diff --git a/emu/cores/nukedopl3.c b/emu/cores/nukedopl3.c
index 8ff67cc6..2c90cd39 100644
--- a/emu/cores/nukedopl3.c
+++ b/emu/cores/nukedopl3.c
@@ -1,3 +1,5 @@
+// license:LGPL-2.1+
+// copyright-holders:Nuke.YKT
 /* Nuked OPL3
  * Copyright (C) 2013-2020 Nuke.YKT
  *
@@ -39,9 +41,20 @@
 #include "nukedopl3.h"
 #include "nukedopl3_int.h"
 
+#if OPL_ENABLE_STEREOEXT && !defined OPL_SIN
+#include "../EmuHelper.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
+
 static const int16_t zeromod = 0;
 
-// muting channel IDs
+/* muting channel IDs */
 enum {
     mch_bd = 18+0,
     mch_sd = 18+1,
@@ -52,7 +65,7 @@ enum {
 
 #define RSM_FRAC    10
 
-// Channel types
+/* Channel types */
 
 enum {
     ch_2op = 0,
@@ -61,7 +74,7 @@ enum {
     ch_drum = 3
 };
 
-// Envelope key types
+/* Envelope key types */
 
 enum {
     egk_norm = 0x01,
@@ -69,9 +82,9 @@ enum {
 };
 
 
-//
-// logsin table
-//
+/*
+    logsin table
+*/
 
 static const uint16_t logsinrom[256] = {
     0x859, 0x6c3, 0x607, 0x58b, 0x52e, 0x4e4, 0x4a6, 0x471,
@@ -108,9 +121,9 @@ static const uint16_t logsinrom[256] = {
     0x000, 0x000, 0x000, 0x000, 0x000, 0x000, 0x000, 0x000
 };
 
-//
-// exp table
-//
+/*
+    exp table
+*/
 
 static const uint16_t exprom[256] = {
     0x7fa, 0x7f5, 0x7ef, 0x7ea, 0x7e4, 0x7df, 0x7da, 0x7d4,
@@ -147,19 +160,19 @@ static const uint16_t exprom[256] = {
     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
-//
+/*
+    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
-//
+/*
+    ksl table
+*/
 
 static const uint8_t kslrom[16] = {
     0, 32, 40, 45, 48, 51, 53, 55, 56, 58, 59, 60, 61, 62, 63, 64
@@ -169,9 +182,9 @@ static const uint8_t kslshift[4] = {
     8, 1, 2, 0
 };
 
-//
-// envelope generator constants
-//
+/*
+    envelope generator constants
+*/
 
 static const uint8_t eg_incstep[4][4] = {
     { 0, 0, 0, 0 },
@@ -180,9 +193,9 @@ static const uint8_t eg_incstep[4][4] = {
     { 1, 1, 1, 0 }
 };
 
-//
-// address decoding
-//
+/*
+    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,
@@ -193,9 +206,18 @@ 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
 };
 
-//
-// Envelope generator
-//
+#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);
@@ -206,7 +228,7 @@ INLINE int16_t OPL3_EnvelopeCalcExp(uint32_t level)
     {
         level = 0x1fff;
     }
-    return (exprom[level & 0xff] << 1) >> (level >> 8);
+    return (exprom[level & 0xffu] << 1) >> (level >> 8);
 }
 
 static int16_t OPL3_EnvelopeCalcSin0(uint16_t phase, uint16_t envelope)
@@ -220,11 +242,11 @@ static int16_t OPL3_EnvelopeCalcSin0(uint16_t phase, uint16_t envelope)
     }
     if (phase & 0x100)
     {
-        out = logsinrom[(phase & 0xff) ^ 0xff];
+        out = logsinrom[(phase & 0xffu) ^ 0xffu];
     }
     else
     {
-        out = logsinrom[phase & 0xff];
+        out = logsinrom[phase & 0xffu];
     }
     return OPL3_EnvelopeCalcExp(out + (envelope << 3)) ^ neg;
 }
@@ -239,11 +261,11 @@ static int16_t OPL3_EnvelopeCalcSin1(uint16_t phase, uint16_t envelope)
     }
     else if (phase & 0x100)
     {
-        out = logsinrom[(phase & 0xff) ^ 0xff];
+        out = logsinrom[(phase & 0xffu) ^ 0xffu];
     }
     else
     {
-        out = logsinrom[phase & 0xff];
+        out = logsinrom[phase & 0xffu];
     }
     return OPL3_EnvelopeCalcExp(out + (envelope << 3));
 }
@@ -254,11 +276,11 @@ static int16_t OPL3_EnvelopeCalcSin2(uint16_t phase, uint16_t envelope)
     phase &= 0x3ff;
     if (phase & 0x100)
     {
-        out = logsinrom[(phase & 0xff) ^ 0xff];
+        out = logsinrom[(phase & 0xffu) ^ 0xffu];
     }
     else
     {
-        out = logsinrom[phase & 0xff];
+        out = logsinrom[phase & 0xffu];
     }
     return OPL3_EnvelopeCalcExp(out + (envelope << 3));
 }
@@ -273,7 +295,7 @@ static int16_t OPL3_EnvelopeCalcSin3(uint16_t phase, uint16_t envelope)
     }
     else
     {
-        out = logsinrom[phase & 0xff];
+        out = logsinrom[phase & 0xffu];
     }
     return OPL3_EnvelopeCalcExp(out + (envelope << 3));
 }
@@ -293,11 +315,11 @@ static int16_t OPL3_EnvelopeCalcSin4(uint16_t phase, uint16_t envelope)
     }
     else if (phase & 0x80)
     {
-        out = logsinrom[((phase ^ 0xff) << 1) & 0xff];
+        out = logsinrom[((phase ^ 0xffu) << 1u) & 0xffu];
     }
     else
     {
-        out = logsinrom[(phase << 1) & 0xff];
+        out = logsinrom[(phase << 1u) & 0xffu];
     }
     return OPL3_EnvelopeCalcExp(out + (envelope << 3)) ^ neg;
 }
@@ -312,11 +334,11 @@ static int16_t OPL3_EnvelopeCalcSin5(uint16_t phase, uint16_t envelope)
     }
     else if (phase & 0x80)
     {
-        out = logsinrom[((phase ^ 0xff) << 1) & 0xff];
+        out = logsinrom[((phase ^ 0xffu) << 1u) & 0xffu];
     }
     else
     {
-        out = logsinrom[(phase << 1) & 0xff];
+        out = logsinrom[(phase << 1u) & 0xffu];
     }
     return OPL3_EnvelopeCalcExp(out + (envelope << 3));
 }
@@ -367,7 +389,7 @@ enum envelope_gen_num
 
 INLINE void OPL3_EnvelopeUpdateKSL(opl3_slot *slot)
 {
-    int16_t ksl = (kslrom[slot->channel->f_num >> 6] << 2)
+    int16_t ksl = (kslrom[slot->channel->f_num >> 6u] << 2)
                - ((0x08 - slot->channel->block) << 5);
     if (ksl < 0)
     {
@@ -453,7 +475,7 @@ static void OPL3_EnvelopeCalc(opl3_slot *slot)
         }
         else
         {
-            shift = (rate_hi & 0x03) + eg_incstep[rate_lo][slot->chip->timer & 0x03];
+            shift = (rate_hi & 0x03) + eg_incstep[rate_lo][slot->chip->timer & 0x03u];
             if (shift & 0x04)
             {
                 shift = 0x03;
@@ -467,12 +489,12 @@ static void OPL3_EnvelopeCalc(opl3_slot *slot)
     eg_rout = slot->eg_rout;
     eg_inc = 0;
     eg_off = 0;
-    // Instant attack
+    /* Instant attack */
     if (reset && rate_hi == 0x0f)
     {
         eg_rout = 0x00;
     }
-    // Envelope off
+    /* Envelope off */
     if ((slot->eg_rout & 0x1f8) == 0x1f8)
     {
         eg_off = 1;
@@ -490,7 +512,7 @@ static void OPL3_EnvelopeCalc(opl3_slot *slot)
         }
         else if (slot->key && shift > 0 && rate_hi != 0x0f)
         {
-            eg_inc = ((~slot->eg_rout) << shift) >> 4;
+            eg_inc = ~slot->eg_rout >> (4 - shift);
         }
         break;
     case envelope_gen_num_decay:
@@ -512,7 +534,7 @@ static void OPL3_EnvelopeCalc(opl3_slot *slot)
         break;
     }
     slot->eg_rout = (eg_rout + eg_inc) & 0x1ff;
-    // Key off
+    /* Key off */
     if (reset)
     {
         slot->eg_gen = envelope_gen_num_attack;
@@ -528,7 +550,7 @@ INLINE void OPL3_EnvelopeKeyOn(opl3_slot *slot, uint8_t type)
     slot->key |= type;
 #ifndef NOPL_ENABLE_WRITEBUF
     if (slot->key && slot->eg_gen != envelope_gen_num_attack)
-        OPL3_EnvelopeCalc(slot);    // hack to make key off+on at the sample sample work
+        OPL3_EnvelopeCalc(slot);    /* hack to make key off+on at the sample sample work */
 #endif
 }
 
@@ -537,13 +559,13 @@ INLINE void OPL3_EnvelopeKeyOff(opl3_slot *slot, uint8_t type)
     slot->key &= ~type;
 #ifndef NOPL_ENABLE_WRITEBUF
     if (! slot->key && slot->eg_gen != envelope_gen_num_release)
-        OPL3_EnvelopeCalc(slot);    // hack to make key off+on at the sample sample work
+        OPL3_EnvelopeCalc(slot);    /* hack to make key off+on at the sample sample work */
 #endif
 }
 
-//
-// Phase Generator
-//
+/*
+    Phase Generator
+*/
 
 static void OPL3_PhaseGenerate(opl3_slot *slot)
 {
@@ -587,17 +609,17 @@ static void OPL3_PhaseGenerate(opl3_slot *slot)
         slot->pg_phase = 0;
     }
     slot->pg_phase += (basefreq * mt[slot->reg_mult]) >> 1;
-    // Rhythm mode
+    /* Rhythm mode */
     noise = chip->noise;
     slot->pg_phase_out = phase;
-    if (slot->slot_num == 13) // hh
+    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
+    if (slot->slot_num == 17 && (chip->rhy & 0x20)) /* tc */
     {
         chip->rm_tc_bit3 = (phase >> 3) & 1;
         chip->rm_tc_bit5 = (phase >> 5) & 1;
@@ -609,7 +631,7 @@ static void OPL3_PhaseGenerate(opl3_slot *slot)
                | (chip->rm_tc_bit3 ^ chip->rm_tc_bit5);
         switch (slot->slot_num)
         {
-        case 13: // hh
+        case 13: /* hh */
             slot->pg_phase_out = rm_xor << 9;
             if (rm_xor ^ (noise & 1))
             {
@@ -620,11 +642,11 @@ static void OPL3_PhaseGenerate(opl3_slot *slot)
                 slot->pg_phase_out |= 0x34;
             }
             break;
-        case 16: // sd
+        case 16: /* sd */
             slot->pg_phase_out = (chip->rm_hh_bit8 << 9)
                                | ((chip->rm_hh_bit8 ^ (noise & 1)) << 8);
             break;
-        case 17: // tc
+        case 17: /* tc */
             slot->pg_phase_out = (rm_xor << 9) | 0x80;
             break;
         default:
@@ -635,9 +657,9 @@ static void OPL3_PhaseGenerate(opl3_slot *slot)
     chip->noise = (noise >> 1) | (n_bit << 22);
 }
 
-//
-// Slot
-//
+/*
+    Slot
+*/
 
 INLINE void OPL3_SlotWrite20(opl3_slot *slot, uint8_t data)
 {
@@ -705,9 +727,9 @@ INLINE void OPL3_SlotCalcFB(opl3_slot *slot)
     slot->prout = slot->out;
 }
 
-//
-// Channel
-//
+/*
+    Channel
+*/
 
 static void OPL3_ChannelSetupAlg(opl3_channel *channel);
 
@@ -716,18 +738,18 @@ static void OPL3_RhythmSetupAlg(opl3_chip *chip)
     opl3_channel *channel6 = &chip->channel[6];
     opl3_channel *channel7 = &chip->channel[7];
     opl3_channel *channel8 = &chip->channel[8];
-    channel6->out[0] = (chip->muteMask & (1 << mch_bd)) ? &zeromod : &channel6->slots[1]->out;
-    channel6->out[1] = (chip->muteMask & (1 << mch_bd)) ? &zeromod : &channel6->slots[1]->out;
+    channel6->out[0] = (chip->muteMask & (1 << mch_bd)) ? &zeromod : &channel6->slotz[1]->out;
+    channel6->out[1] = (chip->muteMask & (1 << mch_bd)) ? &zeromod : &channel6->slotz[1]->out;
     channel6->out[2] = &zeromod;
     channel6->out[3] = &zeromod;
-    channel7->out[0] = (chip->muteMask & (1 << mch_hh)) ? &zeromod : &channel7->slots[0]->out;
-    channel7->out[1] = (chip->muteMask & (1 << mch_hh)) ? &zeromod : &channel7->slots[0]->out;
-    channel7->out[2] = (chip->muteMask & (1 << mch_sd)) ? &zeromod : &channel7->slots[1]->out;
-    channel7->out[3] = (chip->muteMask & (1 << mch_sd)) ? &zeromod : &channel7->slots[1]->out;
-    channel8->out[0] = (chip->muteMask & (1 << mch_tt)) ? &zeromod : &channel8->slots[0]->out;
-    channel8->out[1] = (chip->muteMask & (1 << mch_tt)) ? &zeromod : &channel8->slots[0]->out;
-    channel8->out[2] = (chip->muteMask & (1 << mch_tc)) ? &zeromod : &channel8->slots[1]->out;
-    channel8->out[3] = (chip->muteMask & (1 << mch_tc)) ? &zeromod : &channel8->slots[1]->out;
+    channel7->out[0] = (chip->muteMask & (1 << mch_hh)) ? &zeromod : &channel7->slotz[0]->out;
+    channel7->out[1] = (chip->muteMask & (1 << mch_hh)) ? &zeromod : &channel7->slotz[0]->out;
+    channel7->out[2] = (chip->muteMask & (1 << mch_sd)) ? &zeromod : &channel7->slotz[1]->out;
+    channel7->out[3] = (chip->muteMask & (1 << mch_sd)) ? &zeromod : &channel7->slotz[1]->out;
+    channel8->out[0] = (chip->muteMask & (1 << mch_tt)) ? &zeromod : &channel8->slotz[0]->out;
+    channel8->out[1] = (chip->muteMask & (1 << mch_tt)) ? &zeromod : &channel8->slotz[0]->out;
+    channel8->out[2] = (chip->muteMask & (1 << mch_tc)) ? &zeromod : &channel8->slotz[1]->out;
+    channel8->out[3] = (chip->muteMask & (1 << mch_tc)) ? &zeromod : &channel8->slotz[1]->out;
 }
 
 static void OPL3_ChannelUpdateRhythm(opl3_chip *chip, uint8_t data)
@@ -752,52 +774,52 @@ static void OPL3_ChannelUpdateRhythm(opl3_chip *chip, uint8_t data)
         OPL3_ChannelSetupAlg(channel6);
         OPL3_ChannelSetupAlg(channel7);
         OPL3_ChannelSetupAlg(channel8);
-        //hh
+        /* hh */
         if (chip->rhy & 0x01)
         {
-            OPL3_EnvelopeKeyOn(channel7->slots[0], egk_drum);
+            OPL3_EnvelopeKeyOn(channel7->slotz[0], egk_drum);
         }
         else
         {
-            OPL3_EnvelopeKeyOff(channel7->slots[0], egk_drum);
+            OPL3_EnvelopeKeyOff(channel7->slotz[0], egk_drum);
         }
-        //tc
+        /* tc */
         if (chip->rhy & 0x02)
         {
-            OPL3_EnvelopeKeyOn(channel8->slots[1], egk_drum);
+            OPL3_EnvelopeKeyOn(channel8->slotz[1], egk_drum);
         }
         else
         {
-            OPL3_EnvelopeKeyOff(channel8->slots[1], egk_drum);
+            OPL3_EnvelopeKeyOff(channel8->slotz[1], egk_drum);
         }
-        //tom
+        /* tom */
         if (chip->rhy & 0x04)
         {
-            OPL3_EnvelopeKeyOn(channel8->slots[0], egk_drum);
+            OPL3_EnvelopeKeyOn(channel8->slotz[0], egk_drum);
         }
         else
         {
-            OPL3_EnvelopeKeyOff(channel8->slots[0], egk_drum);
+            OPL3_EnvelopeKeyOff(channel8->slotz[0], egk_drum);
         }
-        //sd
+        /* sd */
         if (chip->rhy & 0x08)
         {
-            OPL3_EnvelopeKeyOn(channel7->slots[1], egk_drum);
+            OPL3_EnvelopeKeyOn(channel7->slotz[1], egk_drum);
         }
         else
         {
-            OPL3_EnvelopeKeyOff(channel7->slots[1], egk_drum);
+            OPL3_EnvelopeKeyOff(channel7->slotz[1], egk_drum);
         }
-        //bd
+        /* bd */
         if (chip->rhy & 0x10)
         {
-            OPL3_EnvelopeKeyOn(channel6->slots[0], egk_drum);
-            OPL3_EnvelopeKeyOn(channel6->slots[1], egk_drum);
+            OPL3_EnvelopeKeyOn(channel6->slotz[0], egk_drum);
+            OPL3_EnvelopeKeyOn(channel6->slotz[1], egk_drum);
         }
         else
         {
-            OPL3_EnvelopeKeyOff(channel6->slots[0], egk_drum);
-            OPL3_EnvelopeKeyOff(channel6->slots[1], egk_drum);
+            OPL3_EnvelopeKeyOff(channel6->slotz[0], egk_drum);
+            OPL3_EnvelopeKeyOff(channel6->slotz[1], egk_drum);
         }
     }
     else
@@ -807,8 +829,8 @@ static void OPL3_ChannelUpdateRhythm(opl3_chip *chip, uint8_t data)
             chip->channel[chnum].chtype = ch_2op;
             chip->channel[chnum].muted = (chip->muteMask >> chnum) & 0x01;
             OPL3_ChannelSetupAlg(&chip->channel[chnum]);
-            OPL3_EnvelopeKeyOff(chip->channel[chnum].slots[0], egk_drum);
-            OPL3_EnvelopeKeyOff(chip->channel[chnum].slots[1], egk_drum);
+            OPL3_EnvelopeKeyOff(chip->channel[chnum].slotz[0], egk_drum);
+            OPL3_EnvelopeKeyOff(chip->channel[chnum].slotz[1], egk_drum);
         }
     }
 }
@@ -822,14 +844,14 @@ INLINE void OPL3_ChannelWriteA0(opl3_channel *channel, uint8_t data)
     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]);
+    OPL3_EnvelopeUpdateKSL(channel->slotz[0]);
+    OPL3_EnvelopeUpdateKSL(channel->slotz[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]);
+        OPL3_EnvelopeUpdateKSL(channel->pair->slotz[0]);
+        OPL3_EnvelopeUpdateKSL(channel->pair->slotz[1]);
     }
 }
 
@@ -843,15 +865,15 @@ INLINE void OPL3_ChannelWriteB0(opl3_channel *channel, uint8_t data)
     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]);
+    OPL3_EnvelopeUpdateKSL(channel->slotz[0]);
+    OPL3_EnvelopeUpdateKSL(channel->slotz[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]);
+        OPL3_EnvelopeUpdateKSL(channel->pair->slotz[0]);
+        OPL3_EnvelopeUpdateKSL(channel->pair->slotz[1]);
     }
 }
 
@@ -861,19 +883,19 @@ static void OPL3_ChannelSetupAlg(opl3_channel *channel)
     {
         if (channel->ch_num == 7 || channel->ch_num == 8)
         {
-            channel->slots[0]->mod = &zeromod;
-            channel->slots[1]->mod = &zeromod;
+            channel->slotz[0]->mod = &zeromod;
+            channel->slotz[1]->mod = &zeromod;
             return;
         }
         switch (channel->alg & 0x01)
         {
         case 0x00:
-            channel->slots[0]->mod = &channel->slots[0]->fbmod;
-            channel->slots[1]->mod = &channel->slots[0]->out;
+            channel->slotz[0]->mod = &channel->slotz[0]->fbmod;
+            channel->slotz[1]->mod = &channel->slotz[0]->out;
             break;
         case 0x01:
-            channel->slots[0]->mod = &channel->slots[0]->fbmod;
-            channel->slots[1]->mod = &zeromod;
+            channel->slotz[0]->mod = &channel->slotz[0]->fbmod;
+            channel->slotz[1]->mod = &zeromod;
             break;
         }
         return;
@@ -891,43 +913,43 @@ static void OPL3_ChannelSetupAlg(opl3_channel *channel)
         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->pair->slotz[0]->mod = &channel->pair->slotz[0]->fbmod;
+            channel->pair->slotz[1]->mod = &channel->pair->slotz[0]->out;
+            channel->slotz[0]->mod = &channel->pair->slotz[1]->out;
+            channel->slotz[1]->mod = &channel->slotz[0]->out;
+            channel->out[0] = &channel->slotz[1]->out;
             channel->out[1] = &zeromod;
             channel->out[2] = &zeromod;
             channel->out[3] = &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 = &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->pair->slotz[0]->mod = &channel->pair->slotz[0]->fbmod;
+            channel->pair->slotz[1]->mod = &channel->pair->slotz[0]->out;
+            channel->slotz[0]->mod = &zeromod;
+            channel->slotz[1]->mod = &channel->slotz[0]->out;
+            channel->out[0] = &channel->pair->slotz[1]->out;
+            channel->out[1] = &channel->slotz[1]->out;
             channel->out[2] = &zeromod;
             channel->out[3] = &zeromod;
             break;
         case 0x02:
-            channel->pair->slots[0]->mod = &channel->pair->slots[0]->fbmod;
-            channel->pair->slots[1]->mod = &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->pair->slotz[0]->mod = &channel->pair->slotz[0]->fbmod;
+            channel->pair->slotz[1]->mod = &zeromod;
+            channel->slotz[0]->mod = &channel->pair->slotz[1]->out;
+            channel->slotz[1]->mod = &channel->slotz[0]->out;
+            channel->out[0] = &channel->pair->slotz[0]->out;
+            channel->out[1] = &channel->slotz[1]->out;
             channel->out[2] = &zeromod;
             channel->out[3] = &zeromod;
             break;
         case 0x03:
-            channel->pair->slots[0]->mod = &channel->pair->slots[0]->fbmod;
-            channel->pair->slots[1]->mod = &zeromod;
-            channel->slots[0]->mod = &channel->pair->slots[1]->out;
-            channel->slots[1]->mod = &zeromod;
-            channel->out[0] = &channel->pair->slots[0]->out;
-            channel->out[1] = &channel->slots[0]->out;
-            channel->out[2] = &channel->slots[1]->out;
+            channel->pair->slotz[0]->mod = &channel->pair->slotz[0]->fbmod;
+            channel->pair->slotz[1]->mod = &zeromod;
+            channel->slotz[0]->mod = &channel->pair->slotz[1]->out;
+            channel->slotz[1]->mod = &zeromod;
+            channel->out[0] = &channel->pair->slotz[0]->out;
+            channel->out[1] = &channel->slotz[0]->out;
+            channel->out[2] = &channel->slotz[1]->out;
             channel->out[3] = &zeromod;
             break;
         }
@@ -937,18 +959,18 @@ static void OPL3_ChannelSetupAlg(opl3_channel *channel)
         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->slotz[0]->mod = &channel->slotz[0]->fbmod;
+            channel->slotz[1]->mod = &channel->slotz[0]->out;
+            channel->out[0] = &channel->slotz[1]->out;
             channel->out[1] = &zeromod;
             channel->out[2] = &zeromod;
             channel->out[3] = &zeromod;
             break;
         case 0x01:
-            channel->slots[0]->mod = &channel->slots[0]->fbmod;
-            channel->slots[1]->mod = &zeromod;
-            channel->out[0] = &channel->slots[0]->out;
-            channel->out[1] = &channel->slots[1]->out;
+            channel->slotz[0]->mod = &channel->slotz[0]->fbmod;
+            channel->slotz[1]->mod = &zeromod;
+            channel->out[0] = &channel->slotz[0]->out;
+            channel->out[1] = &channel->slotz[1]->out;
             channel->out[2] = &zeromod;
             channel->out[3] = &zeromod;
             break;
@@ -956,10 +978,8 @@ static void OPL3_ChannelSetupAlg(opl3_channel *channel)
     }
 }
 
-INLINE void OPL3_ChannelWriteC0(opl3_channel *channel, uint8_t data)
+static void OPL3_ChannelUpdateAlg(opl3_channel *channel)
 {
-    channel->fb = (data & 0x0e) >> 1;
-    channel->con = data & 0x01;
     channel->alg = channel->con;
     if (channel->chip->newm)
     {
@@ -984,16 +1004,45 @@ INLINE void OPL3_ChannelWriteC0(opl3_channel *channel, uint8_t data)
     {
         OPL3_ChannelSetupAlg(channel);
     }
+}
+
+INLINE 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 ^ 0xffu];
+        channel->rightpan = panpot_lut[data];
     }
 }
+#endif
 
 INLINE void OPL3_ChannelKeyOn(opl3_channel *channel)
 {
@@ -1001,21 +1050,21 @@ INLINE void OPL3_ChannelKeyOn(opl3_channel *channel)
     {
         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);
+            OPL3_EnvelopeKeyOn(channel->slotz[0], egk_norm);
+            OPL3_EnvelopeKeyOn(channel->slotz[1], egk_norm);
+            OPL3_EnvelopeKeyOn(channel->pair->slotz[0], egk_norm);
+            OPL3_EnvelopeKeyOn(channel->pair->slotz[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);
+            OPL3_EnvelopeKeyOn(channel->slotz[0], egk_norm);
+            OPL3_EnvelopeKeyOn(channel->slotz[1], egk_norm);
         }
     }
     else
     {
-        OPL3_EnvelopeKeyOn(channel->slots[0], egk_norm);
-        OPL3_EnvelopeKeyOn(channel->slots[1], egk_norm);
+        OPL3_EnvelopeKeyOn(channel->slotz[0], egk_norm);
+        OPL3_EnvelopeKeyOn(channel->slotz[1], egk_norm);
     }
 }
 
@@ -1025,21 +1074,21 @@ INLINE void OPL3_ChannelKeyOff(opl3_channel *channel)
     {
         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);
+            OPL3_EnvelopeKeyOff(channel->slotz[0], egk_norm);
+            OPL3_EnvelopeKeyOff(channel->slotz[1], egk_norm);
+            OPL3_EnvelopeKeyOff(channel->pair->slotz[0], egk_norm);
+            OPL3_EnvelopeKeyOff(channel->pair->slotz[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);
+            OPL3_EnvelopeKeyOff(channel->slotz[0], egk_norm);
+            OPL3_EnvelopeKeyOff(channel->slotz[1], egk_norm);
         }
     }
     else
     {
-        OPL3_EnvelopeKeyOff(channel->slots[0], egk_norm);
-        OPL3_EnvelopeKeyOff(channel->slots[1], egk_norm);
+        OPL3_EnvelopeKeyOff(channel->slotz[0], egk_norm);
+        OPL3_EnvelopeKeyOff(channel->slotz[1], egk_norm);
     }
 }
 
@@ -1057,12 +1106,15 @@ INLINE void OPL3_ChannelSet4Op(opl3_chip *chip, uint8_t data)
         if ((data >> bit) & 0x01)
         {
             chip->channel[chnum].chtype = ch_4op;
-            chip->channel[chnum + 3].chtype = ch_4op2;
+            chip->channel[chnum + 3u].chtype = ch_4op2;
+            OPL3_ChannelUpdateAlg(&chip->channel[chnum]);
         }
         else
         {
             chip->channel[chnum].chtype = ch_2op;
-            chip->channel[chnum + 3].chtype = ch_2op;
+            chip->channel[chnum + 3u].chtype = ch_2op;
+            OPL3_ChannelUpdateAlg(&chip->channel[chnum]);
+            OPL3_ChannelUpdateAlg(&chip->channel[chnum + 3u]);
         }
     }
 }
@@ -1082,76 +1134,98 @@ INLINE int16_t OPL3_ClipSample(int32_t sample)
 }
 #endif
 
-void NOPL3_Generate(opl3_chip *chip, int32_t *buf)
+INLINE void NOPL3_ProcessSlot(opl3_slot *slot)
 {
+    OPL3_SlotCalcFB(slot);
+    OPL3_EnvelopeCalc(slot);
+    OPL3_PhaseGenerate(slot);
+    OPL3_SlotGenerate(slot);
+}
+
+void NOPL3_Generate4Ch(opl3_chip *chip, int32_t *buf4)
+{
+    opl3_channel *channel;
+    const int16_t **out;
+    int32_t mix[2];
     uint8_t ii;
-    uint8_t jj;
     int16_t accm;
     uint8_t shift = 0;
 
-    //buf[1] = OPL3_ClipSample(chip->mixbuff[1]);
-    buf[1] = chip->mixbuff[1];
+    //buf4[1] = OPL3_ClipSample(chip->mixbuff[1]);
+    //buf4[3] = OPL3_ClipSample(chip->mixbuff[3]);
+    buf4[1] = chip->mixbuff[1];
+    buf4[3] = chip->mixbuff[3];
 
+#if OPL_QUIRK_CHANNELSAMPLEDELAY
     for (ii = 0; ii < 15; ii++)
+#else
+    for (ii = 0; ii < 36; ii++)
+#endif
     {
-        OPL3_SlotCalcFB(&chip->slot[ii]);
-        OPL3_EnvelopeCalc(&chip->slot[ii]);
-        OPL3_PhaseGenerate(&chip->slot[ii]);
-        OPL3_SlotGenerate(&chip->slot[ii]);
+        NOPL3_ProcessSlot(&chip->slot[ii]);
     }
 
-    chip->mixbuff[0] = 0;
+    mix[0] = mix[1] = 0;
     for (ii = 0; ii < 18; ii++)
     {
-        if (chip->channel[ii].muted)
+        channel = &chip->channel[ii];
+        if (channel->muted)
             continue;
-        accm = 0;
-        for (jj = 0; jj < 4; jj++)
-        {
-            accm += *chip->channel[ii].out[jj];
-        }
-        chip->mixbuff[0] += (int16_t)(accm & chip->channel[ii].cha);
+        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_SlotCalcFB(&chip->slot[ii]);
-        OPL3_EnvelopeCalc(&chip->slot[ii]);
-        OPL3_PhaseGenerate(&chip->slot[ii]);
-        OPL3_SlotGenerate(&chip->slot[ii]);
+        NOPL3_ProcessSlot(&chip->slot[ii]);
     }
+#endif
 
-    //buf[0] = OPL3_ClipSample(chip->mixbuff[0]);
-    buf[0] = chip->mixbuff[0];
+    //buf4[0] = OPL3_ClipSample(chip->mixbuff[0]);
+    //buf4[2] = OPL3_ClipSample(chip->mixbuff[2]);
+    buf4[0] = chip->mixbuff[0];
+    buf4[2] = chip->mixbuff[2];
 
+#if OPL_QUIRK_CHANNELSAMPLEDELAY
     for (ii = 18; ii < 33; ii++)
     {
-        OPL3_SlotCalcFB(&chip->slot[ii]);
-        OPL3_EnvelopeCalc(&chip->slot[ii]);
-        OPL3_PhaseGenerate(&chip->slot[ii]);
-        OPL3_SlotGenerate(&chip->slot[ii]);
+        NOPL3_ProcessSlot(&chip->slot[ii]);
     }
+#endif
 
-    chip->mixbuff[1] = 0;
+    mix[0] = mix[1] = 0;
     for (ii = 0; ii < 18; ii++)
     {
-        if (chip->channel[ii].muted)
+        channel = &chip->channel[ii];
+        if (channel->muted)
             continue;
-        accm = 0;
-        for (jj = 0; jj < 4; jj++)
-        {
-            accm += *chip->channel[ii].out[jj];
-        }
-        chip->mixbuff[1] += (int16_t)(accm & chip->channel[ii].chb);
+        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_SlotCalcFB(&chip->slot[ii]);
-        OPL3_EnvelopeCalc(&chip->slot[ii]);
-        OPL3_PhaseGenerate(&chip->slot[ii]);
-        OPL3_SlotGenerate(&chip->slot[ii]);
+        NOPL3_ProcessSlot(&chip->slot[ii]);
     }
+#endif
 
     if ((chip->timer & 0x3f) == 0x3f)
     {
@@ -1192,7 +1266,7 @@ void NOPL3_Generate(opl3_chip *chip, int32_t *buf)
 
     if (chip->eg_timerrem || chip->eg_state)
     {
-        if (chip->eg_timer == 0xfffffffff)
+        if (chip->eg_timer == (uint64_t)0xfffffffff)
         {
             chip->eg_timer = 0;
             chip->eg_timerrem = 1;
@@ -1222,13 +1296,23 @@ void NOPL3_Generate(opl3_chip *chip, int32_t *buf)
 #endif
 }
 
-void NOPL3_GenerateResampled(opl3_chip *chip, int32_t *buf)
+void NOPL3_Generate(opl3_chip *chip, int32_t *buf)
+{
+    int32_t samples[4];
+    NOPL3_Generate4Ch(chip, samples);
+    buf[0] = samples[0];
+    buf[1] = samples[1];
+}
+
+void NOPL3_Generate4ChResampled(opl3_chip *chip, int32_t *buf4)
 {
     if (chip->rateratio == (1 << RSM_FRAC))
     {
-        NOPL3_Generate(chip, chip->samples);
-        buf[0] = (int32_t)chip->samples[0];
-        buf[1] = (int32_t)chip->samples[1];
+        NOPL3_Generate4Ch(chip, chip->samples);
+        buf4[0] = (int32_t)chip->samples[0];
+        buf4[1] = (int32_t)chip->samples[1];
+        buf4[2] = (int32_t)chip->samples[2];
+        buf4[3] = (int32_t)chip->samples[3];
         return;
     }
 
@@ -1237,56 +1321,80 @@ void NOPL3_GenerateResampled(opl3_chip *chip, int32_t *buf)
     {
         chip->oldsamples[0] = chip->samples[0];
         chip->oldsamples[1] = chip->samples[1];
-        NOPL3_Generate(chip, chip->samples);
+        chip->oldsamples[2] = chip->samples[2];
+        chip->oldsamples[3] = chip->samples[3];
+        NOPL3_Generate4Ch(chip, chip->samples);
         chip->samplecnt -= chip->rateratio;
     }
-    buf[0] = (int32_t)((chip->oldsamples[0] * (chip->rateratio - chip->samplecnt)
+    buf4[0] = (int32_t)((chip->oldsamples[0] * (chip->rateratio - chip->samplecnt)
                      + chip->samples[0] * chip->samplecnt) / chip->rateratio);
-    buf[1] = (int32_t)((chip->oldsamples[1] * (chip->rateratio - chip->samplecnt)
+    buf4[1] = (int32_t)((chip->oldsamples[1] * (chip->rateratio - chip->samplecnt)
                      + chip->samples[1] * chip->samplecnt) / chip->rateratio);
+    buf4[2] = (int32_t)((chip->oldsamples[2] * (chip->rateratio - chip->samplecnt)
+                     + chip->samples[2] * chip->samplecnt) / chip->rateratio);
+    buf4[3] = (int32_t)((chip->oldsamples[3] * (chip->rateratio - chip->samplecnt)
+                     + chip->samples[3] * chip->samplecnt) / chip->rateratio);
+}
+
+void NOPL3_GenerateResampled(opl3_chip *chip, int32_t *buf)
+{
+    int32_t samples[4];
+    NOPL3_Generate4ChResampled(chip, samples);
+    buf[0] = samples[0];
+    buf[1] = samples[1];
 }
 
 void NOPL3_Reset(opl3_chip *chip, uint32_t clock, 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));
     memset(chip->channel, 0x00, sizeof(opl3_channel) * 18);
     memset(chip->slot, 0x00, sizeof(opl3_slot) * 36);
     for (slotnum = 0; slotnum < 36; slotnum++)
     {
-        chip->slot[slotnum].chip = chip;
-        chip->slot[slotnum].mod = &zeromod;
-        chip->slot[slotnum].eg_rout = 0x1ff;
-        chip->slot[slotnum].eg_out = 0x1ff;
-        chip->slot[slotnum].eg_gen = envelope_gen_num_release;
-        chip->slot[slotnum].trem = (const uint8_t*)&zeromod;
-        chip->slot[slotnum].slot_num = slotnum;
+        slot = &chip->slot[slotnum];
+        slot->chip = chip;
+        slot->mod = &zeromod;
+        slot->eg_rout = 0x1ff;
+        slot->eg_out = 0x1ff;
+        slot->eg_gen = envelope_gen_num_release;
+        slot->trem = (const uint8_t*)&zeromod;
+        slot->slot_num = slotnum;
     }
     for (channum = 0; channum < 18; channum++)
     {
-        chip->channel[channum].slots[0] = &chip->slot[ch_slot[channum]];
-        chip->channel[channum].slots[1] = &chip->slot[ch_slot[channum] + 3];
-        chip->slot[ch_slot[channum]].channel = &chip->channel[channum];
-        chip->slot[ch_slot[channum] + 3].channel = &chip->channel[channum];
+        channel = &chip->channel[channum];
+        local_ch_slot = ch_slot[channum];
+        channel->slotz[0] = &chip->slot[local_ch_slot];
+        channel->slotz[1] = &chip->slot[local_ch_slot + 3u];
+        chip->slot[local_ch_slot].channel = &chip->channel[channum];
+        chip->slot[local_ch_slot + 3u].channel = &chip->channel[channum];
         if ((channum % 9) < 3)
         {
-            chip->channel[channum].pair = &chip->channel[channum + 3];
+            channel->pair = &chip->channel[channum + 3u];
         }
         else if ((channum % 9) < 6)
         {
-            chip->channel[channum].pair = &chip->channel[channum - 3];
+            channel->pair = &chip->channel[channum - 3u];
         }
-        chip->channel[channum].chip = chip;
-        chip->channel[channum].out[0] = &zeromod;
-        chip->channel[channum].out[1] = &zeromod;
-        chip->channel[channum].out[2] = &zeromod;
-        chip->channel[channum].out[3] = &zeromod;
-        chip->channel[channum].chtype = ch_2op;
-        chip->channel[channum].cha = 0xffff;
-        chip->channel[channum].chb = 0xffff;
-        chip->channel[channum].ch_num = channum;
+        channel->chip = chip;
+        channel->out[0] = &zeromod;
+        channel->out[1] = &zeromod;
+        channel->out[2] = &zeromod;
+        channel->out[3] = &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(&chip->channel[channum]);
     }
     chip->noise = 1;
@@ -1298,6 +1406,18 @@ void NOPL3_Reset(opl3_chip *chip, uint32_t clock, uint32_t samplerate)
     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
+
     chip->address = 0;
     chip->timer = 0;
     chip->eg_timer = 0;
@@ -1337,6 +1457,9 @@ void NOPL3_WriteReg(opl3_chip *chip, uint16_t reg, uint8_t v)
                 break;
             case 0x05:
                 chip->newm = v & 0x01;
+#if OPL_ENABLE_STEREOEXT
+                chip->stereoext = (v >> 1) & 0x01;
+#endif
                 break;
             }
         }
@@ -1352,43 +1475,43 @@ void NOPL3_WriteReg(opl3_chip *chip, uint16_t reg, uint8_t v)
         break;
     case 0x20:
     case 0x30:
-        if (ad_slot[regm & 0x1f] >= 0)
+        if (ad_slot[regm & 0x1fu] >= 0)
         {
-            OPL3_SlotWrite20(&chip->slot[18 * high + ad_slot[regm & 0x1f]], v);
+            OPL3_SlotWrite20(&chip->slot[18u * high + ad_slot[regm & 0x1fu]], v);
         }
         break;
     case 0x40:
     case 0x50:
-        if (ad_slot[regm & 0x1f] >= 0)
+        if (ad_slot[regm & 0x1fu] >= 0)
         {
-            OPL3_SlotWrite40(&chip->slot[18 * high + ad_slot[regm & 0x1f]], v);
+            OPL3_SlotWrite40(&chip->slot[18u * high + ad_slot[regm & 0x1fu]], v);
         }
         break;
     case 0x60:
     case 0x70:
-        if (ad_slot[regm & 0x1f] >= 0)
+        if (ad_slot[regm & 0x1fu] >= 0)
         {
-            OPL3_SlotWrite60(&chip->slot[18 * high + ad_slot[regm & 0x1f]], v);
+            OPL3_SlotWrite60(&chip->slot[18u * high + ad_slot[regm & 0x1fu]], v);
         }
         break;
     case 0x80:
     case 0x90:
-        if (ad_slot[regm & 0x1f] >= 0)
+        if (ad_slot[regm & 0x1fu] >= 0)
         {
-            OPL3_SlotWrite80(&chip->slot[18 * high + ad_slot[regm & 0x1f]], v);
+            OPL3_SlotWrite80(&chip->slot[18u * high + ad_slot[regm & 0x1fu]], v);
         }
         break;
     case 0xe0:
     case 0xf0:
-        if (ad_slot[regm & 0x1f] >= 0)
+        if (ad_slot[regm & 0x1fu] >= 0)
         {
-            OPL3_SlotWriteE0(&chip->slot[18 * high + ad_slot[regm & 0x1f]], v);
+            OPL3_SlotWriteE0(&chip->slot[18u * high + ad_slot[regm & 0x1fu]], v);
         }
         break;
     case 0xa0:
         if ((regm & 0x0f) < 9)
         {
-            OPL3_ChannelWriteA0(&chip->channel[9 * high + (regm & 0x0f)], v);
+            OPL3_ChannelWriteA0(&chip->channel[9u * high + (regm & 0x0fu)], v);
         }
         break;
     case 0xb0:
@@ -1397,29 +1520,37 @@ void NOPL3_WriteReg(opl3_chip *chip, uint16_t reg, uint8_t v)
             chip->tremoloshift = (((v >> 7) ^ 1) << 1) + 2;
             chip->vibshift = ((v >> 6) & 0x01) ^ 1;
             if ((v & 0x20) && (v & 0x1F))
-                chip->isDisabled = 0x00;
+                chip->isDisabled = 0;
             OPL3_ChannelUpdateRhythm(chip, v);
         }
         else if ((regm & 0x0f) < 9)
         {
-            OPL3_ChannelWriteB0(&chip->channel[9 * high + (regm & 0x0f)], v);
+            OPL3_ChannelWriteB0(&chip->channel[9u * high + (regm & 0x0fu)], v);
             if (v & 0x20)
             {
-                chip->isDisabled = 0x00;
-                OPL3_ChannelKeyOn(&chip->channel[9 * high + (regm & 0x0f)]);
+                chip->isDisabled = 0;
+                OPL3_ChannelKeyOn(&chip->channel[9u * high + (regm & 0x0fu)]);
             }
             else
             {
-                OPL3_ChannelKeyOff(&chip->channel[9 * high + (regm & 0x0f)]);
+                OPL3_ChannelKeyOff(&chip->channel[9u * high + (regm & 0x0fu)]);
             }
         }
         break;
     case 0xc0:
         if ((regm & 0x0f) < 9)
         {
-            OPL3_ChannelWriteC0(&chip->channel[9 * high + (regm & 0x0f)], v);
+            OPL3_ChannelWriteC0(&chip->channel[9u * high + (regm & 0x0fu)], v);
         }
         break;
+#if OPL_ENABLE_STEREOEXT
+    case 0xd0:
+        if ((regm & 0x0f) < 9)
+        {
+            OPL3_ChannelWriteD0(&chip->channel[9u * high + (regm & 0x0fu)], v);
+        }
+        break;
+#endif
     }
 }
 
@@ -1427,18 +1558,22 @@ void NOPL3_WriteRegBuffered(opl3_chip *chip, uint16_t reg, uint8_t v)
 {
 #ifdef NOPL_ENABLE_WRITEBUF
     uint64_t time1, time2;
+    opl3_writebuf *writebuf;
+    uint32_t writebuf_last;
 
-    if (chip->writebuf[chip->writebuf_last].reg & 0x200)
+    writebuf_last = chip->writebuf_last;
+    writebuf = &chip->writebuf[writebuf_last];
+
+    if (writebuf->reg & 0x200)
     {
-        NOPL3_WriteReg(chip, chip->writebuf[chip->writebuf_last].reg & 0x1ff,
-                       chip->writebuf[chip->writebuf_last].data);
+        NOPL3_WriteReg(chip, writebuf->reg & 0x1ff, writebuf->data);
 
-        chip->writebuf_cur = (chip->writebuf_last + 1) % OPL_WRITEBUF_SIZE;
-        chip->writebuf_samplecnt = chip->writebuf[chip->writebuf_last].time;
+        chip->writebuf_cur = (writebuf_last + 1) % OPL_WRITEBUF_SIZE;
+        chip->writebuf_samplecnt = writebuf->time;
     }
 
-    chip->writebuf[chip->writebuf_last].reg = reg | 0x200;
-    chip->writebuf[chip->writebuf_last].data = v;
+    writebuf->reg = reg | 0x200;
+    writebuf->data = v;
     time1 = chip->writebuf_lasttime + OPL_WRITEBUF_DELAY;
     time2 = chip->writebuf_samplecnt;
 
@@ -1447,14 +1582,31 @@ void NOPL3_WriteRegBuffered(opl3_chip *chip, uint16_t reg, uint8_t v)
         time1 = time2;
     }
 
-    chip->writebuf[chip->writebuf_last].time = time1;
+    writebuf->time = time1;
     chip->writebuf_lasttime = time1;
-    chip->writebuf_last = (chip->writebuf_last + 1) % OPL_WRITEBUF_SIZE;
+    chip->writebuf_last = (writebuf_last + 1) % OPL_WRITEBUF_SIZE;
 #else
     NOPL3_WriteReg(chip, reg, v);
 #endif
 }
 
+void NOPL3_Generate4ChStream(opl3_chip *chip, int32_t *sndptr1, int32_t *sndptr2, uint32_t numsamples)
+{
+    uint32_t i;
+    int32_t samples[4];
+
+    for(i = 0; i < numsamples; i++)
+    {
+        NOPL3_Generate4ChResampled(chip, samples);
+        sndptr1[0] = samples[0];
+        sndptr1[1] = samples[1];
+        sndptr2[0] = samples[2];
+        sndptr2[1] = samples[3];
+        sndptr1 += 2;
+        sndptr2 += 2;
+    }
+}
+
 void NOPL3_GenerateStream(opl3_chip *chip, int32_t *sndptr, uint32_t numsamples)
 {
     uint32_t i;
@@ -1540,7 +1692,7 @@ void nukedopl3_reset_chip(void *chip)
 	NOPL3_Reset(opl3, opl3->clock, opl3->smplRate);
 	NOPL3_RefreshMuteMasks(opl3);
 	
-	opl3->isDisabled = 0x01;	// OPL4 speed hack
+	opl3->isDisabled = 1;	// OPL4 speed hack
 }
 
 void nukedopl3_update(void *chip, UINT32 samples, DEV_SMPL **out)
diff --git a/emu/cores/nukedopl3_int.h b/emu/cores/nukedopl3_int.h
index 241d5661..adc62eca 100644
--- a/emu/cores/nukedopl3_int.h
+++ b/emu/cores/nukedopl3_int.h
@@ -1,3 +1,5 @@
+// license:LGPL-2.1+
+// copyright-holders:Nuke.YKT
 /* Nuked OPL3
  * Copyright (C) 2013-2020 Nuke.YKT
  *
@@ -31,13 +33,21 @@
  */
 
 // Nuked OPL3 internal structures/functions
-#ifndef __NUKEDOPL3_INT_H__
-#define __NUKEDOPL3_INT_H__
+#ifndef NUKEDOPL3_INT_H
+#define NUKEDOPL3_INT_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
 
 #include "../../stdtype.h"
 #include "../snddef.h"
 #include "emutypes.h"
 
+#ifndef OPL_ENABLE_STEREOEXT
+#define OPL_ENABLE_STEREOEXT 0
+#endif
+
 //#define NOPL_ENABLE_WRITEBUF
 
 #define OPL_WRITEBUF_SIZE   1024
@@ -54,8 +64,8 @@ struct _opl3_slot {
     int16_t fbmod;
     const int16_t *mod;
     int16_t prout;
-    int16_t eg_rout;
-    int16_t eg_out;
+    uint16_t eg_rout;
+    uint16_t eg_out;
     uint8_t eg_inc;
     uint8_t eg_gen;
     uint8_t eg_rate;
@@ -80,10 +90,16 @@ struct _opl3_slot {
 };
 
 struct _opl3_channel {
-    opl3_slot *slots[2];
+    opl3_slot *slotz[2];/*Don't use "slots" keyword to avoid conflict with Qt applications*/
     opl3_channel *pair;
     opl3_chip *chip;
     const int16_t *out[4];
+
+#if OPL_ENABLE_STEREOEXT
+    int32_t leftpan;
+    int32_t rightpan;
+#endif
+
     uint8_t chtype;
     uint8_t muted;
     uint16_t f_num;
@@ -93,6 +109,7 @@ struct _opl3_channel {
     uint8_t alg;
     uint8_t ksv;
     uint16_t cha, chb;
+    uint16_t chc, chd;
     uint8_t ch_num;
 };
 
@@ -126,18 +143,23 @@ struct _opl3_chip {
     uint8_t tremoloshift;
     uint32_t noise;
     //int16_t zeromod;
-    int32_t mixbuff[2];
+    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;
-    //OPL3L
+
+#if OPL_ENABLE_STEREOEXT
+    uint8_t stereoext;
+#endif
+
+    /* OPL3L */
     int32_t rateratio;
     int32_t samplecnt;
-    int32_t oldsamples[2];
-    int32_t samples[2];
+    int32_t oldsamples[4];
+    int32_t samples[4];
 
     uint32_t muteMask;
     int32_t masterVolL;   // master volume left (.12 fixed point)
@@ -159,4 +181,12 @@ void NOPL3_WriteReg(opl3_chip *chip, uint16_t reg, uint8_t v);
 void NOPL3_WriteRegBuffered(opl3_chip *chip, uint16_t reg, uint8_t v);
 void NOPL3_GenerateStream(opl3_chip *chip, int32_t *sndptr, uint32_t numsamples);
 
-#endif	// __NUKEDOPL3_INT_H__
+void NOPL3_Generate4Ch(opl3_chip *chip, int32_t *buf4);
+void NOPL3_Generate4ChResampled(opl3_chip *chip, int32_t *buf4);
+void NOPL3_Generate4ChStream(opl3_chip *chip, int32_t *sndptr1, int32_t *sndptr2, uint32_t numsamples);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif	// NUKEDOPL3_INT_H
diff --git a/emu/cores/nukedopll.c b/emu/cores/nukedopll.c
index 2d72f16e..493e08da 100644
--- a/emu/cores/nukedopll.c
+++ b/emu/cores/nukedopll.c
@@ -1,5 +1,7 @@
+// license:GPL-2.0+
+// copyright-holders:Nuke.YKT
 /*
- * Copyright (C) 2019 Nuke.YKT
+ * Copyright (C) 2019-2023 Nuke.YKT
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License
@@ -17,7 +19,7 @@
  *      siliconpr0n.org(digshadow, John McMaster):
  *          VRC VII decap and die shot.
  *
- *  version: 1.0.1
+ *  version: 1.0.2
  */
 
 #include <string.h>
@@ -174,7 +176,7 @@ static const opll_patch_t patch_ds1001[opll_patch_max] = {
     { 0x00, 0x00, 0x00, 0x00,{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x01, 0x00 },{ 0x00, 0x00 },{ 0x0c, 0x00 },{ 0x08, 0x00 },{ 0x0a, 0x00 },{ 0x07, 0x00 } },
     { 0x00, 0x00, 0x00, 0x00,{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x05, 0x00 },{ 0x00, 0x00 },{ 0x0f, 0x00 },{ 0x08, 0x00 },{ 0x05, 0x00 },{ 0x09, 0x00 } },
     { 0x00, 0x00, 0x00, 0x00,{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x00, 0x01 },{ 0x00, 0x00 },{ 0x00, 0x0f },{ 0x00, 0x08 },{ 0x00, 0x06 },{ 0x00, 0x0d } },
-    { 0x00, 0x00, 0x00, 0x00,{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x00, 0x01 },{ 0x00, 0x00 },{ 0x00, 0x0d },{ 0x00, 0x08 },{ 0x00, 0x06 },{ 0x00, 0x08 } },
+    { 0x00, 0x00, 0x00, 0x00,{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x00, 0x01 },{ 0x00, 0x00 },{ 0x00, 0x0d },{ 0x00, 0x08 },{ 0x00, 0x04 },{ 0x00, 0x08 } },
     { 0x00, 0x00, 0x00, 0x00,{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x00, 0x00 },{ 0x00, 0x01 },{ 0x00, 0x00 },{ 0x00, 0x0a },{ 0x00, 0x0a },{ 0x00, 0x05 },{ 0x00, 0x05 } }
 };
 
@@ -281,9 +283,8 @@ static void OPLL_DoIO(opll_t *chip) {
 }
 
 static void OPLL_DoModeWrite(opll_t *chip) {
-    uint8_t slot;
     if ((chip->write_mode_address & 0x10) && chip->write_d_en) {
-        slot = chip->write_mode_address & 0x01;
+        uint8_t slot = chip->write_mode_address & 0x01;
         switch (chip->write_mode_address & 0x0f) {
         case 0x00:
         case 0x01:
@@ -376,8 +377,6 @@ void NOPLL_Reset(opll_t *chip, uint32_t chip_type, uint32_t rate, uint32_t clock
 }
 
 static void OPLL_DoRegWrite(opll_t *chip) {
-    uint32_t channel;
-
     /* Address */
     if (chip->write_a_en) {
         if ((chip->write_data & 0xc0) == 0x00) {
@@ -396,7 +395,7 @@ static void OPLL_DoRegWrite(opll_t *chip) {
     /* Update registers */
     if (chip->write_fm_data && !chip->write_a_en) {
         if ((chip->address & 0x0f) == chip->cycles && chip->cycles < 16) {
-            channel = chip->cycles % 9;
+            uint32_t channel = chip->cycles % 9;
             switch (chip->address & 0xf0) {
             case 0x10:
                 if (chip->chip_type == opll_type_ym2420)
@@ -515,8 +514,8 @@ static void OPLL_PreparePatch2(opll_t *chip) {
 static void OPLL_PhaseGenerate(opll_t *chip) {
     uint32_t ismod;
     uint32_t phase;
-    uint8_t rm_bit;
     uint16_t pg_out;
+    uint8_t rm_bit;
 
     chip->pg_phase[(chip->cycles + 17) % 18] = chip->pg_phase_next + chip->pg_inc;
 
@@ -878,11 +877,9 @@ static void OPLL_EnvelopeGenerate(opll_t *chip) {
 }
 
 static void OPLL_Channel(opll_t *chip) {
-    int16_t sign;
     int16_t ch_out = chip->ch_out;
     uint8_t ismod = (chip->cycles / 3) & 1;
     uint8_t mute_m = ismod || ((chip->rm_enable&0x40) && (chip->cycles+15)%18 >= 12);
-    uint8_t mute_r = 1;
     if (chip->chip_type == opll_type_ds1001) {
         chip->output_m = ch_out;
         if (chip->output_m >= 0) {
@@ -894,6 +891,7 @@ static void OPLL_Channel(opll_t *chip) {
         chip->output_r = 0;
         return;
     } else {
+        uint8_t mute_r = 1;
         /* TODO: This might be incorrect */
         if ((chip->rm_enable & 0x40)) {
             switch (chip->cycles) {
@@ -921,7 +919,7 @@ static void OPLL_Channel(opll_t *chip) {
             else
                 chip->output_r = ch_out;
         } else {
-            sign = ch_out >> 8;
+            int16_t sign = ch_out >> 8;
             if (ch_out >= 0) {
                 ch_out++;
                 sign++;
@@ -1049,6 +1047,9 @@ static void OPLL_Operator(opll_t *chip) {
         }
     }
 
+    if (!(chip->rm_enable & 0x80))
+        routput = 0;
+
     chip->ch_out = ismod1 ? routput : (output>>3);
 }
 
@@ -1062,13 +1063,12 @@ static void OPLL_DoRhythm(opll_t *chip) {
 }
 
 static void OPLL_DoLFO(opll_t *chip) {
-    uint8_t vib_step;
     uint8_t am_inc = 0;
     uint8_t am_bit;
     
     /* Update counter */
     if (chip->cycles == 17) {
-        vib_step = ((chip->lfo_counter & 0x3ff) + 1) >> 10;
+        uint8_t vib_step = ((chip->lfo_counter & 0x3ff) + 1) >> 10;
         chip->lfo_am_step = ((chip->lfo_counter & 0x3f) + 1) >> 6;
         vib_step |= (chip->testmode >> 3) & 0x01;
         chip->lfo_vib_counter += vib_step;
diff --git a/emu/cores/nukedopll_int.h b/emu/cores/nukedopll_int.h
index a2008c19..7273b906 100644
--- a/emu/cores/nukedopll_int.h
+++ b/emu/cores/nukedopll_int.h
@@ -1,3 +1,5 @@
+// license:GPL-2.0+
+// copyright-holders:Nuke.YKT
 /*
  * Copyright (C) 2019 Nuke.YKT
  *
@@ -21,8 +23,8 @@
  */
 
 // Nuked OPLL internal structures/functions
-#ifndef __NUKEDOPLL_INT_H__
-#define __NUKEDOPLL_INT_H__
+#ifndef NUKEDOPLL_INT_H
+#define NUKEDOPLL_INT_H
 
 #include "../../stdtype.h"
 #include "../snddef.h"
@@ -227,4 +229,4 @@ void NOPLL_Write(opll_t *chip, uint32_t port, uint8_t data);
 
 void NOPLL_WriteBuffered(opll_t*chip, uint32_t port, uint8_t data);
 
-#endif	// __NUKEDOPLL_INT_H__
+#endif	// NUKEDOPLL_INT_H
diff --git a/emu/cores/nukedopm.c b/emu/cores/nukedopm.c
index ae7d9e52..84ec2bd6 100644
--- a/emu/cores/nukedopm.c
+++ b/emu/cores/nukedopm.c
@@ -1,5 +1,7 @@
+// license:LGPL-2.1+
+// copyright-holders:Nuke.YKT
 /* Nuked OPM
- * Copyright (C) 2020 Nuke.YKT
+ * Copyright (C) 2022 Nuke.YKT
  *
  * This file is part of Nuked OPM.
  *
@@ -21,7 +23,7 @@
  *      siliconpr0n.org(digshadow, John McMaster):
  *          YM2151 and other FM chip decaps and die shots.
  *
- * version: 0.9.1 beta
+ * version: 0.9.3 beta
  */
 #include <string.h>
 #include <stdlib.h>
@@ -692,7 +694,7 @@ static void OPM_EnvelopePhase4(opm_t *chip)
     chip->eg_instantattack = chip->eg_ratemax[1] && (kon || !chip->eg_ratemax[1]);
 
     eg_off = (chip->eg_level[slot] & 0x3f0) == 0x3f0;
-    slreach = (chip->eg_level[slot] >> 5) == chip->eg_sl[1];
+    slreach = (chip->eg_level[slot] >> 4) == (chip->eg_sl[1] << 1);
     eg_zero = chip->eg_level[slot] == 0;
 
     chip->eg_mute = eg_off && chip->eg_state[slot] != eg_num_attack && !kon;
@@ -1532,7 +1534,7 @@ static void OPM_DoLFO1(opm_t *chip)
 
     lfo_pm_sign = chip->lfo_wave == 2 ? chip->lfo_trig_sign : chip->lfo_saw_sign;
 
-    w[5] = ampm_sel ? chip->lfo_saw_sign : (chip->lfo_wave != 2 || chip->lfo_trig_sign);
+    w[5] = ampm_sel ? chip->lfo_saw_sign : (chip->lfo_wave != 2 || !chip->lfo_trig_sign);
 
     w[1] = !chip->lfo_clock || chip->lfo_wave == 3 || (chip->cycles & 15) != 15;
     w[2] = chip->lfo_wave == 2 && !w[1];
diff --git a/emu/cores/nukedopm_int.h b/emu/cores/nukedopm_int.h
index 1188c5d8..f4986337 100644
--- a/emu/cores/nukedopm_int.h
+++ b/emu/cores/nukedopm_int.h
@@ -1,3 +1,5 @@
+// license:LGPL-2.1+
+// copyright-holders:Nuke.YKT
 /* Nuked OPM
  * Copyright (C) 2020 Nuke.YKT
  *
@@ -21,10 +23,10 @@
  *      siliconpr0n.org(digshadow, John McMaster):
  *          YM2151 and other FM chip decaps and die shots.
  *
- * version: 0.9 beta
+ * version: 0.9.2 beta
  */
-#ifndef __NUKEDOPM_INT_H__
-#define __NUKEDOPM_INT_H__
+#ifndef NUKEDOPM_INT_H
+#define NUKEDOPM_INT_H
 
 #include "../../stdtype.h"
 #include "../snddef.h"
@@ -115,7 +117,7 @@ typedef struct {
     uint8_t eg_mute;
     uint16_t eg_outtemp[2];
     uint16_t eg_out[2];
-    uint8_t eg_am;
+    uint16_t eg_am;
     uint8_t eg_ams[2];
     uint8_t eg_timercarry;
     uint32_t eg_timer;
@@ -294,4 +296,4 @@ void NOPM_Reset(opm_t* chip, uint32_t rate, uint32_t clock);
 } // extern "C"
 #endif
 
-#endif	// __NUKEDOPM_INT_H__
+#endif	// NUKEDOPM_INT_H
diff --git a/emu/cores/ym3438.c b/emu/cores/ym3438.c
index ce5b9169..3e34f32e 100644
--- a/emu/cores/ym3438.c
+++ b/emu/cores/ym3438.c
@@ -1,20 +1,23 @@
+// license:LGPL-2.1+
+// copyright-holders:Nuke.YKT
 /*
- * Copyright (C) 2017-2018 Alexey Khokholov (Nuke.YKT)
+ * Copyright (C) 2017-2022 Alexey Khokholov (Nuke.YKT)
  *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
+ * This file is part of Nuked OPN2.
  *
- * This program 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 General Public License for more details.
+ * This library 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.
  *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * This library 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 this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  *
  *  Nuked OPN2(Yamaha YM3438) emulator.
  *  Thanks:
@@ -23,7 +26,7 @@
  *      OPLx decapsulated(Matthew Gambrell, Olli Niemitalo):
  *          OPL2 ROMs.
  *
- * version: 1.0.10
+ * version: 1.0.12
  */
 
 #include <stdlib.h>
@@ -38,6 +41,8 @@
 #define FILTER_CUTOFF 0.512331301282628 // 5894Hz  single pole IIR low pass
 #define FILTER_CUTOFF_I (1-FILTER_CUTOFF)
 
+#define SIGN_EXTEND(bit_index, value) (((value) & ((1u << (bit_index)) - 1u)) - ((value) & (1u << (bit_index))))
+
 enum {
     eg_num_attack = 0,
     eg_num_decay = 1,
@@ -227,7 +232,7 @@ static const Bit32u fm_algorithm[4][6][8] = {
 
 //static Bit32u chip_type = ym3438_mode_readmode;	// moved into ym3438_t struct
 
-void NOPN2_DoIO(ym3438_t *chip)
+static void NOPN2_DoIO(ym3438_t *chip)
 {
     /* Write signal check */
     chip->write_a_en = (chip->write_a & 0x03) == 0x01;
@@ -241,7 +246,7 @@ void NOPN2_DoIO(ym3438_t *chip)
     chip->write_busy_cnt &= 0x1f;
 }
 
-void NOPN2_DoRegWrite(ym3438_t *chip)
+static void NOPN2_DoRegWrite(ym3438_t *chip)
 {
     Bit32u i;
     Bit32u slot = chip->cycles % 12;
@@ -460,7 +465,7 @@ void NOPN2_DoRegWrite(ym3438_t *chip)
     }
 }
 
-void NOPN2_PhaseCalcIncrement(ym3438_t *chip)
+static void NOPN2_PhaseCalcIncrement(ym3438_t *chip)
 {
     Bit32u chan = chip->channel;
     Bit32u slot = chip->cycles;
@@ -529,7 +534,7 @@ void NOPN2_PhaseCalcIncrement(ym3438_t *chip)
     chip->pg_inc[slot] &= 0xfffff;
 }
 
-void NOPN2_PhaseGenerate(ym3438_t *chip)
+static void NOPN2_PhaseGenerate(ym3438_t *chip)
 {
     Bit32u slot;
     /* Mask increment */
@@ -548,14 +553,13 @@ void NOPN2_PhaseGenerate(ym3438_t *chip)
     chip->pg_phase[slot] &= 0xfffff;
 }
 
-void NOPN2_EnvelopeSSGEG(ym3438_t *chip)
+static void NOPN2_EnvelopeSSGEG(ym3438_t *chip)
 {
     Bit32u slot = chip->cycles;
     Bit8u direction = 0;
     chip->eg_ssg_pgrst_latch[slot] = 0;
     chip->eg_ssg_repeat_latch[slot] = 0;
     chip->eg_ssg_hold_up_latch[slot] = 0;
-    chip->eg_ssg_inv[slot] = 0;
     if (chip->ssg_eg[slot] & 0x08)
     {
         direction = chip->eg_ssg_dir[slot];
@@ -588,14 +592,14 @@ void NOPN2_EnvelopeSSGEG(ym3438_t *chip)
             chip->eg_ssg_hold_up_latch[slot] = 1;
         }
         direction &= chip->eg_kon[slot];
-        chip->eg_ssg_inv[slot] = (chip->eg_ssg_dir[slot] ^ ((chip->ssg_eg[slot] >> 2) & 0x01))
-                               & chip->eg_kon[slot];
     }
     chip->eg_ssg_dir[slot] = direction;
     chip->eg_ssg_enable[slot] = (chip->ssg_eg[slot] >> 3) & 0x01;
+    chip->eg_ssg_inv[slot] = (chip->eg_ssg_dir[slot] ^ (((chip->ssg_eg[slot] >> 2) & 0x01) & ((chip->ssg_eg[slot] >> 3) & 0x01)))
+                           & chip->eg_kon[slot];
 }
 
-void NOPN2_EnvelopeADSR(ym3438_t *chip)
+static void NOPN2_EnvelopeADSR(ym3438_t *chip)
 {
     Bit32u slot = (chip->cycles + 22) % 24;
 
@@ -668,7 +672,7 @@ void NOPN2_EnvelopeADSR(ym3438_t *chip)
             }
             break;
         case eg_num_decay:
-            if ((level >> 5) == chip->eg_sl[1])
+            if ((level >> 4) == (chip->eg_sl[1] << 1))
             {
                 nextstate = eg_num_sustain;
             }
@@ -719,7 +723,7 @@ void NOPN2_EnvelopeADSR(ym3438_t *chip)
     chip->eg_state[slot] = nextstate;
 }
 
-void NOPN2_EnvelopePrepare(ym3438_t *chip)
+static void NOPN2_EnvelopePrepare(ym3438_t *chip)
 {
     Bit8u rate;
     Bit8u sum;
@@ -807,7 +811,7 @@ void NOPN2_EnvelopePrepare(ym3438_t *chip)
     chip->eg_sl[0] = chip->sl[slot];
 }
 
-void NOPN2_EnvelopeGenerate(ym3438_t *chip)
+static void NOPN2_EnvelopeGenerate(ym3438_t *chip)
 {
     Bit32u slot = (chip->cycles + 23) % 24;
     Bit16u level;
@@ -840,7 +844,7 @@ void NOPN2_EnvelopeGenerate(ym3438_t *chip)
     chip->eg_out[slot] = level;
 }
 
-void NOPN2_UpdateLFO(ym3438_t *chip)
+static void NOPN2_UpdateLFO(ym3438_t *chip)
 {
     if ((chip->lfo_quotient & lfo_cycles[chip->lfo_freq]) == lfo_cycles[chip->lfo_freq])
     {
@@ -854,7 +858,7 @@ void NOPN2_UpdateLFO(ym3438_t *chip)
     chip->lfo_cnt &= chip->lfo_en;
 }
 
-void NOPN2_FMPrepare(ym3438_t *chip)
+static void NOPN2_FMPrepare(ym3438_t *chip)
 {
     Bit32u slot = (chip->cycles + 6) % 24;
     Bit32u channel = chip->channel;
@@ -916,7 +920,7 @@ void NOPN2_FMPrepare(ym3438_t *chip)
     }
 }
 
-void NOPN2_ChGenerate(ym3438_t *chip)
+static void NOPN2_ChGenerate(ym3438_t *chip)
 {
     Bit32u slot = (chip->cycles + 18) % 24;
     Bit32u channel = chip->channel;
@@ -951,7 +955,7 @@ void NOPN2_ChGenerate(ym3438_t *chip)
     chip->ch_acc[channel] = sum;
 }
 
-void NOPN2_ChOutput(ym3438_t *chip)
+static void NOPN2_ChOutput(ym3438_t *chip)
 {
     Bit32u cycles = chip->cycles;
     Bit32u slot = chip->cycles;
@@ -980,8 +984,7 @@ void NOPN2_ChOutput(ym3438_t *chip)
     if (((cycles >> 2) == 1 && chip->dacen) || test_dac)
     {
         out = (Bit16s)chip->dacdata;
-        out <<= 7;
-        out >>= 7;
+        out = SIGN_EXTEND(8, out);
     }
     else
     {
@@ -1034,7 +1037,7 @@ void NOPN2_ChOutput(ym3438_t *chip)
     }
 }
 
-void NOPN2_FMGenerate(ym3438_t *chip)
+static void NOPN2_FMGenerate(ym3438_t *chip)
 {
     Bit32u slot = (chip->cycles + 19) % 24;
     /* Calculate phase */
@@ -1067,12 +1070,11 @@ void NOPN2_FMGenerate(ym3438_t *chip)
     {
         output = output ^ (chip->mode_test_21[4] << 13);
     }
-    output <<= 2;
-    output >>= 2;
+    output = SIGN_EXTEND(13, output);
     chip->fm_out[slot] = output;
 }
 
-void NOPN2_DoTimerA(ym3438_t *chip)
+static void NOPN2_DoTimerA(ym3438_t *chip)
 {
     Bit16u time;
     Bit8u load;
@@ -1121,7 +1123,7 @@ void NOPN2_DoTimerA(ym3438_t *chip)
     chip->timer_a_cnt = time & 0x3ff;
 }
 
-void NOPN2_DoTimerB(ym3438_t *chip)
+static void NOPN2_DoTimerB(ym3438_t *chip)
 {
     Bit16u time;
     Bit8u load;
@@ -1166,7 +1168,7 @@ void NOPN2_DoTimerB(ym3438_t *chip)
     chip->timer_b_cnt = time & 0xff;
 }
 
-void NOPN2_KeyOn(ym3438_t*chip)
+static void NOPN2_KeyOn(ym3438_t*chip)
 {
     Bit32u slot = chip->cycles;
     Bit32u chan = chip->channel;
diff --git a/emu/cores/ym3438_int.h b/emu/cores/ym3438_int.h
index cc6b7648..d8633d3e 100644
--- a/emu/cores/ym3438_int.h
+++ b/emu/cores/ym3438_int.h
@@ -1,20 +1,23 @@
+// license:LGPL-2.1+
+// copyright-holders:Nuke.YKT
 /*
- * Copyright (C) 2017-2018 Alexey Khokholov (Nuke.YKT)
+ * Copyright (C) 2017-2021 Alexey Khokholov (Nuke.YKT)
  *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
+ * This file is part of Nuked OPN2.
  *
- * This program 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 General Public License for more details.
+ * This library 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.
  *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ * This library 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 this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  *
  *  Nuked OPN2(Yamaha YM3438) emulator.
  *  Thanks:
@@ -23,12 +26,16 @@
  *      OPLx decapsulated(Matthew Gambrell, Olli Niemitalo):
  *          OPL2 ROMs.
  *
- * version: 1.0.10
+ * version: 1.0.9
  */
 
 // Nuked OPN2 internal structures/functions
-#ifndef __YM3438_INT_H__
-#define __YM3438_INT_H__
+#ifndef YM3438_INT_H
+#define YM3438_INT_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
 
 #include "../../stdtype.h"
 #include "../snddef.h"
@@ -152,7 +159,7 @@ typedef struct
     Bit8u timer_a_load_latch;
     Bit8u timer_a_overflow_flag;
     Bit8u timer_a_overflow;
-    
+
     Bit16u timer_b_cnt;
     Bit8u timer_b_subcnt;
     Bit16u timer_b_reg;
@@ -163,7 +170,7 @@ typedef struct
     Bit8u timer_b_load_latch;
     Bit8u timer_b_overflow_flag;
     Bit8u timer_b_overflow;
-    
+
     /* Register set */
     Bit8u mode_test_21[8];
     Bit8u mode_test_2c[8];
@@ -175,7 +182,7 @@ typedef struct
     Bit8u mode_kon_csm;
     Bit8u dacen;
     Bit16s dacdata;
-    
+
     Bit8u ks[24];
     Bit8u ar[24];
     Bit8u sr[24];
@@ -187,7 +194,7 @@ typedef struct
     Bit8u am[24];
     Bit8u tl[24];
     Bit8u ssg_eg[24];
-    
+
     Bit16u fnum[6];
     Bit8u block[6];
     Bit8u kcode[6];
@@ -203,7 +210,7 @@ typedef struct
     Bit8u pms[6];
     Bit8u status;
     Bit32u status_time;
-    
+
     Bit32u chip_type;
     Bit32u use_filter;
     Bit32u mute[7];
@@ -228,4 +235,8 @@ Bit32u NOPN2_ReadTestPin(ym3438_t *chip);
 Bit32u NOPN2_ReadIRQPin(ym3438_t *chip);
 Bit8u NOPN2_Read(ym3438_t *chip, Bit32u port);
 
-#endif	// __YM3438_INT_H__
+#ifdef __cplusplus
+}
+#endif
+
+#endif	// YM3438_INT_H