#include "spu.h"
#include "cdrom.h"
#include "common/audio_stream.h"
#include "common/log.h"
#include "common/state_wrapper.h"
#include "common/wav_writer.h"
#include "dma.h"
#include "host_interface.h"
#include "interrupt_controller.h"
#include "system.h"
#ifdef WITH_IMGUI
#include "imgui.h"
#endif
Log_SetChannel(SPU);

SPU g_spu;

SPU::SPU() = default;

SPU::~SPU() = default;

void SPU::Initialize()
{
  // (X * D) / N / 768 -> (X * D) / (N * 768)
  m_cpu_ticks_per_spu_tick = System::ScaleTicksToOverclock(SYSCLK_TICKS_PER_SPU_TICK);
  m_cpu_tick_divider = static_cast<TickCount>(g_settings.cpu_overclock_numerator * SYSCLK_TICKS_PER_SPU_TICK);
  m_tick_event = TimingEvents::CreateTimingEvent("SPU Sample", m_cpu_ticks_per_spu_tick, m_cpu_ticks_per_spu_tick,
                                                 std::bind(&SPU::Execute, this, std::placeholders::_1), false);
  m_transfer_event =
    TimingEvents::CreateTimingEvent("SPU Transfer", TRANSFER_TICKS_PER_HALFWORD, TRANSFER_TICKS_PER_HALFWORD,
                                    std::bind(&SPU::ExecuteTransfer, this, std::placeholders::_1), false);

  Reset();
}

void SPU::CPUClockChanged()
{
  // (X * D) / N / 768 -> (X * D) / (N * 768)
  m_cpu_ticks_per_spu_tick = System::ScaleTicksToOverclock(SYSCLK_TICKS_PER_SPU_TICK);
  m_cpu_tick_divider = static_cast<TickCount>(g_settings.cpu_overclock_numerator * SYSCLK_TICKS_PER_SPU_TICK);
  m_ticks_carry = 0;
  UpdateEventInterval();
}

void SPU::Shutdown()
{
  m_tick_event.reset();
  m_transfer_event.reset();
  m_dump_writer.reset();
}

void SPU::Reset()
{
  m_ticks_carry = 0;

  m_SPUCNT.bits = 0;
  m_SPUSTAT.bits = 0;
  m_transfer_address = 0;
  m_transfer_address_reg = 0;
  m_irq_address = 0;
  m_capture_buffer_position = 0;
  m_main_volume_left_reg.bits = 0;
  m_main_volume_right_reg.bits = 0;
  m_main_volume_left = {};
  m_main_volume_right = {};
  m_cd_audio_volume_left = 0;
  m_cd_audio_volume_right = 0;
  m_external_volume_left = 0;
  m_external_volume_right = 0;
  m_key_on_register = 0;
  m_key_off_register = 0;
  m_endx_register = 0;
  m_pitch_modulation_enable_register = 0;

  m_noise_mode_register = 0;
  m_noise_count = 0;
  m_noise_level = 1;

  m_reverb_on_register = 0;
  m_reverb_registers = {};
  m_reverb_registers.mBASE = 0;
  m_reverb_base_address = m_reverb_current_address = ZeroExtend32(m_reverb_registers.mBASE) << 2;
  m_reverb_downsample_buffer = {};
  m_reverb_upsample_buffer = {};
  m_reverb_resample_buffer_position = 0;

  for (u32 i = 0; i < NUM_VOICES; i++)
  {
    Voice& v = m_voices[i];
    v.current_address = 0;
    std::fill_n(v.regs.index, NUM_VOICE_REGISTERS, u16(0));
    v.counter.bits = 0;
    v.current_block_flags.bits = 0;
    v.current_block_samples.fill(s16(0));
    v.previous_block_last_samples.fill(s16(0));
    v.adpcm_last_samples.fill(s32(0));
    v.adsr_envelope.Reset(0, false, false);
    v.adsr_phase = ADSRPhase::Off;
    v.adsr_target = 0;
    v.has_samples = false;
    v.ignore_loop_address = false;
  }

  m_transfer_fifo.Clear();
  m_transfer_event->Deactivate();
  m_ram.fill(0);
  UpdateEventInterval();
}

bool SPU::DoState(StateWrapper& sw)
{
  sw.Do(&m_ticks_carry);
  sw.Do(&m_SPUCNT.bits);
  sw.Do(&m_SPUSTAT.bits);
  sw.Do(&m_transfer_control.bits);
  sw.Do(&m_transfer_address);
  sw.Do(&m_transfer_address_reg);
  sw.Do(&m_irq_address);
  sw.Do(&m_capture_buffer_position);
  sw.Do(&m_main_volume_left_reg.bits);
  sw.Do(&m_main_volume_right_reg.bits);
  sw.DoPOD(&m_main_volume_left);
  sw.DoPOD(&m_main_volume_right);
  sw.Do(&m_cd_audio_volume_left);
  sw.Do(&m_cd_audio_volume_right);
  sw.Do(&m_external_volume_left);
  sw.Do(&m_external_volume_right);
  sw.Do(&m_key_on_register);
  sw.Do(&m_key_off_register);
  sw.Do(&m_endx_register);
  sw.Do(&m_pitch_modulation_enable_register);
  sw.Do(&m_noise_mode_register);
  sw.Do(&m_noise_count);
  sw.Do(&m_noise_level);
  sw.Do(&m_reverb_on_register);
  sw.Do(&m_reverb_base_address);
  sw.Do(&m_reverb_current_address);
  sw.Do(&m_reverb_registers.vLOUT);
  sw.Do(&m_reverb_registers.vROUT);
  sw.Do(&m_reverb_registers.mBASE);
  sw.DoArray(m_reverb_registers.rev, NUM_REVERB_REGS);
  for (u32 i = 0; i < 2; i++)
    sw.DoArray(m_reverb_downsample_buffer.data(), m_reverb_downsample_buffer.size());
  for (u32 i = 0; i < 2; i++)
    sw.DoArray(m_reverb_upsample_buffer.data(), m_reverb_upsample_buffer.size());
  sw.Do(&m_reverb_resample_buffer_position);
  for (u32 i = 0; i < NUM_VOICES; i++)
  {
    Voice& v = m_voices[i];
    sw.Do(&v.current_address);
    sw.DoArray(v.regs.index, NUM_VOICE_REGISTERS);
    sw.Do(&v.counter.bits);
    sw.Do(&v.current_block_flags.bits);
    sw.Do(&v.current_block_samples);
    sw.Do(&v.previous_block_last_samples);
    sw.Do(&v.adpcm_last_samples);
    sw.Do(&v.last_volume);
    sw.DoPOD(&v.left_volume);
    sw.DoPOD(&v.right_volume);
    sw.DoPOD(&v.adsr_envelope);
    sw.Do(&v.adsr_phase);
    sw.Do(&v.adsr_target);
    sw.Do(&v.has_samples);
    sw.Do(&v.ignore_loop_address);
  }

  sw.Do(&m_transfer_fifo);
  sw.DoBytes(m_ram.data(), RAM_SIZE);

  if (sw.IsReading())
  {
    g_host_interface->GetAudioStream()->EmptyBuffers();
    UpdateEventInterval();
    UpdateTransferEvent();
  }

  return !sw.HasError();
}

u16 SPU::ReadRegister(u32 offset)
{
  switch (offset)
  {
    case 0x1F801D80 - SPU_BASE:
      return m_main_volume_left_reg.bits;

    case 0x1F801D82 - SPU_BASE:
      return m_main_volume_right_reg.bits;

    case 0x1F801D84 - SPU_BASE:
      return m_reverb_registers.vLOUT;

    case 0x1F801D86 - SPU_BASE:
      return m_reverb_registers.vROUT;

    case 0x1F801D88 - SPU_BASE:
      return Truncate16(m_key_on_register);

    case 0x1F801D8A - SPU_BASE:
      return Truncate16(m_key_on_register >> 16);

    case 0x1F801D8C - SPU_BASE:
      return Truncate16(m_key_off_register);

    case 0x1F801D8E - SPU_BASE:
      return Truncate16(m_key_off_register >> 16);

    case 0x1F801D90 - SPU_BASE:
      return Truncate16(m_pitch_modulation_enable_register);

    case 0x1F801D92 - SPU_BASE:
      return Truncate16(m_pitch_modulation_enable_register >> 16);

    case 0x1F801D94 - SPU_BASE:
      return Truncate16(m_noise_mode_register);

    case 0x1F801D96 - SPU_BASE:
      return Truncate16(m_noise_mode_register >> 16);

    case 0x1F801D98 - SPU_BASE:
      return Truncate16(m_reverb_on_register);

    case 0x1F801D9A - SPU_BASE:
      return Truncate16(m_reverb_on_register >> 16);

    case 0x1F801D9C - SPU_BASE:
      return Truncate16(m_endx_register);

    case 0x1F801D9E - SPU_BASE:
      return Truncate16(m_endx_register >> 16);

    case 0x1F801DA2 - SPU_BASE:
      return m_reverb_registers.mBASE;

    case 0x1F801DA4 - SPU_BASE:
      Log_TracePrintf("SPU IRQ address -> 0x%04X", ZeroExtend32(m_irq_address));
      return m_irq_address;

    case 0x1F801DA6 - SPU_BASE:
      Log_TracePrintf("SPU transfer address register -> 0x%04X", ZeroExtend32(m_transfer_address_reg));
      return m_transfer_address_reg;

    case 0x1F801DA8 - SPU_BASE:
      Log_TracePrintf("SPU transfer data register read");
      return UINT16_C(0xFFFF);

    case 0x1F801DAA - SPU_BASE:
      Log_TracePrintf("SPU control register -> 0x%04X", ZeroExtend32(m_SPUCNT.bits));
      return m_SPUCNT.bits;

    case 0x1F801DAC - SPU_BASE:
      Log_TracePrintf("SPU transfer control register -> 0x%04X", ZeroExtend32(m_transfer_control.bits));
      return m_transfer_control.bits;

    case 0x1F801DAE - SPU_BASE:
      m_tick_event->InvokeEarly();
      m_transfer_event->InvokeEarly();
      Log_TracePrintf("SPU status register -> 0x%04X", ZeroExtend32(m_SPUCNT.bits));
      return m_SPUSTAT.bits;

    case 0x1F801DB0 - SPU_BASE:
      return m_cd_audio_volume_left;

    case 0x1F801DB2 - SPU_BASE:
      return m_cd_audio_volume_right;

    case 0x1F801DB4 - SPU_BASE:
      return m_external_volume_left;

    case 0x1F801DB6 - SPU_BASE:
      return m_external_volume_right;

    case 0x1F801DB8 - SPU_BASE:
      m_tick_event->InvokeEarly();
      return m_main_volume_left.current_level;

    case 0x1F801DBA - SPU_BASE:
      m_tick_event->InvokeEarly();
      return m_main_volume_right.current_level;

    default:
    {
      if (offset < (0x1F801D80 - SPU_BASE))
        return ReadVoiceRegister(offset);

      if (offset >= (0x1F801DC0 - SPU_BASE) && offset < (0x1F801E00 - SPU_BASE))
        return m_reverb_registers.rev[(offset - (0x1F801DC0 - SPU_BASE)) / 2];

      if (offset >= (0x1F801E00 - SPU_BASE) && offset < (0x1F801E60 - SPU_BASE))
      {
        const u32 voice_index = (offset - (0x1F801E00 - SPU_BASE)) / 4;
        m_tick_event->InvokeEarly();
        if (offset & 0x02)
          return m_voices[voice_index].left_volume.current_level;
        else
          return m_voices[voice_index].right_volume.current_level;
      }

      Log_ErrorPrintf("Unknown SPU register read: offset 0x%X (address 0x%08X)", offset, offset | SPU_BASE);
      return UINT16_C(0xFFFF);
    }
  }
}

void SPU::WriteRegister(u32 offset, u16 value)
{
  switch (offset)
  {
    case 0x1F801D80 - SPU_BASE:
    {
      Log_DebugPrintf("SPU main volume left <- 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly();
      m_main_volume_left_reg.bits = value;
      m_main_volume_left.Reset(m_main_volume_left_reg);
      return;
    }

    case 0x1F801D82 - SPU_BASE:
    {
      Log_DebugPrintf("SPU main volume right <- 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly();
      m_main_volume_right_reg.bits = value;
      m_main_volume_right.Reset(m_main_volume_right_reg);
      return;
    }

    case 0x1F801D84 - SPU_BASE:
    {
      Log_DebugPrintf("SPU reverb output volume left <- 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly();
      m_reverb_registers.vLOUT = value;
      return;
    }

    case 0x1F801D86 - SPU_BASE:
    {
      Log_DebugPrintf("SPU reverb output volume right <- 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly();
      m_reverb_registers.vROUT = value;
      return;
    }

    case 0x1F801D88 - SPU_BASE:
    {
      Log_DebugPrintf("SPU key on low <- 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly();
      m_key_on_register = (m_key_on_register & 0xFFFF0000) | ZeroExtend32(value);
    }
    break;

    case 0x1F801D8A - SPU_BASE:
    {
      Log_DebugPrintf("SPU key on high <- 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly();
      m_key_on_register = (m_key_on_register & 0x0000FFFF) | (ZeroExtend32(value) << 16);
    }
    break;

    case 0x1F801D8C - SPU_BASE:
    {
      Log_DebugPrintf("SPU key off low <- 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly();
      m_key_off_register = (m_key_off_register & 0xFFFF0000) | ZeroExtend32(value);
    }
    break;

    case 0x1F801D8E - SPU_BASE:
    {
      Log_DebugPrintf("SPU key off high <- 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly();
      m_key_off_register = (m_key_off_register & 0x0000FFFF) | (ZeroExtend32(value) << 16);
    }
    break;

    case 0x1F801D90 - SPU_BASE:
    {
      m_tick_event->InvokeEarly();
      m_pitch_modulation_enable_register = (m_pitch_modulation_enable_register & 0xFFFF0000) | ZeroExtend32(value);
      Log_DebugPrintf("SPU pitch modulation enable register <- 0x%08X", m_pitch_modulation_enable_register);
    }
    break;

    case 0x1F801D92 - SPU_BASE:
    {
      m_tick_event->InvokeEarly();
      m_pitch_modulation_enable_register =
        (m_pitch_modulation_enable_register & 0x0000FFFF) | (ZeroExtend32(value) << 16);
      Log_DebugPrintf("SPU pitch modulation enable register <- 0x%08X", m_pitch_modulation_enable_register);
    }
    break;

    case 0x1F801D94 - SPU_BASE:
    {
      Log_DebugPrintf("SPU noise mode register <- 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly();
      m_noise_mode_register = (m_noise_mode_register & 0xFFFF0000) | ZeroExtend32(value);
    }
    break;

    case 0x1F801D96 - SPU_BASE:
    {
      Log_DebugPrintf("SPU noise mode register <- 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly();
      m_noise_mode_register = (m_noise_mode_register & 0x0000FFFF) | (ZeroExtend32(value) << 16);
    }
    break;

    case 0x1F801D98 - SPU_BASE:
    {
      Log_DebugPrintf("SPU reverb on register <- 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly();
      m_reverb_on_register = (m_reverb_on_register & 0xFFFF0000) | ZeroExtend32(value);
    }
    break;

    case 0x1F801D9A - SPU_BASE:
    {
      Log_DebugPrintf("SPU reverb on register <- 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly();
      m_reverb_on_register = (m_reverb_on_register & 0x0000FFFF) | (ZeroExtend32(value) << 16);
    }
    break;

    case 0x1F801DA2 - SPU_BASE:
    {
      Log_DebugPrintf("SPU reverb base address < 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly();
      m_reverb_registers.mBASE = value;
      m_reverb_base_address = ZeroExtend32(value << 2) & 0x3FFFFu;
      m_reverb_current_address = m_reverb_base_address;
    }
    break;

    case 0x1F801DA4 - SPU_BASE:
    {
      Log_DebugPrintf("SPU IRQ address register <- 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly();
      m_irq_address = value;
      return;
    }

    case 0x1F801DA6 - SPU_BASE:
    {
      Log_DebugPrintf("SPU transfer address register <- 0x%04X", ZeroExtend32(value));
      m_transfer_address_reg = value;
      m_transfer_address = ZeroExtend32(value) * 8;
      return;
    }

    case 0x1F801DA8 - SPU_BASE:
    {
      Log_TracePrintf("SPU transfer data register <- 0x%04X (RAM offset 0x%08X)", ZeroExtend32(value),
                      m_transfer_address);

      ManualTransferWrite(value);
      return;
    }

    case 0x1F801DAA - SPU_BASE:
    {
      Log_DebugPrintf("SPU control register <- 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly(true);

      const SPUCNT new_value{value};
      if (new_value.ram_transfer_mode != m_SPUCNT.ram_transfer_mode &&
          new_value.ram_transfer_mode == RAMTransferMode::Stopped)
      {
        // clear the fifo here?
        if (!m_transfer_fifo.IsEmpty())
        {
          Log_WarningPrintf("Clearing SPU transfer FIFO with %u bytes left", m_transfer_fifo.GetSize());
          m_transfer_fifo.Clear();
        }
      }

      if (!new_value.enable && m_SPUCNT.enable)
      {
        // Mute all voices.
        // Interestingly, hardware tests found this seems to happen immediately, not on the next 44100hz cycle.
        for (u32 i = 0; i < NUM_VOICES; i++)
          m_voices[i].ForceOff();
      }

      m_SPUCNT.bits = new_value.bits;
      m_SPUSTAT.mode = m_SPUCNT.mode.GetValue();

      if (!m_SPUCNT.irq9_enable)
        m_SPUSTAT.irq9_flag = false;

      UpdateEventInterval();
      UpdateDMARequest();
      UpdateTransferEvent();
      return;
    }

    case 0x1F801DAC - SPU_BASE:
    {
      Log_DebugPrintf("SPU transfer control register <- 0x%04X", ZeroExtend32(value));
      m_transfer_control.bits = value;
      return;
    }

    case 0x1F801DB0 - SPU_BASE:
    {
      Log_DebugPrintf("SPU left cd audio register <- 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly();
      m_cd_audio_volume_left = value;
    }
    break;

    case 0x1F801DB2 - SPU_BASE:
    {
      Log_DebugPrintf("SPU right cd audio register <- 0x%04X", ZeroExtend32(value));
      m_tick_event->InvokeEarly();
      m_cd_audio_volume_right = value;
    }
    break;

    case 0x1F801DB4 - SPU_BASE:
    {
      // External volumes aren't used, so don't bother syncing.
      Log_DebugPrintf("SPU left external volume register <- 0x%04X", ZeroExtend32(value));
      m_external_volume_left = value;
    }
    break;

    case 0x1F801DB6 - SPU_BASE:
    {
      // External volumes aren't used, so don't bother syncing.
      Log_DebugPrintf("SPU right external volume register <- 0x%04X", ZeroExtend32(value));
      m_external_volume_right = value;
    }
    break;

      // read-only registers
    case 0x1F801DAE - SPU_BASE:
    {
      return;
    }

    default:
    {
      if (offset < (0x1F801D80 - SPU_BASE))
      {
        WriteVoiceRegister(offset, value);
        return;
      }

      if (offset >= (0x1F801DC0 - SPU_BASE) && offset < (0x1F801E00 - SPU_BASE))
      {
        const u32 reg = (offset - (0x1F801DC0 - SPU_BASE)) / 2;
        Log_DebugPrintf("SPU reverb register %u <- 0x%04X", reg, value);
        m_tick_event->InvokeEarly();
        m_reverb_registers.rev[reg] = value;
        return;
      }

      Log_ErrorPrintf("Unknown SPU register write: offset 0x%X (address 0x%08X) value 0x%04X", offset,
                      offset | SPU_BASE, ZeroExtend32(value));
      return;
    }
  }
}

u16 SPU::ReadVoiceRegister(u32 offset)
{
  const u32 reg_index = (offset % 0x10) / 2; //(offset & 0x0F) / 2;
  const u32 voice_index = (offset / 0x10);   //((offset >> 4) & 0x1F);
  Assert(voice_index < 24);

  // ADSR volume needs to be updated when reading. A voice might be off as well, but key on is pending.
  const Voice& voice = m_voices[voice_index];
  if (reg_index >= 6 && (voice.IsOn() || m_key_on_register & (1u << voice_index)))
    m_tick_event->InvokeEarly();

  Log_TracePrintf("Read voice %u register %u -> 0x%02X", voice_index, reg_index, voice.regs.index[reg_index]);
  return voice.regs.index[reg_index];
}

void SPU::WriteVoiceRegister(u32 offset, u16 value)
{
  // per-voice registers
  const u32 reg_index = (offset % 0x10);
  const u32 voice_index = (offset / 0x10);
  Assert(voice_index < 24);

  Voice& voice = m_voices[voice_index];
  if (voice.IsOn() || m_key_on_register & (1u << voice_index))
    m_tick_event->InvokeEarly();

  switch (reg_index)
  {
    case 0x00: // volume left
    {
      Log_DebugPrintf("SPU voice %u volume left <- 0x%04X", voice_index, value);
      voice.regs.volume_left.bits = value;
      voice.left_volume.Reset(voice.regs.volume_left);
    }
    break;

    case 0x02: // volume right
    {
      Log_DebugPrintf("SPU voice %u volume right <- 0x%04X", voice_index, value);
      voice.regs.volume_right.bits = value;
      voice.right_volume.Reset(voice.regs.volume_right);
    }
    break;

    case 0x04: // sample rate
    {
      Log_DebugPrintf("SPU voice %u ADPCM sample rate <- 0x%04X", voice_index, value);
      voice.regs.adpcm_sample_rate = value;
    }
    break;

    case 0x06: // start address
    {
      Log_DebugPrintf("SPU voice %u ADPCM start address <- 0x%04X", voice_index, value);
      voice.regs.adpcm_start_address = value;
    }
    break;

    case 0x08: // adsr low
    {
      Log_DebugPrintf("SPU voice %u ADSR low <- 0x%04X (was 0x%04X)", voice_index, value, voice.regs.adsr.bits_low);
      voice.regs.adsr.bits_low = value;
      if (voice.IsOn())
        voice.UpdateADSREnvelope();
    }
    break;

    case 0x0A: // adsr high
    {
      Log_DebugPrintf("SPU voice %u ADSR high <- 0x%04X (was 0x%04X)", voice_index, value, voice.regs.adsr.bits_low);
      voice.regs.adsr.bits_high = value;
      if (voice.IsOn())
        voice.UpdateADSREnvelope();
    }
    break;

    case 0x0C: // adsr volume
    {
      Log_DebugPrintf("SPU voice %u ADSR volume <- 0x%04X (was 0x%04X)", voice_index, value, voice.regs.adsr_volume);
      voice.regs.adsr_volume = value;
    }
    break;

    case 0x0E: // repeat address
    {
      Log_DebugPrintf("SPU voice %u ADPCM repeat address <- 0x%04X", voice_index, value);
      voice.regs.adpcm_repeat_address = value;
      voice.ignore_loop_address = true;
    }
    break;

    default:
    {
      Log_ErrorPrintf("Unknown SPU voice %u register write: offset 0x%X (address 0x%08X) value 0x%04X", offset,
                      voice_index, offset | SPU_BASE, ZeroExtend32(value));
    }
    break;
  }
}

void SPU::CheckRAMIRQ(u32 address)
{
  if (!m_SPUCNT.irq9_enable)
    return;

  if (ZeroExtend32(m_irq_address) * 8 == address)
  {
    Log_DebugPrintf("SPU IRQ at address 0x%08X", address);
    m_SPUSTAT.irq9_flag = true;
    g_interrupt_controller.InterruptRequest(InterruptController::IRQ::SPU);
  }
}

void SPU::WriteToCaptureBuffer(u32 index, s16 value)
{
  const u32 ram_address = (index * CAPTURE_BUFFER_SIZE_PER_CHANNEL) | ZeroExtend16(m_capture_buffer_position);
  // Log_DebugPrintf("write to capture buffer %u (0x%08X) <- 0x%04X", index, ram_address, u16(value));
  std::memcpy(&m_ram[ram_address], &value, sizeof(value));
  CheckRAMIRQ(ram_address);
}

void SPU::IncrementCaptureBufferPosition()
{
  m_capture_buffer_position += sizeof(s16);
  m_capture_buffer_position %= CAPTURE_BUFFER_SIZE_PER_CHANNEL;
  m_SPUSTAT.second_half_capture_buffer = m_capture_buffer_position >= (CAPTURE_BUFFER_SIZE_PER_CHANNEL / 2);
}

void SPU::Execute(TickCount ticks)
{
  u32 remaining_frames;
  if (g_settings.cpu_overclock_active)
  {
    // (X * D) / N / 768 -> (X * D) / (N * 768)
    const u64 num = (static_cast<u64>(ticks) * g_settings.cpu_overclock_denominator) + static_cast<u32>(m_ticks_carry);
    remaining_frames = static_cast<u32>(num / m_cpu_tick_divider);
    m_ticks_carry = static_cast<TickCount>(num % m_cpu_tick_divider);
  }
  else
  {
    remaining_frames = static_cast<u32>((ticks + m_ticks_carry) / SYSCLK_TICKS_PER_SPU_TICK);
    m_ticks_carry = (ticks + m_ticks_carry) % SYSCLK_TICKS_PER_SPU_TICK;
  }

  while (remaining_frames > 0)
  {
    AudioStream* const output_stream = g_host_interface->GetAudioStream();
    s16* output_frame_start;
    u32 output_frame_space = remaining_frames;
    output_stream->BeginWrite(&output_frame_start, &output_frame_space);

    s16* output_frame = output_frame_start;
    const u32 frames_in_this_batch = std::min(remaining_frames, output_frame_space);
    for (u32 i = 0; i < frames_in_this_batch; i++)
    {
      s32 left_sum = 0;
      s32 right_sum = 0;
      s32 reverb_in_left = 0;
      s32 reverb_in_right = 0;

      u32 key_on_register = m_key_on_register;
      m_key_on_register = 0;
      u32 key_off_register = m_key_off_register;
      m_key_off_register = 0;
      u32 reverb_on_register = m_reverb_on_register;

      for (u32 voice = 0; voice < NUM_VOICES; voice++)
      {
        const auto [left, right] = SampleVoice(voice);
        left_sum += left;
        right_sum += right;

        if (reverb_on_register & 1u)
        {
          reverb_in_left += left;
          reverb_in_right += right;
        }
        reverb_on_register >>= 1;

        if (key_off_register & 1u)
          m_voices[voice].KeyOff();
        key_off_register >>= 1;

        if (key_on_register & 1u)
        {
          m_endx_register &= ~(1u << voice);
          m_voices[voice].KeyOn();
        }
        key_on_register >>= 1;
      }

      if (!m_SPUCNT.mute_n)
      {
        left_sum = 0;
        right_sum = 0;
      }

      // Update noise once per frame.
      UpdateNoise();

      // Mix in CD audio.
      const auto [cd_audio_left, cd_audio_right] = g_cdrom.GetAudioFrame();
      if (m_SPUCNT.cd_audio_enable)
      {
        const s32 cd_audio_volume_left = ApplyVolume(s32(cd_audio_left), m_cd_audio_volume_left);
        const s32 cd_audio_volume_right = ApplyVolume(s32(cd_audio_right), m_cd_audio_volume_right);

        left_sum += cd_audio_volume_left;
        right_sum += cd_audio_volume_right;

        if (m_SPUCNT.cd_audio_reverb)
        {
          reverb_in_left += cd_audio_volume_left;
          reverb_in_right += cd_audio_volume_right;
        }
      }

      // Compute reverb.
      s32 reverb_out_left, reverb_out_right;
      ProcessReverb(static_cast<s16>(Clamp16(reverb_in_left)), static_cast<s16>(Clamp16(reverb_in_right)),
                    &reverb_out_left, &reverb_out_right);

      // Mix in reverb.
      left_sum += reverb_out_left;
      right_sum += reverb_out_right;

      // Apply main volume after clamping. A maximum volume should not overflow here because both are 16-bit values.
      *(output_frame++) = static_cast<s16>(ApplyVolume(Clamp16(left_sum), m_main_volume_left.current_level));
      *(output_frame++) = static_cast<s16>(ApplyVolume(Clamp16(right_sum), m_main_volume_right.current_level));
      m_main_volume_left.Tick();
      m_main_volume_right.Tick();

      // Write to capture buffers.
      WriteToCaptureBuffer(0, cd_audio_left);
      WriteToCaptureBuffer(1, cd_audio_right);
      WriteToCaptureBuffer(2, static_cast<s16>(Clamp16(m_voices[1].last_volume)));
      WriteToCaptureBuffer(3, static_cast<s16>(Clamp16(m_voices[3].last_volume)));
      IncrementCaptureBufferPosition();
    }

    if (m_dump_writer)
      m_dump_writer->WriteFrames(output_frame_start, frames_in_this_batch);

    output_stream->EndWrite(frames_in_this_batch);
    remaining_frames -= frames_in_this_batch;
  }
}

void SPU::UpdateEventInterval()
{
  // Don't generate more than the audio buffer since in a single slice, otherwise we'll both overflow the buffers when
  // we do write it, and the audio thread will underflow since it won't have enough data it the game isn't messing with
  // the SPU state.
  const u32 max_slice_frames = g_host_interface->GetAudioStream()->GetBufferSize();

  // TODO: Make this predict how long until the interrupt will be hit instead...
  const u32 interval = (m_SPUCNT.enable && m_SPUCNT.irq9_enable) ? 1 : max_slice_frames;
  const TickCount interval_ticks = static_cast<TickCount>(interval) * m_cpu_ticks_per_spu_tick;
  if (m_tick_event->IsActive() && m_tick_event->GetInterval() == interval_ticks)
    return;

  // Ensure all pending ticks have been executed, since we won't get them back after rescheduling.
  m_tick_event->InvokeEarly(true);
  m_tick_event->SetInterval(interval_ticks);

  TickCount downcount = interval_ticks;
  if (!g_settings.cpu_overclock_active)
    downcount -= m_ticks_carry;

  m_tick_event->Schedule(downcount);
}

void SPU::ExecuteTransfer(TickCount ticks)
{
  const RAMTransferMode mode = m_SPUCNT.ram_transfer_mode;
  Assert(mode != RAMTransferMode::Stopped);

  if (mode == RAMTransferMode::DMARead)
  {
    while (ticks > 0 && !m_transfer_fifo.IsFull())
    {
      while (ticks > 0 && !m_transfer_fifo.IsFull())
      {
        u16 value;
        std::memcpy(&value, &m_ram[m_transfer_address], sizeof(u16));
        m_transfer_address = (m_transfer_address + sizeof(u16)) & RAM_MASK;
        m_transfer_fifo.Push(value);
        ticks -= TRANSFER_TICKS_PER_HALFWORD;
      }

      // this can result in the FIFO being emptied, hence double the while loop
      UpdateDMARequest();
    }

    // we're done if we have no more data to read
    if (m_transfer_fifo.IsFull())
    {
      m_SPUSTAT.transfer_busy = false;
      m_transfer_event->Deactivate();
      return;
    }

    m_SPUSTAT.transfer_busy = true;
    const TickCount ticks_until_complete =
      TickCount(m_transfer_fifo.GetSpace() * u32(TRANSFER_TICKS_PER_HALFWORD)) + ((ticks < 0) ? -ticks : 0);
    m_transfer_event->Schedule(ticks_until_complete);
  }
  else
  {
    // write the fifo to ram, request dma again when empty
    while (ticks > 0 && !m_transfer_fifo.IsEmpty())
    {
      while (ticks > 0 && !m_transfer_fifo.IsEmpty())
      {
        u16 value = m_transfer_fifo.Pop();
        std::memcpy(&m_ram[m_transfer_address], &value, sizeof(u16));
        m_transfer_address = (m_transfer_address + sizeof(u16)) & RAM_MASK;
        ticks -= TRANSFER_TICKS_PER_HALFWORD;
      }

      // similar deal here, the FIFO can be written out in a long slice
      UpdateDMARequest();
    }

    // we're done if we have no more data to write
    if (m_transfer_fifo.IsEmpty())
    {
      m_SPUSTAT.transfer_busy = false;
      m_transfer_event->Deactivate();
      return;
    }

    m_SPUSTAT.transfer_busy = true;
    const TickCount ticks_until_complete =
      TickCount(m_transfer_fifo.GetSize() * u32(TRANSFER_TICKS_PER_HALFWORD)) + ((ticks < 0) ? -ticks : 0);
    m_transfer_event->Schedule(ticks_until_complete);
  }
}

void SPU::ManualTransferWrite(u16 value)
{
  if (m_transfer_fifo.IsFull())
  {
    Log_WarningPrintf("FIFO full, dropping write of 0x%04X", value);
    return;
  }

  m_transfer_fifo.Push(value);
  UpdateTransferEvent();
}

void SPU::UpdateTransferEvent()
{
  const RAMTransferMode mode = m_SPUCNT.ram_transfer_mode;
  if (mode == RAMTransferMode::Stopped)
  {
    m_transfer_event->Deactivate();
    return;
  }

  if (mode == RAMTransferMode::DMARead)
  {
    // transfer event fills the fifo
    if (m_transfer_fifo.IsFull())
      m_transfer_event->Deactivate();
    else if (!m_transfer_event->IsActive())
      m_transfer_event->Schedule(TickCount(m_transfer_fifo.GetSpace() * u32(TRANSFER_TICKS_PER_HALFWORD)));
  }
  else
  {
    // transfer event copies from fifo to ram
    if (m_transfer_fifo.IsEmpty())
      m_transfer_event->Deactivate();
    else if (!m_transfer_event->IsActive())
      m_transfer_event->Schedule(TickCount(m_transfer_fifo.GetSize() * u32(TRANSFER_TICKS_PER_HALFWORD)));
  }

  m_SPUSTAT.transfer_busy = m_transfer_event->IsActive();
}

void SPU::UpdateDMARequest()
{
  switch (m_SPUCNT.ram_transfer_mode)
  {
    case RAMTransferMode::DMARead:
      m_SPUSTAT.dma_read_request = m_transfer_fifo.IsFull();
      m_SPUSTAT.dma_write_request = false;
      m_SPUSTAT.dma_request = m_SPUSTAT.dma_read_request;
      break;

    case RAMTransferMode::DMAWrite:
      m_SPUSTAT.dma_read_request = false;
      m_SPUSTAT.dma_write_request = m_transfer_fifo.IsEmpty();
      m_SPUSTAT.dma_request = m_SPUSTAT.dma_write_request;
      break;

    case RAMTransferMode::Stopped:
    case RAMTransferMode::ManualWrite:
    default:
      m_SPUSTAT.dma_read_request = false;
      m_SPUSTAT.dma_write_request = false;
      m_SPUSTAT.dma_request = false;
      break;
  }

  // This might call us back directly.
  g_dma.SetRequest(DMA::Channel::SPU, m_SPUSTAT.dma_request);
}

void SPU::DMARead(u32* words, u32 word_count)
{
  /*
    From @JaCzekanski - behavior when block size is larger than the FIFO size
    for blocks <= 0x16 - all data is transferred correctly
    using block size 0x20 transfer behaves strange:
    % Writing 524288 bytes to SPU RAM to 0x00000000 using DMA... ok
    % Reading 256 bytes from SPU RAM from 0x00001000 using DMA... ok
    % 0x00001000: 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f ................
    % 0x00001010: 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f ................
    % 0x00001020: 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f  !"#$%&'()*+,-./
    % 0x00001030: 30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f 0123456789:;<=>?
    % 0x00001040: 3e 3f 3e 3f 3e 3f 3e 3f 3e 3f 3e 3f 3e 3f 3e 3f >?>?>?>?>?>?>?>?
    % 0x00001050: 3e 3f 3e 3f 3e 3f 3e 3f 3e 3f 3e 3f 3e 3f 3e 3f >?>?>?>?>?>?>?>?
    % 0x00001060: 3e 3f 3e 3f 3e 3f 3e 3f 3e 3f 3e 3f 3e 3f 3e 3f >?>?>?>?>?>?>?>?
    % 0x00001070: 3e 3f 3e 3f 3e 3f 3e 3f 3e 3f 3e 3f 3e 3f 3e 3f >?>?>?>?>?>?>?>?
    % 0x00001080: 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f @ABCDEFGHIJKLMNO
    % 0x00001090: 50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f PQRSTUVWXYZ[\]^_
    % 0x000010a0: 60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f `abcdefghijklmno
    % 0x000010b0: 70 71 72 73 74 75 76 77 78 79 7a 7b 7c 7d 7e 7f pqrstuvwxyz{|}~.
    % 0x000010c0: 7e 7f 7e 7f 7e 7f 7e 7f 7e 7f 7e 7f 7e 7f 7e 7f ~.~.~.~.~.~.~.~.
    % 0x000010d0: 7e 7f 7e 7f 7e 7f 7e 7f 7e 7f 7e 7f 7e 7f 7e 7f ~.~.~.~.~.~.~.~.
    % 0x000010e0: 7e 7f 7e 7f 7e 7f 7e 7f 7e 7f 7e 7f 7e 7f 7e 7f ~.~.~.~.~.~.~.~.
    % 0x000010f0: 7e 7f 7e 7f 7e 7f 7e 7f 7e 7f 7e 7f 7e 7f 7e 7f ~.~.~.~.~.~.~.~.
    Using Block size = 0x10 (correct data)
    % Reading 256 bytes from SPU RAM from 0x00001000 using DMA... ok
    % 0x00001000: 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f ................
    % 0x00001010: 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f ................
    % 0x00001020: 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f  !"#$%&'()*+,-./
    % 0x00001030: 30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f 0123456789:;<=>?
    % 0x00001040: 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f @ABCDEFGHIJKLMNO
    % 0x00001050: 50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f PQRSTUVWXYZ[\]^_
    % 0x00001060: 60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f `abcdefghijklmno
    % 0x00001070: 70 71 72 73 74 75 76 77 78 79 7a 7b 7c 7d 7e 7f pqrstuvwxyz{|}~.
    % 0x00001080: 80 81 82 83 84 85 86 87 88 89 8a 8b 8c 8d 8e 8f ................
    % 0x00001090: 90 91 92 93 94 95 96 97 98 99 9a 9b 9c 9d 9e 9f ................
    % 0x000010a0: a0 a1 a2 a3 a4 a5 a6 a7 a8 a9 aa ab ac ad ae af ................
    % 0x000010b0: b0 b1 b2 b3 b4 b5 b6 b7 b8 b9 ba bb bc bd be bf ................
    % 0x000010c0: c0 c1 c2 c3 c4 c5 c6 c7 c8 c9 ca cb cc cd ce cf ................
    % 0x000010d0: d0 d1 d2 d3 d4 d5 d6 d7 d8 d9 da db dc dd de df ................
    % 0x000010e0: e0 e1 e2 e3 e4 e5 e6 e7 e8 e9 ea eb ec ed ee ef ................
    % 0x000010f0: f0 f1 f2 f3 f4 f5 f6 f7 f8 f9 fa fb fc fd fe ff ................
   */

  u16* halfwords = reinterpret_cast<u16*>(words);
  u32 halfword_count = word_count * 2;

  const u32 size = m_transfer_fifo.GetSize();
  if (word_count > size)
  {
    u16 fill_value = 0;
    if (size > 0)
    {
      m_transfer_fifo.PopRange(halfwords, size);
      fill_value = halfwords[size - 1];
    }

    Log_WarningPrintf("Transfer FIFO underflow, filling with 0x%04X", fill_value);
    std::fill_n(&halfwords[size], halfword_count - size, fill_value);
  }
  else
  {
    m_transfer_fifo.PopRange(halfwords, halfword_count);
  }

  UpdateDMARequest();
  UpdateTransferEvent();
}

void SPU::DMAWrite(const u32* words, u32 word_count)
{
  const u16* halfwords = reinterpret_cast<const u16*>(words);
  u32 halfword_count = word_count * 2;

  const u32 words_to_transfer = std::min(m_transfer_fifo.GetSpace(), halfword_count);
  m_transfer_fifo.PushRange(halfwords, words_to_transfer);

  if (words_to_transfer != halfword_count)
    Log_WarningPrintf("Transfer FIFO overflow, dropping %u halfwords", halfword_count - words_to_transfer);

  UpdateDMARequest();
  UpdateTransferEvent();
}

void SPU::GeneratePendingSamples()
{
  m_tick_event->InvokeEarly();
}

bool SPU::StartDumpingAudio(const char* filename)
{
  if (m_dump_writer)
    m_dump_writer.reset();

  m_dump_writer = std::make_unique<Common::WAVWriter>();
  if (!m_dump_writer->Open(filename, SAMPLE_RATE, 2))
  {
    Log_ErrorPrintf("Failed to open '%s'", filename);
    m_dump_writer.reset();
    return false;
  }

  return true;
}

bool SPU::StopDumpingAudio()
{
  if (!m_dump_writer)
    return false;

  m_dump_writer.reset();
  return true;
}

void SPU::Voice::KeyOn()
{
  current_address = regs.adpcm_start_address & ~u16(1);
  regs.adsr_volume = 0;
  adpcm_last_samples.fill(0);
  has_samples = false;
  ignore_loop_address = false;
  adsr_phase = ADSRPhase::Attack;
  UpdateADSREnvelope();
}

void SPU::Voice::KeyOff()
{
  if (adsr_phase == ADSRPhase::Off || adsr_phase == ADSRPhase::Release)
    return;

  adsr_phase = ADSRPhase::Release;
  UpdateADSREnvelope();
}

void SPU::Voice::ForceOff()
{
  if (adsr_phase == ADSRPhase::Off)
    return;

  regs.adsr_volume = 0;
  adsr_phase = ADSRPhase::Off;
}

SPU::ADSRPhase SPU::GetNextADSRPhase(ADSRPhase phase)
{
  switch (phase)
  {
    case ADSRPhase::Attack:
      // attack -> decay
      return ADSRPhase::Decay;

    case ADSRPhase::Decay:
      // decay -> sustain
      return ADSRPhase::Sustain;

    case ADSRPhase::Sustain:
      // sustain stays in sustain until key off
      return ADSRPhase::Sustain;

    default:
    case ADSRPhase::Release:
      // end of release disables the voice
      return ADSRPhase::Off;
  }
}

struct ADSRTableEntry
{
  s32 ticks;
  s32 step;
};
enum : u32
{
  NUM_ADSR_TABLE_ENTRIES = 128,
  NUM_ADSR_DIRECTIONS = 2 // increasing, decreasing
};
using ADSRTableEntries = std::array<std::array<ADSRTableEntry, NUM_ADSR_TABLE_ENTRIES>, NUM_ADSR_DIRECTIONS>;

static constexpr ADSRTableEntries ComputeADSRTableEntries()
{
  ADSRTableEntries entries = {};
  for (u32 decreasing = 0; decreasing < 2; decreasing++)
  {
    for (u32 rate = 0; rate < NUM_ADSR_TABLE_ENTRIES; rate++)
    {
      if (rate < 48)
      {
        entries[decreasing][rate].ticks = 1;
        if (decreasing != 0)
          entries[decreasing][rate].step =
            static_cast<s32>(static_cast<u32>(-8 + static_cast<s32>(rate & 3)) << (11 - (rate >> 2)));
        else
          entries[decreasing][rate].step = (7 - static_cast<s32>(rate & 3)) << (11 - (rate >> 2));
      }
      else
      {
        entries[decreasing][rate].ticks = 1 << (static_cast<s32>(rate >> 2) - 11);
        if (decreasing != 0)
          entries[decreasing][rate].step = (-8 + static_cast<s32>(rate & 3));
        else
          entries[decreasing][rate].step = (7 - static_cast<s32>(rate & 3));
      }
    }
  }

  return entries;
}

static constexpr ADSRTableEntries s_adsr_table = ComputeADSRTableEntries();

void SPU::VolumeEnvelope::Reset(u8 rate_, bool decreasing_, bool exponential_)
{
  rate = rate_;
  decreasing = decreasing_;
  exponential = exponential_;

  const ADSRTableEntry& table_entry = s_adsr_table[BoolToUInt8(decreasing)][rate];
  counter = table_entry.ticks;
}

s16 SPU::VolumeEnvelope::Tick(s16 current_level)
{
  counter--;
  if (counter > 0)
    return current_level;

  const ADSRTableEntry& table_entry = s_adsr_table[BoolToUInt8(decreasing)][rate];
  s32 this_step = table_entry.step;
  counter = table_entry.ticks;

  if (exponential)
  {
    if (decreasing)
    {
      this_step = (this_step * current_level) >> 15;
    }
    else
    {
      if (current_level >= 0x6000)
      {
        if (rate < 40)
        {
          this_step >>= 2;
        }
        else if (rate >= 44)
        {
          counter >>= 2;
        }
        else
        {
          this_step >>= 1;
          counter >>= 1;
        }
      }
    }
  }

  return static_cast<s16>(
    std::clamp<s32>(static_cast<s32>(current_level) + this_step, ENVELOPE_MIN_VOLUME, ENVELOPE_MAX_VOLUME));
}

void SPU::VolumeSweep::Reset(VolumeRegister reg)
{
  if (!reg.sweep_mode)
  {
    current_level = reg.fixed_volume_shr1 * 2;
    envelope_active = false;
    return;
  }

  envelope.Reset(reg.sweep_rate, reg.sweep_direction_decrease, reg.sweep_exponential);
  envelope_active = true;
}

void SPU::VolumeSweep::Tick()
{
  if (!envelope_active)
    return;

  current_level = envelope.Tick(current_level);
  envelope_active =
    (envelope.decreasing ? (current_level > ENVELOPE_MIN_VOLUME) : (current_level < ENVELOPE_MAX_VOLUME));
}

void SPU::Voice::UpdateADSREnvelope()
{
  switch (adsr_phase)
  {
    case ADSRPhase::Off:
      adsr_target = 0;
      adsr_envelope.Reset(0, false, false);
      return;

    case ADSRPhase::Attack:
      adsr_target = 32767; // 0 -> max
      adsr_envelope.Reset(regs.adsr.attack_rate, false, regs.adsr.attack_exponential);
      break;

    case ADSRPhase::Decay:
      adsr_target = static_cast<s16>(std::min<s32>((u32(regs.adsr.sustain_level.GetValue()) + 1) * 0x800,
                                                   ENVELOPE_MAX_VOLUME)); // max -> sustain level
      adsr_envelope.Reset(regs.adsr.decay_rate_shr2 << 2, true, true);
      break;

    case ADSRPhase::Sustain:
      adsr_target = 0;
      adsr_envelope.Reset(regs.adsr.sustain_rate, regs.adsr.sustain_direction_decrease, regs.adsr.sustain_exponential);
      break;

    case ADSRPhase::Release:
      adsr_target = 0;
      adsr_envelope.Reset(regs.adsr.release_rate_shr2 << 2, true, regs.adsr.release_exponential);
      break;

    default:
      break;
  }
}

void SPU::Voice::TickADSR()
{
  regs.adsr_volume = adsr_envelope.Tick(regs.adsr_volume);

  if (adsr_phase != ADSRPhase::Sustain)
  {
    const bool reached_target =
      adsr_envelope.decreasing ? (regs.adsr_volume <= adsr_target) : (regs.adsr_volume >= adsr_target);
    if (reached_target)
    {
      adsr_phase = GetNextADSRPhase(adsr_phase);
      UpdateADSREnvelope();
    }
  }
}

void SPU::Voice::DecodeBlock(const ADPCMBlock& block)
{
  static constexpr std::array<s32, 5> filter_table_pos = {{0, 60, 115, 98, 122}};
  static constexpr std::array<s32, 5> filter_table_neg = {{0, 0, -52, -55, -60}};

  // store samples needed for interpolation
  previous_block_last_samples[2] = current_block_samples[NUM_SAMPLES_PER_ADPCM_BLOCK - 1];
  previous_block_last_samples[1] = current_block_samples[NUM_SAMPLES_PER_ADPCM_BLOCK - 2];
  previous_block_last_samples[0] = current_block_samples[NUM_SAMPLES_PER_ADPCM_BLOCK - 3];

  // pre-lookup
  const u8 shift = block.GetShift();
  const u8 filter_index = block.GetFilter();
  const s32 filter_pos = filter_table_pos[filter_index];
  const s32 filter_neg = filter_table_neg[filter_index];
  s16 last_samples[2] = {adpcm_last_samples[0], adpcm_last_samples[1]};

  // samples
  for (u32 i = 0; i < NUM_SAMPLES_PER_ADPCM_BLOCK; i++)
  {
    // extend 4-bit to 16-bit, apply shift from header and mix in previous samples
    s32 sample = s32(static_cast<s16>(ZeroExtend16(block.GetNibble(i)) << 12) >> shift);
    sample += (last_samples[0] * filter_pos) >> 6;
    sample += (last_samples[1] * filter_neg) >> 6;

    last_samples[1] = last_samples[0];
    current_block_samples[i] = last_samples[0] = static_cast<s16>(Clamp16(sample));
  }

  std::copy(last_samples, last_samples + countof(last_samples), adpcm_last_samples.begin());
  current_block_flags.bits = block.flags.bits;
}

s16 SPU::Voice::SampleBlock(s32 index) const
{
  if (index < 0)
  {
    DebugAssert(index >= -3);
    return previous_block_last_samples[index + 3];
  }

  return current_block_samples[index];
}

s32 SPU::Voice::Interpolate() const
{
  static constexpr std::array<s16, 0x200> gauss = {{
    -0x001, -0x001, -0x001, -0x001, -0x001, -0x001, -0x001, -0x001, //
    -0x001, -0x001, -0x001, -0x001, -0x001, -0x001, -0x001, -0x001, //
    0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0000, 0x0001, //
    0x0001, 0x0001, 0x0001, 0x0002, 0x0002, 0x0002, 0x0003, 0x0003, //
    0x0003, 0x0004, 0x0004, 0x0005, 0x0005, 0x0006, 0x0007, 0x0007, //
    0x0008, 0x0009, 0x0009, 0x000A, 0x000B, 0x000C, 0x000D, 0x000E, //
    0x000F, 0x0010, 0x0011, 0x0012, 0x0013, 0x0015, 0x0016, 0x0018, // entry
    0x0019, 0x001B, 0x001C, 0x001E, 0x0020, 0x0021, 0x0023, 0x0025, // 000..07F
    0x0027, 0x0029, 0x002C, 0x002E, 0x0030, 0x0033, 0x0035, 0x0038, //
    0x003A, 0x003D, 0x0040, 0x0043, 0x0046, 0x0049, 0x004D, 0x0050, //
    0x0054, 0x0057, 0x005B, 0x005F, 0x0063, 0x0067, 0x006B, 0x006F, //
    0x0074, 0x0078, 0x007D, 0x0082, 0x0087, 0x008C, 0x0091, 0x0096, //
    0x009C, 0x00A1, 0x00A7, 0x00AD, 0x00B3, 0x00BA, 0x00C0, 0x00C7, //
    0x00CD, 0x00D4, 0x00DB, 0x00E3, 0x00EA, 0x00F2, 0x00FA, 0x0101, //
    0x010A, 0x0112, 0x011B, 0x0123, 0x012C, 0x0135, 0x013F, 0x0148, //
    0x0152, 0x015C, 0x0166, 0x0171, 0x017B, 0x0186, 0x0191, 0x019C, //
    0x01A8, 0x01B4, 0x01C0, 0x01CC, 0x01D9, 0x01E5, 0x01F2, 0x0200, //
    0x020D, 0x021B, 0x0229, 0x0237, 0x0246, 0x0255, 0x0264, 0x0273, //
    0x0283, 0x0293, 0x02A3, 0x02B4, 0x02C4, 0x02D6, 0x02E7, 0x02F9, //
    0x030B, 0x031D, 0x0330, 0x0343, 0x0356, 0x036A, 0x037E, 0x0392, //
    0x03A7, 0x03BC, 0x03D1, 0x03E7, 0x03FC, 0x0413, 0x042A, 0x0441, //
    0x0458, 0x0470, 0x0488, 0x04A0, 0x04B9, 0x04D2, 0x04EC, 0x0506, //
    0x0520, 0x053B, 0x0556, 0x0572, 0x058E, 0x05AA, 0x05C7, 0x05E4, // entry
    0x0601, 0x061F, 0x063E, 0x065C, 0x067C, 0x069B, 0x06BB, 0x06DC, // 080..0FF
    0x06FD, 0x071E, 0x0740, 0x0762, 0x0784, 0x07A7, 0x07CB, 0x07EF, //
    0x0813, 0x0838, 0x085D, 0x0883, 0x08A9, 0x08D0, 0x08F7, 0x091E, //
    0x0946, 0x096F, 0x0998, 0x09C1, 0x09EB, 0x0A16, 0x0A40, 0x0A6C, //
    0x0A98, 0x0AC4, 0x0AF1, 0x0B1E, 0x0B4C, 0x0B7A, 0x0BA9, 0x0BD8, //
    0x0C07, 0x0C38, 0x0C68, 0x0C99, 0x0CCB, 0x0CFD, 0x0D30, 0x0D63, //
    0x0D97, 0x0DCB, 0x0E00, 0x0E35, 0x0E6B, 0x0EA1, 0x0ED7, 0x0F0F, //
    0x0F46, 0x0F7F, 0x0FB7, 0x0FF1, 0x102A, 0x1065, 0x109F, 0x10DB, //
    0x1116, 0x1153, 0x118F, 0x11CD, 0x120B, 0x1249, 0x1288, 0x12C7, //
    0x1307, 0x1347, 0x1388, 0x13C9, 0x140B, 0x144D, 0x1490, 0x14D4, //
    0x1517, 0x155C, 0x15A0, 0x15E6, 0x162C, 0x1672, 0x16B9, 0x1700, //
    0x1747, 0x1790, 0x17D8, 0x1821, 0x186B, 0x18B5, 0x1900, 0x194B, //
    0x1996, 0x19E2, 0x1A2E, 0x1A7B, 0x1AC8, 0x1B16, 0x1B64, 0x1BB3, //
    0x1C02, 0x1C51, 0x1CA1, 0x1CF1, 0x1D42, 0x1D93, 0x1DE5, 0x1E37, //
    0x1E89, 0x1EDC, 0x1F2F, 0x1F82, 0x1FD6, 0x202A, 0x207F, 0x20D4, //
    0x2129, 0x217F, 0x21D5, 0x222C, 0x2282, 0x22DA, 0x2331, 0x2389, // entry
    0x23E1, 0x2439, 0x2492, 0x24EB, 0x2545, 0x259E, 0x25F8, 0x2653, // 100..17F
    0x26AD, 0x2708, 0x2763, 0x27BE, 0x281A, 0x2876, 0x28D2, 0x292E, //
    0x298B, 0x29E7, 0x2A44, 0x2AA1, 0x2AFF, 0x2B5C, 0x2BBA, 0x2C18, //
    0x2C76, 0x2CD4, 0x2D33, 0x2D91, 0x2DF0, 0x2E4F, 0x2EAE, 0x2F0D, //
    0x2F6C, 0x2FCC, 0x302B, 0x308B, 0x30EA, 0x314A, 0x31AA, 0x3209, //
    0x3269, 0x32C9, 0x3329, 0x3389, 0x33E9, 0x3449, 0x34A9, 0x3509, //
    0x3569, 0x35C9, 0x3629, 0x3689, 0x36E8, 0x3748, 0x37A8, 0x3807, //
    0x3867, 0x38C6, 0x3926, 0x3985, 0x39E4, 0x3A43, 0x3AA2, 0x3B00, //
    0x3B5F, 0x3BBD, 0x3C1B, 0x3C79, 0x3CD7, 0x3D35, 0x3D92, 0x3DEF, //
    0x3E4C, 0x3EA9, 0x3F05, 0x3F62, 0x3FBD, 0x4019, 0x4074, 0x40D0, //
    0x412A, 0x4185, 0x41DF, 0x4239, 0x4292, 0x42EB, 0x4344, 0x439C, //
    0x43F4, 0x444C, 0x44A3, 0x44FA, 0x4550, 0x45A6, 0x45FC, 0x4651, //
    0x46A6, 0x46FA, 0x474E, 0x47A1, 0x47F4, 0x4846, 0x4898, 0x48E9, //
    0x493A, 0x498A, 0x49D9, 0x4A29, 0x4A77, 0x4AC5, 0x4B13, 0x4B5F, //
    0x4BAC, 0x4BF7, 0x4C42, 0x4C8D, 0x4CD7, 0x4D20, 0x4D68, 0x4DB0, //
    0x4DF7, 0x4E3E, 0x4E84, 0x4EC9, 0x4F0E, 0x4F52, 0x4F95, 0x4FD7, // entry
    0x5019, 0x505A, 0x509A, 0x50DA, 0x5118, 0x5156, 0x5194, 0x51D0, // 180..1FF
    0x520C, 0x5247, 0x5281, 0x52BA, 0x52F3, 0x532A, 0x5361, 0x5397, //
    0x53CC, 0x5401, 0x5434, 0x5467, 0x5499, 0x54CA, 0x54FA, 0x5529, //
    0x5558, 0x5585, 0x55B2, 0x55DE, 0x5609, 0x5632, 0x565B, 0x5684, //
    0x56AB, 0x56D1, 0x56F6, 0x571B, 0x573E, 0x5761, 0x5782, 0x57A3, //
    0x57C3, 0x57E2, 0x57FF, 0x581C, 0x5838, 0x5853, 0x586D, 0x5886, //
    0x589E, 0x58B5, 0x58CB, 0x58E0, 0x58F4, 0x5907, 0x5919, 0x592A, //
    0x593A, 0x5949, 0x5958, 0x5965, 0x5971, 0x597C, 0x5986, 0x598F, //
    0x5997, 0x599E, 0x59A4, 0x59A9, 0x59AD, 0x59B0, 0x59B2, 0x59B3  //
  }};

  const u8 i = counter.interpolation_index;
  const s32 s = static_cast<s32>(ZeroExtend32(counter.sample_index.GetValue()));

  s32 out = s32(gauss[0x0FF - i]) * s32(SampleBlock(s - 3));
  out += s32(gauss[0x1FF - i]) * s32(SampleBlock(s - 2));
  out += s32(gauss[0x100 + i]) * s32(SampleBlock(s - 1));
  out += s32(gauss[0x000 + i]) * s32(SampleBlock(s - 0));
  return out >> 15;
}

void SPU::ReadADPCMBlock(u16 address, ADPCMBlock* block)
{
  u32 ram_address = (ZeroExtend32(address) * 8) & RAM_MASK;
  CheckRAMIRQ(ram_address);
  CheckRAMIRQ((ram_address + 8) & RAM_MASK);

  // fast path - no wrap-around
  if ((ram_address + sizeof(ADPCMBlock)) <= RAM_SIZE)
  {
    std::memcpy(block, &m_ram[ram_address], sizeof(ADPCMBlock));
    return;
  }

  block->shift_filter.bits = m_ram[ram_address];
  ram_address = (ram_address + 1) & RAM_MASK;
  block->flags.bits = m_ram[ram_address];
  ram_address = (ram_address + 1) & RAM_MASK;
  for (u32 i = 0; i < 14; i++)
  {
    block->data[i] = m_ram[ram_address];
    ram_address = (ram_address + 1) & RAM_MASK;
  }
}

std::tuple<s32, s32> SPU::SampleVoice(u32 voice_index)
{
  Voice& voice = m_voices[voice_index];
  if (!voice.IsOn() && !m_SPUCNT.irq9_enable)
  {
    voice.last_volume = 0;
    return {};
  }

  if (!voice.has_samples)
  {
    ADPCMBlock block;
    ReadADPCMBlock(voice.current_address, &block);
    voice.DecodeBlock(block);
    voice.has_samples = true;

    if (voice.current_block_flags.loop_start && !voice.ignore_loop_address)
    {
      Log_TracePrintf("Voice %u loop start @ 0x%08X", voice_index, ZeroExtend32(voice.current_address));
      voice.regs.adpcm_repeat_address = voice.current_address;
    }
  }

  // skip interpolation when the volume is muted anyway
  s32 volume;
  if (voice.regs.adsr_volume != 0)
  {
    // interpolate/sample and apply ADSR volume
    s32 sample;
    if (IsVoiceNoiseEnabled(voice_index))
      sample = GetVoiceNoiseLevel();
    else
      sample = voice.Interpolate();

    volume = ApplyVolume(sample, voice.regs.adsr_volume);
  }
  else
  {
    volume = 0;
  }

  voice.last_volume = volume;

  if (voice.adsr_phase != ADSRPhase::Off)
    voice.TickADSR();

  // Pitch modulation
  u16 step = voice.regs.adpcm_sample_rate;
  if (IsPitchModulationEnabled(voice_index))
  {
    const s32 factor = std::clamp<s32>(m_voices[voice_index - 1].last_volume, -0x8000, 0x7FFF) + 0x8000;
    step = Truncate16(static_cast<u32>((SignExtend32(step) * factor) >> 15));
  }
  step = std::min<u16>(step, 0x3FFF);

  // Shouldn't ever overflow because if sample_index == 27, step == 0x4000 there won't be a carry out from the
  // interpolation index. If there is a carry out, bit 12 will never be 1, so it'll never add more than 4 to
  // sample_index, which should never be >27.
  DebugAssert(voice.counter.sample_index < NUM_SAMPLES_PER_ADPCM_BLOCK);
  voice.counter.bits += step;

  if (voice.counter.sample_index >= NUM_SAMPLES_PER_ADPCM_BLOCK)
  {
    // next block
    voice.counter.sample_index -= NUM_SAMPLES_PER_ADPCM_BLOCK;
    voice.has_samples = false;
    voice.current_address += 2;

    // handle flags
    if (voice.current_block_flags.loop_end)
    {
      m_endx_register |= (u32(1) << voice_index);
      if (!voice.current_block_flags.loop_repeat)
      {
        Log_TracePrintf("Voice %u loop end+mute @ 0x%08X", voice_index, ZeroExtend32(voice.current_address));
        voice.ForceOff();
      }
      else
      {
        Log_TracePrintf("Voice %u loop end+repeat @ 0x%08X", voice_index, ZeroExtend32(voice.current_address));
        voice.current_address = voice.regs.adpcm_repeat_address & ~u16(1);
      }
    }
  }

  // apply per-channel volume
  const s32 left = ApplyVolume(volume, voice.left_volume.current_level);
  const s32 right = ApplyVolume(volume, voice.right_volume.current_level);
  voice.left_volume.Tick();
  voice.right_volume.Tick();
  return std::make_tuple(left, right);
}

void SPU::UpdateNoise()
{
  // Dr Hell's noise waveform, implementation borrowed from pcsx-r.
  static constexpr std::array<u8, 64> noise_wave_add = {
    {1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0,
     0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1}};
  static constexpr std::array<u8, 5> noise_freq_add = {{0, 84, 140, 180, 210}};

  const u32 noise_clock = m_SPUCNT.noise_clock;
  const u32 level = (0x8000u >> (noise_clock >> 2)) << 16;

  m_noise_count += 0x10000u + noise_freq_add[noise_clock & 3u];
  if ((m_noise_count & 0xFFFFu) >= noise_freq_add[4])
  {
    m_noise_count += 0x10000;
    m_noise_count -= noise_freq_add[noise_clock & 3u];
  }

  if (m_noise_count < level)
    return;

  m_noise_count %= level;
  m_noise_level = (m_noise_level << 1) | noise_wave_add[(m_noise_level >> 10) & 63u];
}

/************************************************************************/
/* Reverb algorithm from Mednafen-PSX                                   */
/************************************************************************/

u32 SPU::ReverbMemoryAddress(u32 address) const
{
  // Ensures address does not leave the reverb work area.
  static constexpr u32 MASK = (RAM_SIZE - 1) / 2;
  u32 offset = m_reverb_current_address + (address & MASK);
  offset += m_reverb_base_address & ((s32)(offset << 13) >> 31);

  // We address RAM in bytes. TODO: Change this to words.
  return (offset & MASK) * 2u;
}

s16 SPU::ReverbRead(u32 address, s32 offset)
{
  // TODO: This should check interrupts.
  const u32 real_address = ReverbMemoryAddress((address << 2) + offset);

  s16 data;
  std::memcpy(&data, &m_ram[real_address], sizeof(data));
  return data;
}

void SPU::ReverbWrite(u32 address, s16 data)
{
  // TODO: This should check interrupts.
  const u32 real_address = ReverbMemoryAddress(address << 2);
  std::memcpy(&m_ram[real_address], &data, sizeof(data));
}

// Zeroes optimized out; middle removed too(it's 16384)
static constexpr std::array<s16, 20> s_reverb_resample_coefficients = {
  -1, 2, -10, 35, -103, 266, -616, 1332, -2960, 10246, 10246, -2960, 1332, -616, 266, -103, 35, -10, 2, -1,
};
static s16 s_last_reverb_input[2];
static s32 s_last_reverb_output[2];

ALWAYS_INLINE static s32 Reverb4422(const s16* src)
{
  s32 out = 0; // 32-bits is adequate(it won't overflow)
  for (u32 i = 0; i < 20; i++)
    out += s_reverb_resample_coefficients[i] * src[i * 2];

  // Middle non-zero
  out += 0x4000 * src[19];
  out >>= 15;
  return std::clamp<s32>(out, -32768, 32767);
}

template<bool phase>
ALWAYS_INLINE static s32 Reverb2244(const s16* src)
{
  s32 out; // 32-bits is adequate(it won't overflow)
  if (phase)
  {
    // Middle non-zero
    out = src[9];
  }
  else
  {
    out = 0;
    for (u32 i = 0; i < 20; i++)
      out += s_reverb_resample_coefficients[i] * src[i];

    out >>= 14;
    out = std::clamp<s32>(out, -32768, 32767);
  }

  return out;
}

ALWAYS_INLINE static s16 ReverbSat(s32 val)
{
  return static_cast<s16>(std::clamp<s32>(val, -0x8000, 0x7FFF));
}

ALWAYS_INLINE static s32 IIASM(const s16 IIR_ALPHA, const s16 insamp)
{
  if (IIR_ALPHA == -32768)
  {
    if (insamp == -32768)
      return 0;
    else
      return insamp * -65536;
  }
  else
    return insamp * (32768 - IIR_ALPHA);
}

void SPU::ComputeReverb()
{
  std::array<s32, 2> downsampled;
  for (unsigned lr = 0; lr < 2; lr++)
    downsampled[lr] = Reverb4422(&m_reverb_downsample_buffer[lr][(m_reverb_resample_buffer_position - 39) & 0x3F]);

  if (m_SPUCNT.reverb_master_enable)
  {
    const s16 IIR_INPUT_A0 =
      ReverbSat(((ReverbRead(m_reverb_registers.IIR_SRC_A0) * m_reverb_registers.IIR_COEF) >> 15) +
                ((downsampled[0] * m_reverb_registers.IN_COEF_L) >> 15));
    const s16 IIR_INPUT_A1 =
      ReverbSat(((ReverbRead(m_reverb_registers.IIR_SRC_A1) * m_reverb_registers.IIR_COEF) >> 15) +
                ((downsampled[1] * m_reverb_registers.IN_COEF_R) >> 15));
    const s16 IIR_INPUT_B0 =
      ReverbSat(((ReverbRead(m_reverb_registers.IIR_SRC_B0) * m_reverb_registers.IIR_COEF) >> 15) +
                ((downsampled[0] * m_reverb_registers.IN_COEF_L) >> 15));
    const s16 IIR_INPUT_B1 =
      ReverbSat(((ReverbRead(m_reverb_registers.IIR_SRC_B1) * m_reverb_registers.IIR_COEF) >> 15) +
                ((downsampled[1] * m_reverb_registers.IN_COEF_R) >> 15));

    const s16 IIR_A0 =
      ReverbSat((((IIR_INPUT_A0 * m_reverb_registers.IIR_ALPHA) >> 14) +
                 (IIASM(m_reverb_registers.IIR_ALPHA, ReverbRead(m_reverb_registers.IIR_DEST_A0, -1)) >> 14)) >>
                1);
    const s16 IIR_A1 =
      ReverbSat((((IIR_INPUT_A1 * m_reverb_registers.IIR_ALPHA) >> 14) +
                 (IIASM(m_reverb_registers.IIR_ALPHA, ReverbRead(m_reverb_registers.IIR_DEST_A1, -1)) >> 14)) >>
                1);
    const s16 IIR_B0 =
      ReverbSat((((IIR_INPUT_B0 * m_reverb_registers.IIR_ALPHA) >> 14) +
                 (IIASM(m_reverb_registers.IIR_ALPHA, ReverbRead(m_reverb_registers.IIR_DEST_B0, -1)) >> 14)) >>
                1);
    const s16 IIR_B1 =
      ReverbSat((((IIR_INPUT_B1 * m_reverb_registers.IIR_ALPHA) >> 14) +
                 (IIASM(m_reverb_registers.IIR_ALPHA, ReverbRead(m_reverb_registers.IIR_DEST_B1, -1)) >> 14)) >>
                1);

    ReverbWrite(m_reverb_registers.IIR_DEST_A0, IIR_A0);
    ReverbWrite(m_reverb_registers.IIR_DEST_A1, IIR_A1);
    ReverbWrite(m_reverb_registers.IIR_DEST_B0, IIR_B0);
    ReverbWrite(m_reverb_registers.IIR_DEST_B1, IIR_B1);

    const s16 ACC0 = ReverbSat((((ReverbRead(m_reverb_registers.ACC_SRC_A0) * m_reverb_registers.ACC_COEF_A) >> 14) +
                                ((ReverbRead(m_reverb_registers.ACC_SRC_B0) * m_reverb_registers.ACC_COEF_B) >> 14) +
                                ((ReverbRead(m_reverb_registers.ACC_SRC_C0) * m_reverb_registers.ACC_COEF_C) >> 14) +
                                ((ReverbRead(m_reverb_registers.ACC_SRC_D0) * m_reverb_registers.ACC_COEF_D) >> 14)) >>
                               1);

    const s16 ACC1 = ReverbSat((((ReverbRead(m_reverb_registers.ACC_SRC_A1) * m_reverb_registers.ACC_COEF_A) >> 14) +
                                ((ReverbRead(m_reverb_registers.ACC_SRC_B1) * m_reverb_registers.ACC_COEF_B) >> 14) +
                                ((ReverbRead(m_reverb_registers.ACC_SRC_C1) * m_reverb_registers.ACC_COEF_C) >> 14) +
                                ((ReverbRead(m_reverb_registers.ACC_SRC_D1) * m_reverb_registers.ACC_COEF_D) >> 14)) >>
                               1);

    const s16 FB_A0 = ReverbRead(m_reverb_registers.MIX_DEST_A0 - m_reverb_registers.FB_SRC_A);
    const s16 FB_A1 = ReverbRead(m_reverb_registers.MIX_DEST_A1 - m_reverb_registers.FB_SRC_A);
    const s16 FB_B0 = ReverbRead(m_reverb_registers.MIX_DEST_B0 - m_reverb_registers.FB_SRC_B);
    const s16 FB_B1 = ReverbRead(m_reverb_registers.MIX_DEST_B1 - m_reverb_registers.FB_SRC_B);

    ReverbWrite(m_reverb_registers.MIX_DEST_A0, ReverbSat(ACC0 - ((FB_A0 * m_reverb_registers.FB_ALPHA) >> 15)));
    ReverbWrite(m_reverb_registers.MIX_DEST_A1, ReverbSat(ACC1 - ((FB_A1 * m_reverb_registers.FB_ALPHA) >> 15)));

    ReverbWrite(m_reverb_registers.MIX_DEST_B0,
                ReverbSat(((m_reverb_registers.FB_ALPHA * ACC0) >> 15) -
                          ((FB_A0 * (s16)(0x8000 ^ m_reverb_registers.FB_ALPHA)) >> 15) -
                          ((FB_B0 * m_reverb_registers.FB_X) >> 15)));
    ReverbWrite(m_reverb_registers.MIX_DEST_B1,
                ReverbSat(((m_reverb_registers.FB_ALPHA * ACC1) >> 15) -
                          ((FB_A1 * (s16)(0x8000 ^ m_reverb_registers.FB_ALPHA)) >> 15) -
                          ((FB_B1 * m_reverb_registers.FB_X) >> 15)));
  }

  m_reverb_upsample_buffer[0][(m_reverb_resample_buffer_position >> 1) | 0x20] =
    m_reverb_upsample_buffer[0][m_reverb_resample_buffer_position >> 1] =
      (ReverbRead(m_reverb_registers.MIX_DEST_A0) + ReverbRead(m_reverb_registers.MIX_DEST_B0)) >> 1;
  m_reverb_upsample_buffer[1][(m_reverb_resample_buffer_position >> 1) | 0x20] =
    m_reverb_upsample_buffer[1][m_reverb_resample_buffer_position >> 1] =
      (ReverbRead(m_reverb_registers.MIX_DEST_A1) + ReverbRead(m_reverb_registers.MIX_DEST_B1)) >> 1;

  m_reverb_current_address = (m_reverb_current_address + 1) & 0x3FFFFu;
  if (m_reverb_current_address == 0)
    m_reverb_current_address = m_reverb_base_address;
}

void SPU::ProcessReverb(s16 left_in, s16 right_in, s32* left_out, s32* right_out)
{
  s_last_reverb_input[0] = left_in;
  s_last_reverb_input[1] = right_in;
  m_reverb_downsample_buffer[0][m_reverb_resample_buffer_position | 0x00] = left_in;
  m_reverb_downsample_buffer[0][m_reverb_resample_buffer_position | 0x40] = left_in;
  m_reverb_downsample_buffer[1][m_reverb_resample_buffer_position | 0x00] = right_in;
  m_reverb_downsample_buffer[1][m_reverb_resample_buffer_position | 0x40] = right_in;

  s32 out[2];
  if (m_reverb_resample_buffer_position & 1u)
  {
    ComputeReverb();
    for (u32 i = 0; i < 2; i++)
      out[i] = Reverb2244<true>(&m_reverb_upsample_buffer[i][((m_reverb_resample_buffer_position - 39) & 0x3F) >> 1]);
  }
  else
  {
    for (u32 i = 0; i < 2; i++)
      out[i] = Reverb2244<false>(&m_reverb_upsample_buffer[i][((m_reverb_resample_buffer_position - 39) & 0x3F) >> 1]);
  }

  m_reverb_resample_buffer_position = (m_reverb_resample_buffer_position + 1) & 0x3F;

  s_last_reverb_output[0] = *left_out = ApplyVolume(out[0], m_reverb_registers.vLOUT);
  s_last_reverb_output[1] = *right_out = ApplyVolume(out[1], m_reverb_registers.vROUT);
}

void SPU::DrawDebugStateWindow()
{
#ifdef WITH_IMGUI
  static const ImVec4 active_color{1.0f, 1.0f, 1.0f, 1.0f};
  static const ImVec4 inactive_color{0.4f, 0.4f, 0.4f, 1.0f};
  const float framebuffer_scale = ImGui::GetIO().DisplayFramebufferScale.x;

  ImGui::SetNextWindowSize(ImVec2(800.0f * framebuffer_scale, 800.0f * framebuffer_scale), ImGuiCond_FirstUseEver);
  if (!ImGui::Begin("SPU State", &g_settings.debugging.show_spu_state))
  {
    ImGui::End();
    return;
  }

  // status
  if (ImGui::CollapsingHeader("Status", ImGuiTreeNodeFlags_DefaultOpen))
  {
    static constexpr std::array<const char*, 4> transfer_modes = {
      {"Transfer Stopped", "Manual Write", "DMA Write", "DMA Read"}};
    const std::array<float, 6> offsets = {{100.0f * framebuffer_scale, 200.0f * framebuffer_scale,
                                           300.0f * framebuffer_scale, 420.0f * framebuffer_scale,
                                           500.0f * framebuffer_scale, 600.0f * framebuffer_scale}};

    ImGui::Text("Control: ");
    ImGui::SameLine(offsets[0]);
    ImGui::TextColored(m_SPUCNT.enable ? active_color : inactive_color, "SPU Enable");
    ImGui::SameLine(offsets[1]);
    ImGui::TextColored(m_SPUCNT.mute_n ? inactive_color : active_color, "Mute SPU");
    ImGui::SameLine(offsets[2]);
    ImGui::TextColored(m_SPUCNT.external_audio_enable ? active_color : inactive_color, "External Audio");
    ImGui::SameLine(offsets[3]);
    ImGui::TextColored(m_SPUCNT.ram_transfer_mode != RAMTransferMode::Stopped ? active_color : inactive_color, "%s",
                       transfer_modes[static_cast<u8>(m_SPUCNT.ram_transfer_mode.GetValue())]);

    ImGui::Text("Status: ");
    ImGui::SameLine(offsets[0]);
    ImGui::TextColored(m_SPUSTAT.irq9_flag ? active_color : inactive_color, "IRQ9");
    ImGui::SameLine(offsets[1]);
    ImGui::TextColored(m_SPUSTAT.dma_request ? active_color : inactive_color, "DMA Request");
    ImGui::SameLine(offsets[2]);
    ImGui::TextColored(m_SPUSTAT.dma_read_request ? active_color : inactive_color, "DMA Read");
    ImGui::SameLine(offsets[3]);
    ImGui::TextColored(m_SPUSTAT.dma_write_request ? active_color : inactive_color, "DMA Write");
    ImGui::SameLine(offsets[4]);
    ImGui::TextColored(m_SPUSTAT.transfer_busy ? active_color : inactive_color, "Transfer Busy");
    ImGui::SameLine(offsets[5]);
    ImGui::TextColored(m_SPUSTAT.second_half_capture_buffer ? active_color : inactive_color, "Second Capture Buffer");

    ImGui::Text("Interrupt: ");
    ImGui::SameLine(offsets[0]);
    ImGui::TextColored(m_SPUCNT.irq9_enable ? active_color : inactive_color,
                       m_SPUCNT.irq9_enable ? "Enabled @ 0x%04X (actual 0x%08X)" : "Disabled @ 0x%04X (actual 0x%08X)",
                       m_irq_address, (ZeroExtend32(m_irq_address) * 8) & RAM_MASK);

    ImGui::Text("Volume: ");
    ImGui::SameLine(offsets[0]);
    ImGui::Text("Left: %d%%", ApplyVolume(100, m_main_volume_left.current_level));
    ImGui::SameLine(offsets[1]);
    ImGui::Text("Right: %d%%", ApplyVolume(100, m_main_volume_right.current_level));

    ImGui::Text("CD Audio: ");
    ImGui::SameLine(offsets[0]);
    ImGui::TextColored(m_SPUCNT.cd_audio_enable ? active_color : inactive_color,
                       m_SPUCNT.cd_audio_enable ? "Enabled" : "Disabled");
    ImGui::SameLine(offsets[1]);
    ImGui::TextColored(m_SPUCNT.cd_audio_enable ? active_color : inactive_color, "Left Volume: %d%%",
                       ApplyVolume(100, m_cd_audio_volume_left));
    ImGui::SameLine(offsets[3]);
    ImGui::TextColored(m_SPUCNT.cd_audio_enable ? active_color : inactive_color, "Right Volume: %d%%",
                       ApplyVolume(100, m_cd_audio_volume_left));

    ImGui::Text("Transfer FIFO: ");
    ImGui::SameLine(offsets[0]);
    ImGui::TextColored(m_transfer_event->IsActive() ? active_color : inactive_color, "%u halfwords (%u bytes)",
                       m_transfer_fifo.GetSize(), m_transfer_fifo.GetSize() * 2);
  }

  // draw voice states
  if (ImGui::CollapsingHeader("Voice State", ImGuiTreeNodeFlags_DefaultOpen))
  {
    static constexpr u32 NUM_COLUMNS = 12;

    ImGui::Columns(NUM_COLUMNS);

    // headers
    static constexpr std::array<const char*, NUM_COLUMNS> column_titles = {
      {"#", "InterpIndex", "SampleIndex", "CurAddr", "StartAddr", "RepeatAddr", "SampleRate", "VolLeft", "VolRight",
       "ADSRPhase", "ADSRVol", "ADSRTicks"}};
    static constexpr std::array<const char*, 5> adsr_phases = {{"Off", "Attack", "Decay", "Sustain", "Release"}};
    for (u32 i = 0; i < NUM_COLUMNS; i++)
    {
      ImGui::TextUnformatted(column_titles[i]);
      ImGui::NextColumn();
    }

    // states
    for (u32 voice_index = 0; voice_index < NUM_VOICES; voice_index++)
    {
      const Voice& v = m_voices[voice_index];
      ImVec4 color = v.IsOn() ? ImVec4(1.0f, 1.0f, 1.0f, 1.0f) : ImVec4(0.5f, 0.5f, 0.5f, 1.0f);
      ImGui::TextColored(color, "%u", ZeroExtend32(voice_index));
      ImGui::NextColumn();
      if (IsVoiceNoiseEnabled(voice_index))
        ImGui::TextColored(color, "NOISE");
      else
        ImGui::TextColored(color, "%u", ZeroExtend32(v.counter.interpolation_index.GetValue()));
      ImGui::NextColumn();
      ImGui::TextColored(color, "%u", ZeroExtend32(v.counter.sample_index.GetValue()));
      ImGui::NextColumn();
      ImGui::TextColored(color, "%04X", ZeroExtend32(v.current_address));
      ImGui::NextColumn();
      ImGui::TextColored(color, "%04X", ZeroExtend32(v.regs.adpcm_start_address));
      ImGui::NextColumn();
      ImGui::TextColored(color, "%04X", ZeroExtend32(v.regs.adpcm_repeat_address));
      ImGui::NextColumn();
      ImGui::TextColored(color, "%.2f", (float(v.regs.adpcm_sample_rate) / 4096.0f) * 44100.0f);
      ImGui::NextColumn();
      ImGui::TextColored(color, "%d%%", ApplyVolume(100, v.left_volume.current_level));
      ImGui::NextColumn();
      ImGui::TextColored(color, "%d%%", ApplyVolume(100, v.right_volume.current_level));
      ImGui::NextColumn();
      ImGui::TextColored(color, "%s", adsr_phases[static_cast<u8>(v.adsr_phase)]);
      ImGui::NextColumn();
      ImGui::TextColored(color, "%d%%", ApplyVolume(100, v.regs.adsr_volume));
      ImGui::NextColumn();
      ImGui::TextColored(color, "%d", v.adsr_envelope.counter);
      ImGui::NextColumn();
    }

    ImGui::Columns(1);
  }

  if (ImGui::CollapsingHeader("Reverb", ImGuiTreeNodeFlags_DefaultOpen))
  {
    ImGui::TextColored(m_SPUCNT.reverb_master_enable ? active_color : inactive_color, "Master Enable: %s",
                       m_SPUCNT.reverb_master_enable ? "Yes" : "No");
    ImGui::Text("Voices Enabled: ");

    for (u32 i = 0; i < NUM_VOICES; i++)
    {
      ImGui::SameLine(0.0f, 16.0f);

      const bool active = IsVoiceReverbEnabled(i);
      ImGui::TextColored(active ? active_color : inactive_color, "%u", i);
    }

    ImGui::TextColored(m_SPUCNT.cd_audio_reverb ? active_color : inactive_color, "CD Audio Enable: %s",
                       m_SPUCNT.cd_audio_reverb ? "Yes" : "No");

    ImGui::TextColored(m_SPUCNT.external_audio_reverb ? active_color : inactive_color, "External Audio Enable: %s",
                       m_SPUCNT.external_audio_reverb ? "Yes" : "No");

    ImGui::Text("Current Address: 0x%08X", m_reverb_current_address);
    ImGui::Text("Current Volume: Input (%d, %d) Output (%d, %d)", s_last_reverb_input[0], s_last_reverb_input[1],
                s_last_reverb_output[0], s_last_reverb_output[1]);

    ImGui::Text("Pitch Modulation: ");
    for (u32 i = 1; i < NUM_VOICES; i++)
    {
      ImGui::SameLine(0.0f, 16.0f);

      const bool active = IsPitchModulationEnabled(i);
      ImGui::TextColored(active ? active_color : inactive_color, "%u", i);
    }
  }

  if (ImGui::CollapsingHeader("Hacks", ImGuiTreeNodeFlags_DefaultOpen))
  {
    if (ImGui::Button("Key Off All Voices"))
    {
      for (u32 i = 0; i < NUM_VOICES; i++)
      {
        m_voices[i].KeyOff();
        m_voices[i].adsr_envelope.counter = 0;
        m_voices[i].regs.adsr_volume = 0;
      }
    }
  }

  ImGui::End();
#endif
}