soundux.cpp

SFC游戏模拟器 snes9x 1.43 的原代码

					{
						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 stereo_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 stereo_exit;
					}
					break;
					
				case SOUND_GAIN:
					S9xSetEnvRate (ch, 0, -1, 0);
					break;
		}
		ch-> left_vol_level = (ch->envx * ch->volume_left) / 128;
		ch->right_vol_level = (ch->envx * ch->volume_right) / 128;
		VL = (ch->sample * ch-> left_vol_level) / 128;
		VR = (ch->sample * ch->right_vol_level) / 128;
		}

		ch->count += freq;
		if (ch->count >= FIXED_POINT)
		{
			VL = ch->count >> FIXED_POINT_SHIFT;
			ch->sample_pointer += VL;
			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 stereo_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
						{
							S9xAPUSetEndX (J);
							ch->last_block = FALSE;
							uint8 *dir = S9xGetSampleAddress (ch->sample_number);
							ch->block_pointer = READ_WORD(dir + 2);
						}
					}
					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 (;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)
{
    static int wave[SOUND_BUFFER_SIZE];

    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 S9xMixSamplesO (uint8 *buffer, int sample_count, int byte_offset)
{
    S9xMixSamples (buffer+byte_offset, sample_count);
}
#ifdef __DJGPP
END_OF_FUNCTION(S9xMixSamplesO);
#endif

void S9xMixSamples (uint8 *buffer, int sample_count)
{
    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, 0, byte_count);
		}
		else
		{
			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] = 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];