apu.cpp

著名SFC模拟器Snes9x的源代码。

			      (((byte << 8) + APU.DSP [reg - 1]) & FREQUENCY_MASK) * 8);
	break;

    case APU_SRCN + 0x00:
    case APU_SRCN + 0x10:
    case APU_SRCN + 0x20:
    case APU_SRCN + 0x30:
    case APU_SRCN + 0x40:
    case APU_SRCN + 0x50:
    case APU_SRCN + 0x60:
    case APU_SRCN + 0x70:
	if (byte != APU.DSP [reg])
	{
#ifdef DEBUGGER
	    if (Settings.TraceSoundDSP)
		S9xTraceSoundDSP ("[%d] %d sample number: %d\n",
				  ICPU.Scanline, reg>>4, byte);
#endif
	    S9xSetSoundSample (reg >> 4, byte);
	}
	break;
	
    case APU_ADSR1 + 0x00:
    case APU_ADSR1 + 0x10:
    case APU_ADSR1 + 0x20:
    case APU_ADSR1 + 0x30:
    case APU_ADSR1 + 0x40:
    case APU_ADSR1 + 0x50:
    case APU_ADSR1 + 0x60:
    case APU_ADSR1 + 0x70:
	if (byte != APU.DSP [reg])
	{
#ifdef DEBUGGER
	    if (Settings.TraceSoundDSP)
		S9xTraceSoundDSP ("[%d] %d adsr1: %02x\n",
				  ICPU.Scanline, reg>>4, byte);
#endif
	    {
		S9xFixEnvelope (reg >> 4, APU.DSP [reg + 2], byte, 
			     APU.DSP [reg + 1]);
	    }
	}
	break;

    case APU_ADSR2 + 0x00:
    case APU_ADSR2 + 0x10:
    case APU_ADSR2 + 0x20:
    case APU_ADSR2 + 0x30:
    case APU_ADSR2 + 0x40:
    case APU_ADSR2 + 0x50:
    case APU_ADSR2 + 0x60:
    case APU_ADSR2 + 0x70:
	if (byte != APU.DSP [reg])
	{
#ifdef DEBUGGER
	    if (Settings.TraceSoundDSP)
		S9xTraceSoundDSP ("[%d] %d adsr2: %02x\n", 
				  ICPU.Scanline, reg>>4, byte);
#endif
	    {
		S9xFixEnvelope (reg >> 4, APU.DSP [reg + 1], APU.DSP [reg - 1],
			     byte);
	    }
	}
	break;

    case APU_GAIN + 0x00:
    case APU_GAIN + 0x10:
    case APU_GAIN + 0x20:
    case APU_GAIN + 0x30:
    case APU_GAIN + 0x40:
    case APU_GAIN + 0x50:
    case APU_GAIN + 0x60:
    case APU_GAIN + 0x70:
	if (byte != APU.DSP [reg])
	{
#ifdef DEBUGGER
	    if (Settings.TraceSoundDSP)
		S9xTraceSoundDSP ("[%d] %d gain: %02x\n",
				  ICPU.Scanline, reg>>4, byte);
#endif
	    {
		S9xFixEnvelope (reg >> 4, byte, APU.DSP [reg - 2],
			     APU.DSP [reg - 1]);
	    }
	}
	break;

    case APU_ENVX + 0x00:
    case APU_ENVX + 0x10:
    case APU_ENVX + 0x20:
    case APU_ENVX + 0x30:
    case APU_ENVX + 0x40:
    case APU_ENVX + 0x50:
    case APU_ENVX + 0x60:
    case APU_ENVX + 0x70:
	break;

    case APU_OUTX + 0x00:
    case APU_OUTX + 0x10:
    case APU_OUTX + 0x20:
    case APU_OUTX + 0x30:
    case APU_OUTX + 0x40:
    case APU_OUTX + 0x50:
    case APU_OUTX + 0x60:
    case APU_OUTX + 0x70:
	break;
    
    case APU_DIR:
#ifdef DEBUGGER
	if (Settings.TraceSoundDSP)
	    S9xTraceSoundDSP ("[%d] Sample directory to: %02x\n",
			      ICPU.Scanline, byte);
#endif
	break;

    case APU_PMON:
	if (byte != APU.DSP [APU_PMON])
	{
#ifdef DEBUGGER
	    if (Settings.TraceSoundDSP)
	    {
		S9xTraceSoundDSP ("[%d] FreqMod:", ICPU.Scanline);
		uint8 mask = 1;
		for (int c = 0; c < 8; c++, mask <<= 1)
		{
		    if (byte & mask)
		    {
			if (APU.DSP [reg] & mask)
			    S9xTraceSoundDSP ("%d", c);
			else
			    S9xTraceSoundDSP ("%d(on),", c);
		    }
		    else
		    {
			if (APU.DSP [reg] & mask)
			    S9xTraceSoundDSP ("%d(off),", c);
		    }
		}
		S9xTraceSoundDSP ("\n");
	    }
#endif
		S9xSetFrequencyModulationEnable (byte);
	}
	break;

    case APU_EON:
	if (byte != APU.DSP [APU_EON])
	{
#ifdef DEBUGGER
	    if (Settings.TraceSoundDSP)
	    {
		S9xTraceSoundDSP ("[%d] Echo:", ICPU.Scanline);
		uint8 mask = 1;
		for (int c = 0; c < 8; c++, mask <<= 1)
		{
		    if (byte & mask)
		    {
			if (APU.DSP [reg] & mask)
			    S9xTraceSoundDSP ("%d", c);
			else
			    S9xTraceSoundDSP ("%d(on),", c);
		    }
		    else
		    {
			if (APU.DSP [reg] & mask)
			    S9xTraceSoundDSP ("%d(off),", c);
		    }
		}
		S9xTraceSoundDSP ("\n");
	    }
#endif
		S9xSetEchoEnable (byte);
	}
	break;

    case APU_EFB:
	S9xSetEchoFeedback ((signed char) byte);
	break;

    case APU_ESA:
	break;

    case APU_EDL:
	S9xSetEchoDelay (byte & 0xf);
	break;

    case APU_C0:
    case APU_C1:
    case APU_C2:
    case APU_C3:
    case APU_C4:
    case APU_C5:
    case APU_C6:
    case APU_C7:
	S9xSetFilterCoefficient (reg >> 4, (signed char) byte);
	break;
    default:
// XXX
//printf ("Write %02x to unknown APU register %02x\n", byte, reg);
	break;
    }

    if (reg < 0x80)
	APU.DSP [reg] = byte;
}

void S9xFixEnvelope (int channel, uint8 gain, uint8 adsr1, uint8 adsr2)
{
    if (adsr1 & 0x80)
    {
	// ADSR mode
	static unsigned long AttackRate [16] = {
	    4100, 2600, 1500, 1000, 640, 380, 260, 160,
	    96, 64, 40, 24, 16, 10, 6, 1
	};
	static unsigned long DecayRate [8] = {
	    1200, 740, 440, 290, 180, 110, 74, 37
	};
	static unsigned long SustainRate [32] = {
	    ~0, 38000, 28000, 24000, 19000, 14000, 12000, 9400,
	    7100, 5900, 4700, 3500, 2900, 2400, 1800, 1500,
	    1200, 880, 740, 590, 440, 370, 290, 220,
	    180, 150, 110, 92, 74, 55, 37, 18
	};
	// XXX: can DSP be switched to ADSR mode directly from GAIN/INCREASE/
	// DECREASE mode? And if so, what stage of the sequence does it start
	// at?
	if (S9xSetSoundMode (channel, MODE_ADSR))
	{
	    // Hack for ROMs that use a very short attack rate, key on a 
	    // channel, then switch to decay mode. e.g. Final Fantasy II.

	    int attack = AttackRate [adsr1 & 0xf];

	    if (attack == 1 && (!Settings.SoundSync
#ifdef __WIN32__
                || Settings.SoundDriver != WIN_SNES9X_DIRECT_SOUND_DRIVER
#endif
                ))
		attack = 0;

	    S9xSetSoundADSR (channel, attack,
			     DecayRate [(adsr1 >> 4) & 7],
			     SustainRate [adsr2 & 0x1f],
			     (adsr2 >> 5) & 7, 8);
	}
    }
    else
    {
	// Gain mode
	if ((gain & 0x80) == 0)
	{
	    if (S9xSetSoundMode (channel, MODE_GAIN))
	    {
		S9xSetEnvelopeRate (channel, 0, 0, gain & 0x7f);
		S9xSetEnvelopeHeight (channel, gain & 0x7f);
	    }
	}
	else
	{
	    static unsigned long IncreaseRate [32] = {
		~0, 4100, 3100, 2600, 2000, 1500, 1300, 1000,
		770, 640, 510, 380, 320, 260, 190, 160,
		130, 96, 80, 64, 48, 40, 32, 24,
		20, 16, 12, 10, 8, 6, 4, 2
	    };
	    static unsigned long DecreaseRateExp [32] = {
		~0, 38000, 28000, 24000, 19000, 14000, 12000, 9400,
		7100, 5900, 4700, 3500, 2900, 2400, 1800, 1500,
		1200, 880, 740, 590, 440, 370, 290, 220,
		180, 150, 110, 92, 74, 55, 37, 18
	    };
	    if (gain & 0x40)
	    {
		// Increase mode
		if (S9xSetSoundMode (channel, (gain & 0x20) ?
					  MODE_INCREASE_BENT_LINE :
					  MODE_INCREASE_LINEAR))
		{
		    S9xSetEnvelopeRate (channel, IncreaseRate [gain & 0x1f],
					1, 127);
		}
	    }
	    else
	    {
		uint32 rate = (gain & 0x20) ? DecreaseRateExp [gain & 0x1f] / 2 :
					      IncreaseRate [gain & 0x1f];
		int mode = (gain & 0x20) ? MODE_DECREASE_EXPONENTIAL
					 : MODE_DECREASE_LINEAR;

		if (S9xSetSoundMode (channel, mode))
		    S9xSetEnvelopeRate (channel, rate, -1, 0);
	    }
	}
    }
}

void S9xSetAPUControl (uint8 byte)
{
//if (byte & 0x40)
//printf ("*** Special SPC700 timing enabled\n");
    if ((byte & 1) != 0 && !APU.TimerEnabled [0])
    {
	APU.Timer [0] = 0;
	IAPU.RAM [0xfd] = 0;
	if ((APU.TimerTarget [0] = IAPU.RAM [0xfa]) == 0)
	    APU.TimerTarget [0] = 0x100;
    }
    if ((byte & 2) != 0 && !APU.TimerEnabled [1])
    {
	APU.Timer [1] = 0;
	IAPU.RAM [0xfe] = 0;
	if ((APU.TimerTarget [1] = IAPU.RAM [0xfb]) == 0)
	    APU.TimerTarget [1] = 0x100;
    }
    if ((byte & 4) != 0 && !APU.TimerEnabled [2])
    {
	APU.Timer [2] = 0;
	IAPU.RAM [0xff] = 0;
	if ((APU.TimerTarget [2] = IAPU.RAM [0xfc]) == 0)
	    APU.TimerTarget [2] = 0x100;
    }
    APU.TimerEnabled [0] = byte & 1;
    APU.TimerEnabled [1] = (byte & 2) >> 1;
    APU.TimerEnabled [2] = (byte & 4) >> 2;

    if (byte & 0x10)
	IAPU.RAM [0xF4] = IAPU.RAM [0xF5] = 0;

    if (byte & 0x20)
	IAPU.RAM [0xF6] = IAPU.RAM [0xF7] = 0;

    if (byte & 0x80)
    {
	if (!APU.ShowROM)
	{
	    memmove (&IAPU.RAM [0xffc0], APUROM, sizeof (APUROM));
	    APU.ShowROM = TRUE;
	}
    }
    else
    {
	if (APU.ShowROM)
	{
	    APU.ShowROM = FALSE;
	    memmove (&IAPU.RAM [0xffc0], APU.ExtraRAM, sizeof (APUROM));
	}
    }
    IAPU.RAM [0xf1] = byte;
}

void S9xSetAPUTimer (uint16 Address, uint8 byte)
{
    IAPU.RAM [Address] = byte;

    switch (Address)
    {
    case 0xfa:
	if ((APU.TimerTarget [0] = IAPU.RAM [0xfa]) == 0)
	    APU.TimerTarget [0] = 0x100;
	APU.TimerValueWritten [0] = TRUE;
	break;
    case 0xfb:
	if ((APU.TimerTarget [1] = IAPU.RAM [0xfb]) == 0)
	    APU.TimerTarget [1] = 0x100;
	APU.TimerValueWritten [1] = TRUE;
	break;
    case 0xfc:
	if ((APU.TimerTarget [2] = IAPU.RAM [0xfc]) == 0)
	    APU.TimerTarget [2] = 0x100;
	APU.TimerValueWritten [2] = TRUE;
	break;
    }
}

uint8 S9xGetAPUDSP ()
{
    uint8 reg = IAPU.RAM [0xf2] & 0x7f;
    uint8 byte = APU.DSP [reg];

    switch (reg)
    {
    case APU_OUTX + 0x00:
    case APU_OUTX + 0x10:
    case APU_OUTX + 0x20:
    case APU_OUTX + 0x30:
    case APU_OUTX + 0x40:
    case APU_OUTX + 0x50:
    case APU_OUTX + 0x60:
    case APU_OUTX + 0x70:
	if (SoundData.channels [reg >> 4].state == SOUND_SILENT)
	    return (0);
	return ((SoundData.channels [reg >> 4].sample >> 8) |
		(SoundData.channels [reg >> 4].sample & 0xff));

    case APU_ENVX + 0x00:
    case APU_ENVX + 0x10:
    case APU_ENVX + 0x20:
    case APU_ENVX + 0x30:
    case APU_ENVX + 0x40:
    case APU_ENVX + 0x50:
    case APU_ENVX + 0x60:
    case APU_ENVX + 0x70:
	return ((uint8) S9xGetEnvelopeHeight (reg >> 4));

    case APU_ENDX:
// To fix speech in Magical Drop 2 6/11/00
//	APU.DSP [APU_ENDX] = 0;
	break;
    default:
	break;
    }
    return (byte);
}