[Decompilation] [th05] Shinki's 32×32 balls: Update function

Completes P0188, funded by [Anonymous] and nrook.

th05/main/bullet/b6ball.cpp

@@ -2,16 +2,22 @@
 
 #include "platform.h"
 #include "pc98.h"
+#include "th01/math/overlap.hpp"
 #include "th01/math/subpixel.hpp"
 #include "th04/math/motion.hpp"
 extern "C" {
 #include "th04/math/vector.hpp"
 #include "th04/main/playfld.hpp"
+#include "th04/main/player/player.hpp"
+#include "th04/main/bullet/clearzap.hpp"
+#include "th05/sprites/main_pat.h"
 #include "th05/main/playperf.hpp"
 }
 #include "th05/main/custom.h"
 #include "th05/main/bullet/b6ball.hpp"
 
+inline void optimization_barrier(void) {}
+
 void near b6balls_add(void)
 {
 	subpixel_t speed = playperf_speedtune(b6ball_template.speed);
@@ -29,3 +35,63 @@ void near b6balls_add(void)
 		return;
 	}
 }
+
+void near b6balls_update(void)
+{
+	CUSTOM_VERIFY(b6ball_t, B6BALL_COUNT);
+
+	b6ball_t near *p;
+	int i;
+	for((p = b6balls, i = 1); i < (1 + B6BALL_COUNT); (i++, p++)) {
+		if(p->flag == B6BF_FREE) {
+			continue;
+		}
+		if(p->flag == B6BF_CLOUD) {
+			p->cloud_radius -= 2.0f;
+			if(p->cloud_radius.v < to_sp(B6BALL_W / 2)) {
+				static_cast<unsigned char>(p->flag)++;
+			} else {
+				continue;
+			}
+		}
+
+		if(bullet_clear_time || bullet_zap.active) {
+			p->flag = B6BF_DECAY;
+		}
+
+		p->age++;
+		/* DX:AX = */ p->pos.update_seg3();
+		if(!playfield_encloses(_AX, _DX, B6BALL_W, B6BALL_H)) {
+			optimization_barrier();
+			p->flag = B6BF_FREE;
+		} else if(p->flag != B6BF_DECAY) {
+			_AX -= player_pos.cur.x.v;
+			_DX -= player_pos.cur.y.v;
+			if(overlap_wh_inplace_fast(
+				_AX, _DX, to_sp(B6BALL_W / 2), to_sp(B6BALL_H / 2)
+			)) {
+				player_is_hit = true;
+				p->flag = B6BF_DECAY;
+				continue;
+			}
+			optimization_barrier();
+		} else if(p->patnum_tiny < PAT_DECAY_B6BALL) {
+			// Rather brave to assume that the regular patnums of this entity
+			// can't be smaller. You know how you properly DRY decay state
+			// initialization? By moving it into a function...
+			p->patnum_tiny = PAT_DECAY_B6BALL;
+			p->pos.velocity.x.v /= 2;
+			p->pos.velocity.y.v /= 2;
+			p->decay_frames = 0;
+		} else /* if(p->flag == B6BF_DECAY) */ {
+			p->decay_frames++;
+			if((p->decay_frames % 4) == 0) {
+				p->patnum_tiny++;
+				if(p->patnum_tiny >= (PAT_DECAY_B6BALL_last + 1)) {
+					p->flag = B6BF_FREE;
+				}
+			}
+		}
+	loop_end:
+	}
+}

th05/main/bullet/b6ball.hpp

@@ -18,7 +18,7 @@ typedef struct {
 	b6ball_flag_t flag;
 	unsigned char angle; // unused
 	PlayfieldMotion pos;
-	unsigned int age;
+	unsigned int age; // unused and broken, because it's never reset
 	Subpixel cloud_radius;
 	int patnum_tiny;
 	int decay_frames;
@@ -33,5 +33,5 @@ typedef struct {
 // Spawns a new ball bullet according to the [b6ball_template].
 void near b6balls_add();
 
-void pascal near b6balls_update();
+void near b6balls_update();
 void pascal near b6balls_render();

th05_main.asm

@@ -19673,10 +19673,10 @@ main_035_TEXT	ends
 
 BOSS_6_TEXT	segment	byte public 'CODE' use16
 	@b6balls_add$qv procdesc near
+	@b6balls_update$qv procdesc near
 BOSS_6_TEXT	ends
 
 BOSS_X_TEXT	segment	byte public 'CODE' use16
-include th05/main/bullet/b6balls_add_update.asm
 
 ; =============== S U B	R O U T	I N E =======================================
 
@@ -21130,7 +21130,7 @@ loc_1E522:
 		call	@boss_defeat_update$qui pascal, 65
 
 loc_1E527:
-		call	b6balls_update
+		call	@b6balls_update$qv
 		call	@curvebullets_update$qv
 		call	hud_hp_update_and_render pascal, _boss_hp, 22800
 		pop	di