?
+	spawn_state	db ?
+	move_state	db ?
+	special_motion	db ?
+	speed_final	db ?
+
+	slowdown_time	label byte
+	turn_count	label byte
+		db ?
+
+	slowdown_speed_delta	label byte
+	turn_angle	label byte
+		db ?
+
+	BULLET_patnum	dw ?
+
+	if GAME eq 5
+		BULLET_origin	Point <?>
+		distance	dw ?
+	endif
+bullet_t ends
+
+PELLET_W = 8
+PELLET_H = 8
+BULLET16_W = 16
+BULLET16_H = 16
+
+if GAME eq 5
+	PELLET_COUNT = 180
+	BULLET16_COUNT = 220
+else
+	PELLET_COUNT = 240
+	BULLET16_COUNT = 200
+endif
+
+BULLET_COUNT = (PELLET_COUNT + BULLET16_COUNT)
+
+public _bullets, _pellets, _bullets16
+_bullets label bullet_t
+_pellets	bullet_t PELLET_COUNT dup(<?>)
+_bullets16	bullet_t BULLET16_COUNT dup(<?>)