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Diffstat (limited to 'src/devices/sound/ay8910.cpp')
-rw-r--r--src/devices/sound/ay8910.cpp22
1 files changed, 10 insertions, 12 deletions
diff --git a/src/devices/sound/ay8910.cpp b/src/devices/sound/ay8910.cpp
index 26e99cf1bc7..8ba53fb8b3f 100644
--- a/src/devices/sound/ay8910.cpp
+++ b/src/devices/sound/ay8910.cpp
@@ -1108,12 +1108,13 @@ void ay8910_device::sound_stream_update(sound_stream &stream, std::vector<read_s
for (int chan = 0; chan < NUM_CHANNELS; chan++)
{
tone = &m_tone[chan];
- tone->count++;
- if (tone->count >= tone->period)
+ const int period = std::max<int>(1,tone->period);
+ tone->count += is_expanded_mode() ? 16 : 1;
+ while (tone->count >= period)
{
tone->duty_cycle = (tone->duty_cycle - 1) & 0x1f;
- tone->output = (m_feature & PSG_HAS_EXPANDED_MODE) ? BIT(duty_cycle[tone_duty(tone)], tone->duty_cycle) : BIT(tone->duty_cycle, 0);
- tone->count = 0;
+ tone->output = is_expanded_mode() ? BIT(duty_cycle[tone_duty(tone)], tone->duty_cycle) : BIT(tone->duty_cycle, 0);
+ tone->count -= period;
}
}
@@ -1124,8 +1125,9 @@ void ay8910_device::sound_stream_update(sound_stream &stream, std::vector<read_s
* channels.
*/
m_count_noise = 0;
+ m_prescale_noise ^= 1;
- if (!m_prescale_noise)
+ if (!m_prescale_noise || is_expanded_mode()) // AY8930 noise generator rate is twice compares as compatibility mode
{
/* The Random Number Generator of the 8910 is a 17-bit shift */
/* register. The input to the shift register is bit0 XOR bit3 */
@@ -1134,9 +1136,7 @@ void ay8910_device::sound_stream_update(sound_stream &stream, std::vector<read_s
// TODO : get actually algorithm for AY8930
m_rng ^= (((m_rng & 1) ^ ((m_rng >> 3) & 1)) << 17);
m_rng >>= 1;
- m_prescale_noise = (m_feature & PSG_HAS_EXPANDED_MODE) ? 16 : 1;
}
- m_prescale_noise--;
}
for (int chan = 0; chan < NUM_CHANNELS; chan++)
@@ -1336,7 +1336,7 @@ void ay8910_device::device_start()
/* The envelope is pacing twice as fast for the YM2149 as for the AY-3-8910, */
/* This handled by the step parameter. Consequently we use a multipler of 2 here. */
- m_channel = stream_alloc(0, m_streams, (m_feature & PSG_HAS_EXPANDED_MODE) ? master_clock * 2 : master_clock / 8);
+ m_channel = stream_alloc(0, m_streams, master_clock / 8);
ay_set_clock(master_clock);
ay8910_statesave();
@@ -1389,9 +1389,9 @@ void ay8910_device::ay_set_clock(int clock)
{
// FIXME: this doesn't belong here, it should be an input pin exposed via devcb
if (((m_feature & PSG_PIN26_IS_CLKSEL) && (m_flags & YM2149_PIN26_LOW)) || (m_feature & PSG_HAS_INTERNAL_DIVIDER))
- m_channel->set_sample_rate((m_feature & PSG_HAS_EXPANDED_MODE) ? clock : clock / 16);
+ m_channel->set_sample_rate(clock / 16);
else
- m_channel->set_sample_rate((m_feature & PSG_HAS_EXPANDED_MODE) ? clock * 2 : clock / 8);
+ m_channel->set_sample_rate(clock / 8);
}
void ay8910_device::device_clock_changed()
@@ -1659,8 +1659,6 @@ void ay8910_device::set_type(psg_type_t psg_type)
m_par = &ym2149_param;
m_par_env = &ym2149_param_env;
}
- if (m_feature & PSG_HAS_EXPANDED_MODE)
- m_step *= 16;
}
DEFINE_DEVICE_TYPE(AY8912, ay8912_device, "ay8912", "AY-3-8912A PSG")