Add YM2414 (OPZ) support via ymfm (#145)

- Add DEVID_YM2414 (0x30) device ID
- Vendor ymfm source files (commit 17decfa) in emu/cores/ymfm/
  - ymfm.h - Core infrastructure
  - ymfm_opz.h - YM2414 (OPZ) implementation
  - ymfm_fm.h/ipp - FM engine
- Create C++ wrapper (ymfmintf.cpp/h) with extern C interface
- Integrate into build system (CMakeLists.txt, Makefile)
- Register device in SoundEmu.c
- YM2414 specs: 8 FM channels, 4 operators per channel
- Used in Yamaha TX81Z, DX11, YS200 synthesizers

The implementation follows existing patterns (similar to ICS2115) and is
designed to support future ymfm chip additions (OPN, OPM, OPLL, etc.).

Author: vampirefrog

Makefile

@@ -230,6 +230,7 @@ LIBEMUOBJS = \
 	$(LIBEMUOBJ)/cores/x1_010.o \
 	$(LIBEMUOBJ)/cores/c352.o \
 	$(LIBEMUOBJ)/cores/iremga20.o \
+	$(LIBEMUOBJ)/cores/ymfmintf.o \
 	$(LIBEMUOBJ)/Resampler.o \
 	$(LIBEMUOBJ)/panning.o \
 	$(LIBEMUOBJ)/dac_control.o

emu/CMakeLists.txt

@@ -86,6 +86,7 @@ option(SNDEMU_MSM5205_ALL "Sound Device MSM5205: all cores" OFF)
 option(SNDEMU_MSM5232_ALL "Sound Device MSM5232: all cores" OFF)
 option(SNDEMU_BSMT2000_ALL "Sound Device BSMT2000: all cores" OFF)
 option(SNDEMU_ICS2115_ALL "Sound Device ICS2115: all cores" OFF)
+option(SNDEMU_YM2414_YMFM "Sound Device YM2414 (OPZ): ymfm core" OFF)
 
 # console/computer presets
 option(SNDEMU__PRESET_SMS "Sound Dev. Preset: Sega Master System/Game Gear" OFF)
@@ -151,6 +152,7 @@ if(SNDEMU__ALL)
 	set(SNDEMU_MSM5232_ALL ON)
 	set(SNDEMU_BSMT2000_ALL ON)
 	set(SNDEMU_ICS2115_ALL ON)
+	set(SNDEMU_YM2414_YMFM ON)
 endif()
 
 
@@ -648,6 +650,16 @@ if(SNDEMU_ICS2115_ALL)
 	set(EMU_FILES ${EMU_FILES} cores/ics2115.c)
 	set(EMU_CORE_HEADERS ${EMU_CORE_HEADERS} cores/ics2115.h)
 endif()
+if(SNDEMU_YM2414_YMFM)
+	set(EMU_DEFS ${EMU_DEFS} " SNDDEV_YM2414" " EC_YM2414_YMFM")
+	set(EMU_FILES ${EMU_FILES} cores/ymfmintf.cpp cores/ymfm/ymfm_opz.cpp)
+	set(EMU_CORE_HEADERS ${EMU_CORE_HEADERS} cores/ymfmintf.h)
+	set(EMU_CORE_HEADERS ${EMU_CORE_HEADERS}
+		cores/ymfm/ymfm.h
+		cores/ymfm/ymfm_opz.h
+		cores/ymfm/ymfm_fm.h
+	)
+endif()
 
 add_library(${PROJECT_NAME} ${LIBRARY_TYPE} ${EMU_FILES})
 set_target_properties(${PROJECT_NAME} PROPERTIES POSITION_INDEPENDENT_CODE ON)

emu/SoundDevs.h

@@ -49,4 +49,5 @@
 #define DEVID_MSM5232	0x2D
 #define DEVID_BSMT2000	0x2E
 #define DEVID_ICS2115	0x2F
+#define DEVID_YM2414	0x30	// YM2414 (OPZ), used in TX81Z
 #endif	// __SOUNDDEVS_H__

emu/SoundEmu.c

@@ -56,6 +56,7 @@
 #define SNDDEV_MSM5232
 #define SNDDEV_BSMT2000
 #define SNDDEV_ICS2115
+#define SNDDEV_YM2414
 #endif
 
 #ifdef SNDDEV_SN76496
@@ -190,6 +191,9 @@
 #ifdef SNDDEV_ICS2115
 #include "cores/ics2115.h"
 #endif
+#ifdef SNDDEV_YM2414
+#include "cores/ymfmintf.h"
+#endif
 
 const DEV_DECL* sndEmu_Devices[] = {
 #ifdef SNDDEV_SN76496
@@ -335,6 +339,9 @@ const DEV_DECL* sndEmu_Devices[] = {
 #endif
 #ifdef SNDDEV_ICS2115
 	&sndDev_ICS2115,
+#endif
+#ifdef SNDDEV_YM2414
+	&sndDev_YM2414,
 #endif
 	NULL	// list end
 };

emu/cores/ymfm/README.md

@@ -0,0 +1,26 @@
+# ymfm - Yamaha FM sound cores
+
+This directory contains vendored source files from the ymfm project.
+
+## Source
+- **Project**: ymfm (Yamaha FM sound cores)
+- **Author**: Aaron Giles
+- **Repository**: https://github.com/aaronsgiles/ymfm
+- **Commit**: 17decfae857b92ab55fbb30ade2287ace095a381
+- **Date**: 2025-12-31
+
+## License
+BSD-3-Clause
+
+Copyright (c) 2020-2021 Aaron Giles
+
+See the header comments in each file for full license text.
+
+## Files
+- `ymfm.h` - Base classes and core infrastructure
+- `ymfm_opz.h` - YM2414 (OPZ) implementation
+- `ymfm_fm.h` - FM engine base classes
+- `ymfm_fm.ipp` - FM engine template implementations
+
+## Integration
+These files are used by `ymfmintf.cpp` to provide YM2414 (OPZ) emulation support in libvgm.