/*
 * Reverb.cpp
 * ----------
 * Purpose: Mixing code for reverb.
 * Notes  : Ugh... This should really be removed at some point.
 * Authors: Olivier Lapicque
 *          OpenMPT Devs
 * The OpenMPT source code is released under the BSD license. Read LICENSE for more details.
 */


#include "stdafx.h"

#ifndef NO_REVERB
#include "Reverb.h"
#if defined(MPT_WANT_ARCH_INTRINSICS_X86_SSE2)
#include "../common/mptCPU.h"
#endif
#include "../soundlib/MixerLoops.h"
#include "mpt/base/numbers.hpp"

#include <cstring>

#if defined(MPT_WANT_ARCH_INTRINSICS_X86_SSE2) && defined(MPT_ARCH_INTRINSICS_X86_SSE2)
#if MPT_COMPILER_MSVC
#include <intrin.h>
#endif
#include <emmintrin.h>
#if defined(MPT_ARCH_QUIRK_SSE2_UNALIGNED_LOAD_STORE_REQUIRES_IMMINTRIN_H)
#include <immintrin.h>
#endif
#endif

#endif // NO_REVERB


OPENMPT_NAMESPACE_BEGIN


#ifndef NO_REVERB


#if defined(MPT_WANT_ARCH_INTRINSICS_X86_SSE2) && defined(MPT_ARCH_INTRINSICS_X86_SSE2)
#if defined(MPT_ARCH_QUIRK_SSE2_NO_UNALIGNED_LOAD_STORE)
MPT_ATTR_ALWAYSINLINE MPT_INLINE_FORCE static __m128i mpt_mm_loadu_si64(void const *mem_addr) {
	__m128i tmp;
	std::memset(&tmp, 0, sizeof(__m128i));
	std::memcpy(&tmp, mem_addr, 8);
	return _mm_loadl_epi64(&tmp);
}
MPT_ATTR_ALWAYSINLINE MPT_INLINE_FORCE static void mpt_mm_storeu_si64(void *mem_addr, __m128i a) {
	std::memcpy(mem_addr, &a, 8);
}
#else
MPT_ATTR_ALWAYSINLINE MPT_INLINE_FORCE static __m128i mpt_mm_loadu_si64(void const *mem_addr) {
	return _mm_loadu_si64(mem_addr);
}
MPT_ATTR_ALWAYSINLINE MPT_INLINE_FORCE static void mpt_mm_storeu_si64(void *mem_addr, __m128i a) {
	_mm_storeu_si64(mem_addr, a);
}
#endif
#endif


CReverb::CReverb()
{
	// Reverb mix buffers
	MemsetZero(g_RefDelay);
	MemsetZero(g_LateReverb);
}


static int32 OnePoleLowPassCoef(int32 scale, double g, double F_c, double F_s)
{
	if(g > 0.999999) return 0;

	g *= g;
	double scale_over_1mg = scale / (1.0 - g);
	double cosw = std::cos((2.0 * mpt::numbers::pi) * F_c / F_s);
	return mpt::saturate_round<int32>((1.0 - (std::sqrt((g + g) * (1.0 - cosw) - g * g * (1.0 - cosw * cosw)) + g * cosw)) * scale_over_1mg);
}

static double mBToLinear(int32 value_mB)
{
	if(!value_mB) return 1;
	if(value_mB <= -100000) return 0;

	const double val = value_mB * 3.321928094887362304 / (100.0 * 20.0);	// log2(10)/(100*20)
	return std::pow(2.0, val - static_cast<int32>(0.5 + val));
}

static int32 mBToLinear(int32 scale, int32 value_mB)
{
	return mpt::saturate_round<int32>(mBToLinear(value_mB) * scale);
}

static constexpr std::pair<SNDMIX_REVERB_PROPERTIES, const char *> ReverbPresets[NUM_REVERBTYPES] =
{
	// Examples simulating General MIDI 2'musical' reverb presets
	// Name  (Decay time)  Description
	// Plate       (1.3s)  A plate reverb simulation.
	{{ -1000, -200, 1.30f,0.90f,     0,0.002f,     0,0.010f,100.0f, 75.0f }, "GM Plate"},
	// Small Room  (1.1s)  A small size room with a length of 5m or so.
	{{ -1000, -600, 1.10f,0.83f,  -400,0.005f,   500,0.010f,100.0f,100.0f }, "GM Small Room"},
	// Medium Room (1.3s)  A medium size room with a length of 10m or so.
	{{ -1000, -600, 1.30f,0.83f, -1000,0.010f,  -200,0.020f,100.0f,100.0f }, "GM Medium Room"},
	// Large Room  (1.5s)  A large size room suitable for live performances.
	{{ -1000, -600, 1.50f,0.83f, -1600,0.020f, -1000,0.040f,100.0f,100.0f }, "GM Large Room"},
	// Medium Hall (1.8s)  A medium size concert hall.
	{{ -1000, -600, 1.80f,0.70f, -1300,0.015f,  -800,0.030f,100.0f,100.0f }, "GM Medium Hall"},
	// Large Hall  (1.8s)  A large size concert hall suitable for a full orchestra.
	{{ -1000, -600, 1.80f,0.70f, -2000,0.030f, -1400,0.060f,100.0f,100.0f }, "GM Large Hall"},

	{{ -1000, -100, 1.49f,0.83f, -2602,0.007f,   200,0.011f,100.0f,100.0f }, "Generic"},
	{{ -1000,-6000, 0.17f,0.10f, -1204,0.001f,   207,0.002f,100.0f,100.0f }, "Padded Cell"},
	{{ -1000, -454, 0.40f,0.83f, -1646,0.002f,    53,0.003f,100.0f,100.0f }, "Room"},
	{{ -1000,-1200, 1.49f,0.54f,  -370,0.007f,  1030,0.011f,100.0f, 60.0f }, "Bathroom"},
	{{ -1000,-6000, 0.50f,0.10f, -1376,0.003f, -1104,0.004f,100.0f,100.0f }, "Living Room"},
	{{ -1000, -300, 2.31f,0.64f,  -711,0.012f,    83,0.017f,100.0f,100.0f }, "Stone Room"},
	{{ -1000, -476, 4.32f,0.59f,  -789,0.020f,  -289,0.030f,100.0f,100.0f }, "Auditorium"},
	{{ -1000, -500, 3.92f,0.70f, -1230,0.020f,    -2,0.029f,100.0f,100.0f }, "Concert Hall"},
	{{ -1000,    0, 2.91f,1.30f,  -602,0.015f,  -302,0.022f,100.0f,100.0f }, "Cave"},
	{{ -1000, -698, 7.24f,0.33f, -1166,0.020f,    16,0.030f,100.0f,100.0f }, "Arena"},
	{{ -1000,-1000,10.05f,0.23f,  -602,0.020f,   198,0.030f,100.0f,100.0f }, "Hangar"},
	{{ -1000,-4000, 0.30f,0.10f, -1831,0.002f, -1630,0.030f,100.0f,100.0f }, "Carpeted Hallway"},
	{{ -1000, -300, 1.49f,0.59f, -1219,0.007f,   441,0.011f,100.0f,100.0f }, "Hallway"},
	{{ -1000, -237, 2.70f,0.79f, -1214,0.013f,   395,0.020f,100.0f,100.0f }, "Stone Corridor"},
	{{ -1000, -270, 1.49f,0.86f, -1204,0.007f,    -4,0.011f,100.0f,100.0f }, "Alley"},
	{{ -1000,-3300, 1.49f,0.54f, -2560,0.162f,  -613,0.088f, 79.0f,100.0f }, "Forest"},
	{{ -1000, -800, 1.49f,0.67f, -2273,0.007f, -2217,0.011f, 50.0f,100.0f }, "City"},
	{{ -1000,-2500, 1.49f,0.21f, -2780,0.300f, -2014,0.100f, 27.0f,100.0f }, "Mountains"},
	{{ -1000,-1000, 1.49f,0.83f,-10000,0.061f,   500,0.025f,100.0f,100.0f }, "Quarry"},
	{{ -1000,-2000, 1.49f,0.50f, -2466,0.179f, -2514,0.100f, 21.0f,100.0f }, "Plain"},
	{{ -1000,    0, 1.65f,1.50f, -1363,0.008f, -1153,0.012f,100.0f,100.0f }, "Parking Lot"},
	{{ -1000,-1000, 2.81f,0.14f,   429,0.014f,   648,0.021f, 80.0f, 60.0f }, "Sewer Pipe"},
	{{ -1000,-4000, 1.49f,0.10f,  -449,0.007f,  1700,0.011f,100.0f,100.0f }, "Underwater"},
};

mpt::ustring GetReverbPresetName(uint32 preset)
{
	return (preset < NUM_REVERBTYPES) ? mpt::ToUnicode(mpt::Charset::ASCII, ReverbPresets[preset].second) : mpt::ustring{};
}

const SNDMIX_REVERB_PROPERTIES *GetReverbPreset(uint32 preset)
{
	return (preset < NUM_REVERBTYPES) ? &ReverbPresets[preset].first : nullptr;
}

//////////////////////////////////////////////////////////////////////////
//
// I3DL2 environmental reverb support
//

struct REFLECTIONPRESET
{
	int32 lDelayFactor;
	int16 sGainLL, sGainRR, sGainLR, sGainRL;
};

static const REFLECTIONPRESET gReflectionsPreset[ENVIRONMENT_NUMREFLECTIONS] =
{
	// %Delay, ll,    rr,   lr,    rl
	{0,    9830,   6554,	  0,     0},
	{10,   6554,  13107,	  0,     0},
	{24,  -9830,  13107,	  0,     0},
	{36,  13107,  -6554,      0,     0},
	{54,  16384,  16384,  -1638, -1638},
	{61, -13107,   8192,   -328,  -328},
	{73, -11468, -11468,  -3277,  3277},
	{87,  13107,  -9830,   4916, -4916}
};

////////////////////////////////////////////////////////////////////////////////////
//
// Implementation
//

static void I3dl2_to_Generic(
				const SNDMIX_REVERB_PROPERTIES *pReverb,
				EnvironmentReverb *pRvb,
				float flOutputFreq,
				int32 lMinRefDelay,
				int32 lMaxRefDelay,
				int32 lMinRvbDelay,
				int32 lMaxRvbDelay,
				int32 lTankLength)
{
	float flDelayFactor, flDelayFactorHF, flDecayTimeHF;
	int32 lDensity, lTailDiffusion;

	// Common parameters
	pRvb->ReverbLevel = pReverb->lReverb;
	pRvb->ReflectionsLevel = pReverb->lReflections;
	pRvb->RoomHF = pReverb->lRoomHF;

	// HACK: Somewhat normalize the reverb output level
	int32 lMaxLevel = (pRvb->ReverbLevel > pRvb->ReflectionsLevel) ? pRvb->ReverbLevel : pRvb->ReflectionsLevel;
	if (lMaxLevel < -600)
	{
		lMaxLevel += 600;
		pRvb->ReverbLevel -= lMaxLevel;
		pRvb->ReflectionsLevel -= lMaxLevel;
	}

	// Pre-Diffusion factor (for both reflections and late reverb)
	lDensity = 8192 + static_cast<int32>(79.31f * pReverb->flDensity);
	pRvb->PreDiffusion = lDensity;

	// Late reverb diffusion
	lTailDiffusion = static_cast<int32>((0.15f + pReverb->flDiffusion * (0.36f*0.01f)) * 32767.0f);
	if (lTailDiffusion > 0x7f00) lTailDiffusion = 0x7f00;
	pRvb->TankDiffusion = lTailDiffusion;

	// Verify reflections and reverb delay parameters
	float flRefDelay = pReverb->flReflectionsDelay;
	if (flRefDelay > 0.100f) flRefDelay = 0.100f;
	int32 lReverbDelay = static_cast<int32>(pReverb->flReverbDelay * flOutputFreq);
	int32 lReflectionsDelay = static_cast<int32>(flRefDelay * flOutputFreq);
	int32 lReverbDecayTime = static_cast<int32>(pReverb->flDecayTime * flOutputFreq);
	if (lReflectionsDelay < lMinRefDelay)
	{
		lReverbDelay -= (lMinRefDelay - lReflectionsDelay);
		lReflectionsDelay = lMinRefDelay;
	}
	if (lReflectionsDelay > lMaxRefDelay)
	{
		lReverbDelay += (lReflectionsDelay - lMaxRefDelay);
		lReflectionsDelay = lMaxRefDelay;
	}
	// Adjust decay time when adjusting reverb delay
	if (lReverbDelay < lMinRvbDelay)
	{
		lReverbDecayTime -= (lMinRvbDelay - lReverbDelay);
		lReverbDelay = lMinRvbDelay;
	}
	if (lReverbDelay > lMaxRvbDelay)
	{
		lReverbDecayTime += (lReverbDelay - lMaxRvbDelay);
		lReverbDelay = lMaxRvbDelay;
	}
	pRvb->ReverbDelay = lReverbDelay;
	pRvb->ReverbDecaySamples = lReverbDecayTime;
	// Setup individual reflections delay and gains
	for (uint32 iRef=0; iRef<ENVIRONMENT_NUMREFLECTIONS; iRef++)
	{
		EnvironmentReflection &ref = pRvb->Reflections[iRef];
		ref.Delay = lReflectionsDelay + (gReflectionsPreset[iRef].lDelayFactor * lReverbDelay + 50)/100;
		ref.GainLL = gReflectionsPreset[iRef].sGainLL;
		ref.GainRL = gReflectionsPreset[iRef].sGainRL;
		ref.GainLR = gReflectionsPreset[iRef].sGainLR;
		ref.GainRR = gReflectionsPreset[iRef].sGainRR;
	}

	// Late reverb decay time
	if (lTankLength < 10) lTankLength = 10;
	flDelayFactor = (lReverbDecayTime <= lTankLength) ? 1.0f : ((float)lTankLength / (float)lReverbDecayTime);
	pRvb->ReverbDecay = static_cast<int32>(std::pow(0.001f, flDelayFactor) * 32768.0f);

	// Late Reverb Decay HF
	flDecayTimeHF = (float)lReverbDecayTime * pReverb->flDecayHFRatio;
	flDelayFactorHF = (flDecayTimeHF <= (float)lTankLength) ? 1.0f : ((float)lTankLength / flDecayTimeHF);
	pRvb->flReverbDamping = std::pow(0.001f, flDelayFactorHF);
}


void CReverb::Shutdown(MixSampleInt &gnRvbROfsVol, MixSampleInt &gnRvbLOfsVol)
{
	gnReverbSend = false;

	gnRvbLOfsVol = 0;
	gnRvbROfsVol = 0;

	// Clear out all reverb state
	g_bLastInPresent = false;
	g_bLastOutPresent = false;
	g_nLastRvbIn_xl = g_nLastRvbIn_xr = 0;
	g_nLastRvbIn_yl = g_nLastRvbIn_yr = 0;
	g_nLastRvbOut_xl = g_nLastRvbOut_xr = 0;
	MemsetZero(gnDCRRvb_X1);
	MemsetZero(gnDCRRvb_Y1);

	// Zero internal buffers
	MemsetZero(g_LateReverb.Diffusion1);
	MemsetZero(g_LateReverb.Diffusion2);
	MemsetZero(g_LateReverb.Delay1);
	MemsetZero(g_LateReverb.Delay2);
	MemsetZero(g_RefDelay.RefDelayBuffer);
	MemsetZero(g_RefDelay.PreDifBuffer);
	MemsetZero(g_RefDelay.RefOut);
}


void CReverb::Initialize(bool bReset, MixSampleInt &gnRvbROfsVol, MixSampleInt &gnRvbLOfsVol, uint32 MixingFreq)
{
	if (m_Settings.m_nReverbType >= NUM_REVERBTYPES) m_Settings.m_nReverbType = 0;
	const SNDMIX_REVERB_PROPERTIES *rvbPreset = &ReverbPresets[m_Settings.m_nReverbType].first;

	if ((rvbPreset != m_currentPreset) || (bReset))
	{
		// Reverb output frequency is half of the dry output rate
		float flOutputFrequency = (float)MixingFreq;
		EnvironmentReverb rvb;

		// Reset reverb parameters
		m_currentPreset = rvbPreset;
		I3dl2_to_Generic(rvbPreset, &rvb, flOutputFrequency,
							RVBMINREFDELAY, RVBMAXREFDELAY,
							RVBMINRVBDELAY, RVBMAXRVBDELAY,
							( RVBDIF1L_LEN + RVBDIF1R_LEN
							+ RVBDIF2L_LEN + RVBDIF2R_LEN
							+ RVBDLY1L_LEN + RVBDLY1R_LEN
							+ RVBDLY2L_LEN + RVBDLY2R_LEN) / 2);

		// Store reverb decay time (in samples) for reverb auto-shutdown
		gnReverbDecaySamples = rvb.ReverbDecaySamples;

		// Room attenuation at high frequencies
		int32 nRoomLP;
		nRoomLP = OnePoleLowPassCoef(32768, mBToLinear(rvb.RoomHF), 5000, static_cast<double>(flOutputFrequency));
		g_RefDelay.nCoeffs.c.l = (int16)nRoomLP;
		g_RefDelay.nCoeffs.c.r = (int16)nRoomLP;

		// Pre-Diffusion factor (for both reflections and late reverb)
		g_RefDelay.nPreDifCoeffs.c.l = (int16)(rvb.PreDiffusion*2);
		g_RefDelay.nPreDifCoeffs.c.r = (int16)(rvb.PreDiffusion*2);

		// Setup individual reflections delay and gains
		for (uint32 iRef=0; iRef<8; iRef++)
		{
			SWRvbReflection &ref = g_RefDelay.Reflections[iRef];
			ref.DelayDest = rvb.Reflections[iRef].Delay;
			ref.Delay = ref.DelayDest;
			ref.Gains[0].c.l = rvb.Reflections[iRef].GainLL;
			ref.Gains[0].c.r = rvb.Reflections[iRef].GainRL;
			ref.Gains[1].c.l = rvb.Reflections[iRef].GainLR;
			ref.Gains[1].c.r = rvb.Reflections[iRef].GainRR;
		}
		g_LateReverb.nReverbDelay = rvb.ReverbDelay;

		// Reflections Master Gain
		uint32 lReflectionsGain = 0;
		if (rvb.ReflectionsLevel > -9000)
		{
			lReflectionsGain = mBToLinear(32768, rvb.ReflectionsLevel);
		}
		g_RefDelay.lMasterGain = lReflectionsGain;

		// Late reverb master gain
		uint32 lReverbGain = 0;
		if (rvb.ReverbLevel > -9000)
		{
			lReverbGain = mBToLinear(32768, rvb.ReverbLevel);
		}
		g_LateReverb.lMasterGain = lReverbGain;

		// Late reverb diffusion
		uint32 nTailDiffusion = rvb.TankDiffusion;
		if (nTailDiffusion > 0x7f00) nTailDiffusion = 0x7f00;
		g_LateReverb.nDifCoeffs[0].c.l = (int16)nTailDiffusion;
		g_LateReverb.nDifCoeffs[0].c.r = (int16)nTailDiffusion;
		g_LateReverb.nDifCoeffs[1].c.l = (int16)nTailDiffusion;
		g_LateReverb.nDifCoeffs[1].c.r = (int16)nTailDiffusion;
		g_LateReverb.Dif2InGains[0].c.l = 0x7000;
		g_LateReverb.Dif2InGains[0].c.r = 0x1000;
		g_LateReverb.Dif2InGains[1].c.l = 0x1000;
		g_LateReverb.Dif2InGains[1].c.r = 0x7000;

		// Late reverb decay time
		int32 nReverbDecay = rvb.ReverbDecay;
		Limit(nReverbDecay, 0, 0x7ff0);
		g_LateReverb.nDecayDC[0].c.l = (int16)nReverbDecay;
		g_LateReverb.nDecayDC[0].c.r = 0;
		g_LateReverb.nDecayDC[1].c.l = 0;
		g_LateReverb.nDecayDC[1].c.r = (int16)nReverbDecay;

		// Late Reverb Decay HF
		float fReverbDamping = rvb.flReverbDamping * rvb.flReverbDamping;
		int32 nDampingLowPass;

		nDampingLowPass = OnePoleLowPassCoef(32768, static_cast<double>(fReverbDamping), 5000, static_cast<double>(flOutputFrequency));
		Limit(nDampingLowPass, 0x100, 0x7f00);
		
		g_LateReverb.nDecayLP[0].c.l = (int16)nDampingLowPass;
		g_LateReverb.nDecayLP[0].c.r = 0;
		g_LateReverb.nDecayLP[1].c.l = 0;
		g_LateReverb.nDecayLP[1].c.r = (int16)nDampingLowPass;
	}
	if (bReset)
	{
		gnReverbSamples = 0;
		Shutdown(gnRvbROfsVol, gnRvbLOfsVol);
	}
	// Wait at least 5 seconds before shutting down the reverb
	if (gnReverbDecaySamples < MixingFreq*5)
	{
		gnReverbDecaySamples = MixingFreq*5;
	}
}


void CReverb::TouchReverbSendBuffer(MixSampleInt *MixReverbBuffer, MixSampleInt &gnRvbROfsVol, MixSampleInt &gnRvbLOfsVol, uint32 nSamples)
{
	if(!gnReverbSend)
	{ // and we did not clear the buffer yet, do it now because we will get new data
		StereoFill(MixReverbBuffer, nSamples, gnRvbROfsVol, gnRvbLOfsVol);
	}
	gnReverbSend = true; // we will have to process reverb
}


// Reverb
void CReverb::Process(MixSampleInt *MixSoundBuffer, MixSampleInt *MixReverbBuffer, MixSampleInt &gnRvbROfsVol, MixSampleInt &gnRvbLOfsVol, uint32 nSamples)
{
	if((!gnReverbSend) && (!gnReverbSamples))
	{ // no data is sent to reverb and reverb decayed completely
		return;
	}
	if(!gnReverbSend)
	{ // no input data in MixReverbBuffer, so the buffer got not cleared in TouchReverbSendBuffer(), do it now for decay
		StereoFill(MixReverbBuffer, nSamples, gnRvbROfsVol, gnRvbLOfsVol);
	}

	uint32 nIn, nOut;
	// Dynamically adjust reverb master gains
	int32 lMasterGain;
	lMasterGain = ((g_RefDelay.lMasterGain * m_Settings.m_nReverbDepth) >> 4);
	if (lMasterGain > 0x7fff) lMasterGain = 0x7fff;
	g_RefDelay.ReflectionsGain.c.l = (int16)lMasterGain;
	g_RefDelay.ReflectionsGain.c.r = (int16)lMasterGain;
	lMasterGain = ((g_LateReverb.lMasterGain * m_Settings.m_nReverbDepth) >> 4);
	if (lMasterGain > 0x10000) lMasterGain = 0x10000;
	g_LateReverb.RvbOutGains[0].c.l = (int16)((lMasterGain+0x7f) >> 3);	// l->l
	g_LateReverb.RvbOutGains[0].c.r = (int16)((lMasterGain+0xff) >> 4);	// r->l
	g_LateReverb.RvbOutGains[1].c.l = (int16)((lMasterGain+0xff) >> 4);	// l->r
	g_LateReverb.RvbOutGains[1].c.r = (int16)((lMasterGain+0x7f) >> 3);	// r->r
	// Process Dry/Wet Mix
	int32 lMaxRvbGain = (g_RefDelay.lMasterGain > g_LateReverb.lMasterGain) ? g_RefDelay.lMasterGain : g_LateReverb.lMasterGain;
	if (lMaxRvbGain > 32768) lMaxRvbGain = 32768;
	int32 lDryVol = (36 - m_Settings.m_nReverbDepth)>>1;
	if (lDryVol < 8) lDryVol = 8;
	if (lDryVol > 16) lDryVol = 16;
	lDryVol = 16 - (((16-lDryVol) * lMaxRvbGain) >> 15);
	ReverbDryMix(MixSoundBuffer, MixReverbBuffer, lDryVol, nSamples);
	// Downsample 2x + 1st stage of lowpass filter
	nIn = ReverbProcessPreFiltering1x(MixReverbBuffer, nSamples);
	nOut = nIn;
	// Main reverb processing: split into small chunks (needed for short reverb delays)
	// Reverb Input + Low-Pass stage #2 + Pre-diffusion
	if (nIn > 0) ProcessPreDelay(&g_RefDelay, MixReverbBuffer, nIn);
	// Process Reverb Reflections and Late Reverberation
	int32 *pRvbOut = MixReverbBuffer;
	uint32 nRvbSamples = nOut;
	while (nRvbSamples > 0)
	{
		uint32 nPosRef = g_RefDelay.nRefOutPos & SNDMIX_REVERB_DELAY_MASK;
		uint32 nPosRvb = (nPosRef - g_LateReverb.nReverbDelay) & SNDMIX_REVERB_DELAY_MASK;
		uint32 nmax1 = (SNDMIX_REVERB_DELAY_MASK+1) - nPosRef;
		uint32 nmax2 = (SNDMIX_REVERB_DELAY_MASK+1) - nPosRvb;
		nmax1 = (nmax1 < nmax2) ? nmax1 : nmax2;
		uint32 n = nRvbSamples;
		if (n > nmax1) n = nmax1;
		if (n > 64) n = 64;
		// Reflections output + late reverb delay
		ProcessReflections(&g_RefDelay, &g_RefDelay.RefOut[nPosRef], pRvbOut, n);
		// Late Reverberation
		ProcessLateReverb(&g_LateReverb, &g_RefDelay.RefOut[nPosRvb], pRvbOut, n);
		// Update delay positions
		g_RefDelay.nRefOutPos = (g_RefDelay.nRefOutPos + n) & SNDMIX_REVERB_DELAY_MASK;
		g_RefDelay.nDelayPos = (g_RefDelay.nDelayPos + n) & SNDMIX_REFLECTIONS_DELAY_MASK;
		pRvbOut += n*2;
		nRvbSamples -= n;
	}
	// Adjust nDelayPos, in case nIn != nOut
	g_RefDelay.nDelayPos = (g_RefDelay.nDelayPos - nOut + nIn) & SNDMIX_REFLECTIONS_DELAY_MASK;
	// Upsample 2x
	ReverbProcessPostFiltering1x(MixReverbBuffer, MixSoundBuffer, nSamples);
	// Automatically shut down if needed
	if(gnReverbSend) gnReverbSamples = gnReverbDecaySamples; // reset decay counter
	else if(gnReverbSamples > nSamples) gnReverbSamples -= nSamples; // decay
	else // decayed
	{
		Shutdown(gnRvbROfsVol, gnRvbLOfsVol);
		gnReverbSamples = 0;
	}
	gnReverbSend = false; // no input data in MixReverbBuffer
}


void CReverb::ReverbDryMix(int32 * MPT_RESTRICT pDry, int32 * MPT_RESTRICT pWet, int lDryVol, uint32 nSamples)
{
	for (uint32 i=0; i<nSamples; i++)
	{
		pDry[i*2] += (pWet[i*2]>>4) * lDryVol;
		pDry[i*2+1] += (pWet[i*2+1]>>4) * lDryVol;
	}
}


uint32 CReverb::ReverbProcessPreFiltering2x(int32 * MPT_RESTRICT pWet, uint32 nSamples)
{
	uint32 nOutSamples = 0;
	int lowpass = g_RefDelay.nCoeffs.c.l;
	int y1_l = g_nLastRvbIn_yl, y1_r = g_nLastRvbIn_yr;
	uint32 n = nSamples;

	if (g_bLastInPresent)
	{
		int x1_l = g_nLastRvbIn_xl, x1_r = g_nLastRvbIn_xr;
		int x2_l = pWet[0], x2_r = pWet[1];
		x1_l = (x1_l+x2_l)>>13;
		x1_r = (x1_r+x2_r)>>13;
		y1_l = x1_l + (((x1_l - y1_l)*lowpass)>>15);
		y1_r = x1_r + (((x1_r - y1_r)*lowpass)>>15);
		pWet[0] = y1_l;
		pWet[1] = y1_r;
		pWet+=2;
		n--;
		nOutSamples = 1;
		g_bLastInPresent = false;
	}
	if (n & 1)
	{
		n--;
		g_nLastRvbIn_xl = pWet[n*2];
		g_nLastRvbIn_xr = pWet[n*2+1];
		g_bLastInPresent = true;
	}
	n >>= 1;
	for (uint32 i=0; i<n; i++)
	{
		int x1_l = pWet[i*4];
		int x2_l = pWet[i*4+2];
		x1_l = (x1_l+x2_l)>>13;
		int x1_r = pWet[i*4+1];
		int x2_r = pWet[i*4+3];
		x1_r = (x1_r+x2_r)>>13;
		y1_l = x1_l + (((x1_l - y1_l)*lowpass)>>15);
		y1_r = x1_r + (((x1_r - y1_r)*lowpass)>>15);
		pWet[i*2] = y1_l;
		pWet[i*2+1] = y1_r;
	}
	g_nLastRvbIn_yl = y1_l;
	g_nLastRvbIn_yr = y1_r;
	return nOutSamples + n;
}


uint32 CReverb::ReverbProcessPreFiltering1x(int32 * MPT_RESTRICT pWet, uint32 nSamples)
{
	int lowpass = g_RefDelay.nCoeffs.c.l;
	int y1_l = g_nLastRvbIn_yl, y1_r = g_nLastRvbIn_yr;

	for (uint32 i=0; i<nSamples; i++)
	{
		int x_l = pWet[i*2] >> 12;
		int x_r = pWet[i*2+1] >> 12;
		y1_l = x_l + (((x_l - y1_l)*lowpass)>>15);
		y1_r = x_r + (((x_r - y1_r)*lowpass)>>15);
		pWet[i*2] = y1_l;
		pWet[i*2+1] = y1_r;
	}
	g_nLastRvbIn_yl = y1_l;
	g_nLastRvbIn_yr = y1_r;
	return nSamples;
}


void CReverb::ReverbProcessPostFiltering2x(const int32 * MPT_RESTRICT pRvb, int32 * MPT_RESTRICT pDry, uint32 nSamples)
{
	uint32 n0 = nSamples, n;
	int x1_l = g_nLastRvbOut_xl, x1_r = g_nLastRvbOut_xr;

	if (g_bLastOutPresent)
	{
		pDry[0] += x1_l;
		pDry[1] += x1_r;
		pDry += 2;
		n0--;
		g_bLastOutPresent = false;
	}
	n  = n0 >> 1;
	for (uint32 i=0; i<n; i++)
	{
		int x_l = pRvb[i*2], x_r = pRvb[i*2+1];
		pDry[i*4] += (x_l + x1_l)>>1;
		pDry[i*4+1] += (x_r + x1_r)>>1;
		pDry[i*4+2] += x_l;
		pDry[i*4+3] += x_r;
		x1_l = x_l;
		x1_r = x_r;
	}
	if (n0 & 1)
	{
		int x_l = pRvb[n*2], x_r = pRvb[n*2+1];
		pDry[n*4] += (x_l + x1_l)>>1;
		pDry[n*4+1] += (x_r + x1_r)>>1;
		x1_l = x_l;
		x1_r = x_r;
		g_bLastOutPresent = true;
	}
	g_nLastRvbOut_xl = x1_l;
	g_nLastRvbOut_xr = x1_r;
}


#define DCR_AMOUNT		9

// Stereo Add + DC removal
void CReverb::ReverbProcessPostFiltering1x(const int32 * MPT_RESTRICT pRvb, int32 * MPT_RESTRICT pDry, uint32 nSamples)
{
#if defined(MPT_WANT_ARCH_INTRINSICS_X86_SSE2) && defined(MPT_ARCH_INTRINSICS_X86_SSE2)
	if(CPU::HasFeatureSetAndModesEnabled(CPU::feature::sse2, CPU::mode::xmm128sse))
	{
		mpt::arch::feature_fence_guard arch_feature_guard;
		__m128i nDCRRvb_Y1 = mpt_mm_loadu_si64(gnDCRRvb_Y1);
		__m128i nDCRRvb_X1 = mpt_mm_loadu_si64(gnDCRRvb_X1);
		__m128i in = _mm_set1_epi32(0);
		while(nSamples--)
		{
			in = mpt_mm_loadu_si64(pRvb);
			pRvb += 2;
			// x(n-1) - x(n)
			__m128i diff = _mm_sub_epi32(nDCRRvb_X1, in);
			nDCRRvb_X1 = _mm_add_epi32(nDCRRvb_Y1, _mm_sub_epi32(_mm_srai_epi32(diff, DCR_AMOUNT + 1), diff));
			__m128i out = _mm_add_epi32(mpt_mm_loadu_si64(pDry), nDCRRvb_X1);
			nDCRRvb_Y1 = _mm_sub_epi32(nDCRRvb_X1, _mm_srai_epi32(nDCRRvb_X1, DCR_AMOUNT));
			nDCRRvb_X1 = in;
			mpt_mm_storeu_si64(pDry, out);
			pDry += 2;
		}
		mpt_mm_storeu_si64(gnDCRRvb_X1, in);
		mpt_mm_storeu_si64(gnDCRRvb_Y1, nDCRRvb_Y1);
		return;
	}
#endif
	int32 X1L = gnDCRRvb_X1[0], X1R = gnDCRRvb_X1[1];
	int32 Y1L = gnDCRRvb_Y1[0], Y1R = gnDCRRvb_Y1[1];
	int32 inL = 0, inR = 0;
	while(nSamples--)
	{
		inL = pRvb[0];
		inR = pRvb[1];
		pRvb += 2;
		int32 outL = pDry[0], outR = pDry[1];

		// x(n-1) - x(n)
		X1L -= inL;
		X1R -= inR;
		X1L = X1L / (1 << (DCR_AMOUNT + 1)) - X1L;
		X1R = X1R / (1 << (DCR_AMOUNT + 1)) - X1R;
		Y1L += X1L;
		Y1R += X1R;
		// add to dry mix
		outL += Y1L;
		outR += Y1R;
		Y1L -= Y1L / (1 << DCR_AMOUNT);
		Y1R -= Y1R / (1 << DCR_AMOUNT);
		X1L = inL;
		X1R = inR;

		pDry[0] = outL;
		pDry[1] = outR;
		pDry += 2;
	}
	gnDCRRvb_Y1[0] = Y1L;
	gnDCRRvb_Y1[1] = Y1R;
	gnDCRRvb_X1[0] = inL;
	gnDCRRvb_X1[1] = inR;
}


void CReverb::ReverbDCRemoval(int32 * MPT_RESTRICT pBuffer, uint32 nSamples)
{
#if defined(MPT_WANT_ARCH_INTRINSICS_X86_SSE2) && defined(MPT_ARCH_INTRINSICS_X86_SSE2)
	if(CPU::HasFeatureSetAndModesEnabled(CPU::feature::sse2, CPU::mode::xmm128sse))
	{
		mpt::arch::feature_fence_guard arch_feature_guard;
		__m128i nDCRRvb_Y1 = mpt_mm_loadu_si64(gnDCRRvb_Y1);
		__m128i nDCRRvb_X1 = mpt_mm_loadu_si64(gnDCRRvb_X1);
		while(nSamples--)
		{
			__m128i in = mpt_mm_loadu_si64(pBuffer);
			__m128i diff = _mm_sub_epi32(nDCRRvb_X1, in);
			__m128i out = _mm_add_epi32(nDCRRvb_Y1, _mm_sub_epi32(_mm_srai_epi32(diff, DCR_AMOUNT + 1), diff));
			mpt_mm_storeu_si64(pBuffer, out);
			pBuffer += 2;
			nDCRRvb_Y1 = _mm_sub_epi32(out, _mm_srai_epi32(out, DCR_AMOUNT));
			nDCRRvb_X1 = in;
		}
		mpt_mm_storeu_si64(gnDCRRvb_X1, nDCRRvb_X1);
		mpt_mm_storeu_si64(gnDCRRvb_Y1, nDCRRvb_Y1);
		return;
	}
#endif
	int32 X1L = gnDCRRvb_X1[0], X1R = gnDCRRvb_X1[1];
	int32 Y1L = gnDCRRvb_Y1[0], Y1R = gnDCRRvb_Y1[1];
	int32 inL = 0, inR = 0;
	while(nSamples--)
	{
		inL = pBuffer[0];
		inR = pBuffer[1];
		// x(n-1) - x(n)
		X1L -= inL;
		X1R -= inR;
		X1L = X1L / (1 << (DCR_AMOUNT + 1)) - X1L;
		X1R = X1R / (1 << (DCR_AMOUNT + 1)) - X1R;
		Y1L += X1L;
		Y1R += X1R;
		pBuffer[0] = Y1L;
		pBuffer[1] = Y1R;
		pBuffer += 2;
		Y1L -= Y1L / (1 << DCR_AMOUNT);
		Y1R -= Y1R / (1 << DCR_AMOUNT);
		X1L = inL;
		X1R = inR;
	}
	gnDCRRvb_Y1[0] = Y1L;
	gnDCRRvb_Y1[1] = Y1R;
	gnDCRRvb_X1[0] = inL;
	gnDCRRvb_X1[1] = inR;
}


//////////////////////////////////////////////////////////////////////////
//
// Pre-Delay:
//
// 1. Saturate and low-pass the reverb input (stage 2 of roomHF)
// 2. Process pre-diffusion
// 3. Insert the result in the reflections delay buffer
//

// Save some typing
MPT_ATTR_ALWAYSINLINE MPT_INLINE_FORCE static int32 Clamp16(int32 x) { return Clamp(x, std::numeric_limits<int16>::min(), std::numeric_limits<int16>::max()); }

void CReverb::ProcessPreDelay(SWRvbRefDelay * MPT_RESTRICT pPreDelay, const int32 * MPT_RESTRICT pIn, uint32 nSamples)
{
	uint32 preDifPos = pPreDelay->nPreDifPos;
	uint32 delayPos = pPreDelay->nDelayPos - 1;
#if defined(MPT_WANT_ARCH_INTRINSICS_X86_SSE2) && defined(MPT_ARCH_INTRINSICS_X86_SSE2)
	if(CPU::HasFeatureSetAndModesEnabled(CPU::feature::sse2, CPU::mode::xmm128sse))
	{
		mpt::arch::feature_fence_guard arch_feature_guard;
		__m128i coeffs = _mm_cvtsi32_si128(pPreDelay->nCoeffs.lr);
		__m128i history = _mm_cvtsi32_si128(pPreDelay->History.lr);
		__m128i preDifCoeffs = _mm_cvtsi32_si128(pPreDelay->nPreDifCoeffs.lr);
		while(nSamples--)
		{
			__m128i in32 = mpt_mm_loadu_si64(pIn);					// 16-bit unsaturated reverb input [  r  |  l  ]
			__m128i inSat = _mm_packs_epi32(in32, in32);	// [ r | l | r | l ] (16-bit saturated)
			pIn += 2;
			// Low-pass
			__m128i lp = _mm_mulhi_epi16(_mm_subs_epi16(history, inSat), coeffs);
			__m128i preDif = _mm_cvtsi32_si128(pPreDelay->PreDifBuffer[preDifPos].lr);
			history = _mm_adds_epi16(_mm_adds_epi16(lp, lp), inSat);
			// Pre-Diffusion
			preDifPos = (preDifPos + 1) & SNDMIX_PREDIFFUSION_DELAY_MASK;
			delayPos = (delayPos + 1) & SNDMIX_REFLECTIONS_DELAY_MASK;
			__m128i preDif2 = _mm_subs_epi16(history, _mm_mulhi_epi16(preDif, preDifCoeffs));
			pPreDelay->PreDifBuffer[preDifPos].lr = _mm_cvtsi128_si32(preDif2);
			pPreDelay->RefDelayBuffer[delayPos].lr = _mm_cvtsi128_si32(_mm_adds_epi16(_mm_mulhi_epi16(preDifCoeffs, preDif2), preDif));
		}
		pPreDelay->nPreDifPos = preDifPos;
		pPreDelay->History.lr = _mm_cvtsi128_si32(history);
		return;
	}
#endif
	const int32 coeffsL = pPreDelay->nCoeffs.c.l, coeffsR = pPreDelay->nCoeffs.c.r;
	const int32 preDifCoeffsL = pPreDelay->nPreDifCoeffs.c.l, preDifCoeffsR = pPreDelay->nPreDifCoeffs.c.r;
	int16 historyL = pPreDelay->History.c.l, historyR = pPreDelay->History.c.r;
	while(nSamples--)
	{
		int32 inL = Clamp16(pIn[0]);
		int32 inR = Clamp16(pIn[1]);
		pIn += 2;
		// Low-pass
		int32 lpL = (Clamp16(historyL - inL) * coeffsL) / 65536;
		int32 lpR = (Clamp16(historyR - inR) * coeffsR) / 65536;
		historyL = mpt::saturate_cast<int16>(Clamp16(lpL + lpL) + inL);
		historyR = mpt::saturate_cast<int16>(Clamp16(lpR + lpR) + inR);
		// Pre-Diffusion
		int32 preDifL = pPreDelay->PreDifBuffer[preDifPos].c.l;
		int32 preDifR = pPreDelay->PreDifBuffer[preDifPos].c.r;
		preDifPos = (preDifPos + 1) & SNDMIX_PREDIFFUSION_DELAY_MASK;
		delayPos = (delayPos + 1) & SNDMIX_REFLECTIONS_DELAY_MASK;
		int16 preDif2L = mpt::saturate_cast<int16>(historyL - preDifL * preDifCoeffsL / 65536);
		int16 preDif2R = mpt::saturate_cast<int16>(historyR - preDifR * preDifCoeffsR / 65536);
		pPreDelay->PreDifBuffer[preDifPos].c.l = preDif2L;
		pPreDelay->PreDifBuffer[preDifPos].c.r = preDif2R;
		pPreDelay->RefDelayBuffer[delayPos].c.l = mpt::saturate_cast<int16>(preDifCoeffsL * preDif2L / 65536 + preDifL);
		pPreDelay->RefDelayBuffer[delayPos].c.r = mpt::saturate_cast<int16>(preDifCoeffsR * preDif2R / 65536 + preDifR);
	}
	pPreDelay->nPreDifPos = preDifPos;
	pPreDelay->History.c.l = historyL;
	pPreDelay->History.c.r = historyR;
}


////////////////////////////////////////////////////////////////////
//
// ProcessReflections:
// First stage:
//	- process 4 reflections, output to pRefOut
//	- output results to pRefOut
// Second stage:
//	- process another 3 reflections
//	- sum with pRefOut
//	- apply reflections master gain and accumulate in the given output
//

void CReverb::ProcessReflections(SWRvbRefDelay * MPT_RESTRICT pPreDelay, LR16 * MPT_RESTRICT pRefOut, int32 * MPT_RESTRICT pOut, uint32 nSamples)
{
#if defined(MPT_WANT_ARCH_INTRINSICS_X86_SSE2) && defined(MPT_ARCH_INTRINSICS_X86_SSE2)
	if(CPU::HasFeatureSetAndModesEnabled(CPU::feature::sse2, CPU::mode::xmm128sse))
	{
		mpt::arch::feature_fence_guard arch_feature_guard;
		union
		{
			__m128i xmm;
			int16 i[8];
		} pos;
		const LR16 *refDelayBuffer = pPreDelay->RefDelayBuffer;
#define GETDELAY(x) static_cast<int16>(pPreDelay->Reflections[x].Delay)
		__m128i delayPos = _mm_set_epi16(GETDELAY(7), GETDELAY(6), GETDELAY(5), GETDELAY(4), GETDELAY(3), GETDELAY(2), GETDELAY(1), GETDELAY(0));
#undef GETDELAY
		delayPos = _mm_sub_epi16(_mm_set1_epi16(static_cast<int16>(pPreDelay->nDelayPos - 1)), delayPos);
		__m128i gain12 = _mm_unpacklo_epi64(mpt_mm_loadu_si64(pPreDelay->Reflections[0].Gains), mpt_mm_loadu_si64(pPreDelay->Reflections[1].Gains));
		__m128i gain34 = _mm_unpacklo_epi64(mpt_mm_loadu_si64(pPreDelay->Reflections[2].Gains), mpt_mm_loadu_si64(pPreDelay->Reflections[3].Gains));
		__m128i gain56 = _mm_unpacklo_epi64(mpt_mm_loadu_si64(pPreDelay->Reflections[4].Gains), mpt_mm_loadu_si64(pPreDelay->Reflections[5].Gains));
		__m128i gain78 = _mm_unpacklo_epi64(mpt_mm_loadu_si64(pPreDelay->Reflections[6].Gains), mpt_mm_loadu_si64(pPreDelay->Reflections[7].Gains));
		// For 28-bit final output: 16+15-3 = 28
		__m128i refGain = _mm_srai_epi32(_mm_set_epi32(0, 0, pPreDelay->ReflectionsGain.c.r, pPreDelay->ReflectionsGain.c.l), 3);
		__m128i delayInc = _mm_set1_epi16(1), delayMask = _mm_set1_epi16(SNDMIX_REFLECTIONS_DELAY_MASK);
		while(nSamples--)
		{
			delayPos = _mm_and_si128(_mm_add_epi16(delayInc, delayPos), delayMask);
			_mm_storeu_si128(&pos.xmm, delayPos);
			__m128i ref12 = _mm_set_epi32(refDelayBuffer[pos.i[1]].lr, refDelayBuffer[pos.i[1]].lr, refDelayBuffer[pos.i[0]].lr, refDelayBuffer[pos.i[0]].lr);
			__m128i ref34 = _mm_set_epi32(refDelayBuffer[pos.i[3]].lr, refDelayBuffer[pos.i[3]].lr, refDelayBuffer[pos.i[2]].lr, refDelayBuffer[pos.i[2]].lr);
			__m128i ref56 = _mm_set_epi32(refDelayBuffer[pos.i[5]].lr, refDelayBuffer[pos.i[5]].lr, refDelayBuffer[pos.i[4]].lr, refDelayBuffer[pos.i[4]].lr);
			__m128i ref78 = _mm_set_epi32(0,                           0,                           refDelayBuffer[pos.i[6]].lr, refDelayBuffer[pos.i[6]].lr);
			// First stage
			__m128i refOut1 = _mm_add_epi32(_mm_madd_epi16(ref12, gain12), _mm_madd_epi16(ref34, gain34));
			refOut1 = _mm_srai_epi32(_mm_add_epi32(refOut1, _mm_shuffle_epi32(refOut1, _MM_SHUFFLE(1, 0, 3, 2))), 15);

			// Second stage
			__m128i refOut2 = _mm_add_epi32(_mm_madd_epi16(ref56, gain56), _mm_madd_epi16(ref78, gain78));
			refOut2 = _mm_srai_epi32(_mm_add_epi32(refOut2, _mm_shuffle_epi32(refOut2, _MM_SHUFFLE(1, 0, 3, 2))), 15);

			// Saturate to 16-bit and sum stages
			__m128i refOut = _mm_adds_epi16(_mm_packs_epi32(refOut1, refOut1), _mm_packs_epi32(refOut2, refOut2));
			pRefOut->lr = _mm_cvtsi128_si32(refOut);
			pRefOut++;

			__m128i out = _mm_madd_epi16(_mm_unpacklo_epi16(refOut, refOut), refGain);	// Apply reflections gain
			// At this, point, this is the only output of the reverb
			mpt_mm_storeu_si64(pOut, out);
			pOut += 2;
		}
		return;
	}
#endif
	int pos[7];
	for(int i = 0; i < 7; i++)
		pos[i] = pPreDelay->nDelayPos - pPreDelay->Reflections[i].Delay - 1;
	// For 28-bit final output: 16+15-3 = 28
	int16 refGain = pPreDelay->ReflectionsGain.c.l / (1 << 3);
	while(nSamples--)
	{
		// First stage
		int32 refOutL = 0, refOutR = 0;
		for(int i = 0; i < 4; i++)
		{
			pos[i] = (pos[i] + 1) & SNDMIX_REFLECTIONS_DELAY_MASK;
			int16 refL = pPreDelay->RefDelayBuffer[pos[i]].c.l, refR = pPreDelay->RefDelayBuffer[pos[i]].c.r;
			refOutL += refL * pPreDelay->Reflections[i].Gains[0].c.l + refR * pPreDelay->Reflections[i].Gains[0].c.r;
			refOutR += refL * pPreDelay->Reflections[i].Gains[1].c.l + refR * pPreDelay->Reflections[i].Gains[1].c.r;
		}
		int16 stage1l = mpt::saturate_cast<int16>(refOutL / (1 << 15));
		int16 stage1r = mpt::saturate_cast<int16>(refOutR / (1 << 15));
		// Second stage
		refOutL = 0;
		refOutR = 0;
		for(int i = 4; i < 7; i++)
		{
			pos[i] = (pos[i] + 1) & SNDMIX_REFLECTIONS_DELAY_MASK;
			int16 refL = pPreDelay->RefDelayBuffer[pos[i]].c.l, refR = pPreDelay->RefDelayBuffer[pos[i]].c.r;
			refOutL += refL * pPreDelay->Reflections[i].Gains[0].c.l + refR * pPreDelay->Reflections[i].Gains[0].c.r;
			refOutR += refL * pPreDelay->Reflections[i].Gains[1].c.l + refR * pPreDelay->Reflections[i].Gains[1].c.r;
		}
		pOut[0] = (pRefOut->c.l = mpt::saturate_cast<int16>(stage1l + refOutL / (1 << 15))) * refGain;
		pOut[1] = (pRefOut->c.r = mpt::saturate_cast<int16>(stage1r + refOutR / (1 << 15))) * refGain;
		pRefOut++;
		pOut += 2;
	}
}


//////////////////////////////////////////////////////////////////////////
//
// Late reverberation (with SW reflections)
//

void CReverb::ProcessLateReverb(SWLateReverb * MPT_RESTRICT pReverb, LR16 * MPT_RESTRICT pRefOut, int32 * MPT_RESTRICT pMixOut, uint32 nSamples)
{
	// Calculate delay line offset from current delay position
	#define DELAY_OFFSET(x) ((delayPos - (x)) & RVBDLY_MASK)

#if defined(MPT_WANT_ARCH_INTRINSICS_X86_SSE2) && defined(MPT_ARCH_INTRINSICS_X86_SSE2)
	if(CPU::HasFeatureSetAndModesEnabled(CPU::feature::sse2, CPU::mode::xmm128sse))
	{
		mpt::arch::feature_fence_guard arch_feature_guard;
		int delayPos = pReverb->nDelayPos & RVBDLY_MASK;
		__m128i rvbOutGains = mpt_mm_loadu_si64(pReverb->RvbOutGains);
		__m128i difCoeffs = mpt_mm_loadu_si64(pReverb->nDifCoeffs);
		__m128i decayLP = mpt_mm_loadu_si64(pReverb->nDecayLP);
		__m128i lpHistory = mpt_mm_loadu_si64(pReverb->LPHistory);
		while(nSamples--)
		{
			__m128i refIn = _mm_cvtsi32_si128(pRefOut->lr);	// 16-bit stereo input
			pRefOut++;

			__m128i delay2 = _mm_unpacklo_epi32(
				_mm_cvtsi32_si128(pReverb->Delay2[DELAY_OFFSET(RVBDLY2L_LEN)].lr),
				_mm_cvtsi32_si128(pReverb->Delay2[DELAY_OFFSET(RVBDLY2R_LEN)].lr));

			// Unsigned to avoid sign extension
			uint16 diff1L = pReverb->Diffusion1[DELAY_OFFSET(RVBDIF1L_LEN)].c.l;
			uint16 diff1R = pReverb->Diffusion1[DELAY_OFFSET(RVBDIF1R_LEN)].c.r;
			int32 diffusion1 = diff1L | (diff1R << 16);	// diffusion1 history

			uint16 diff2L = pReverb->Diffusion2[DELAY_OFFSET(RVBDIF2L_LEN)].c.l;
			uint16 diff2R = pReverb->Diffusion2[DELAY_OFFSET(RVBDIF2R_LEN)].c.r;
			int32 diffusion2 = diff2L | (diff2R << 16);	// diffusion2 history

			__m128i lpDecay = _mm_mulhi_epi16(_mm_subs_epi16(lpHistory, delay2), decayLP);
			lpHistory = _mm_adds_epi16(_mm_adds_epi16(lpDecay, lpDecay), delay2);	// Low-passed decay

			// Apply decay gain
			__m128i histDecay = _mm_srai_epi32(_mm_madd_epi16(mpt_mm_loadu_si64(pReverb->nDecayDC), lpHistory), 15);
			__m128i histDecayPacked = _mm_shuffle_epi32(_mm_packs_epi32(histDecay, histDecay), _MM_SHUFFLE(2, 0, 2, 0));
			__m128i histDecayIn = _mm_adds_epi16(histDecayPacked, _mm_srai_epi16(_mm_unpacklo_epi32(refIn, refIn), 2));
			__m128i histDecayInDiff = _mm_subs_epi16(histDecayIn, _mm_mulhi_epi16(_mm_cvtsi32_si128(diffusion1), difCoeffs));
			pReverb->Diffusion1[delayPos].lr = _mm_cvtsi128_si32(histDecayInDiff);

			__m128i delay1Out = _mm_adds_epi16(_mm_mulhi_epi16(difCoeffs, histDecayInDiff), _mm_cvtsi32_si128(diffusion1));
			// Insert the diffusion output in the reverb delay line
			pReverb->Delay1[delayPos].lr = _mm_cvtsi128_si32(delay1Out);
			__m128i histDecayInDelay = _mm_adds_epi16(histDecayIn, _mm_unpacklo_epi32(delay1Out, delay1Out));

			// Input to second diffuser
			__m128i delay1 = _mm_unpacklo_epi32(
				_mm_cvtsi32_si128(pReverb->Delay1[DELAY_OFFSET(RVBDLY1L_LEN)].lr),
				_mm_cvtsi32_si128(pReverb->Delay1[DELAY_OFFSET(RVBDLY1R_LEN)].lr));

			__m128i delay1Gains = _mm_srai_epi32(_mm_madd_epi16(delay1, mpt_mm_loadu_si64(pReverb->Dif2InGains)), 15);
			__m128i delay1GainsSat = _mm_shuffle_epi32(_mm_packs_epi32(delay1Gains, delay1Gains), _MM_SHUFFLE(2, 0, 2, 0));
			__m128i histDelay1 = _mm_subs_epi16(_mm_adds_epi16(histDecayInDelay, delay1), delay1GainsSat);	// accumulate with reverb output
			__m128i diff2out = _mm_subs_epi16(delay1GainsSat, _mm_mulhi_epi16(_mm_cvtsi32_si128(diffusion2), difCoeffs));
			__m128i diff2outCoeffs = _mm_mulhi_epi16(difCoeffs, diff2out);
			pReverb->Diffusion2[delayPos].lr = _mm_cvtsi128_si32(diff2out);

			__m128i mixOut = mpt_mm_loadu_si64(pMixOut);
			__m128i delay2out = _mm_adds_epi16(diff2outCoeffs, _mm_cvtsi32_si128(diffusion2));
			pReverb->Delay2[delayPos].lr = _mm_cvtsi128_si32(delay2out);
			delayPos = (delayPos + 1) & RVBDLY_MASK;
			// Accumulate with reverb output
			__m128i out = _mm_add_epi32(_mm_madd_epi16(_mm_adds_epi16(histDelay1, delay2out), rvbOutGains), mixOut);
			mpt_mm_storeu_si64(pMixOut, out);
			pMixOut += 2;
		}
		mpt_mm_storeu_si64(pReverb->LPHistory, lpHistory);
		pReverb->nDelayPos = delayPos;
		return;
	}
#endif
	int delayPos = pReverb->nDelayPos & RVBDLY_MASK;
	while(nSamples--)
	{
		int16 refInL = pRefOut->c.l, refInR = pRefOut->c.r;
		pRefOut++;

		int32 delay2LL = pReverb->Delay2[DELAY_OFFSET(RVBDLY2L_LEN)].c.l, delay2LR = pReverb->Delay2[DELAY_OFFSET(RVBDLY2L_LEN)].c.r;
		int32 delay2RL = pReverb->Delay2[DELAY_OFFSET(RVBDLY2R_LEN)].c.l, delay2RR = pReverb->Delay2[DELAY_OFFSET(RVBDLY2R_LEN)].c.r;

		int32 diff1L = pReverb->Diffusion1[DELAY_OFFSET(RVBDIF1L_LEN)].c.l;
		int32 diff1R = pReverb->Diffusion1[DELAY_OFFSET(RVBDIF1R_LEN)].c.r;

		int32 diff2L = pReverb->Diffusion2[DELAY_OFFSET(RVBDIF2L_LEN)].c.l;
		int32 diff2R = pReverb->Diffusion2[DELAY_OFFSET(RVBDIF2R_LEN)].c.r;

		int32 lpDecayLL = Clamp16(pReverb->LPHistory[0].c.l - delay2LL) * pReverb->nDecayLP[0].c.l / 65536;
		int32 lpDecayLR = Clamp16(pReverb->LPHistory[0].c.r - delay2LR) * pReverb->nDecayLP[0].c.r / 65536;
		int32 lpDecayRL = Clamp16(pReverb->LPHistory[1].c.l - delay2RL) * pReverb->nDecayLP[1].c.l / 65536;
		int32 lpDecayRR = Clamp16(pReverb->LPHistory[1].c.r - delay2RR) * pReverb->nDecayLP[1].c.r / 65536;
		// Low-passed decay
		pReverb->LPHistory[0].c.l = mpt::saturate_cast<int16>(Clamp16(lpDecayLL + lpDecayLL) + delay2LL);
		pReverb->LPHistory[0].c.r = mpt::saturate_cast<int16>(Clamp16(lpDecayLR + lpDecayLR) + delay2LR);
		pReverb->LPHistory[1].c.l = mpt::saturate_cast<int16>(Clamp16(lpDecayRL + lpDecayRL) + delay2RL);
		pReverb->LPHistory[1].c.r = mpt::saturate_cast<int16>(Clamp16(lpDecayRR + lpDecayRR) + delay2RR);

		// Apply decay gain
		int32 histDecayL = Clamp16((int32)pReverb->nDecayDC[0].c.l * pReverb->LPHistory[0].c.l / (1 << 15));
		int32 histDecayR = Clamp16((int32)pReverb->nDecayDC[1].c.r * pReverb->LPHistory[1].c.r / (1 << 15));
		int32 histDecayInL = Clamp16(histDecayL + refInL / 4);
		int32 histDecayInR = Clamp16(histDecayR + refInR / 4);
		int32 histDecayInDiffL = Clamp16(histDecayInL - diff1L * pReverb->nDifCoeffs[0].c.l / 65536);
		int32 histDecayInDiffR = Clamp16(histDecayInR - diff1R * pReverb->nDifCoeffs[0].c.r / 65536);
		pReverb->Diffusion1[delayPos].c.l = static_cast<int16>(histDecayInDiffL);
		pReverb->Diffusion1[delayPos].c.r = static_cast<int16>(histDecayInDiffR);

		int32 delay1L = Clamp16(pReverb->nDifCoeffs[0].c.l * histDecayInDiffL / 65536 + diff1L);
		int32 delay1R = Clamp16(pReverb->nDifCoeffs[0].c.r * histDecayInDiffR / 65536 + diff1R);
		// Insert the diffusion output in the reverb delay line
		pReverb->Delay1[delayPos].c.l = static_cast<int16>(delay1L);
		pReverb->Delay1[delayPos].c.r = static_cast<int16>(delay1R);
		int32 histDecayInDelayL = Clamp16(histDecayInL + delay1L);
		int32 histDecayInDelayR = Clamp16(histDecayInR + delay1R);

		// Input to second diffuser
		int32 delay1LL = pReverb->Delay1[DELAY_OFFSET(RVBDLY1L_LEN)].c.l, delay1LR = pReverb->Delay1[DELAY_OFFSET(RVBDLY1L_LEN)].c.r;
		int32 delay1RL = pReverb->Delay1[DELAY_OFFSET(RVBDLY1R_LEN)].c.l, delay1RR = pReverb->Delay1[DELAY_OFFSET(RVBDLY1R_LEN)].c.r;

		int32 delay1GainsL = Clamp16((delay1LL * pReverb->Dif2InGains[0].c.l + delay1LR * pReverb->Dif2InGains[0].c.r) / (1 << 15));
		int32 delay1GainsR = Clamp16((delay1RL * pReverb->Dif2InGains[1].c.l + delay1RR * pReverb->Dif2InGains[1].c.r) / (1 << 15));

		// accumulate with reverb output
		int32 histDelay1LL = Clamp16(Clamp16(histDecayInDelayL + delay1LL) - delay1GainsL);
		int32 histDelay1LR = Clamp16(Clamp16(histDecayInDelayR + delay1LR) - delay1GainsR);
		int32 histDelay1RL = Clamp16(Clamp16(histDecayInDelayL + delay1RL) - delay1GainsL);
		int32 histDelay1RR = Clamp16(Clamp16(histDecayInDelayR + delay1RR) - delay1GainsR);
		int32 diff2outL = Clamp16(delay1GainsL - diff2L * pReverb->nDifCoeffs[0].c.l / 65536);
		int32 diff2outR = Clamp16(delay1GainsR - diff2R * pReverb->nDifCoeffs[0].c.r / 65536);
		int32 diff2outCoeffsL = pReverb->nDifCoeffs[0].c.l * diff2outL / 65536;
		int32 diff2outCoeffsR = pReverb->nDifCoeffs[0].c.r * diff2outR / 65536;
		pReverb->Diffusion2[delayPos].c.l = static_cast<int16>(diff2outL);
		pReverb->Diffusion2[delayPos].c.r = static_cast<int16>(diff2outR);

		int32 delay2outL = Clamp16(diff2outCoeffsL + diff2L);
		int32 delay2outR = Clamp16(diff2outCoeffsR + diff2R);
		pReverb->Delay2[delayPos].c.l = static_cast<int16>(delay2outL);
		pReverb->Delay2[delayPos].c.r = static_cast<int16>(delay2outR);
		delayPos = (delayPos + 1) & RVBDLY_MASK;
		// Accumulate with reverb output
		pMixOut[0] += Clamp16(histDelay1LL + delay2outL) * pReverb->RvbOutGains[0].c.l + Clamp16(histDelay1LR + delay2outR) * pReverb->RvbOutGains[0].c.r;
		pMixOut[1] += Clamp16(histDelay1RL + Clamp16(diff2outCoeffsL)) * pReverb->RvbOutGains[1].c.l + Clamp16(histDelay1RR + Clamp16(diff2outCoeffsR)) * pReverb->RvbOutGains[1].c.r;
		pMixOut += 2;
	}
	pReverb->nDelayPos = delayPos;

	#undef DELAY_OFFSET
}


#else


MPT_MSVC_WORKAROUND_LNK4221(Reverb)


#endif // NO_REVERB


OPENMPT_NAMESPACE_END

