Added OPL3 supportsound-opl3

9 files changed, 2591 insertions, 15 deletions

diff --git a/.gitignore b/.gitignore
index dd2005d..5c414e5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,3 +5,5 @@ Makefile.deps
 tr8as
 tr8vm
 *.tr8
+*.a
+*.so
diff --git a/Makefile b/Makefile
index 3660c37..a49e820 100644
--- a/Makefile
+++ b/Makefile
@@ -1,15 +1,17 @@
 # common
 CC 	:= gcc
-CFLAGS	:= -Wpedantic -s -O2 -Wall -I.
+CFLAGS	:= -Wpedantic -s -O2 -Wall -I. -I./Nuked-OPL3
 LDFLAGS	:= 
 
-# only for the vm
+# only for the vm player
 SDL2_CONFIG 	:= sdl2-config
-LIBS		:= `$(SDL2_CONFIG) --libs` -lSDL2_mixer
+OPL3_PATH	:= `realpath ./Nuked-OPL3`
+LIBS		:= `$(SDL2_CONFIG) --libs` -L$(OPL3_PATH) -Wl,-rpath,$(OPL3_PATH) -lopl3
 
 all: tr8as tr8vm
 
 tr8vm: tr8vm.c vm.o vm.h
+	make -C Nuked-OPL3
 	$(CC) -std=c99 $(CFLAGS) `$(SDL2_CONFIG) --cflags` $< vm.o `$(SDL2_CONFIG) --libs` $(LIBS) -o $@
 
 tr8as: tr8as.c stb_image.o
@@ -32,6 +34,7 @@ example.tr8: example.asm assets/icon.png tr8as
 
 clean:
 	make -C game clean
+	make -C Nuked-OPL3
 	rm -f tr8as tr8vm example.tr8 *.o
 
 .PHONY: clean all example game
diff --git a/Nuked-OPL3/LICENSE b/Nuked-OPL3/LICENSE
new file mode 100644
index 0000000..8000a6f
--- /dev/null
+++ b/Nuked-OPL3/LICENSE
@@ -0,0 +1,504 @@
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diff --git a/Nuked-OPL3/Makefile b/Nuked-OPL3/Makefile
new file mode 100644
index 0000000..f896792
--- /dev/null
+++ b/Nuked-OPL3/Makefile
@@ -0,0 +1,21 @@
+CC 	:= gcc
+AR	:= ar
+CFLAGS	:= -Wpedantic -s -O2 -Wall -I. -fPIC
+LDFLAGS	:= -shared
+
+all: libopl3.so
+
+libopl3.so: libopl3.a
+	$(CC) $(LDFLAGS) -o libopl3.so opl3.o
+
+libopl3.a: opl3.o
+	ar crs libopl3.a opl3.o
+
+opl3.o: opl3.c opl3.h
+	$(CC) $(CFLAGS) -c $< -o $@
+
+clean:
+	rm -f opl3.o libopl3.a libopl3.so
+
+.PHONY: clean all
+
diff --git a/Nuked-OPL3/opl3.c b/Nuked-OPL3/opl3.c
new file mode 100644
index 0000000..9128ba8
--- /dev/null
+++ b/Nuked-OPL3/opl3.c
@@ -0,0 +1,1530 @@
+/* Nuked OPL3
+ * Copyright (C) 2013-2020 Nuke.YKT
+ *
+ * This file is part of Nuked OPL3.
+ *
+ * Nuked OPL3 is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 2.1
+ * of the License, or (at your option) any later version.
+ *
+ * Nuked OPL3 is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Nuked OPL3. If not, see <https://www.gnu.org/licenses/>.
+
+ *  Nuked OPL3 emulator.
+ *  Thanks:
+ *      MAME Development Team(Jarek Burczynski, Tatsuyuki Satoh):
+ *          Feedback and Rhythm part calculation information.
+ *      forums.submarine.org.uk(carbon14, opl3):
+ *          Tremolo and phase generator calculation information.
+ *      OPLx decapsulated(Matthew Gambrell, Olli Niemitalo):
+ *          OPL2 ROMs.
+ *      siliconpr0n.org(John McMaster, digshadow):
+ *          YMF262 and VRC VII decaps and die shots.
+ *
+ * version: 1.8
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "opl3.h"
+
+#if OPL_ENABLE_STEREOEXT && !defined OPL_SIN
+#ifndef _USE_MATH_DEFINES
+#define _USE_MATH_DEFINES 1
+#endif
+#include <math.h>
+/* input: [0, 256), output: [0, 65536] */
+#define OPL_SIN(x) ((int32_t)(sin((x) * M_PI / 512.0) * 65536.0))
+#endif
+
+/* Quirk: Some FM channels are output one sample later on the left side than the right. */
+#ifndef OPL_QUIRK_CHANNELSAMPLEDELAY
+#define OPL_QUIRK_CHANNELSAMPLEDELAY (!OPL_ENABLE_STEREOEXT)
+#endif
+
+#define RSM_FRAC    10
+
+/* Channel types */
+
+enum {
+    ch_2op = 0,
+    ch_4op = 1,
+    ch_4op2 = 2,
+    ch_drum = 3
+};
+
+/* Envelope key types */
+
+enum {
+    egk_norm = 0x01,
+    egk_drum = 0x02
+};
+
+
+/*
+    logsin table
+*/
+
+static const uint16_t logsinrom[256] = {
+    0x859, 0x6c3, 0x607, 0x58b, 0x52e, 0x4e4, 0x4a6, 0x471,
+    0x443, 0x41a, 0x3f5, 0x3d3, 0x3b5, 0x398, 0x37e, 0x365,
+    0x34e, 0x339, 0x324, 0x311, 0x2ff, 0x2ed, 0x2dc, 0x2cd,
+    0x2bd, 0x2af, 0x2a0, 0x293, 0x286, 0x279, 0x26d, 0x261,
+    0x256, 0x24b, 0x240, 0x236, 0x22c, 0x222, 0x218, 0x20f,
+    0x206, 0x1fd, 0x1f5, 0x1ec, 0x1e4, 0x1dc, 0x1d4, 0x1cd,
+    0x1c5, 0x1be, 0x1b7, 0x1b0, 0x1a9, 0x1a2, 0x19b, 0x195,
+    0x18f, 0x188, 0x182, 0x17c, 0x177, 0x171, 0x16b, 0x166,
+    0x160, 0x15b, 0x155, 0x150, 0x14b, 0x146, 0x141, 0x13c,
+    0x137, 0x133, 0x12e, 0x129, 0x125, 0x121, 0x11c, 0x118,
+    0x114, 0x10f, 0x10b, 0x107, 0x103, 0x0ff, 0x0fb, 0x0f8,
+    0x0f4, 0x0f0, 0x0ec, 0x0e9, 0x0e5, 0x0e2, 0x0de, 0x0db,
+    0x0d7, 0x0d4, 0x0d1, 0x0cd, 0x0ca, 0x0c7, 0x0c4, 0x0c1,
+    0x0be, 0x0bb, 0x0b8, 0x0b5, 0x0b2, 0x0af, 0x0ac, 0x0a9,
+    0x0a7, 0x0a4, 0x0a1, 0x09f, 0x09c, 0x099, 0x097, 0x094,
+    0x092, 0x08f, 0x08d, 0x08a, 0x088, 0x086, 0x083, 0x081,
+    0x07f, 0x07d, 0x07a, 0x078, 0x076, 0x074, 0x072, 0x070,
+    0x06e, 0x06c, 0x06a, 0x068, 0x066, 0x064, 0x062, 0x060,
+    0x05e, 0x05c, 0x05b, 0x059, 0x057, 0x055, 0x053, 0x052,
+    0x050, 0x04e, 0x04d, 0x04b, 0x04a, 0x048, 0x046, 0x045,
+    0x043, 0x042, 0x040, 0x03f, 0x03e, 0x03c, 0x03b, 0x039,
+    0x038, 0x037, 0x035, 0x034, 0x033, 0x031, 0x030, 0x02f,
+    0x02e, 0x02d, 0x02b, 0x02a, 0x029, 0x028, 0x027, 0x026,
+    0x025, 0x024, 0x023, 0x022, 0x021, 0x020, 0x01f, 0x01e,
+    0x01d, 0x01c, 0x01b, 0x01a, 0x019, 0x018, 0x017, 0x017,
+    0x016, 0x015, 0x014, 0x014, 0x013, 0x012, 0x011, 0x011,
+    0x010, 0x00f, 0x00f, 0x00e, 0x00d, 0x00d, 0x00c, 0x00c,
+    0x00b, 0x00a, 0x00a, 0x009, 0x009, 0x008, 0x008, 0x007,
+    0x007, 0x007, 0x006, 0x006, 0x005, 0x005, 0x005, 0x004,
+    0x004, 0x004, 0x003, 0x003, 0x003, 0x002, 0x002, 0x002,
+    0x002, 0x001, 0x001, 0x001, 0x001, 0x001, 0x001, 0x001,
+    0x000, 0x000, 0x000, 0x000, 0x000, 0x000, 0x000, 0x000
+};
+
+/*
+    exp table
+*/
+
+static const uint16_t exprom[256] = {
+    0x7fa, 0x7f5, 0x7ef, 0x7ea, 0x7e4, 0x7df, 0x7da, 0x7d4,
+    0x7cf, 0x7c9, 0x7c4, 0x7bf, 0x7b9, 0x7b4, 0x7ae, 0x7a9,
+    0x7a4, 0x79f, 0x799, 0x794, 0x78f, 0x78a, 0x784, 0x77f,
+    0x77a, 0x775, 0x770, 0x76a, 0x765, 0x760, 0x75b, 0x756,
+    0x751, 0x74c, 0x747, 0x742, 0x73d, 0x738, 0x733, 0x72e,
+    0x729, 0x724, 0x71f, 0x71a, 0x715, 0x710, 0x70b, 0x706,
+    0x702, 0x6fd, 0x6f8, 0x6f3, 0x6ee, 0x6e9, 0x6e5, 0x6e0,
+    0x6db, 0x6d6, 0x6d2, 0x6cd, 0x6c8, 0x6c4, 0x6bf, 0x6ba,
+    0x6b5, 0x6b1, 0x6ac, 0x6a8, 0x6a3, 0x69e, 0x69a, 0x695,
+    0x691, 0x68c, 0x688, 0x683, 0x67f, 0x67a, 0x676, 0x671,
+    0x66d, 0x668, 0x664, 0x65f, 0x65b, 0x657, 0x652, 0x64e,
+    0x649, 0x645, 0x641, 0x63c, 0x638, 0x634, 0x630, 0x62b,
+    0x627, 0x623, 0x61e, 0x61a, 0x616, 0x612, 0x60e, 0x609,
+    0x605, 0x601, 0x5fd, 0x5f9, 0x5f5, 0x5f0, 0x5ec, 0x5e8,
+    0x5e4, 0x5e0, 0x5dc, 0x5d8, 0x5d4, 0x5d0, 0x5cc, 0x5c8,
+    0x5c4, 0x5c0, 0x5bc, 0x5b8, 0x5b4, 0x5b0, 0x5ac, 0x5a8,
+    0x5a4, 0x5a0, 0x59c, 0x599, 0x595, 0x591, 0x58d, 0x589,
+    0x585, 0x581, 0x57e, 0x57a, 0x576, 0x572, 0x56f, 0x56b,
+    0x567, 0x563, 0x560, 0x55c, 0x558, 0x554, 0x551, 0x54d,
+    0x549, 0x546, 0x542, 0x53e, 0x53b, 0x537, 0x534, 0x530,
+    0x52c, 0x529, 0x525, 0x522, 0x51e, 0x51b, 0x517, 0x514,
+    0x510, 0x50c, 0x509, 0x506, 0x502, 0x4ff, 0x4fb, 0x4f8,
+    0x4f4, 0x4f1, 0x4ed, 0x4ea, 0x4e7, 0x4e3, 0x4e0, 0x4dc,
+    0x4d9, 0x4d6, 0x4d2, 0x4cf, 0x4cc, 0x4c8, 0x4c5, 0x4c2,
+    0x4be, 0x4bb, 0x4b8, 0x4b5, 0x4b1, 0x4ae, 0x4ab, 0x4a8,
+    0x4a4, 0x4a1, 0x49e, 0x49b, 0x498, 0x494, 0x491, 0x48e,
+    0x48b, 0x488, 0x485, 0x482, 0x47e, 0x47b, 0x478, 0x475,
+    0x472, 0x46f, 0x46c, 0x469, 0x466, 0x463, 0x460, 0x45d,
+    0x45a, 0x457, 0x454, 0x451, 0x44e, 0x44b, 0x448, 0x445,
+    0x442, 0x43f, 0x43c, 0x439, 0x436, 0x433, 0x430, 0x42d,
+    0x42a, 0x428, 0x425, 0x422, 0x41f, 0x41c, 0x419, 0x416,
+    0x414, 0x411, 0x40e, 0x40b, 0x408, 0x406, 0x403, 0x400
+};
+
+/*
+    freq mult table multiplied by 2
+
+    1/2, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 12, 12, 15, 15
+*/
+
+static const uint8_t mt[16] = {
+    1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 20, 24, 24, 30, 30
+};
+
+/*
+    ksl table
+*/
+
+static const uint8_t kslrom[16] = {
+    0, 32, 40, 45, 48, 51, 53, 55, 56, 58, 59, 60, 61, 62, 63, 64
+};
+
+static const uint8_t kslshift[4] = {
+    8, 1, 2, 0
+};
+
+/*
+    envelope generator constants
+*/
+
+static const uint8_t eg_incstep[4][4] = {
+    { 0, 0, 0, 0 },
+    { 1, 0, 0, 0 },
+    { 1, 0, 1, 0 },
+    { 1, 1, 1, 0 }
+};
+
+/*
+    address decoding
+*/
+
+static const int8_t ad_slot[0x20] = {
+    0, 1, 2, 3, 4, 5, -1, -1, 6, 7, 8, 9, 10, 11, -1, -1,
+    12, 13, 14, 15, 16, 17, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
+};
+
+static const uint8_t ch_slot[18] = {
+    0, 1, 2, 6, 7, 8, 12, 13, 14, 18, 19, 20, 24, 25, 26, 30, 31, 32
+};
+
+#if OPL_ENABLE_STEREOEXT
+/*
+    stereo extension panning table
+*/
+
+static int32_t panpot_lut[256];
+static uint8_t panpot_lut_build = 0;
+#endif
+
+/*
+    Envelope generator
+*/
+
+typedef int16_t(*envelope_sinfunc)(uint16_t phase, uint16_t envelope);
+typedef void(*envelope_genfunc)(opl3_slot *slott);
+
+static int16_t OPL3_EnvelopeCalcExp(uint32_t level)
+{
+    if (level > 0x1fff)
+    {
+        level = 0x1fff;
+    }
+    return (exprom[level & 0xff] << 1) >> (level >> 8);
+}
+
+static int16_t OPL3_EnvelopeCalcSin0(uint16_t phase, uint16_t envelope)
+{
+    uint16_t out = 0;
+    uint16_t neg = 0;
+    phase &= 0x3ff;
+    if (phase & 0x200)
+    {
+        neg = 0xffff;
+    }
+    if (phase & 0x100)
+    {
+        out = logsinrom[(phase & 0xff) ^ 0xff];
+    }
+    else
+    {
+        out = logsinrom[phase & 0xff];
+    }
+    return OPL3_EnvelopeCalcExp(out + (envelope << 3)) ^ neg;
+}
+
+static int16_t OPL3_EnvelopeCalcSin1(uint16_t phase, uint16_t envelope)
+{
+    uint16_t out = 0;
+    phase &= 0x3ff;
+    if (phase & 0x200)
+    {
+        out = 0x1000;
+    }
+    else if (phase & 0x100)
+    {
+        out = logsinrom[(phase & 0xff) ^ 0xff];
+    }
+    else
+    {
+        out = logsinrom[phase & 0xff];
+    }
+    return OPL3_EnvelopeCalcExp(out + (envelope << 3));
+}
+
+static int16_t OPL3_EnvelopeCalcSin2(uint16_t phase, uint16_t envelope)
+{
+    uint16_t out = 0;
+    phase &= 0x3ff;
+    if (phase & 0x100)
+    {
+        out = logsinrom[(phase & 0xff) ^ 0xff];
+    }
+    else
+    {
+        out = logsinrom[phase & 0xff];
+    }
+    return OPL3_EnvelopeCalcExp(out + (envelope << 3));
+}
+
+static int16_t OPL3_EnvelopeCalcSin3(uint16_t phase, uint16_t envelope)
+{
+    uint16_t out = 0;
+    phase &= 0x3ff;
+    if (phase & 0x100)
+    {
+        out = 0x1000;
+    }
+    else
+    {
+        out = logsinrom[phase & 0xff];
+    }
+    return OPL3_EnvelopeCalcExp(out + (envelope << 3));
+}
+
+static int16_t OPL3_EnvelopeCalcSin4(uint16_t phase, uint16_t envelope)
+{
+    uint16_t out = 0;
+    uint16_t neg = 0;
+    phase &= 0x3ff;
+    if ((phase & 0x300) == 0x100)
+    {
+        neg = 0xffff;
+    }
+    if (phase & 0x200)
+    {
+        out = 0x1000;
+    }
+    else if (phase & 0x80)
+    {
+        out = logsinrom[((phase ^ 0xff) << 1) & 0xff];
+    }
+    else
+    {
+        out = logsinrom[(phase << 1) & 0xff];
+    }
+    return OPL3_EnvelopeCalcExp(out + (envelope << 3)) ^ neg;
+}
+
+static int16_t OPL3_EnvelopeCalcSin5(uint16_t phase, uint16_t envelope)
+{
+    uint16_t out = 0;
+    phase &= 0x3ff;
+    if (phase & 0x200)
+    {
+        out = 0x1000;
+    }
+    else if (phase & 0x80)
+    {
+        out = logsinrom[((phase ^ 0xff) << 1) & 0xff];
+    }
+    else
+    {
+        out = logsinrom[(phase << 1) & 0xff];
+    }
+    return OPL3_EnvelopeCalcExp(out + (envelope << 3));
+}
+
+static int16_t OPL3_EnvelopeCalcSin6(uint16_t phase, uint16_t envelope)
+{
+    uint16_t neg = 0;
+    phase &= 0x3ff;
+    if (phase & 0x200)
+    {
+        neg = 0xffff;
+    }
+    return OPL3_EnvelopeCalcExp(envelope << 3) ^ neg;
+}
+
+static int16_t OPL3_EnvelopeCalcSin7(uint16_t phase, uint16_t envelope)
+{
+    uint16_t out = 0;
+    uint16_t neg = 0;
+    phase &= 0x3ff;
+    if (phase & 0x200)
+    {
+        neg = 0xffff;
+        phase = (phase & 0x1ff) ^ 0x1ff;
+    }
+    out = phase << 3;
+    return OPL3_EnvelopeCalcExp(out + (envelope << 3)) ^ neg;
+}
+
+static const envelope_sinfunc envelope_sin[8] = {
+    OPL3_EnvelopeCalcSin0,
+    OPL3_EnvelopeCalcSin1,
+    OPL3_EnvelopeCalcSin2,
+    OPL3_EnvelopeCalcSin3,
+    OPL3_EnvelopeCalcSin4,
+    OPL3_EnvelopeCalcSin5,
+    OPL3_EnvelopeCalcSin6,
+    OPL3_EnvelopeCalcSin7
+};
+
+enum envelope_gen_num
+{
+    envelope_gen_num_attack = 0,
+    envelope_gen_num_decay = 1,
+    envelope_gen_num_sustain = 2,
+    envelope_gen_num_release = 3
+};
+
+static void OPL3_EnvelopeUpdateKSL(opl3_slot *slot)
+{
+    int16_t ksl = (kslrom[slot->channel->f_num >> 6] << 2)
+               - ((0x08 - slot->channel->block) << 5);
+    if (ksl < 0)
+    {
+        ksl = 0;
+    }
+    slot->eg_ksl = (uint8_t)ksl;
+}
+
+static void OPL3_EnvelopeCalc(opl3_slot *slot)
+{
+    uint8_t nonzero;
+    uint8_t rate;
+    uint8_t rate_hi;
+    uint8_t rate_lo;
+    uint8_t reg_rate = 0;
+    uint8_t ks;
+    uint8_t eg_shift, shift;
+    uint16_t eg_rout;
+    int16_t eg_inc;
+    uint8_t eg_off;
+    uint8_t reset = 0;
+    slot->eg_out = slot->eg_rout + (slot->reg_tl << 2)
+                 + (slot->eg_ksl >> kslshift[slot->reg_ksl]) + *slot->trem;
+    if (slot->key && slot->eg_gen == envelope_gen_num_release)
+    {
+        reset = 1;
+        reg_rate = slot->reg_ar;
+    }
+    else
+    {
+        switch (slot->eg_gen)
+        {
+        case envelope_gen_num_attack:
+            reg_rate = slot->reg_ar;
+            break;
+        case envelope_gen_num_decay:
+            reg_rate = slot->reg_dr;
+            break;
+        case envelope_gen_num_sustain:
+            if (!slot->reg_type)
+            {
+                reg_rate = slot->reg_rr;
+            }
+            break;
+        case envelope_gen_num_release:
+            reg_rate = slot->reg_rr;
+            break;
+        }
+    }
+    slot->pg_reset = reset;
+    ks = slot->channel->ksv >> ((slot->reg_ksr ^ 1) << 1);
+    nonzero = (reg_rate != 0);
+    rate = ks + (reg_rate << 2);
+    rate_hi = rate >> 2;
+    rate_lo = rate & 0x03;
+    if (rate_hi & 0x10)
+    {
+        rate_hi = 0x0f;
+    }
+    eg_shift = rate_hi + slot->chip->eg_add;
+    shift = 0;
+    if (nonzero)
+    {
+        if (rate_hi < 12)
+        {
+            if (slot->chip->eg_state)
+            {
+                switch (eg_shift)
+                {
+                case 12:
+                    shift = 1;
+                    break;
+                case 13:
+                    shift = (rate_lo >> 1) & 0x01;
+                    break;
+                case 14:
+                    shift = rate_lo & 0x01;
+                    break;
+                default:
+                    break;
+                }
+            }
+        }
+        else
+        {
+            shift = (rate_hi & 0x03) + eg_incstep[rate_lo][slot->chip->timer & 0x03];
+            if (shift & 0x04)
+            {
+                shift = 0x03;
+            }
+            if (!shift)
+            {
+                shift = slot->chip->eg_state;
+            }
+        }
+    }
+    eg_rout = slot->eg_rout;
+    eg_inc = 0;
+    eg_off = 0;
+    /* Instant attack */
+    if (reset && rate_hi == 0x0f)
+    {
+        eg_rout = 0x00;
+    }
+    /* Envelope off */
+    if ((slot->eg_rout & 0x1f8) == 0x1f8)
+    {
+        eg_off = 1;
+    }
+    if (slot->eg_gen != envelope_gen_num_attack && !reset && eg_off)
+    {
+        eg_rout = 0x1ff;
+    }
+    switch (slot->eg_gen)
+    {
+    case envelope_gen_num_attack:
+        if (!slot->eg_rout)
+        {
+            slot->eg_gen = envelope_gen_num_decay;
+        }
+        else if (slot->key && shift > 0 && rate_hi != 0x0f)
+        {
+            eg_inc = ~slot->eg_rout >> (4 - shift);
+        }
+        break;
+    case envelope_gen_num_decay:
+        if ((slot->eg_rout >> 4) == slot->reg_sl)
+        {
+            slot->eg_gen = envelope_gen_num_sustain;
+        }
+        else if (!eg_off && !reset && shift > 0)
+        {
+            eg_inc = 1 << (shift - 1);
+        }
+        break;
+    case envelope_gen_num_sustain:
+    case envelope_gen_num_release:
+        if (!eg_off && !reset && shift > 0)
+        {
+            eg_inc = 1 << (shift - 1);
+        }
+        break;
+    }
+    slot->eg_rout = (eg_rout + eg_inc) & 0x1ff;
+    /* Key off */
+    if (reset)
+    {
+        slot->eg_gen = envelope_gen_num_attack;
+    }
+    if (!slot->key)
+    {
+        slot->eg_gen = envelope_gen_num_release;
+    }
+}
+
+static void OPL3_EnvelopeKeyOn(opl3_slot *slot, uint8_t type)
+{
+    slot->key |= type;
+}
+
+static void OPL3_EnvelopeKeyOff(opl3_slot *slot, uint8_t type)
+{
+    slot->key &= ~type;
+}
+
+/*
+    Phase Generator
+*/
+
+static void OPL3_PhaseGenerate(opl3_slot *slot)
+{
+    opl3_chip *chip;
+    uint16_t f_num;
+    uint32_t basefreq;
+    uint8_t rm_xor, n_bit;
+    uint32_t noise;
+    uint16_t phase;
+
+    chip = slot->chip;
+    f_num = slot->channel->f_num;
+    if (slot->reg_vib)
+    {
+        int8_t range;
+        uint8_t vibpos;
+
+        range = (f_num >> 7) & 7;
+        vibpos = slot->chip->vibpos;
+
+        if (!(vibpos & 3))
+        {
+            range = 0;
+        }
+        else if (vibpos & 1)
+        {
+            range >>= 1;
+        }
+        range >>= slot->chip->vibshift;
+
+        if (vibpos & 4)
+        {
+            range = -range;
+        }
+        f_num += range;
+    }
+    basefreq = (f_num << slot->channel->block) >> 1;
+    phase = (uint16_t)(slot->pg_phase >> 9);
+    if (slot->pg_reset)
+    {
+        slot->pg_phase = 0;
+    }
+    slot->pg_phase += (basefreq * mt[slot->reg_mult]) >> 1;
+    /* Rhythm mode */
+    noise = chip->noise;
+    slot->pg_phase_out = phase;
+    if (slot->slot_num == 13) /* hh */
+    {
+        chip->rm_hh_bit2 = (phase >> 2) & 1;
+        chip->rm_hh_bit3 = (phase >> 3) & 1;
+        chip->rm_hh_bit7 = (phase >> 7) & 1;
+        chip->rm_hh_bit8 = (phase >> 8) & 1;
+    }
+    if (slot->slot_num == 17 && (chip->rhy & 0x20)) /* tc */
+    {
+        chip->rm_tc_bit3 = (phase >> 3) & 1;
+        chip->rm_tc_bit5 = (phase >> 5) & 1;
+    }
+    if (chip->rhy & 0x20)
+    {
+        rm_xor = (chip->rm_hh_bit2 ^ chip->rm_hh_bit7)
+               | (chip->rm_hh_bit3 ^ chip->rm_tc_bit5)
+               | (chip->rm_tc_bit3 ^ chip->rm_tc_bit5);
+        switch (slot->slot_num)
+        {
+        case 13: /* hh */
+            slot->pg_phase_out = rm_xor << 9;
+            if (rm_xor ^ (noise & 1))
+            {
+                slot->pg_phase_out |= 0xd0;
+            }
+            else
+            {
+                slot->pg_phase_out |= 0x34;
+            }
+            break;
+        case 16: /* sd */
+            slot->pg_phase_out = (chip->rm_hh_bit8 << 9)
+                               | ((chip->rm_hh_bit8 ^ (noise & 1)) << 8);
+            break;
+        case 17: /* tc */
+            slot->pg_phase_out = (rm_xor << 9) | 0x80;
+            break;
+        default:
+            break;
+        }
+    }
+    n_bit = ((noise >> 14) ^ noise) & 0x01;
+    chip->noise = (noise >> 1) | (n_bit << 22);
+}
+
+/*
+    Slot
+*/
+
+static void OPL3_SlotWrite20(opl3_slot *slot, uint8_t data)
+{
+    if ((data >> 7) & 0x01)
+    {
+        slot->trem = &slot->chip->tremolo;
+    }
+    else
+    {
+        slot->trem = (uint8_t*)&slot->chip->zeromod;
+    }
+    slot->reg_vib = (data >> 6) & 0x01;
+    slot->reg_type = (data >> 5) & 0x01;
+    slot->reg_ksr = (data >> 4) & 0x01;
+    slot->reg_mult = data & 0x0f;
+}
+
+static void OPL3_SlotWrite40(opl3_slot *slot, uint8_t data)
+{
+    slot->reg_ksl = (data >> 6) & 0x03;
+    slot->reg_tl = data & 0x3f;
+    OPL3_EnvelopeUpdateKSL(slot);
+}
+
+static void OPL3_SlotWrite60(opl3_slot *slot, uint8_t data)
+{
+    slot->reg_ar = (data >> 4) & 0x0f;
+    slot->reg_dr = data & 0x0f;
+}
+
+static void OPL3_SlotWrite80(opl3_slot *slot, uint8_t data)
+{
+    slot->reg_sl = (data >> 4) & 0x0f;
+    if (slot->reg_sl == 0x0f)
+    {
+        slot->reg_sl = 0x1f;
+    }
+    slot->reg_rr = data & 0x0f;
+}
+
+static void OPL3_SlotWriteE0(opl3_slot *slot, uint8_t data)
+{
+    slot->reg_wf = data & 0x07;
+    if (slot->chip->newm == 0x00)
+    {
+        slot->reg_wf &= 0x03;
+    }
+}
+
+static void OPL3_SlotGenerate(opl3_slot *slot)
+{
+    slot->out = envelope_sin[slot->reg_wf](slot->pg_phase_out + *slot->mod, slot->eg_out);
+}
+
+static void OPL3_SlotCalcFB(opl3_slot *slot)
+{
+    if (slot->channel->fb != 0x00)
+    {
+        slot->fbmod = (slot->prout + slot->out) >> (0x09 - slot->channel->fb);
+    }
+    else
+    {
+        slot->fbmod = 0;
+    }
+    slot->prout = slot->out;
+}
+
+/*
+    Channel
+*/
+
+static void OPL3_ChannelSetupAlg(opl3_channel *channel);
+
+static void OPL3_ChannelUpdateRhythm(opl3_chip *chip, uint8_t data)
+{
+    opl3_channel *channel6;
+    opl3_channel *channel7;
+    opl3_channel *channel8;
+    uint8_t chnum;
+
+    chip->rhy = data & 0x3f;
+    if (chip->rhy & 0x20)
+    {
+        channel6 = &chip->channel[6];
+        channel7 = &chip->channel[7];
+        channel8 = &chip->channel[8];
+        channel6->out[0] = &channel6->slots[1]->out;
+        channel6->out[1] = &channel6->slots[1]->out;
+        channel6->out[2] = &chip->zeromod;
+        channel6->out[3] = &chip->zeromod;
+        channel7->out[0] = &channel7->slots[0]->out;
+        channel7->out[1] = &channel7->slots[0]->out;
+        channel7->out[2] = &channel7->slots[1]->out;
+        channel7->out[3] = &channel7->slots[1]->out;
+        channel8->out[0] = &channel8->slots[0]->out;
+        channel8->out[1] = &channel8->slots[0]->out;
+        channel8->out[2] = &channel8->slots[1]->out;
+        channel8->out[3] = &channel8->slots[1]->out;
+        for (chnum = 6; chnum < 9; chnum++)
+        {
+            chip->channel[chnum].chtype = ch_drum;
+        }
+        OPL3_ChannelSetupAlg(channel6);
+        OPL3_ChannelSetupAlg(channel7);
+        OPL3_ChannelSetupAlg(channel8);
+        /* hh */
+        if (chip->rhy & 0x01)
+        {
+            OPL3_EnvelopeKeyOn(channel7->slots[0], egk_drum);
+        }
+        else
+        {
+            OPL3_EnvelopeKeyOff(channel7->slots[0], egk_drum);
+        }
+        /* tc */
+        if (chip->rhy & 0x02)
+        {
+            OPL3_EnvelopeKeyOn(channel8->slots[1], egk_drum);
+        }
+        else
+        {
+            OPL3_EnvelopeKeyOff(channel8->slots[1], egk_drum);
+        }
+        /* tom */
+        if (chip->rhy & 0x04)
+        {
+            OPL3_EnvelopeKeyOn(channel8->slots[0], egk_drum);
+        }
+        else
+        {
+            OPL3_EnvelopeKeyOff(channel8->slots[0], egk_drum);
+        }
+        /* sd */
+        if (chip->rhy & 0x08)
+        {
+            OPL3_EnvelopeKeyOn(channel7->slots[1], egk_drum);
+        }
+        else
+        {
+            OPL3_EnvelopeKeyOff(channel7->slots[1], egk_drum);
+        }
+        /* bd */
+        if (chip->rhy & 0x10)
+        {
+            OPL3_EnvelopeKeyOn(channel6->slots[0], egk_drum);
+            OPL3_EnvelopeKeyOn(channel6->slots[1], egk_drum);
+        }
+        else
+        {
+            OPL3_EnvelopeKeyOff(channel6->slots[0], egk_drum);
+            OPL3_EnvelopeKeyOff(channel6->slots[1], egk_drum);
+        }
+    }
+    else
+    {
+        for (chnum = 6; chnum < 9; chnum++)
+        {
+            chip->channel[chnum].chtype = ch_2op;
+            OPL3_ChannelSetupAlg(&chip->channel[chnum]);
+            OPL3_EnvelopeKeyOff(chip->channel[chnum].slots[0], egk_drum);
+            OPL3_EnvelopeKeyOff(chip->channel[chnum].slots[1], egk_drum);
+        }
+    }
+}
+
+static void OPL3_ChannelWriteA0(opl3_channel *channel, uint8_t data)
+{
+    if (channel->chip->newm && channel->chtype == ch_4op2)
+    {
+        return;
+    }
+    channel->f_num = (channel->f_num & 0x300) | data;
+    channel->ksv = (channel->block << 1)
+                 | ((channel->f_num >> (0x09 - channel->chip->nts)) & 0x01);
+    OPL3_EnvelopeUpdateKSL(channel->slots[0]);
+    OPL3_EnvelopeUpdateKSL(channel->slots[1]);
+    if (channel->chip->newm && channel->chtype == ch_4op)
+    {
+        channel->pair->f_num = channel->f_num;
+        channel->pair->ksv = channel->ksv;
+        OPL3_EnvelopeUpdateKSL(channel->pair->slots[0]);
+        OPL3_EnvelopeUpdateKSL(channel->pair->slots[1]);
+    }
+}
+
+static void OPL3_ChannelWriteB0(opl3_channel *channel, uint8_t data)
+{
+    if (channel->chip->newm && channel->chtype == ch_4op2)
+    {
+        return;
+    }
+    channel->f_num = (channel->f_num & 0xff) | ((data & 0x03) << 8);
+    channel->block = (data >> 2) & 0x07;
+    channel->ksv = (channel->block << 1)
+                 | ((channel->f_num >> (0x09 - channel->chip->nts)) & 0x01);
+    OPL3_EnvelopeUpdateKSL(channel->slots[0]);
+    OPL3_EnvelopeUpdateKSL(channel->slots[1]);
+    if (channel->chip->newm && channel->chtype == ch_4op)
+    {
+        channel->pair->f_num = channel->f_num;
+        channel->pair->block = channel->block;
+        channel->pair->ksv = channel->ksv;
+        OPL3_EnvelopeUpdateKSL(channel->pair->slots[0]);
+        OPL3_EnvelopeUpdateKSL(channel->pair->slots[1]);
+    }
+}
+
+static void OPL3_ChannelSetupAlg(opl3_channel *channel)
+{
+    if (channel->chtype == ch_drum)
+    {
+        if (channel->ch_num == 7 || channel->ch_num == 8)
+        {
+            channel->slots[0]->mod = &channel->chip->zeromod;
+            channel->slots[1]->mod = &channel->chip->zeromod;
+            return;
+        }
+        switch (channel->alg & 0x01)
+        {
+        case 0x00:
+            channel->slots[0]->mod = &channel->slots[0]->fbmod;
+            channel->slots[1]->mod = &channel->slots[0]->out;
+            break;
+        case 0x01:
+            channel->slots[0]->mod = &channel->slots[0]->fbmod;
+            channel->slots[1]->mod = &channel->chip->zeromod;
+            break;
+        }
+        return;
+    }
+    if (channel->alg & 0x08)
+    {
+        return;
+    }
+    if (channel->alg & 0x04)
+    {
+        channel->pair->out[0] = &channel->chip->zeromod;
+        channel->pair->out[1] = &channel->chip->zeromod;
+        channel->pair->out[2] = &channel->chip->zeromod;
+        channel->pair->out[3] = &channel->chip->zeromod;
+        switch (channel->alg & 0x03)
+        {
+        case 0x00:
+            channel->pair->slots[0]->mod = &channel->pair->slots[0]->fbmod;
+            channel->pair->slots[1]->mod = &channel->pair->slots[0]->out;
+            channel->slots[0]->mod = &channel->pair->slots[1]->out;
+            channel->slots[1]->mod = &channel->slots[0]->out;
+            channel->out[0] = &channel->slots[1]->out;
+            channel->out[1] = &channel->chip->zeromod;
+            channel->out[2] = &channel->chip->zeromod;
+            channel->out[3] = &channel->chip->zeromod;
+            break;
+        case 0x01:
+            channel->pair->slots[0]->mod = &channel->pair->slots[0]->fbmod;
+            channel->pair->slots[1]->mod = &channel->pair->slots[0]->out;
+            channel->slots[0]->mod = &channel->chip->zeromod;
+            channel->slots[1]->mod = &channel->slots[0]->out;
+            channel->out[0] = &channel->pair->slots[1]->out;
+            channel->out[1] = &channel->slots[1]->out;
+            channel->out[2] = &channel->chip->zeromod;
+            channel->out[3] = &channel->chip->zeromod;
+            break;
+        case 0x02:
+            channel->pair->slots[0]->mod = &channel->pair->slots[0]->fbmod;
+            channel->pair->slots[1]->mod = &channel->chip->zeromod;
+            channel->slots[0]->mod = &channel->pair->slots[1]->out;
+            channel->slots[1]->mod = &channel->slots[0]->out;
+            channel->out[0] = &channel->pair->slots[0]->out;
+            channel->out[1] = &channel->slots[1]->out;
+            channel->out[2] = &channel->chip->zeromod;
+            channel->out[3] = &channel->chip->zeromod;
+            break;
+        case 0x03:
+            channel->pair->slots[0]->mod = &channel->pair->slots[0]->fbmod;
+            channel->pair->slots[1]->mod = &channel->chip->zeromod;
+            channel->slots[0]->mod = &channel->pair->slots[1]->out;
+            channel->slots[1]->mod = &channel->chip->zeromod;
+            channel->out[0] = &channel->pair->slots[0]->out;
+            channel->out[1] = &channel->slots[0]->out;
+            channel->out[2] = &channel->slots[1]->out;
+            channel->out[3] = &channel->chip->zeromod;
+            break;
+        }
+    }
+    else
+    {
+        switch (channel->alg & 0x01)
+        {
+        case 0x00:
+            channel->slots[0]->mod = &channel->slots[0]->fbmod;
+            channel->slots[1]->mod = &channel->slots[0]->out;
+            channel->out[0] = &channel->slots[1]->out;
+            channel->out[1] = &channel->chip->zeromod;
+            channel->out[2] = &channel->chip->zeromod;
+            channel->out[3] = &channel->chip->zeromod;
+            break;
+        case 0x01:
+            channel->slots[0]->mod = &channel->slots[0]->fbmod;
+            channel->slots[1]->mod = &channel->chip->zeromod;
+            channel->out[0] = &channel->slots[0]->out;
+            channel->out[1] = &channel->slots[1]->out;
+            channel->out[2] = &channel->chip->zeromod;
+            channel->out[3] = &channel->chip->zeromod;
+            break;
+        }
+    }
+}
+
+static void OPL3_ChannelUpdateAlg(opl3_channel *channel)
+{
+    channel->alg = channel->con;
+    if (channel->chip->newm)
+    {
+        if (channel->chtype == ch_4op)
+        {
+            channel->pair->alg = 0x04 | (channel->con << 1) | (channel->pair->con);
+            channel->alg = 0x08;
+            OPL3_ChannelSetupAlg(channel->pair);
+        }
+        else if (channel->chtype == ch_4op2)
+        {
+            channel->alg = 0x04 | (channel->pair->con << 1) | (channel->con);
+            channel->pair->alg = 0x08;
+            OPL3_ChannelSetupAlg(channel);
+        }
+        else
+        {
+            OPL3_ChannelSetupAlg(channel);
+        }
+    }
+    else
+    {
+        OPL3_ChannelSetupAlg(channel);
+    }
+}
+
+static void OPL3_ChannelWriteC0(opl3_channel *channel, uint8_t data)
+{
+    channel->fb = (data & 0x0e) >> 1;
+    channel->con = data & 0x01;
+    OPL3_ChannelUpdateAlg(channel);
+    if (channel->chip->newm)
+    {
+        channel->cha = ((data >> 4) & 0x01) ? ~0 : 0;
+        channel->chb = ((data >> 5) & 0x01) ? ~0 : 0;
+        channel->chc = ((data >> 6) & 0x01) ? ~0 : 0;
+        channel->chd = ((data >> 7) & 0x01) ? ~0 : 0;
+    }
+    else
+    {
+        channel->cha = channel->chb = (uint16_t)~0;
+        // TODO: Verify on real chip if DAC2 output is disabled in compat mode
+        channel->chc = channel->chd = 0;
+    }
+#if OPL_ENABLE_STEREOEXT
+    if (!channel->chip->stereoext)
+    {
+        channel->leftpan = channel->cha << 16;
+        channel->rightpan = channel->chb << 16;
+    }
+#endif
+}
+
+#if OPL_ENABLE_STEREOEXT
+static void OPL3_ChannelWriteD0(opl3_channel* channel, uint8_t data)
+{
+    if (channel->chip->stereoext)
+    {
+        channel->leftpan = panpot_lut[data ^ 0xff];
+        channel->rightpan = panpot_lut[data];
+    }
+}
+#endif
+
+static void OPL3_ChannelKeyOn(opl3_channel *channel)
+{
+    if (channel->chip->newm)
+    {
+        if (channel->chtype == ch_4op)
+        {
+            OPL3_EnvelopeKeyOn(channel->slots[0], egk_norm);
+            OPL3_EnvelopeKeyOn(channel->slots[1], egk_norm);
+            OPL3_EnvelopeKeyOn(channel->pair->slots[0], egk_norm);
+            OPL3_EnvelopeKeyOn(channel->pair->slots[1], egk_norm);
+        }
+        else if (channel->chtype == ch_2op || channel->chtype == ch_drum)
+        {
+            OPL3_EnvelopeKeyOn(channel->slots[0], egk_norm);
+            OPL3_EnvelopeKeyOn(channel->slots[1], egk_norm);
+        }
+    }
+    else
+    {
+        OPL3_EnvelopeKeyOn(channel->slots[0], egk_norm);
+        OPL3_EnvelopeKeyOn(channel->slots[1], egk_norm);
+    }
+}
+
+static void OPL3_ChannelKeyOff(opl3_channel *channel)
+{
+    if (channel->chip->newm)
+    {
+        if (channel->chtype == ch_4op)
+        {
+            OPL3_EnvelopeKeyOff(channel->slots[0], egk_norm);
+            OPL3_EnvelopeKeyOff(channel->slots[1], egk_norm);
+            OPL3_EnvelopeKeyOff(channel->pair->slots[0], egk_norm);
+            OPL3_EnvelopeKeyOff(channel->pair->slots[1], egk_norm);
+        }
+        else if (channel->chtype == ch_2op || channel->chtype == ch_drum)
+        {
+            OPL3_EnvelopeKeyOff(channel->slots[0], egk_norm);
+            OPL3_EnvelopeKeyOff(channel->slots[1], egk_norm);
+        }
+    }
+    else
+    {
+        OPL3_EnvelopeKeyOff(channel->slots[0], egk_norm);
+        OPL3_EnvelopeKeyOff(channel->slots[1], egk_norm);
+    }
+}
+
+static void OPL3_ChannelSet4Op(opl3_chip *chip, uint8_t data)
+{
+    uint8_t bit;
+    uint8_t chnum;
+    for (bit = 0; bit < 6; bit++)
+    {
+        chnum = bit;
+        if (bit >= 3)
+        {
+            chnum += 9 - 3;
+        }
+        if ((data >> bit) & 0x01)
+        {
+            chip->channel[chnum].chtype = ch_4op;
+            chip->channel[chnum + 3].chtype = ch_4op2;
+            OPL3_ChannelUpdateAlg(&chip->channel[chnum]);
+        }
+        else
+        {
+            chip->channel[chnum].chtype = ch_2op;
+            chip->channel[chnum + 3].chtype = ch_2op;
+            OPL3_ChannelUpdateAlg(&chip->channel[chnum]);
+            OPL3_ChannelUpdateAlg(&chip->channel[chnum+3]);
+        }
+    }
+}
+
+static int16_t OPL3_ClipSample(int32_t sample)
+{
+    if (sample > 32767)
+    {
+        sample = 32767;
+    }
+    else if (sample < -32768)
+    {
+        sample = -32768;
+    }
+    return (int16_t)sample;
+}
+
+static void OPL3_ProcessSlot(opl3_slot *slot)
+{
+    OPL3_SlotCalcFB(slot);
+    OPL3_EnvelopeCalc(slot);
+    OPL3_PhaseGenerate(slot);
+    OPL3_SlotGenerate(slot);
+}
+
+inline void OPL3_Generate4Ch(opl3_chip *chip, int16_t *buf4)
+{
+    opl3_channel *channel;
+    opl3_writebuf *writebuf;
+    int16_t **out;
+    int32_t mix[2];
+    uint8_t ii;
+    int16_t accm;
+    uint8_t shift = 0;
+
+    buf4[1] = OPL3_ClipSample(chip->mixbuff[1]);
+    buf4[3] = OPL3_ClipSample(chip->mixbuff[3]);
+
+#if OPL_QUIRK_CHANNELSAMPLEDELAY
+    for (ii = 0; ii < 15; ii++)
+#else
+    for (ii = 0; ii < 36; ii++)
+#endif
+    {
+        OPL3_ProcessSlot(&chip->slot[ii]);
+    }
+
+    mix[0] = mix[1] = 0;
+    for (ii = 0; ii < 18; ii++)
+    {
+        channel = &chip->channel[ii];
+        out = channel->out;
+        accm = *out[0] + *out[1] + *out[2] + *out[3];
+#if OPL_ENABLE_STEREOEXT
+        mix[0] += (int16_t)((accm * channel->leftpan) >> 16);
+#else
+        mix[0] += (int16_t)(accm & channel->cha);
+ #endif
+        mix[1] += (int16_t)(accm & channel->chc);
+    }
+    chip->mixbuff[0] = mix[0];
+    chip->mixbuff[2] = mix[1];
+
+#if OPL_QUIRK_CHANNELSAMPLEDELAY
+    for (ii = 15; ii < 18; ii++)
+    {
+        OPL3_ProcessSlot(&chip->slot[ii]);
+    }
+#endif
+
+    buf4[0] = OPL3_ClipSample(chip->mixbuff[0]);
+    buf4[2] = OPL3_ClipSample(chip->mixbuff[2]);
+
+#if OPL_QUIRK_CHANNELSAMPLEDELAY
+    for (ii = 18; ii < 33; ii++)
+    {
+        OPL3_ProcessSlot(&chip->slot[ii]);
+    }
+#endif
+
+    mix[0] = mix[1] = 0;
+    for (ii = 0; ii < 18; ii++)
+    {
+        channel = &chip->channel[ii];
+        out = channel->out;
+        accm = *out[0] + *out[1] + *out[2] + *out[3];
+#if OPL_ENABLE_STEREOEXT
+        mix[0] += (int16_t)((accm * channel->rightpan) >> 16);
+#else
+        mix[0] += (int16_t)(accm & channel->chb);
+ #endif
+        mix[1] += (int16_t)(accm & channel->chd);
+    }
+    chip->mixbuff[1] = mix[0];
+    chip->mixbuff[3] = mix[1];
+
+#if OPL_QUIRK_CHANNELSAMPLEDELAY
+    for (ii = 33; ii < 36; ii++)
+    {
+        OPL3_ProcessSlot(&chip->slot[ii]);
+    }
+#endif
+
+    if ((chip->timer & 0x3f) == 0x3f)
+    {
+        chip->tremolopos = (chip->tremolopos + 1) % 210;
+    }
+    if (chip->tremolopos < 105)
+    {
+        chip->tremolo = chip->tremolopos >> chip->tremoloshift;
+    }
+    else
+    {
+        chip->tremolo = (210 - chip->tremolopos) >> chip->tremoloshift;
+    }
+
+    if ((chip->timer & 0x3ff) == 0x3ff)
+    {
+        chip->vibpos = (chip->vibpos + 1) & 7;
+    }
+
+    chip->timer++;
+
+    chip->eg_add = 0;
+    if (chip->eg_timer)
+    {
+        while (shift < 36 && ((chip->eg_timer >> shift) & 1) == 0)
+        {
+            shift++;
+        }
+        if (shift > 12)
+        {
+            chip->eg_add = 0;
+        }
+        else
+        {
+            chip->eg_add = shift + 1;
+        }
+    }
+
+    if (chip->eg_timerrem || chip->eg_state)
+    {
+        if (chip->eg_timer == 0xfffffffff)
+        {
+            chip->eg_timer = 0;
+            chip->eg_timerrem = 1;
+        }
+        else
+        {
+            chip->eg_timer++;
+            chip->eg_timerrem = 0;
+        }
+    }
+
+    chip->eg_state ^= 1;
+
+    while ((writebuf = &chip->writebuf[chip->writebuf_cur]), writebuf->time <= chip->writebuf_samplecnt)
+    {
+        if (!(writebuf->reg & 0x200))
+        {
+            break;
+        }
+        writebuf->reg &= 0x1ff;
+        OPL3_WriteReg(chip, writebuf->reg, writebuf->data);
+        chip->writebuf_cur = (chip->writebuf_cur + 1) % OPL_WRITEBUF_SIZE;
+    }
+    chip->writebuf_samplecnt++;
+}
+
+void OPL3_Generate(opl3_chip *chip, int16_t *buf)
+{
+    int16_t samples[4];
+    OPL3_Generate4Ch(chip, samples);
+    buf[0] = samples[0];
+    buf[1] = samples[1];
+}
+
+void OPL3_Generate4ChResampled(opl3_chip *chip, int16_t *buf4)
+{
+    while (chip->samplecnt >= chip->rateratio)
+    {
+        chip->oldsamples[0] = chip->samples[0];
+        chip->oldsamples[1] = chip->samples[1];
+        chip->oldsamples[2] = chip->samples[2];
+        chip->oldsamples[3] = chip->samples[3];
+        OPL3_Generate4Ch(chip, chip->samples);
+        chip->samplecnt -= chip->rateratio;
+    }
+    buf4[0] = (int16_t)((chip->oldsamples[0] * (chip->rateratio - chip->samplecnt)
+                        + chip->samples[0] * chip->samplecnt) / chip->rateratio);
+    buf4[1] = (int16_t)((chip->oldsamples[1] * (chip->rateratio - chip->samplecnt)
+                        + chip->samples[1] * chip->samplecnt) / chip->rateratio);
+    buf4[2] = (int16_t)((chip->oldsamples[2] * (chip->rateratio - chip->samplecnt)
+                        + chip->samples[2] * chip->samplecnt) / chip->rateratio);
+    buf4[3] = (int16_t)((chip->oldsamples[3] * (chip->rateratio - chip->samplecnt)
+                        + chip->samples[3] * chip->samplecnt) / chip->rateratio);
+    chip->samplecnt += 1 << RSM_FRAC;
+}
+
+void OPL3_GenerateResampled(opl3_chip *chip, int16_t *buf)
+{
+    int16_t samples[4];
+    OPL3_Generate4ChResampled(chip, samples);
+    buf[0] = samples[0];
+    buf[1] = samples[1];
+}
+
+void OPL3_Reset(opl3_chip *chip, uint32_t samplerate)
+{
+    opl3_slot *slot;
+    opl3_channel *channel;
+    uint8_t slotnum;
+    uint8_t channum;
+    uint8_t local_ch_slot;
+
+    memset(chip, 0, sizeof(opl3_chip));
+    for (slotnum = 0; slotnum < 36; slotnum++)
+    {
+        slot = &chip->slot[slotnum];
+        slot->chip = chip;
+        slot->mod = &chip->zeromod;
+        slot->eg_rout = 0x1ff;
+        slot->eg_out = 0x1ff;
+        slot->eg_gen = envelope_gen_num_release;
+        slot->trem = (uint8_t*)&chip->zeromod;
+        slot->slot_num = slotnum;
+    }
+    for (channum = 0; channum < 18; channum++)
+    {
+        channel = &chip->channel[channum];
+        local_ch_slot = ch_slot[channum];
+        channel->slots[0] = &chip->slot[local_ch_slot];
+        channel->slots[1] = &chip->slot[local_ch_slot + 3];
+        chip->slot[local_ch_slot].channel = channel;
+        chip->slot[local_ch_slot + 3].channel = channel;
+        if ((channum % 9) < 3)
+        {
+            channel->pair = &chip->channel[channum + 3];
+        }
+        else if ((channum % 9) < 6)
+        {
+            channel->pair = &chip->channel[channum - 3];
+        }
+        channel->chip = chip;
+        channel->out[0] = &chip->zeromod;
+        channel->out[1] = &chip->zeromod;
+        channel->out[2] = &chip->zeromod;
+        channel->out[3] = &chip->zeromod;
+        channel->chtype = ch_2op;
+        channel->cha = 0xffff;
+        channel->chb = 0xffff;
+#if OPL_ENABLE_STEREOEXT
+        channel->leftpan = 0x10000;
+        channel->rightpan = 0x10000;
+#endif
+        channel->ch_num = channum;
+        OPL3_ChannelSetupAlg(channel);
+    }
+    chip->noise = 1;
+    chip->rateratio = (samplerate << RSM_FRAC) / 49716;
+    chip->tremoloshift = 4;
+    chip->vibshift = 1;
+
+#if OPL_ENABLE_STEREOEXT
+    if (!panpot_lut_build)
+    {
+        int32_t i;
+        for (i = 0; i < 256; i++)
+        {
+            panpot_lut[i] = OPL_SIN(i);
+        }
+        panpot_lut_build = 1;
+    }
+#endif
+}
+
+void OPL3_WriteReg(opl3_chip *chip, uint16_t reg, uint8_t v)
+{
+    uint8_t high = (reg >> 8) & 0x01;
+    uint8_t regm = reg & 0xff;
+    switch (regm & 0xf0)
+    {
+    case 0x00:
+        if (high)
+        {
+            switch (regm & 0x0f)
+            {
+            case 0x04:
+                OPL3_ChannelSet4Op(chip, v);
+                break;
+            case 0x05:
+                chip->newm = v & 0x01;
+#if OPL_ENABLE_STEREOEXT
+                chip->stereoext = (v >> 1) & 0x01;
+#endif
+                break;
+            }
+        }
+        else
+        {
+            switch (regm & 0x0f)
+            {
+            case 0x08:
+                chip->nts = (v >> 6) & 0x01;
+                break;
+            }
+        }
+        break;
+    case 0x20:
+    case 0x30:
+        if (ad_slot[regm & 0x1f] >= 0)
+        {
+            OPL3_SlotWrite20(&chip->slot[18 * high + ad_slot[regm & 0x1f]], v);
+        }
+        break;
+    case 0x40:
+    case 0x50:
+        if (ad_slot[regm & 0x1f] >= 0)
+        {
+            OPL3_SlotWrite40(&chip->slot[18 * high + ad_slot[regm & 0x1f]], v);
+        }
+        break;
+    case 0x60:
+    case 0x70:
+        if (ad_slot[regm & 0x1f] >= 0)
+        {
+            OPL3_SlotWrite60(&chip->slot[18 * high + ad_slot[regm & 0x1f]], v);
+        }
+        break;
+    case 0x80:
+    case 0x90:
+        if (ad_slot[regm & 0x1f] >= 0)
+        {
+            OPL3_SlotWrite80(&chip->slot[18 * high + ad_slot[regm & 0x1f]], v);
+        }
+        break;
+    case 0xe0:
+    case 0xf0:
+        if (ad_slot[regm & 0x1f] >= 0)
+        {
+            OPL3_SlotWriteE0(&chip->slot[18 * high + ad_slot[regm & 0x1f]], v);
+        }
+        break;
+    case 0xa0:
+        if ((regm & 0x0f) < 9)
+        {
+            OPL3_ChannelWriteA0(&chip->channel[9 * high + (regm & 0x0f)], v);
+        }
+        break;
+    case 0xb0:
+        if (regm == 0xbd && !high)
+        {
+            chip->tremoloshift = (((v >> 7) ^ 1) << 1) + 2;
+            chip->vibshift = ((v >> 6) & 0x01) ^ 1;
+            OPL3_ChannelUpdateRhythm(chip, v);
+        }
+        else if ((regm & 0x0f) < 9)
+        {
+            OPL3_ChannelWriteB0(&chip->channel[9 * high + (regm & 0x0f)], v);
+            if (v & 0x20)
+            {
+                OPL3_ChannelKeyOn(&chip->channel[9 * high + (regm & 0x0f)]);
+            }
+            else
+            {
+                OPL3_ChannelKeyOff(&chip->channel[9 * high + (regm & 0x0f)]);
+            }
+        }
+        break;
+    case 0xc0:
+        if ((regm & 0x0f) < 9)
+        {
+            OPL3_ChannelWriteC0(&chip->channel[9 * high + (regm & 0x0f)], v);
+        }
+        break;
+#if OPL_ENABLE_STEREOEXT
+    case 0xd0:
+        if ((regm & 0x0f) < 9)
+        {
+            OPL3_ChannelWriteD0(&chip->channel[9 * high + (regm & 0x0f)], v);
+        }
+        break;
+#endif
+    }
+}
+
+void OPL3_WriteRegBuffered(opl3_chip *chip, uint16_t reg, uint8_t v)
+{
+    uint64_t time1, time2;
+    opl3_writebuf *writebuf;
+    uint32_t writebuf_last;
+
+    writebuf_last = chip->writebuf_last;
+    writebuf = &chip->writebuf[writebuf_last];
+
+    if (writebuf->reg & 0x200)
+    {
+        OPL3_WriteReg(chip, writebuf->reg & 0x1ff, writebuf->data);
+
+        chip->writebuf_cur = (writebuf_last + 1) % OPL_WRITEBUF_SIZE;
+        chip->writebuf_samplecnt = writebuf->time;
+    }
+
+    writebuf->reg = reg | 0x200;
+    writebuf->data = v;
+    time1 = chip->writebuf_lasttime + OPL_WRITEBUF_DELAY;
+    time2 = chip->writebuf_samplecnt;
+
+    if (time1 < time2)
+    {
+        time1 = time2;
+    }
+
+    writebuf->time = time1;
+    chip->writebuf_lasttime = time1;
+    chip->writebuf_last = (writebuf_last + 1) % OPL_WRITEBUF_SIZE;
+}
+
+void OPL3_Generate4ChStream(opl3_chip *chip, int16_t *sndptr1, int16_t *sndptr2, uint32_t numsamples)
+{
+    uint_fast32_t i;
+    int16_t samples[4];
+
+    for(i = 0; i < numsamples; i++)
+    {
+        OPL3_Generate4ChResampled(chip, samples);
+        sndptr1[0] = samples[0];
+        sndptr1[1] = samples[1];
+        sndptr2[0] = samples[2];
+        sndptr2[1] = samples[3];
+        sndptr1 += 2;
+        sndptr2 += 2;
+    }
+}
+
+void OPL3_GenerateStream(opl3_chip *chip, int16_t *sndptr, uint32_t numsamples)
+{
+    uint_fast32_t i;
+
+    for(i = 0; i < numsamples; i++)
+    {
+        OPL3_GenerateResampled(chip, sndptr);
+        sndptr += 2;
+    }
+}
diff --git a/Nuked-OPL3/opl3.h b/Nuked-OPL3/opl3.h
new file mode 100644
index 0000000..3977f80
--- /dev/null
+++ b/Nuked-OPL3/opl3.h
@@ -0,0 +1,172 @@
+/* Nuked OPL3
+ * Copyright (C) 2013-2020 Nuke.YKT
+ *
+ * This file is part of Nuked OPL3.
+ *
+ * Nuked OPL3 is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as
+ * published by the Free Software Foundation, either version 2.1
+ * of the License, or (at your option) any later version.
+ *
+ * Nuked OPL3 is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with Nuked OPL3. If not, see <https://www.gnu.org/licenses/>.
+
+ *  Nuked OPL3 emulator.
+ *  Thanks:
+ *      MAME Development Team(Jarek Burczynski, Tatsuyuki Satoh):
+ *          Feedback and Rhythm part calculation information.
+ *      forums.submarine.org.uk(carbon14, opl3):
+ *          Tremolo and phase generator calculation information.
+ *      OPLx decapsulated(Matthew Gambrell, Olli Niemitalo):
+ *          OPL2 ROMs.
+ *      siliconpr0n.org(John McMaster, digshadow):
+ *          YMF262 and VRC VII decaps and die shots.
+ *
+ * version: 1.8
+ */
+
+#ifndef OPL_OPL3_H
+#define OPL_OPL3_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <inttypes.h>
+
+#ifndef OPL_ENABLE_STEREOEXT
+#define OPL_ENABLE_STEREOEXT 0
+#endif
+
+#define OPL_WRITEBUF_SIZE   1024
+#define OPL_WRITEBUF_DELAY  2
+
+typedef struct _opl3_slot opl3_slot;
+typedef struct _opl3_channel opl3_channel;
+typedef struct _opl3_chip opl3_chip;
+
+struct _opl3_slot {
+    opl3_channel *channel;
+    opl3_chip *chip;
+    int16_t out;
+    int16_t fbmod;
+    int16_t *mod;
+    int16_t prout;
+    uint16_t eg_rout;
+    uint16_t eg_out;
+    uint8_t eg_inc;
+    uint8_t eg_gen;
+    uint8_t eg_rate;
+    uint8_t eg_ksl;
+    uint8_t *trem;
+    uint8_t reg_vib;
+    uint8_t reg_type;
+    uint8_t reg_ksr;
+    uint8_t reg_mult;
+    uint8_t reg_ksl;
+    uint8_t reg_tl;
+    uint8_t reg_ar;
+    uint8_t reg_dr;
+    uint8_t reg_sl;
+    uint8_t reg_rr;
+    uint8_t reg_wf;
+    uint8_t key;
+    uint32_t pg_reset;
+    uint32_t pg_phase;
+    uint16_t pg_phase_out;
+    uint8_t slot_num;
+};
+
+struct _opl3_channel {
+    opl3_slot *slots[2];
+    opl3_channel *pair;
+    opl3_chip *chip;
+    int16_t *out[4];
+
+#if OPL_ENABLE_STEREOEXT
+    int32_t leftpan;
+    int32_t rightpan;
+#endif
+
+    uint8_t chtype;
+    uint16_t f_num;
+    uint8_t block;
+    uint8_t fb;
+    uint8_t con;
+    uint8_t alg;
+    uint8_t ksv;
+    uint16_t cha, chb;
+    uint16_t chc, chd;
+    uint8_t ch_num;
+};
+
+typedef struct _opl3_writebuf {
+    uint64_t time;
+    uint16_t reg;
+    uint8_t data;
+} opl3_writebuf;
+
+struct _opl3_chip {
+    opl3_channel channel[18];
+    opl3_slot slot[36];
+    uint16_t timer;
+    uint64_t eg_timer;
+    uint8_t eg_timerrem;
+    uint8_t eg_state;
+    uint8_t eg_add;
+    uint8_t newm;
+    uint8_t nts;
+    uint8_t rhy;
+    uint8_t vibpos;
+    uint8_t vibshift;
+    uint8_t tremolo;
+    uint8_t tremolopos;
+    uint8_t tremoloshift;
+    uint32_t noise;
+    int16_t zeromod;
+    int32_t mixbuff[4];
+    uint8_t rm_hh_bit2;
+    uint8_t rm_hh_bit3;
+    uint8_t rm_hh_bit7;
+    uint8_t rm_hh_bit8;
+    uint8_t rm_tc_bit3;
+    uint8_t rm_tc_bit5;
+
+#if OPL_ENABLE_STEREOEXT
+    uint8_t stereoext;
+#endif
+
+    /* OPL3L */
+    int32_t rateratio;
+    int32_t samplecnt;
+    int16_t oldsamples[4];
+    int16_t samples[4];
+
+    uint64_t writebuf_samplecnt;
+    uint32_t writebuf_cur;
+    uint32_t writebuf_last;
+    uint64_t writebuf_lasttime;
+    opl3_writebuf writebuf[OPL_WRITEBUF_SIZE];
+};
+
+void OPL3_Generate(opl3_chip *chip, int16_t *buf);
+void OPL3_GenerateResampled(opl3_chip *chip, int16_t *buf);
+void OPL3_Reset(opl3_chip *chip, uint32_t samplerate);
+void OPL3_WriteReg(opl3_chip *chip, uint16_t reg, uint8_t v);
+void OPL3_WriteRegBuffered(opl3_chip *chip, uint16_t reg, uint8_t v);
+void OPL3_GenerateStream(opl3_chip *chip, int16_t *sndptr, uint32_t numsamples);
+
+void OPL3_Generate4Ch(opl3_chip *chip, int16_t *buf4);
+void OPL3_Generate4ChResampled(opl3_chip *chip, int16_t *buf4);
+void OPL3_Generate4ChStream(opl3_chip *chip, int16_t *sndptr1, int16_t *sndptr2, uint32_t numsamples);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
diff --git a/README.md b/README.md
index f555daf..6380519 100644
--- a/README.md
+++ b/README.md
@@ -10,7 +10,7 @@ TR8 is an 8-bit fantasy console inspired by MIPS, Z80 and 6502 real world CPUs.
 Display:  128 x 128 pixels 16 colors
 Memory:   64K
 CPU:      TR-8, 4M VM instr/sec
-Sound:    TBD
+Sound:    OPL3
 ```
 
 Other features:
@@ -65,6 +65,10 @@ You can then compile and run the example with `make example`.
 | --- | --- | --- |
 | 0xb0 | write | Blitter control |
 | 0xb1 | write | Blitter settings |
+| 0xc0 | write | Sound register selector (primary) |
+| 0xc1 | write | Sound data (primary) |
+| 0xc2 | write | Sound register selector (secondary)|
+| 0xc3 | write | Sound data (secondary) |
 | 0xf0 | read | Status of the controller 1 |
 | 0xf1 | read | Status of the controller 2 |
 
@@ -169,6 +173,20 @@ Current palette (not final) is the default EGA 16 color palette:
 | 14 | `0xffff55` |
 | 15 | `0xffffff` |
 
+### Sound: OPL3
+
+TR8 includes an OPL3 emulator that can be conttolled using ports `0xc0` to
+select register and `0xc1` to write data in the primary set of registers
+(channels 0 to 8), and `0xc2` to select register and `0xc3` to write data in
+the secondary set of registers (channels 9 to 17).
+
+There are a few good resources online on how to program this chip:
+
+* [Programming the AdLib/Sound Blaster FM Music Chips](http://www.shipbrook.net/jeff/sb.html)
+* [Programmer's Guide to Yamaha YMF 262/OPL3 FM Music Synthesizer](https://www.fit.vutbr.cz/~arnost/opl/opl3.html)
+
+Also look at the example code in this repo for some simple sound drivers.
+
 ### Frame interrupt
 
 When interrupts are enabled (IF not set), 60 times per second there will be a
diff --git a/example.asm b/example.asm
index 992823f..468db3a 100644
--- a/example.asm
+++ b/example.asm
@@ -7,7 +7,8 @@
 .equ INT_VECT 0xff00
 
     ; setup an int handler so we
-    ; can use the frame int to sync
+    ; can use the frame interrupt to sync
+    ; and play sounds in background
     ld a, >INT_VECT
     ld x, <INT_VECT
     ld b, <int_handler
@@ -81,8 +82,10 @@ update_done:
     pop b
     jmp loop
 
-    ; make the sprite change direction
-    ; in: [a : x] inc*
+;
+; Make the sprite change direction and queue a sound
+;
+; in: [a : x] inc*
 turn:
     ;  1 -> -1
     ; -1 -> 1
@@ -96,11 +99,23 @@ turn:
     inc b
     and b, 15
     ld [sp + 2], b
-    ret
 
+    ; play an effect when we turn
+    ; alternating two sounds
+
+    ld x, <effect
+    ld a, >effect
+    ld y, [a : x]
+    xor y, 3
+    ld [a : x], y
+
+    call sound_queue_effect
+    ret
 
-    ; fill frame-buffer
-    ; in: reg b color
+;
+; fill frame-buffer
+;
+; in: reg b color
 fill_screen:
     ld a, 0xbf
     ld x, 0
@@ -116,11 +131,10 @@ fill_loop:
     jmp fill_loop
     ret
 
-int_handler:
-    iret
-
-    ; draw sprite
-    ; in: coordinates in px, py
+;
+; Draw the sprite
+;
+; in: coordinates in px, py
 draw_sprite:
     ; blitter in settings mode
     ld x, 128
@@ -167,3 +181,229 @@ incy:
 py:
     .db 64
 
+effect:
+    .db 1
+
+;
+; Our int handler plays / stops sounds
+;
+int_handler:
+    push a
+    push b
+    push x
+    push y
+    call sound_play
+    pop y
+    pop x
+    pop b
+    pop a
+    iret
+
+;
+; Queue a sound effect to be played
+;
+; in: y sound index (1 based)
+sound_queue_effect:
+    ; can't be interrupted
+    sif
+
+    ld a, >sound_efx
+    ld x, <sound_efx
+    dec y
+    ld b, y
+    add y, y
+    add y, b
+    add x, y
+    bo
+    inc a
+
+    ; effect addr
+    ld b, >sound_queue
+    ld y, <sound_queue
+    push x
+    ld x, [a : x]
+    ld [b : y], x
+    pop x
+    inc x
+    bo
+    inc a
+    inc y
+    bo
+    inc b
+    push x
+    ld x, [a : x]
+    ld [b : y], x
+    pop x
+
+    inc x
+    bo
+    inc a
+    ; x has length
+    ld x, [a : x]
+
+    ; current is 0
+    inc y
+    bo
+    inc b
+    ld a, 0
+    ld [b : y], a
+
+    ; length
+    inc y
+    bo
+    inc b
+    ld [b : y], x
+
+    cif
+    ret
+
+;
+; Plays sound in our queue
+;
+; To be run from the interrupt handler. Can't play effects which data is at 0x0000.
+; It is very simple and uses only channel 0.
+;
+sound_play:
+    ld b, >sound_queue
+    ld y, <sound_queue
+
+    ; check we have a valid addr in the queue (not 0x0000)
+    ld x, [b : y]
+    inc y
+    bo
+    inc b
+    ld a, [b : y]
+    cmp a, 0
+    bnz
+    jmp sound_play_has_addr
+    cmp x, 0
+    bz
+    ret
+
+sound_play_has_addr:
+    push a
+
+    inc y
+    bo
+    inc b
+
+    ; is already playing?
+    ld a, [b : y]
+    cmp a, 0
+    bz
+    jmp sound_play_start
+
+    ; the sound is active
+    pop a
+    ld a, [b : y]
+
+    ; another frame
+    inc a
+    ld [b : y], a
+
+    inc y
+    bo
+    inc b
+
+    ; is the end?
+    ld x, [b : y]
+    cmp x, a
+    bnc
+    ret
+
+    ; no active sound now: set addr to 0x0000
+    ld b, >sound_queue
+    ld y, <sound_queue
+    ld x, 0
+    ld [b : y], x
+    inc y
+    bo
+    inc b
+    ld [b : y], x
+
+    ; stop the sound
+    ld b, 0xc0
+    ld y, 0xb0
+    port b, y
+
+    ld b, 0xc1
+    ld y, 0x11
+    port b, y
+    ret
+
+sound_play_start:
+    ; we start playing
+    inc a
+    ld [b : y], a
+
+    pop a
+    ; a : x has the effect addr
+
+sound_loop:
+    ld y, [a : x]
+    cmp y, 0xff
+    bz
+    ret
+
+    ld b, 0xc0
+    port b, y
+
+    inc x
+    bo
+    inc a
+
+    ld y, [a : x]
+
+    ld b, 0xc1
+    port b, y
+
+    inc x
+    bo
+    inc a
+
+    jmp sound_loop
+
+sound_queue:
+    ; effect addr, current frame count, length
+    .ds 4, 0
+
+sound_efx:
+    ; addr to the instrument data
+    .dw sound_efx_data0
+    ; length in frames
+    .db 2
+    .dw sound_efx_data1
+    .db 2
+
+sound_efx_data0:
+    ; register, value
+    .db 0x20, 0x01
+    .db 0x40, 0x10
+    .db 0x60, 0xF0
+    .db 0x80, 0x77
+    .db 0xA0, 0x81
+    .db 0x23, 0x01
+    .db 0x43, 0x00
+    .db 0x63, 0xF0
+    .db 0x83, 0x77
+    .db 0xe0, 0x03
+    .db 0xB0, 0x31
+    ; end of sequence marker
+    .db 0xff
+
+sound_efx_data1:
+    ; register, value
+    .db 0x20, 0x01
+    .db 0x40, 0x10
+    .db 0x60, 0xF0
+    .db 0x80, 0x77
+    .db 0xA0, 0xb0
+    .db 0x23, 0x01
+    .db 0x43, 0x00
+    .db 0x63, 0xF0
+    .db 0x83, 0x77
+    .db 0xe0, 0x03
+    .db 0xB0, 0x31
+    ; end of sequence marker
+    .db 0xff
+
diff --git a/tr8vm.c b/tr8vm.c
index e75ba9f..fd64c0f 100644
--- a/tr8vm.c
+++ b/tr8vm.c
@@ -27,6 +27,7 @@
 #include <string.h>
 
 #include "SDL.h"
+#include "opl3.h"
 
 #include "vm.h"
 
@@ -42,6 +43,10 @@
 #define WINDOW_W (TR8_W * WINDOW_SCALE)
 #define WINDOW_H (TR8_H * WINDOW_SCALE)
 
+#define TR8_SAMPLE_RATE     44100
+#define TR8_SAMPLE_CHANNELS 1
+#define TR8_SAMPLE_SIZE     1024
+
 static void resize_full_screen(SDL_Window *win, SDL_Renderer *renderer, int fullscreen, SDL_Rect *s)
 {
     if (!fullscreen)
@@ -157,6 +162,26 @@ static void update_ctl(SDL_Event *ev)
     }
 }
 
+SDL_mutex *amutex = NULL;
+
+opl3_chip opl;
+uint8_t snd_reg[2] = { 0 };
+
+static void audio_callback(void *userdata, uint8_t *stream, int32_t len)
+{
+    if (!SDL_LockMutex(amutex))
+    {
+        SDL_memset(stream, 0, len);
+        while (len >= 2)
+        {
+            OPL3_GenerateResampled((opl3_chip *)userdata, (int16_t *)stream);
+            stream += 2;
+            len -= 2;
+        }
+        SDL_UnlockMutex(amutex);
+    }
+}
+
 uint8_t blt_set = 0;
 uint8_t blt_paramc = 0;
 uint8_t blt_param[6] = { 0 };
@@ -240,6 +265,34 @@ uint8_t port(uint8_t p, uint8_t v)
             blt_param[blt_paramc++] = v;
             return p;
 
+        /* sound register selector primary */
+        case 0xc0:
+            snd_reg[0] = v & 0xff;
+            return p;
+
+        /* sound data primary */
+        case 0xc1:
+            if (!SDL_LockMutex(amutex))
+            {
+                OPL3_WriteReg(&opl, snd_reg[0], v);
+                SDL_UnlockMutex(amutex);
+            }
+            return p;
+
+        /* sound register selector secondary */
+        case 0xc2:
+            snd_reg[1] = v & 0xff;
+            return p;
+
+        /* sound data secondary */
+        case 0xc3:
+            if (!SDL_LockMutex(amutex))
+            {
+                OPL3_WriteReg(&opl, 0x100 | snd_reg[1], v);
+                SDL_UnlockMutex(amutex);
+            }
+            return p;
+
         /* controller 1 */
         case 0xf0:
             return ctl[0];
@@ -298,6 +351,33 @@ int main(int argc, char *argv[])
         return 1;
     }
 
+    /* init audio */
+    OPL3_Reset(&opl, TR8_SAMPLE_RATE);
+
+    amutex = SDL_CreateMutex();
+    if (!amutex)
+    {
+        fprintf(stderr, "Failed to create mutex: %s\n", SDL_GetError());
+        return 1;
+    }
+
+    SDL_AudioSpec audio_spec, audio_want;
+
+    SDL_memset(&audio_want, 0, sizeof(audio_want));
+
+    audio_want.freq = TR8_SAMPLE_RATE,
+    audio_want.format = AUDIO_S16,
+    audio_want.channels = TR8_SAMPLE_CHANNELS,
+    audio_want.callback = audio_callback,
+    audio_want.userdata = (void *)&opl;
+    audio_want.samples = TR8_SAMPLE_SIZE;
+
+    SDL_AudioDeviceID audio = SDL_OpenAudioDevice(NULL, 0, &audio_want, &audio_spec, 0);
+    if (audio == 0)
+        fprintf(stderr, "Failed to open audio: %s\n", SDL_GetError());
+    else
+        SDL_PauseAudioDevice(audio, 0);
+
     SDL_Window *screen = SDL_CreateWindow(APP_NAME " " APP_VERSION,
                                           SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
                                           WINDOW_W, WINDOW_H,
@@ -411,6 +491,12 @@ int main(int argc, char *argv[])
     if (fb)
         SDL_DestroyTexture(fb);
 
+    if (audio > 0)
+        SDL_CloseAudioDevice(audio);
+
+    if (amutex)
+        SDL_DestroyMutex(amutex);
+
     SDL_DestroyRenderer(renderer);
     SDL_DestroyWindow(screen);