(nw) cassette: cleanup, and fixed a few minor but annoying bugs

- Create new tape, hit Reset: fatal error - internal error
- Load empty file to record onto, same error
- Randomly have to hit Play a number of times before it takes
- Randomly tape "plays" silently with the motor off.

src/devices/imagedev/cassette.cpp

@@ -11,7 +11,6 @@
 #include "emu.h"
 #include "formats/imageutl.h"
 #include "cassette.h"
-#include "ui/uimain.h"
 
 #define LOG_WARN          (1U<<1)   // Warnings
 #define LOG_DETAIL        (1U<<2)   // Details
@@ -93,7 +92,8 @@ void cassette_image_device::update()
 	{
 		double new_position = m_position + (cur_time - m_position_time)*m_speed*m_direction;
 
-		switch(m_state & CASSETTE_MASK_UISTATE) {
+		switch(m_state & CASSETTE_MASK_UISTATE)
+		{
 		case CASSETTE_RECORD:
 			cassette_put_sample(m_cassette, m_channel, m_position, new_position - m_position, m_value);
 			break;
@@ -124,29 +124,21 @@ void cassette_image_device::update()
 
 void cassette_image_device::change_state(cassette_state state, cassette_state mask)
 {
-	cassette_state new_state;
+	cassette_state new_state = m_state;
-
-	new_state = m_state;
 	new_state = (cassette_state)(new_state & ~mask);
 	new_state = (cassette_state)(new_state | (state & mask));
-
+	if ((m_state ^ new_state) & (CASSETTE_MASK_UISTATE | CASSETTE_MASK_MOTOR))
-	if (new_state != m_state)
+		m_position_time = machine().time().as_double();
-	{
+	m_state = new_state;
-		update();
-		m_state = new_state;
-	}
 }
 
 
 
 double cassette_image_device::input()
 {
-	int32_t sample;
-	double double_value;
-
 	update();
-	sample = m_value;
+	int32_t sample = m_value;
-	double_value = sample / ((double) 0x7FFFFFFF);
+	double double_value = sample / ((double) 0x7FFFFFFF);
 
 	LOGMASKED(LOG_DETAIL, "cassette_input(): time_index=%g value=%g\n", m_position, double_value);
 
@@ -171,11 +163,7 @@ void cassette_image_device::output(double value)
 
 double cassette_image_device::get_position()
 {
-	double position = m_position;
+	return m_position;
-
-	if (is_motor_on())
-		position += (machine().time().as_double() - m_position_time)*m_speed*m_direction;
-	return position;
 }
 
 
@@ -211,11 +199,7 @@ void cassette_image_device::go_reverse()
 
 void cassette_image_device::seek(double time, int origin)
 {
-	double length;
+	double length = get_length();
-
-	update();
-
-	length = get_length();
 
 	switch(origin) {
 	case SEEK_SET:
@@ -272,7 +256,7 @@ image_init_result cassette_image_device::internal_load(bool is_create)
 	device_image_interface *image = nullptr;
 	interface(image);
 
-	if (is_create)
+	if (is_create || (length()==0)) // empty existing images are fine to write over.
 	{
 		// creating an image
 		err = cassette_create((void *)image, &image_ioprocs, &wavfile_format, m_create_opts, CASSETTE_FLAG_READWRITE|CASSETTE_FLAG_SAVEONEXIT, &m_cassette);
@@ -308,7 +292,8 @@ image_init_result cassette_image_device::internal_load(bool is_create)
 	}
 
 	/* set to default state, but only change the UI state */
-	change_state(m_default_state, CASSETTE_MASK_UISTATE);
+	//change_state(m_default_state, CASSETTE_MASK_UISTATE);
+	m_state = m_default_state;
 
 	/* reset the position */
 	m_position = 0.0;
@@ -376,18 +361,15 @@ std::string cassette_image_device::call_display()
 	// only show the image when a cassette is loaded and the motor is on
 	if (exists() && is_motor_on())
 	{
-		int n;
-		double position, length;
-		cassette_state uistate;
 		static char const *const shapes[] = { u8"\u2500", u8"\u2572", u8"\u2502", u8"\u2571" };
 
 		// figure out where we are in the cassette
-		position = get_position();
+		double position = get_position();
-		length = get_length();
+		double length = get_length();
-		uistate = (cassette_state)(get_state() & CASSETTE_MASK_UISTATE);
+		cassette_state uistate = cassette_state(get_state() & CASSETTE_MASK_UISTATE);
 
 		// choose which frame of the animation we are at
-		n = ((int)position / ANIMATION_FPS) % ARRAY_LENGTH(shapes);
+		int n = (int(position) / ANIMATION_FPS) % ARRAY_LENGTH(shapes);
 
 		// play or record
 		const char *status_icon = (uistate == CASSETTE_PLAY)
@@ -404,18 +386,6 @@ std::string cassette_image_device::call_display()
 			((int)length / 60),
 			((int)length % 60),
 			(int)length);
-
-		// make sure tape stops at end when playing
-		if ((m_state & CASSETTE_MASK_UISTATE) == CASSETTE_PLAY)
-		{
-			if (m_cassette)
-			{
-				if (get_position() > get_length())
-				{
-					m_state = (cassette_state)((m_state & ~CASSETTE_MASK_UISTATE) | CASSETTE_STOPPED);
-				}
-			}
-		}
 	}
 	return result;
 }
@@ -426,29 +396,25 @@ std::string cassette_image_device::call_display()
 
 void cassette_image_device::sound_stream_update(sound_stream &stream, stream_sample_t **inputs, stream_sample_t **outputs, int samples)
 {
-	cassette_state state;
-	double time_index;
-	double duration;
 	stream_sample_t *left_buffer = outputs[0];
 	stream_sample_t *right_buffer = nullptr;
-	int i;
 
 	if (m_stereo)
 		right_buffer = outputs[1];
 
-	state = (cassette_state)(get_state() & (CASSETTE_MASK_UISTATE | CASSETTE_MASK_MOTOR | CASSETTE_MASK_SPEAKER));
+	cassette_state state = get_state();
 
 	if (exists() && (state == (CASSETTE_PLAY | CASSETTE_MOTOR_ENABLED | CASSETTE_SPEAKER_ENABLED)))
 	{
 		cassette_image *cassette = get_image();
-		time_index = get_position();
+		double time_index = get_position();
-		duration = ((double) samples) / machine().sample_rate();
+		double duration = ((double) samples) / machine().sample_rate();
 
 		cassette_get_samples(cassette, 0, time_index, duration, samples, 2, left_buffer, CASSETTE_WAVEFORM_16BIT);
 		if (m_stereo)
 			cassette_get_samples(cassette, 1, time_index, duration, samples, 2, right_buffer, CASSETTE_WAVEFORM_16BIT);
 
-		for (i = samples - 1; i >= 0; i--)
+		for (int i = samples - 1; i >= 0; i--)
 		{
 			left_buffer[i] = ((int16_t *) left_buffer)[i];
 			if (m_stereo)