sc01: Fix pitch and closure [O. Galibert]

wow, gorf: Fix sc01 hookup [O. Galibert, Frank Palazzolo, plgDavid]

Note that the dynamic clock changes will sound bad until Aaron's sound
stream fixes are in.

src/devices/sound/flt_rc.cpp

@@ -63,6 +63,7 @@ void filter_rc_device::sound_stream_update(sound_stream &stream, stream_sample_t
 	switch (m_type)
 	{
 		case LOWPASS:
+		case LOWPASS_2C:
 			while (samples--)
 			{
 				memory += ((*src++ - memory) * m_k) / 0x10000;
@@ -93,10 +94,21 @@ void filter_rc_device::recalc()
 			{
 				/* filter disabled */
 				m_k = 0x10000;
+				m_memory = 0x0;
 				return;
 			}
 			Req = (m_R1 * (m_R2 + m_R3)) / (m_R1 + m_R2 + m_R3);
 			break;
+		case LOWPASS_2C:
+			if (m_C == 0.0)
+			{
+				/* filter disabled */
+				m_k = 0x10000;
+				m_memory = 0x0;
+				return;
+			}
+			Req = m_R1;
+			break;
 		case HIGHPASS:
 		case AC:
 			if (m_C == 0.0)

src/devices/sound/flt_rc.h

@@ -18,6 +18,16 @@
  *
  * Set C=0 to disable filter
  *
+ * FLT_RC_LOWPASS_@C:
+ *
+ * signal >--R1--+----> amp
+ *               |
+ *               C
+ *               |
+ *              GND
+ *
+ * Set C=0 to disable filter
+ *
  * FLT_RC_HIGHPASS:
  *
  * signal >--C---+----> amp
@@ -53,8 +63,9 @@ class filter_rc_device : public device_t, public device_sound_interface
 	enum
 	{
 		LOWPASS      = 0,
-		HIGHPASS     = 1,
-		AC           = 2
+		LOWPASS_2C   = 2,
+		HIGHPASS     = 3,
+		AC           = 4
 	};
 
 	filter_rc_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock = 0);
@@ -70,6 +81,16 @@ class filter_rc_device : public device_t, public device_sound_interface
 		return *this;
 	}
 
+	filter_rc_device &set_lowpass(double R, double C)
+	{
+		m_type = LOWPASS_2C;
+		m_R1 = R;
+		m_R2 = 0;
+		m_R3 = 0;
+		m_C = C;
+		return *this;
+	}
+
 	filter_rc_device &filter_rc_set_RC(int type, double R1, double R2, double R3, double C)
 	{
 		m_stream->update();

src/devices/sound/votrax.cpp

@@ -470,14 +470,17 @@ void votrax_sc01_device::chip_update()
 
 	// Pitch counter.  Equality comparison, so it's possible to make
 	// it miss by manipulating the inflection inputs, but it'll wrap.
-	// There's a delay, hence the +1.
-	m_pitch = (m_pitch + 1) & 0x7f;
-	if(m_pitch == (0x7f ^ (m_inflection << 4) ^ m_filt_f1) + 1)
+	// There's a delay, hence the +2.
+
+	// Intrinsically pre-divides by two, so we added one bit on the 7
+
+	m_pitch = (m_pitch + 1) & 0xff;
+	if(m_pitch == (0xe0 ^ (m_inflection << 5) ^ (m_filt_f1 << 1)) + 2)
 		m_pitch = 0;
 
 	// Filters are updated in index 1 of the pitch wave, which does
 	// indeed mean four times in a row.
-	if((m_pitch >> 2) == 1)
+	if((m_pitch & 0xf9) == 0x08)
 		filters_commit(false);
 
 	// Noise shift register.  15 bits, with a nxor on the last two
@@ -486,7 +489,7 @@ void votrax_sc01_device::chip_update()
 	m_noise = ((m_noise << 1) & 0x7ffe) | inp;
 	m_cur_noise = !(((m_noise >> 14) ^ (m_noise >> 13)) & 1);
 
-	//  logerror("tick %02x.%03x 625=%d 208=%d pitch=%02x.%x ns=%04x ni=%d noise=%d cl=%x.%x clf=%d/%d\n", m_ticks, m_phonetick, tick_625, tick_208, m_pitch >> 2, m_pitch & 3, m_noise, inp, m_cur_noise, m_closure >> 2, m_closure & 3, m_rom_closure, m_cur_closure);
+	//	logerror("%s tick %02x.%03x 625=%d 208=%d pitch=%02x.%x ns=%04x ni=%d noise=%d cl=%x.%x clf=%d/%d\n", machine().time().to_string(), m_ticks, m_phonetick, tick_625, tick_208, m_pitch >> 3, m_pitch & 7, m_noise, inp, m_cur_noise, m_closure >> 2, m_closure & 3, m_rom_closure, m_cur_closure);
 }
 
 void votrax_sc01_device::filters_commit(bool force)
@@ -570,7 +573,7 @@ stream_sample_t votrax_sc01_device::analog_calc()
 	// Voice-only path.
 	// 1. Pick up the pitch wave
 
-	double v = m_pitch >= (9 << 2) ? 0 : s_glottal_wave[m_pitch >> 2];
+	double v = m_pitch >= (9 << 3) ? 0 : s_glottal_wave[m_pitch >> 3];
 
 	// 2. Multiply by the initial amplifier.  It's linear on the die,
 	// even if it's not in the patent.
@@ -622,7 +625,7 @@ stream_sample_t votrax_sc01_device::analog_calc()
 	shift_hist(vn, m_vn_4);
 
 	// 13. Apply the glottal closure amplitude, also linear
-	vn = vn * (7 ^ (m_cur_closure >> 2)) / 7.0;
+	vn = vn * (7 ^ (m_closure >> 2)) / 7.0;
 	shift_hist(vn, m_vn_5);
 
 	// 13. Apply the final fixed filter

src/mame/drivers/astrocde.cpp

@@ -124,6 +124,7 @@
 #include "machine/watchdog.h"
 #include "sound/ay8910.h"
 #include "sound/votrax.h"
+#include "sound/flt_rc.h"
 
 #include "speaker.h"
 
@@ -397,10 +398,11 @@ void tenpindx_state::lights_w(uint8_t data)
 
 void astrocde_state::votrax_speech_w(uint8_t data)
 {
-	m_votrax->inflection_w(data >> 6);
+	// Note that the frequency change is smooth, but we just can't
+	// handle that.
+	m_votrax->set_clock(data & 0x40 ? 782000 : 756000);
+	m_votrax->inflection_w(data & 0x80 ? 0 : 2);
 	m_votrax->write(data & 0x3f);
-
-	/* Note : We should really also use volume in this as well as frequency */
 }
 
 
@@ -1355,8 +1357,13 @@ void astrocde_state::wow(machine_config &config)
 	m_astrocade_sound1->so_cb<5>().set("outlatch", FUNC(cd4099_device::write_nibble_d0));
 	m_astrocade_sound1->so_cb<7>().set(FUNC(astrocde_state::votrax_speech_w));
 
-	VOTRAX_SC01(config, m_votrax, 720000);
-	m_votrax->add_route(ALL_OUTPUTS, "center", 0.85);
+	VOTRAX_SC01(config, m_votrax, 756000);
+
+	m_votrax->add_route(0, "f1", 0.85);
+	FILTER_RC(config, "f1").set_lowpass(110e3, 560e-12).add_route(0, "f2", 1.00);
+	FILTER_RC(config, "f2").set_lowpass(110e3, 560e-12).add_route(0, "f3", 1.00);
+	FILTER_RC(config, "f3").set_lowpass(110e3, 560e-12).add_route(0, "f4", 1.00);
+	FILTER_RC(config, "f4").set_lowpass(110e3, 560e-12).add_route(0, "center", 1.00);
 }
 
 void astrocde_state::gorf(machine_config &config)
@@ -1406,7 +1413,7 @@ void astrocde_state::gorf(machine_config &config)
 
 	ASTROCADE_IO(config, "astrocade2", ASTROCADE_CLOCK/4).add_route(ALL_OUTPUTS, "lower", 1.0);
 
-	VOTRAX_SC01(config, m_votrax, 720000);
+	VOTRAX_SC01(config, m_votrax, 756000);
 	m_votrax->add_route(ALL_OUTPUTS, "upper", 0.85);
 }