soundux.cpp

著名SFC模拟器Snes9x的源代码。

		{
		    if (Settings.InterpolatedSound && freq < FIXED_POINT && !mod)
		    {
			ch->interpolate = ((ch->next_sample - ch->sample) * 
					   (long) freq) / (long) FIXED_POINT;
			ch->sample = (int16) (ch->sample + (((ch->next_sample - ch->sample) * 
					   (long) (ch->count)) / (long) FIXED_POINT));
		    }		  
		    else
			ch->interpolate = 0;
		}
		else
		{
		    for (;VL > 0; VL--)
			if ((so.noise_gen <<= 1) & 0x80000000L)
			    so.noise_gen ^= 0x0040001L;
		    ch->sample = (so.noise_gen << 17) >> 17;
		    ch->interpolate = 0;
		}

		VL = (ch->sample * ch-> left_vol_level) / 128;
		VR = (ch->sample * ch->right_vol_level) / 128;
            }
	    else
	    {
		if (ch->interpolate)
		{
		    int32 s = (int32) ch->sample + ch->interpolate;
		    
		    CLIP16(s);
		    ch->sample = (int16) s;
		    VL = (ch->sample * ch-> left_vol_level) / 128;
		    VR = (ch->sample * ch->right_vol_level) / 128;
		}
	    }

	    if (pitch_mod & (1 << (J + 1)))
		wave [I / 2] = ch->sample * ch->envx;

	    MixBuffer [I      ^ Settings.ReverseStereo] += VL;
	    MixBuffer [I + (1 ^ Settings.ReverseStereo)] += VR;
	    ch->echo_buf_ptr [I      ^ Settings.ReverseStereo] += VL;
	    ch->echo_buf_ptr [I + (1 ^ Settings.ReverseStereo)] += VR;
        }
stereo_exit: ;
    }
}

#ifdef __DJGPP
END_OF_FUNCTION(MixStereo);
#endif

void MixMono (int sample_count)
{
#if defined(TARGET_OS_MAC) && TARGET_OS_MAC
    static int wave[SOUND_BUFFER_SIZE];
#else
    int wave[SOUND_BUFFER_SIZE];
#endif
    int pitch_mod = SoundData.pitch_mod & (~APU.DSP[APU_NON]);

    for (uint32 J = 0; J < NUM_CHANNELS; J++) 
    {
	Channel *ch = &SoundData.channels[J];
	unsigned long freq0 = ch->frequency;

	if (ch->state == SOUND_SILENT || !(so.sound_switch & (1 << J)))
	    continue;

//	freq0 = (unsigned long) ((double) freq0 * 0.985);

	bool8 mod = pitch_mod & (1 << J);

	if (ch->needs_decode) 
	{
	    DecodeBlock(ch);
	    ch->needs_decode = FALSE;
	    ch->sample = ch->block[0];
	    ch->sample_pointer = freq0 >> FIXED_POINT_SHIFT;
	    if (ch->sample_pointer == 0)
		ch->sample_pointer = 1;
	    if (ch->sample_pointer > SOUND_DECODE_LENGTH)
		ch->sample_pointer = SOUND_DECODE_LENGTH - 1;
	    ch->next_sample = ch->block[ch->sample_pointer];
	    ch->interpolate = 0;

	    if (Settings.InterpolatedSound && freq0 < FIXED_POINT && !mod)
		ch->interpolate = ((ch->next_sample - ch->sample) * 
				   (long) freq0) / (long) FIXED_POINT;
	}
	int32 V = (ch->sample * ch->left_vol_level) / 128;

	for (uint32 I = 0; I < (uint32) sample_count; I++)
	{
	    unsigned long freq = freq0;

	    if (mod)
		freq = PITCH_MOD(freq, wave [I]);

	    ch->env_error += ch->erate;
	    if (ch->env_error >= FIXED_POINT) 
	    {
		uint32 step = ch->env_error >> FIXED_POINT_SHIFT;

		switch (ch->state)
		{
		case SOUND_ATTACK:
		    ch->env_error &= FIXED_POINT_REMAINDER;
		    ch->envx += step << 1;
		    ch->envxx = ch->envx << ENVX_SHIFT;

		    if (ch->envx >= 126)
		    {
			ch->envx = 127;
			ch->envxx = 127 << ENVX_SHIFT;
			ch->state = SOUND_DECAY;
			if (ch->sustain_level != 8) 
			{
			    S9xSetEnvRate (ch, ch->decay_rate, -1,
						(MAX_ENVELOPE_HEIGHT * ch->sustain_level)
						>> 3);
			    break;
			}
			ch->state = SOUND_SUSTAIN;
			S9xSetEnvRate (ch, ch->sustain_rate, -1, 0);
		    }
		    break;
		
		case SOUND_DECAY:
		    while (ch->env_error >= FIXED_POINT)
		    {
			ch->envxx = (ch->envxx >> 8) * 255;
			ch->env_error -= FIXED_POINT;
		    }
		    ch->envx = ch->envxx >> ENVX_SHIFT;
		    if (ch->envx <= ch->envx_target)
		    {
			if (ch->envx <= 0)
			{
			    S9xAPUSetEndOfSample (J, ch);
			    goto mono_exit;
			}
			ch->state = SOUND_SUSTAIN;
			S9xSetEnvRate (ch, ch->sustain_rate, -1, 0);
		    }
		    break;

		case SOUND_SUSTAIN:
		    while (ch->env_error >= FIXED_POINT)
		    {
			ch->envxx = (ch->envxx >> 8) * 255;
			ch->env_error -= FIXED_POINT;
		    }
		    ch->envx = ch->envxx >> ENVX_SHIFT;
		    if (ch->envx <= 0)
		    {
			S9xAPUSetEndOfSample (J, ch);
			goto mono_exit;
		    }
		    break;
		    
		case SOUND_RELEASE:
		    while (ch->env_error >= FIXED_POINT)
		    {
			ch->envxx -= (MAX_ENVELOPE_HEIGHT << ENVX_SHIFT) / 256;
			ch->env_error -= FIXED_POINT;
		    }
		    ch->envx = ch->envxx >> ENVX_SHIFT;
		    if (ch->envx <= 0)
		    {
			S9xAPUSetEndOfSample (J, ch);
			goto mono_exit;
		    }
		    break;
		
		case SOUND_INCREASE_LINEAR:
		    ch->env_error &= FIXED_POINT_REMAINDER;
		    ch->envx += step << 1;
		    ch->envxx = ch->envx << ENVX_SHIFT;

		    if (ch->envx >= 126)
		    {
			ch->envx = 127;
			ch->envxx = 127 << ENVX_SHIFT;
			ch->state = SOUND_GAIN;
			ch->mode = MODE_GAIN;
			S9xSetEnvRate (ch, 0, -1, 0);
		    }
		    break;

		case SOUND_INCREASE_BENT_LINE:
		    if (ch->envx >= (MAX_ENVELOPE_HEIGHT * 3) / 4)
		    {
			while (ch->env_error >= FIXED_POINT)
			{
			    ch->envxx += (MAX_ENVELOPE_HEIGHT << ENVX_SHIFT) / 256;
			    ch->env_error -= FIXED_POINT;
			}
			ch->envx = ch->envxx >> ENVX_SHIFT;
		    }
		    else
		    {
			ch->env_error &= FIXED_POINT_REMAINDER;
			ch->envx += step << 1;
			ch->envxx = ch->envx << ENVX_SHIFT;
		    }

		    if (ch->envx >= 126)
		    {
			ch->envx = 127;
			ch->envxx = 127 << ENVX_SHIFT;
			ch->state = SOUND_GAIN;
			ch->mode = MODE_GAIN;
			S9xSetEnvRate (ch, 0, -1, 0);
		    }
		    break;

		case SOUND_DECREASE_LINEAR:
		    ch->env_error &= FIXED_POINT_REMAINDER;
		    ch->envx -= step << 1;
		    ch->envxx = ch->envx << ENVX_SHIFT;
		    if (ch->envx <= 0)
		    {
			S9xAPUSetEndOfSample (J, ch);
			goto mono_exit;
		    }
		    break;

		case SOUND_DECREASE_EXPONENTIAL:
		    while (ch->env_error >= FIXED_POINT)
		    {
			ch->envxx = (ch->envxx >> 8) * 255;
			ch->env_error -= FIXED_POINT;
		    }
		    ch->envx = ch->envxx >> ENVX_SHIFT;
		    if (ch->envx <= 0)
		    {
			S9xAPUSetEndOfSample (J, ch);
			goto mono_exit;
		    }
		    break;
		
		case SOUND_GAIN:
		    S9xSetEnvRate (ch, 0, -1, 0);
		    break;
		}
		ch->left_vol_level = (ch->envx * ch->volume_left) / 128;
		V = (ch->sample * ch->left_vol_level) / 128;
	    }

	    ch->count += freq;
	    if (ch->count >= FIXED_POINT)
	    {
		V = ch->count >> FIXED_POINT_SHIFT;
		ch->sample_pointer += V;
		ch->count &= FIXED_POINT_REMAINDER;

		ch->sample = ch->next_sample;
		if (ch->sample_pointer >= SOUND_DECODE_LENGTH)
		{
		    if (JUST_PLAYED_LAST_SAMPLE(ch))
		    {
			S9xAPUSetEndOfSample (J, ch);
			goto mono_exit;
		    }
		    do
		    {
			ch->sample_pointer -= SOUND_DECODE_LENGTH;
			if (ch->last_block)
			{
			    if (!ch->loop)
			    {
				ch->sample_pointer = LAST_SAMPLE;
				ch->next_sample = ch->sample;
				break;
			    }
			    else
			    {
				ch->last_block = FALSE;
				uint8 *dir = S9xGetSampleAddress (ch->sample_number);
				ch->block_pointer = READ_WORD(dir + 2);
				S9xAPUSetEndX (J);
			    }
			}
			DecodeBlock (ch);
		    } while (ch->sample_pointer >= SOUND_DECODE_LENGTH);
		    if (!JUST_PLAYED_LAST_SAMPLE (ch))
			ch->next_sample = ch->block [ch->sample_pointer];
		}
		else
		    ch->next_sample = ch->block [ch->sample_pointer];

		if (ch->type == SOUND_SAMPLE)
		{
		    if (Settings.InterpolatedSound && freq < FIXED_POINT && !mod)
		    {
			ch->interpolate = ((ch->next_sample - ch->sample) * 
					   (long) freq) / (long) FIXED_POINT;
			ch->sample = (int16) (ch->sample + (((ch->next_sample - ch->sample) * 
					   (long) (ch->count)) / (long) FIXED_POINT));
		    }		  
		    else
			ch->interpolate = 0;
		}
		else
		{
		    for (;V > 0; V--)
			if ((so.noise_gen <<= 1) & 0x80000000L)
			    so.noise_gen ^= 0x0040001L;
		    ch->sample = (so.noise_gen << 17) >> 17;
		    ch->interpolate = 0;
		}
		V = (ch->sample * ch-> left_vol_level) / 128;
            }
	    else
	    {
		if (ch->interpolate)
		{
		    int32 s = (int32) ch->sample + ch->interpolate;

		    CLIP16(s);
		    ch->sample = (int16) s;
		    V = (ch->sample * ch-> left_vol_level) / 128;
		}
	    }

	    MixBuffer [I] += V;
	    ch->echo_buf_ptr [I] += V;

	    if (pitch_mod & (1 << (J + 1)))
		wave [I] = ch->sample * ch->envx;
        }
mono_exit: ;
    }
}
#ifdef __DJGPP
END_OF_FUNCTION(MixMono);
#endif

#ifdef __sun
extern uint8 int2ulaw (int);
#endif

// For backwards compatibility with older port specific code
void S9xMixSamples (uint8 *buffer, int sample_count)
{
    S9xMixSamplesO (buffer, sample_count, 0);
}
#ifdef __DJGPP
END_OF_FUNCTION(S9xMixSamples);
#endif

void S9xMixSamplesO (uint8 *buffer, int sample_count, int byte_offset)
{
    int J;
    int I;

    if (!so.mute_sound)
    {
	memset (MixBuffer, 0, sample_count * sizeof (MixBuffer [0]));
	if (SoundData.echo_enable)
	    memset (EchoBuffer, 0, sample_count * sizeof (EchoBuffer [0]));

	if (so.stereo)
	    MixStereo (sample_count);
	else
	    MixMono (sample_count);
    }

    /* Mix and convert waveforms */
    if (so.sixteen_bit)
    {
	int byte_count = sample_count << 1;
	
	// 16-bit sound
	if (so.mute_sound)
	{
            memset (buffer + byte_offset, 0, byte_count);
	}
	else
	{
	    int O = byte_offset >> 1;
	    if (SoundData.echo_enable && SoundData.echo_buffer_size)
	    {
		if (so.stereo)
		{
		    // 16-bit stereo sound with echo enabled ...
		    if (SoundData.no_filter)
		    {
			// ... but no filter defined.
			for (J = 0; J < sample_count; J++)
			{
			    int E = Echo [SoundData.echo_ptr];

			    Echo [SoundData.echo_ptr] = (E * SoundData.echo_feedback) / 128 +
							EchoBuffer [J];

			    if ((SoundData.echo_ptr += 1) >= SoundData.echo_buffer_size)
				SoundData.echo_ptr = 0;

			    I = (MixBuffer [J] * 
				 SoundData.master_volume [J & 1] +
				 E * SoundData.echo_volume [J & 1]) / VOL_DIV16;

			    CLIP16(I);
			    ((signed short *) buffer)[J + O] = I;
			}
		    }
		    else
		    {
			// ... with filter defined.
			for (J = 0; J < sample_count; J++)
			{
			    int E = Echo [SoundData.echo_ptr];

			    Loop [(Z - 0) & 15] = E;
			    E =  E                    * FilterTaps [0];
			    E += Loop [(Z -  2) & 15] * FilterTaps [1];
			    E += Loop [(Z -  4) & 15] * FilterTaps [2];
			    E += Loop [(Z -  6) & 15] * FilterTaps [3];
			    E += Loop [(Z -  8) & 15] * FilterTaps [4];
			    E += Loop [(Z - 10) & 15] * FilterTaps [5];
			    E += Loop [(Z - 12) & 15] * FilterTaps [6];
			    E += Loop [(Z - 14) & 15] * FilterTaps [7];
			    E /= 128;
			    Z++;

			    Echo [SoundData.echo_ptr] = (E * SoundData.echo_feedback) / 128 +
							EchoBuffer [J];

			    if ((SoundData.echo_ptr += 1) >= SoundData.echo_buffer_size)
				SoundData.echo_ptr = 0;

			    I = (MixBuffer [J] * 
				 SoundData.master_volume [J & 1] +
				 E * SoundData.echo_volume [J & 1]) / VOL_DIV16;

			    CLIP16(I);
			    ((signed short *) buffer)[J + O] = I;
			}
		    }
		}
		else
		{
		    // 16-bit mono sound with echo enabled...
		    if (SoundData.no_filter)
		    {
			// ... no filter defined
			for (J = 0; J < sample_count; J++)
			{
			    int E = Echo [SoundData.echo_ptr];

			    Echo [SoundData.echo_ptr] = (E * SoundData.echo_feedback) / 128 +