[Decompilation] [th01] Pellet speed modification

Category: Function comment spells out entire function code because its
effects are impossible to summarize

Part of P0160, funded by Yanga.

th01/main/bullet/pellet.cpp

@@ -178,7 +178,9 @@ inline subpixel_t base_speed_for_rank(void)
 
 #define speed_set(speed) \
 	speed += base_speed_for_rank(); \
-	speed += ((resident->pellet_speed * speed) / to_sp(2.5f)); \
+	/* Note that ((subpixel * pellet_speed_t) / pellet_speed_t) still gives a
+	/* correct subpixel result. */ \
+	speed += ((resident->pellet_speed * speed) / PELLET_SPEED_MULTIPLIER); \
 	if(speed < to_sp(1.0f)) { \
 		speed = to_sp(1.0f); \
 	}

th01/main/bullet/pellet_s.cpp

@@ -0,0 +1,21 @@
+#include "th01/main/bullet/pellet_s.hpp"
+
+void pellet_speed_lower(pellet_speed_t max, pellet_speed_t negative_delta)
+{
+	if(resident->pellet_speed > max) {
+		resident->pellet_speed = max;
+	} else {
+		resident->pellet_speed += negative_delta;
+	}
+	if(resident->pellet_speed < PELLET_SPEED_LOWER_MIN) {
+		resident->pellet_speed = PELLET_SPEED_LOWER_MIN;
+	}
+}
+
+void pellet_speed_raise(pellet_speed_t delta)
+{
+	resident->pellet_speed += delta;
+	if(resident->pellet_speed > PELLET_SPEED_RAISE_MAX) {
+		resident->pellet_speed = PELLET_SPEED_RAISE_MAX;
+	}
+}

th01/main/bullet/pellet_s.hpp

@@ -0,0 +1,19 @@
+#define PELLET_SPEED_LOWER_MIN to_pellet_speed(-0.375f)
+#define PELLET_SPEED_RAISE_MAX to_pellet_speed(0.5f)
+
+// Clamps the resident speed of newly fired pellets to the given maximum value
+// if it's higher, then raises (sic) it by [negative_delta], down to a minimum
+// of [PELLET_SPEED_LOWER_MIN].
+void pellet_speed_lower(pellet_speed_t max, pellet_speed_t negative_delta);
+
+inline void pellet_speed_lower(float max, float negative_delta) {
+	pellet_speed_lower(to_pellet_speed(max), to_pellet_speed(negative_delta));
+}
+
+// Raises the resident speed of newly fired pellets by [delta], up to a
+// maximum of [PELLET_SPEED_RAISE_MAX].
+void pellet_speed_raise(pellet_speed_t delta);
+
+inline void pellet_speed_raise(float delta) {
+	pellet_speed_raise(to_pellet_speed(delta));
+}

th01/main_012.cpp

@@ -2,3 +2,9 @@
  * -----
  * 3rd part of code segment #1 of TH01's REIIDEN.EXE
  */
+
+#include "platform.h"
+#include "th01/common.h"
+#include "th01/resident.hpp"
+
+#include "th01/main/bullet/pellet_s.cpp"

th01/resident.hpp

@@ -9,6 +9,17 @@ typedef enum {
 	MODE_DEBUG = 3
 } mode_t;
 
+// Much like subpixels, pellet speeds are stored pre-multiplied by 40 to allow
+// an effective resolution of 0.025 pixels to be losslessly stored in an
+// integer. This pre-multiplication is reverted by the pellet spawning
+// functions.
+typedef int pellet_speed_t;
+
+static const pellet_speed_t PELLET_SPEED_MULTIPLIER = 40;
+
+#define to_pellet_speed(pixel_v) \
+	static_cast<pellet_speed_t>(pixel_v * PELLET_SPEED_MULTIPLIER)
+
 #define RES_ID "ReiidenConfig"
 typedef struct {
 	char id[sizeof(RES_ID)];
@@ -23,7 +34,7 @@ typedef struct {
 	char snd_need_init;
 	char unused_2;
 	char mode;
-	int pellet_speed;
+	pellet_speed_t pellet_speed;
 	long rand;
 	long score;
 	long continues_total;

th01_reiiden.asm

@@ -1276,65 +1276,8 @@ sub_C942	endp
 main_012_TEXT	ends
 
 main_013_TEXT	segment	byte public 'CODE' use16
-
+	extern @pellet_speed_lower$qii:proc
-; =============== S U B	R O U T	I N E =======================================
+	extern @pellet_speed_raise$qi:proc
-
-; Attributes: bp-based frame
-
-sub_CBBE	proc far
-
-arg_0		= word ptr  6
-arg_2		= word ptr  8
-
-		push	bp
-		mov	bp, sp
-		mov	dx, [bp+arg_0]
-		les	bx, _resident
-		cmp	es:[bx+reiidenconfig_t.bullet_speed], dx
-		jle	short loc_CBD4
-		mov	es:[bx+reiidenconfig_t.bullet_speed], dx
-		jmp	short loc_CBDF
-; ---------------------------------------------------------------------------
-
-loc_CBD4:
-		les	bx, _resident
-		mov	ax, [bp+arg_2]
-		add	es:[bx+reiidenconfig_t.bullet_speed], ax
-
-loc_CBDF:
-		les	bx, _resident
-		cmp	es:[bx+reiidenconfig_t.bullet_speed], -15
-		jge	short loc_CBF0
-		mov	es:[bx+reiidenconfig_t.bullet_speed], -15
-
-loc_CBF0:
-		pop	bp
-		retf
-sub_CBBE	endp
-
-
-; =============== S U B	R O U T	I N E =======================================
-
-; Attributes: bp-based frame
-
-sub_CBF2	proc far
-
-arg_0		= word ptr  6
-
-		push	bp
-		mov	bp, sp
-		les	bx, _resident
-		mov	ax, [bp+arg_0]
-		add	es:[bx+reiidenconfig_t.bullet_speed], ax
-		cmp	es:[bx+reiidenconfig_t.bullet_speed], 20
-		jle	short loc_CC0D
-		mov	es:[bx+reiidenconfig_t.bullet_speed], 20
-
-loc_CC0D:
-		pop	bp
-		retf
-sub_CBF2	endp
-
 
 ; =============== S U B	R O U T	I N E =======================================
 
@@ -1390,9 +1333,7 @@ loc_CD2E:
 		mov	al, es:[bx+reiidenconfig_t.start_lives_extra]
 		add	al, 2
 		mov	es:[bx+reiidenconfig_t.rem_lives], al
-		push	0FFFBFFFEh
+		call	@pellet_speed_lower$qii c, large (-2 and 0FFFFh) or (-5 shl 16)
-		call	sub_CBBE
-		add	sp, 4
 
 loc_CD52:
 		call	_input_sense stdcall, 0
@@ -1717,8 +1658,7 @@ sub_D02F	proc far
 		push	0Fh
 		call	_mdrv2_se_play
 		pop	cx
-		push	1
+		call	@pellet_speed_raise$qi stdcall, 1
-		call	sub_CBF2
 		pop	cx
 
 loc_D076:
@@ -3059,8 +2999,7 @@ loc_DC64:
 		div	ebx
 		cmp	edx, 0
 		jnz	short loc_DC9D
-		push	1
+		call	@pellet_speed_raise$qi stdcall, 1
-		call	sub_CBF2
 		pop	cx
 
 loc_DC9D:
@@ -6368,8 +6307,7 @@ sub_1938A	proc far
 		call	sub_192D6
 		cmp	_stage_timer, 0
 		jnz	short loc_193B8
-		push	2
+		call	@pellet_speed_raise$qi stdcall, 2
-		call	sub_CBF2
 		pop	cx
 		nopcall	@harryup_animate$qv
 		pop	bp
@@ -6581,8 +6519,7 @@ loc_19FB0:
 		jz	short loc_19FDB
 		mov	byte_35B46, 2
 		mov	_input_bomb, 0
-		push	1
+		call	@pellet_speed_raise$qi stdcall, 1
-		call	sub_CBF2
 		jmp	loc_1AC29
 ; ---------------------------------------------------------------------------
 
@@ -8450,13 +8387,7 @@ loc_1B01F:
 
 loc_1B028:
 		call	sub_193BA
-
+		call	@pellet_speed_lower$qii c, large 0 or (-2 shl 16)
-loc_1B02D:
-		push	0FFFE0000h
-
-loc_1B033:
-		call	sub_CBBE
-		add	sp, 4
 		pop	di
 		pop	si
 		leave