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author cam900 <dbtlrchl@naver.com>2019-03-30 06:57:45 +0900
committer R. Belmont <rb6502@users.noreply.github.com>2019-03-29 17:57:45 -0400
commitb9b2a6dd7d64ebe072495b7c596862c3e7d50e6c (patch)
treea1375fac149caada6492bc96bb9c0c51f5b807df
parent80a48d5229eb5ff62b4f27ec6351226b672c0030 (diff)
c6280.cpp : Fix LFO, Frequency behavior (#4822)
* c6280.cpp : Fix LFO enable bit * c6280.cpp : Implement LFO reset bit behavior * c6280.cpp : Correct frequency behavior, Add notes
-rw-r--r--src/devices/sound/c6280.cpp104
-rw-r--r--src/devices/sound/c6280.h9
2 files changed, 51 insertions, 62 deletions
diff --git a/src/devices/sound/c6280.cpp b/src/devices/sound/c6280.cpp
index 0e5873c86de..73ec3e821be 100644
--- a/src/devices/sound/c6280.cpp
+++ b/src/devices/sound/c6280.cpp
@@ -92,16 +92,16 @@ void c6280_device::sound_stream_update(sound_stream &stream, stream_sample_t **i
if((ch >= 4) && (m_channel[ch].m_noise_control & 0x80))
{
/* Noise mode */
- uint32_t step = m_noise_freq_tab[(m_channel[ch].m_noise_control & 0x1F) ^ 0x1F];
+ uint32_t step = (m_channel[ch].m_noise_control & 0x1F) ^ 0x1F;
for (int i = 0; i < samples; i += 1)
{
static int data = 0;
- m_channel[ch].m_noise_counter += step;
- if(m_channel[ch].m_noise_counter >= 0x800)
+ if(m_channel[ch].m_noise_counter <= 0)
{
+ m_channel[ch].m_noise_counter = step << 2;
data = (machine().rand() & 1) ? 0x1F : 0;
}
- m_channel[ch].m_noise_counter &= 0x7FF;
+ m_channel[ch].m_noise_counter--;
outputs[0][i] += (int16_t)(vll * (data - 16));
outputs[1][i] += (int16_t)(vlr * (data - 16));
}
@@ -118,28 +118,40 @@ void c6280_device::sound_stream_update(sound_stream &stream, stream_sample_t **i
}
else
{
- if ((m_lfo_control & 0x80) && (ch < 2))
+ if ((m_lfo_control & 3) && (ch < 2))
{
if (ch == 0) // CH 0 only, CH 1 is muted
{
/* Waveform mode with LFO */
- uint32_t step = m_channel[0].m_frequency;
- uint16_t lfo_step = m_channel[1].m_frequency;
+ uint16_t lfo_step = m_channel[1].m_frequency ? m_channel[1].m_frequency : 0x1000;
for (int i = 0; i < samples; i += 1)
{
- int offset, lfooffset;
- int16_t data, lfo_data;
- lfooffset = (m_channel[1].m_counter >> 12) & 0x1F;
- m_channel[1].m_counter += m_wave_freq_tab[(lfo_step * m_lfo_frequency) & 0xfff]; // TODO : multiply? verify this from real hardware.
- m_channel[1].m_counter &= 0x1FFFF;
- lfo_data = m_channel[1].m_waveform[lfooffset];
- if (m_lfo_control & 3)
+ int32_t step = m_channel[0].m_frequency ? m_channel[0].m_frequency : 0x1000;
+ if (m_lfo_control & 0x80) // reset LFO
+ {
+ m_channel[1].m_tick = lfo_step * m_lfo_frequency;
+ m_channel[1].m_counter = 0;
+ }
+ else
+ {
+ int lfooffset = m_channel[1].m_counter;
+ m_channel[1].m_tick--;
+ if (m_channel[1].m_tick <= 0)
+ {
+ m_channel[1].m_tick = lfo_step * m_lfo_frequency; // TODO : multiply? verify this from real hardware.
+ m_channel[1].m_counter = (m_channel[1].m_counter + 1) & 0x1f;
+ }
+ int16_t lfo_data = m_channel[1].m_waveform[lfooffset];
step += ((lfo_data - 16) << (((m_lfo_control & 3)-1)<<1)); // verified from patent, TODO : same in real hardware?
-
- offset = (m_channel[0].m_counter >> 12) & 0x1F;
- m_channel[0].m_counter += m_wave_freq_tab[step & 0xfff];
- m_channel[0].m_counter &= 0x1FFFF;
- data = m_channel[0].m_waveform[offset];
+ }
+ int offset = m_channel[0].m_counter;
+ m_channel[0].m_tick--;
+ if (m_channel[0].m_tick <= 0)
+ {
+ m_channel[0].m_tick = step;
+ m_channel[0].m_counter = (m_channel[0].m_counter + 1) & 0x1f;
+ }
+ int16_t data = m_channel[0].m_waveform[offset];
outputs[0][i] += (int16_t)(vll * (data - 16));
outputs[1][i] += (int16_t)(vlr * (data - 16));
}
@@ -148,15 +160,17 @@ void c6280_device::sound_stream_update(sound_stream &stream, stream_sample_t **i
else
{
/* Waveform mode */
- uint32_t step = m_wave_freq_tab[m_channel[ch].m_frequency];
+ uint32_t step = m_channel[ch].m_frequency ? m_channel[ch].m_frequency : 0x1000;
for (int i = 0; i < samples; i += 1)
{
- int offset;
- int16_t data;
- offset = (m_channel[ch].m_counter >> 12) & 0x1F;
- m_channel[ch].m_counter += step;
- m_channel[ch].m_counter &= 0x1FFFF;
- data = m_channel[ch].m_waveform[offset];
+ int offset = m_channel[0].m_counter;
+ m_channel[ch].m_tick--;
+ if (m_channel[ch].m_tick <= 0)
+ {
+ m_channel[ch].m_tick = step;
+ m_channel[ch].m_counter = (m_channel[ch].m_counter + 1) & 0x1f;
+ }
+ int16_t data = m_channel[ch].m_waveform[offset];
outputs[0][i] += (int16_t)(vll * (data - 16));
outputs[1][i] += (int16_t)(vlr * (data - 16));
}
@@ -205,6 +219,10 @@ WRITE8_MEMBER( c6280_device::c6280_w )
{
chan->m_index = 0;
}
+ if(((chan->m_control & 0x80) == 0) && (data & 0x80))
+ {
+ chan->m_tick = chan->m_frequency;
+ }
chan->m_control = data;
break;
@@ -261,38 +279,9 @@ c6280_device::c6280_device(const machine_config &mconfig, const char *tag, devic
{
}
-//-------------------------------------------------
-// calculate_clocks - (re)calculate clock-derived
-// members
-//-------------------------------------------------
-
-void c6280_device::calculate_clocks()
-{
- int rate = clock() / 16;
-
- /* Make waveform frequency table */
- for (int i = 0; i < 4096; i += 1)
- {
- double step = (16 * 4096) / (i + 1);
- m_wave_freq_tab[(1 + i) & 0xFFF] = (uint32_t)step;
- }
-
- /* Make noise frequency table */
- for (int i = 0; i < 32; i += 1)
- {
- double step = (16 * 32) / (i+1);
- m_noise_freq_tab[i] = (uint32_t)step;
- }
-
- if (m_stream != nullptr)
- m_stream->set_sample_rate(rate);
- else
- m_stream = machine().sound().stream_alloc(*this, 0, 2, rate);
-}
-
void c6280_device::device_clock_changed()
{
- calculate_clocks();
+ m_stream->set_sample_rate(clock());
}
//-------------------------------------------------
@@ -311,7 +300,7 @@ void c6280_device::device_start()
m_lfo_control = 0;
memset(m_channel, 0, sizeof(channel) * 8);
- calculate_clocks();
+ m_stream = machine().sound().stream_alloc(*this, 0, 2, clock());
/* Make volume table */
/* PSG has 48dB volume range spread over 32 steps */
@@ -338,5 +327,6 @@ void c6280_device::device_start()
save_item(NAME(m_channel[chan].m_noise_control), chan);
save_item(NAME(m_channel[chan].m_noise_counter), chan);
save_item(NAME(m_channel[chan].m_counter), chan);
+ save_item(NAME(m_channel[chan].m_tick), chan);
}
}
diff --git a/src/devices/sound/c6280.h b/src/devices/sound/c6280.h
index 5b7f94bce7f..0cfdc34799b 100644
--- a/src/devices/sound/c6280.h
+++ b/src/devices/sound/c6280.h
@@ -8,6 +8,8 @@
class c6280_device : public device_t, public device_sound_interface
{
public:
+ static constexpr feature_type imperfect_features() { return feature::SOUND; } // Incorrect / Not verified noise / LFO output
+
c6280_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock);
// write only
@@ -22,8 +24,6 @@ protected:
virtual void sound_stream_update(sound_stream &stream, stream_sample_t **inputs, stream_sample_t **outputs, int samples) override;
private:
- void calculate_clocks();
-
struct channel {
uint16_t m_frequency;
uint8_t m_control;
@@ -32,8 +32,9 @@ private:
uint8_t m_index;
int16_t m_dda;
uint8_t m_noise_control;
- uint32_t m_noise_counter;
+ int32_t m_noise_counter;
uint32_t m_counter;
+ int32_t m_tick;
};
// internal state
@@ -44,8 +45,6 @@ private:
uint8_t m_lfo_control;
channel m_channel[8];
int16_t m_volume_table[32];
- uint32_t m_noise_freq_tab[32];
- uint32_t m_wave_freq_tab[4096];
};
DECLARE_DEVICE_TYPE(C6280, c6280_device)