[Decompilation] [th05] snd_bgm_measure(), snd_delay_until_measure()

Umm… but this can't be in the same translation unit as frame_delay(),
because OP.EXE has cdg_put_nocolors() inbetween, which means we'd have
to compile it twice.

What probably happened there: ZUN originally wrote this in C when
frame_delay() was still next to it, then generated ASM from it,
tinkered with that, and ultimately only linked that ASM into the final
game, with the NOPCALL still in there. That might very well be the one
temporary NOPCALL workaround we can never get rid of…

Oh well, at least we got lucky with the padding, and can keep the
cdg_put_nocolors() decompilation from the last commit.

Part of P0133, funded by [Anonymous].

Makefile.mak

@@ -150,7 +150,7 @@ bin\th05\res_kso.com: th05\res_kso.cpp
 $**
 | masters.lib
 
-bin\th05\op.exe: th05\op010.cpp bin\th05\op.obj th05\op011.cpp th05\m_char.cpp th05\cdg_p_nc.cpp bin\th05\frmdelay.obj bin\th04\cdg_load.obj bin\th05\egcrect.obj bin\hfliplut.obj
+bin\th05\op.exe: th05\op010.cpp bin\th05\op.obj th05\op011.cpp th05\m_char.cpp bin\th05\snd_dlym.obj th05\cdg_p_nc.cpp bin\th05\frmdelay.obj bin\th04\cdg_load.obj bin\th05\egcrect.obj bin\hfliplut.obj
 	$(CC) $(CFLAGS) -ml -DGAME=5 -DBINARY='O' -3 -Z -nbin\th05\ -eOP.EXE @&&|
 $**
 |
@@ -160,7 +160,7 @@ bin\th05\main.exe: bin\th05\main.obj th05\main010.cpp th05\main011.cpp th05\p_co
 $**
 |
 
-bin\th05\maine.exe: bin\th05\maine.obj th05\maine011.cpp th05\regist.cpp th05\staff.cpp bin\th05\frmdelay.obj bin\th04\cdg_load.obj bin\th05\egcrect.obj bin\hfliplut.obj
+bin\th05\maine.exe: bin\th05\maine.obj th05\maine011.cpp th05\regist.cpp th05\staff.cpp bin\th05\snd_dlym.obj bin\th05\frmdelay.obj bin\th04\cdg_load.obj bin\th05\egcrect.obj bin\hfliplut.obj
 	$(CC) $(CFLAGS) -ml -DGAME=5 -DBINARY='E' -Z -nbin\th05\ -eMAINE.EXE @&&|
 $**
 |

th03/snd/delaymea.cpp

@@ -12,9 +12,7 @@ extern "C" {
 #endif
 #include "th02/snd/measure.hpp"
 
-void pascal snd_delay_until_measure(
-	unsigned int measure, unsigned int frames_if_no_bgm
-)
+void pascal snd_delay_until_measure(int measure, unsigned int frames_if_no_bgm)
 {
 	if(!snd_is_active()) {
 		frame_delay(frames_if_no_bgm);

th03/snd/snd.h

@@ -1,6 +1,4 @@
 #include "th02/snd/snd.h"
 
 // Adds a customizable delay to the TH02 version.
-void pascal snd_delay_until_measure(
-	unsigned int measure, unsigned int frames_if_no_bgm
-);
+void pascal snd_delay_until_measure(int measure, unsigned int frames_if_no_bgm);

th04/snd/snd.h

@@ -1,4 +1,4 @@
-#include "th02/snd/snd.h"
+#include "th03/snd/snd.h"
 
 typedef enum {
 	SND_BGM_OFF = 0,

th04/zunsoft.asm

@@ -321,8 +321,7 @@ endif
 @@more_pyros?:
 	cmp	si, ZUNSOFT_PYRO_COUNT
 	jl	short @@next_pyro
-	push	(2 shl 16)
-	call	snd_delay_until_measure
+	call	snd_delay_until_measure pascal, (2 shl 16)
 	mov	PaletteTone, 100
 	call	palette_show
 	call	super_entry_bfnt pascal, ds, offset aZun02_bft

th05/snd/delaymea.asm

@@ -1,29 +0,0 @@
-public SND_DELAY_UNTIL_MEASURE
-snd_delay_until_measure	proc far
-
-@@frames_if_no_bgm	= word ptr  6
-@@measure		= word ptr  8
-
-	push	bp
-	mov	bp, sp
-	push	si
-
-@@retry:
-	call	_snd_bgm_measure
-	mov	si, ax
-	or	si, si
-	jge	short @@reached?
-	push	[bp+@@frames_if_no_bgm]
-	nopcall	frame_delay
-	jmp	short @@ret
-
-@@reached?:
-	cmp	si, [bp+@@measure]
-	jl	short @@retry
-
-@@ret:
-	pop	si
-	pop	bp
-	retf	4
-snd_delay_until_measure	endp
-	db 0

th05/snd/delaymea.cpp

@@ -0,0 +1,37 @@
+#pragma codeseg SHARED_
+
+extern "C" {
+#include <dos.h>
+#include "platform.h"
+#include "libs/kaja/kaja.h"
+#include "th02/hardware/frmdelay.h"
+#include "th05/snd/snd.h"
+#include "th02/snd/measure.hpp"
+}
+
+int snd_bgm_measure(void)
+{
+	if(!snd_is_active()) {
+		return -1;
+	}
+	return snd_get_song_measure();
+}
+
+void pascal snd_delay_until_measure(int measure, unsigned int frames_if_no_bgm)
+{
+	int measure_cur;
+	do {
+		measure_cur = snd_bgm_measure();
+		if(measure_cur < 0) {
+			/* TODO: Replace with the decompiled call
+			 * 	frame_delay(frames_if_no_bgm);
+			 * once the segmentation allows us to, if ever */
+			__asm {
+				push frames_if_no_bgm; nop; push cs; call near ptr frame_delay;
+			}
+			return;
+		}
+	} while(measure_cur < measure);
+}
+
+#pragma codestring "\x00"

th05/snd/measure.asm

@@ -1,25 +0,0 @@
-public _snd_bgm_measure
-_snd_bgm_measure	proc far
-	push	bp
-	mov	bp, sp
-	cmp	_snd_bgm_mode, SND_BGM_OFF
-	jnz	short @@BGM_is_active
-	mov	ax, -1
-	pop	bp
-	retf
-
-@@BGM_is_active:
-	mov	ah, KAJA_GET_SONG_MEASURE
-	cmp	_snd_bgm_mode, SND_BGM_MIDI
-	jz	short @@MIDI_is_active
-	int	PMD
-	jmp	short @@ret
-
-@@MIDI_is_active:
-	mov	dx, MMD_TICKS_PER_QUARTER_NOTE * 4
-	int	MMD
-
-@@ret:
-	pop	bp
-	retf
-_snd_bgm_measure	endp

th05/snd_dlym.cpp

@@ -0,0 +1 @@
+#include "th05/snd/delaymea.cpp"

th05_maine.asm

@@ -831,9 +831,7 @@ loc_AB4A:
 		call	sub_A7FE
 		cmp	byte_14F8E, 0
 		jnz	loc_AF8F	; default
-		push	[bp+var_2]
-		push	[bp+var_4]
-		call	snd_delay_until_measure
+		call	snd_delay_until_measure pascal, [bp+var_2], [bp+var_4]
 		jmp	loc_AF8F	; default
 ; ---------------------------------------------------------------------------
 
@@ -7549,8 +7547,8 @@ include th02/initmain.asm
 include th04/hardware/input_sense.asm
 include th05/hardware/input_held.asm
 include th05/hardware/input_wait.asm
-include th05/snd/measure.asm
-include th05/snd/delaymea.asm
+	extern _snd_bgm_measure:proc
+	extern SND_DELAY_UNTIL_MEASURE:proc
 	extern FRAME_DELAY:proc
 	extern CDG_LOAD_ALL_NOALPHA:proc
 	extern CDG_FREE_ALL:proc

th05_op.asm

@@ -2552,8 +2552,7 @@ include th02/initop.asm
 include th04/hardware/input_sense.asm
 include th05/hardware/input_held.asm
 include th05/hardware/input_wait.asm
-include th05/snd/measure.asm
-include th05/snd/delaymea.asm
+	extern SND_DELAY_UNTIL_MEASURE:proc
 	extern CDG_PUT_NOCOLORS_8:proc
 	extern FRAME_DELAY:proc
 	extern CDG_LOAD_SINGLE_NOALPHA:proc