samples: update notes, fix new regression with start_raw at very low samplerate

Author: happppp

src/devices/sound/samples.cpp

@@ -14,6 +14,12 @@ for tape loops and similar.
 - Only supports single channel samples!
 - Maybe this should be part of the presentation layer (artwork etc.)
   with samples specified in .lay files instead of in drivers?
+- Unless it's an infinitely looping sample, start_raw() is not compatible
+  with savestates. Save state right after start_raw(), load state later,
+  and the sample won't be playing.
+- No need for m_samples_start_cb, drivers that need to initialize after
+  samples_device::device_start can just throw missing dependencies.
+- No need for set_volume, can just use set_output_gain, but it's harmless.
 
 ***************************************************************************/
 
@@ -234,14 +240,17 @@ void samples_device::device_start()
 	m_channel.resize(m_channels);
 	for (int channel = 0; channel < m_channels; channel++)
 	{
+		// placeholder, changed to sample SR at start()
+		const uint32_t rate = machine().sample_rate();
+
 		// initialize channel
 		channel_t &chan = m_channel[channel];
-		chan.stream = stream_alloc(0, 1, machine().sample_rate());
+		chan.stream = stream_alloc(0, 1, rate);
 		chan.source = nullptr;
 		chan.source_num = -1;
 		chan.pos = 0.0;
-		chan.basefreq = machine().sample_rate();
-		chan.curfreq = machine().sample_rate();
+		chan.basefreq = rate;
+		chan.curfreq = rate;
 		chan.loop = false;
 		chan.paused = false;
 

src/mame/exidy/exidy.cpp

@@ -297,12 +297,14 @@ class spectar_state : public exidy_state
 
 protected:
 	virtual void machine_start() override ATTR_COLD;
+	virtual void machine_reset() override ATTR_COLD { exidy_state::machine_reset(); init_tonegen(); }
 
 	void set_max_freq(int freq) { m_max_freq = freq; }
 
 	void spectar_audio_1_w(uint8_t data);
 	void spectar_audio_2_w(uint8_t data);
 
+	void init_tonegen();
 	void adjust_sample(uint8_t freq);
 	bool RISING_EDGE(uint8_t data, uint8_t bit) const { return (data & bit) && !(m_port_1_last & bit); }
 	bool FALLING_EDGE(uint8_t data, uint8_t bit) const { return !(data & bit) && (m_port_1_last & bit); }
@@ -1469,14 +1471,6 @@ void spectar_state::machine_start()
 {
 	exidy_state::machine_start();
 
-	/* start_raw can't be called here: chan.source will be set by
-	samples_device::device_start and then nulled out by samples_device::device_reset
-	at the soft_reset stage of init_machine() and will never be set again.
-	Thus, I've moved it to exidy_state::adjust_sample() were it will be set after
-	machine initialization. */
-	//m_samples->set_volume(3, 0);
-	//m_samples->start_raw(3, sine_wave, 32, 1000, true);
-
 	save_item(NAME(m_port_1_last));
 	save_item(NAME(m_tone_freq));
 	save_item(NAME(m_tone_active));
@@ -1700,28 +1694,34 @@ void fax_state::fax(machine_config &config)
 *************************************************************************/
 
 /* Sound channel usage
-   0 = CPU music,  Shoot
+   0 = CPU music, Shoot
    1 = Crash
    2 = Spectar sound
    3 = Tone generator
 */
 
-static const int16_t sine_wave[32] =
-{
-	 0x0f0f,  0x0f0f,  0x0f0f,  0x0606,  0x0606,  0x0909,  0x0909,  0x0606,  0x0606,  0x0909,  0x0606,  0x0d0d,  0x0f0f,  0x0f0f,  0x0d0d,  0x0000,
-	-0x191a, -0x2122, -0x1e1f, -0x191a, -0x1314, -0x191a, -0x1819, -0x1819, -0x1819, -0x1314, -0x1314, -0x1314, -0x1819, -0x1e1f, -0x1e1f, -0x1819
-};
-
-
-void spectar_state::adjust_sample(uint8_t freq)
+void spectar_state::init_tonegen()
 {
-	m_tone_freq = freq;
+	static const int16_t sine_wave[32] =
+	{
+		0x0f0f,  0x0f0f,  0x0f0f,  0x0606,  0x0606,  0x0909,  0x0909,  0x0606,
+		0x0606,  0x0909,  0x0606,  0x0d0d,  0x0f0f,  0x0f0f,  0x0d0d,  0x0000,
+		-0x191a, -0x2122, -0x1e1f, -0x191a, -0x1314, -0x191a, -0x1819, -0x1819,
+		-0x1819, -0x1314, -0x1314, -0x1314, -0x1819, -0x1e1f, -0x1e1f, -0x1819
+	};
 
+	// initialized after samples_device::device_reset
 	if (!m_samples->playing(3))
 	{
 		m_samples->set_volume(3, 0);
-		m_samples->start_raw(3, sine_wave, 32, 1000, true);
+		m_samples->start_raw(3, sine_wave, 32, m_max_freq, true);
 	}
+}
+
+
+void spectar_state::adjust_sample(uint8_t freq)
+{
+	m_tone_freq = freq;
 
 	if ((m_tone_freq == 0xff) || (m_tone_freq == 0x00))
 		m_samples->set_volume(3, 0);

src/mame/meadows/meadows.cpp

@@ -150,8 +150,8 @@ namespace {
 class meadows_state : public driver_device
 {
 public:
-	meadows_state(const machine_config &mconfig, device_type type, const char *tag)
-		: driver_device(mconfig, type, tag),
+	meadows_state(const machine_config &mconfig, device_type type, const char *tag) :
+		driver_device(mconfig, type, tag),
 		m_maincpu(*this, "maincpu"),
 		m_audiocpu(*this, "audiocpu"),
 		m_dac(*this, "dac"),
@@ -175,6 +175,7 @@ class meadows_state : public driver_device
 
 protected:
 	virtual void machine_start() override ATTR_COLD;
+	virtual void machine_reset() override ATTR_COLD { sh_init(); }
 	virtual void video_start() override ATTR_COLD;
 
 private:
@@ -189,9 +190,7 @@ class meadows_state : public driver_device
 	optional_shared_ptr<uint8_t> m_spriteram;
 	required_shared_ptr<uint8_t> m_videoram;
 
-	uint8_t m_channel = 0; // TODO: always 0?
-	uint32_t m_freq1 = 0;
-	uint32_t m_freq2 = 0;
+	uint32_t m_freq[2] = { };
 	uint8_t m_latched_0c01 = 0;
 	uint8_t m_latched_0c02 = 0;
 	uint8_t m_latched_0c03 = 0;
@@ -203,6 +202,10 @@ class meadows_state : public driver_device
 	uint8_t m_0c03 = 0;
 
 	tilemap_t *m_bg_tilemap = nullptr;
+
+	void sh_init();
+	void sh_update();
+
 	uint8_t hsync_chain_r();
 	uint8_t vsync_chain_hi_r();
 	uint8_t vsync_chain_lo_r();
@@ -217,8 +220,7 @@ class meadows_state : public driver_device
 	void minferno_vblank_irq(int state);
 	INTERRUPT_GEN_MEMBER(audio_interrupt);
 	void draw_sprites(bitmap_ind16 &bitmap, const rectangle &clip);
-	void sh_update();
-	SAMPLES_START_CB_MEMBER(sh_start);
+
 	void audio_map(address_map &map) ATTR_COLD;
 	void bowl3d_main_map(address_map &map) ATTR_COLD;
 	void meadows_main_map(address_map &map) ATTR_COLD;
@@ -227,6 +229,12 @@ class meadows_state : public driver_device
 };
 
 
+/*************************************
+ *
+ *  Sound handler
+ *
+ *************************************/
+
 static constexpr uint32_t BASE_CTR1 = (5'000'000 / 256);
 static constexpr uint32_t BASE_CTR2 = (5'000'000 / 32);
 
@@ -237,25 +245,19 @@ static constexpr uint8_t ENABLE_CTR1 = 0x08;
 
 static const int16_t waveform[2] = { -120*256, 120*256 };
 
-/************************************/
-/* Sound handler start              */
-/************************************/
-SAMPLES_START_CB_MEMBER(meadows_state::sh_start)
+void meadows_state::sh_init()
 {
-	m_0c00 = m_0c01 = m_0c02 = m_0c03 = 0;
-	m_channel = 0;
-	m_freq1 = m_freq2 = 1000;
-	m_latched_0c01 = m_latched_0c02 = m_latched_0c03 = 0;
-
-	m_samples->set_volume(0, 0);
-	m_samples->start_raw(0, waveform, std::size(waveform), m_freq1, true);
-	m_samples->set_volume(1, 0);
-	m_samples->start_raw(1, waveform, std::size(waveform), m_freq2, true);
+	// initialized after samples_device::device_reset
+	for (int i = 0; i < 2; i++)
+		if (!m_samples->playing(i))
+		{
+			m_freq[i] = machine().sample_rate();
+
+			m_samples->set_volume(i, 0);
+			m_samples->start_raw(i, waveform, std::size(waveform), m_freq[i], true);
+		}
 }
 
-/************************************/
-/* Sound handler update             */
-/************************************/
 void meadows_state::sh_update()
 {
 	if (m_latched_0c01 != m_0c01 || m_latched_0c03 != m_0c03)
@@ -269,10 +271,10 @@ void meadows_state::sh_update()
 		   bit 0..3 of 0c01 are ctr preset */
 		int const preset = (m_0c01 & 15) ^ 15;
 		if (preset)
-			m_freq1 = BASE_CTR1 / (preset + 1);
+			m_freq[0] = BASE_CTR1 / (preset + 1);
 		else amp = 0;
-		LOGAUDIO("meadows ctr1 channel #%d preset:%3d freq:%5d amp:%d\n", m_channel, preset, m_freq1, amp);
-		m_samples->set_frequency(0, m_freq1 * sizeof(waveform) / 2);
+		LOGAUDIO("meadows ctr1 channel #0 preset:%3d freq:%5d amp:%d\n", preset, m_freq[0], amp);
+		m_samples->set_frequency(0, m_freq[0] * sizeof(waveform) / 2);
 		m_samples->set_volume(0, amp / 255.0);
 	}
 
@@ -284,13 +286,13 @@ void meadows_state::sh_update()
 		int const preset = m_0c02 ^ 0xff;
 		if (preset)
 		{
-			m_freq2 = BASE_CTR2 / (preset + 1) / 2;
+			m_freq[1] = BASE_CTR2 / (preset + 1) / 2;
 			if ((m_0c03 & DIV2OR4_CTR2) == 0)
-				m_freq2 >>= 1;
+				m_freq[1] >>= 1;
 		}
 		else amp = 0;
-		LOGAUDIO("meadows ctr2 channel #%d preset:%3d freq:%5d amp:%d\n", m_channel + 1, preset, m_freq2, amp);
-		m_samples->set_frequency(1, m_freq2 * sizeof(waveform));
+		LOGAUDIO("meadows ctr2 channel #1 preset:%3d freq:%5d amp:%d\n", preset, m_freq[1], amp);
+		m_samples->set_frequency(1, m_freq[1] * sizeof(waveform));
 		m_samples->set_volume(1, amp / 255.0);
 	}
 
@@ -305,10 +307,6 @@ void meadows_state::sh_update()
 }
 
 
-// some constants to make life easier
-static constexpr int8_t SPR_ADJUST_X = -18;
-static constexpr int8_t SPR_ADJUST_Y = -14;
-
 
 /*************************************
  *
@@ -375,8 +373,8 @@ void meadows_state::draw_sprites(bitmap_ind16 &bitmap, const rectangle &clip)
 {
 	for (int i = 0; i < 4; i++)
 	{
-		int const x = m_spriteram[i + 0] + SPR_ADJUST_X;
-		int const y = m_spriteram[i + 4] + SPR_ADJUST_Y;
+		int const x = m_spriteram[i + 0] - 18;
+		int const y = m_spriteram[i + 4] - 14;
 		int const code = m_spriteram[i + 8] & 0x0f;       // bit #0 .. #3 select sprite
 //      int const bank = (m_spriteram[i + 8] >> 4) & 1;      bit #4 selects PROM ???
 		int const bank = i;                               // that fixes it for now :-/
@@ -409,9 +407,7 @@ void meadows_state::machine_start()
 {
 	m_main_sense_state = 0;
 
-	// save_item(NAME(m_channel)); // commented out as it's always 0 right now
-	save_item(NAME(m_freq1));
-	save_item(NAME(m_freq2));
+	save_item(NAME(m_freq));
 	save_item(NAME(m_latched_0c01));
 	save_item(NAME(m_latched_0c02));
 	save_item(NAME(m_latched_0c03));
@@ -421,7 +417,6 @@ void meadows_state::machine_start()
 	save_item(NAME(m_0c01));
 	save_item(NAME(m_0c02));
 	save_item(NAME(m_0c03));
-
 }
 
 
@@ -939,11 +934,10 @@ void meadows_state::meadows(machine_config &config)
 
 	// audio hardware
 	SPEAKER(config, "speaker").front_center();
-	DAC_8BIT_R2R(config, m_dac, 0).add_route(ALL_OUTPUTS, "speaker", 0.5); // unknown DAC
+	DAC_8BIT_R2R(config, m_dac).add_route(ALL_OUTPUTS, "speaker", 0.5); // unknown DAC
 
 	SAMPLES(config, m_samples);
 	m_samples->set_channels(2);
-	m_samples->set_samples_start_callback(FUNC(meadows_state::sh_start));
 	m_samples->add_route(ALL_OUTPUTS, "speaker", 1.0);
 }