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bbd: Add support for a continuously-varying frequency to avoid abusing the sound manager.

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This commit is contained in:
Aaron Giles 2021-05-31 17:40:16 -07:00
parent 1b25f944f3
commit 7b5e54a3df
2 changed files with 70 additions and 11 deletions
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61
src/devices/sound/bbd.cpp
View File

@ -17,7 +17,9 @@ bbd_device_base<Entries, Outputs>::bbd_device_base(const machine_config &mconfig
device_t(mconfig, type, tag, owner, clock),
device_sound_interface(mconfig, *this),
m_stream(nullptr),
m_curpos(0)
m_curpos(0),
m_cv_handler(*this),
m_next_bbdtime(attotime::zero)
{
std::fill_n(&m_buffer[0], Entries, 0);
}
@ -30,8 +32,16 @@ bbd_device_base<Entries, Outputs>::bbd_device_base(const machine_config &mconfig
template<int Entries, int Outputs>
void bbd_device_base<Entries, Outputs>::device_start()
{
m_stream = stream_alloc(1, Outputs, sample_rate());
m_cv_handler.resolve();
if (m_cv_handler.isnull())
m_stream = stream_alloc(1, Outputs, sample_rate());
else
m_stream = stream_alloc(1, Outputs, SAMPLE_RATE_OUTPUT_ADAPTIVE, STREAM_DISABLE_INPUT_RESAMPLING);
save_item(NAME(m_buffer));
save_item(NAME(m_curpos));
save_item(NAME(m_next_bbdtime));
}
@ -56,12 +66,49 @@ void bbd_device_base<Entries, Outputs>::sound_stream_update(sound_stream &stream
// BBDs that I've seen so far typically have 2 outputs, with the first outputting
// sample n-1 and the second outputting sampe n; if chips with more outputs
// or other taps turn up, this logic will need to be made more flexible
for (int sampindex = 0; sampindex < outputs[0].samples(); sampindex++)
if (m_cv_handler.isnull())
{
for (int outnum = 0; outnum < Outputs; outnum++)
outputs[outnum].put(sampindex, m_buffer[(m_curpos + (Outputs - 1) - outnum) % Entries]);
m_buffer[m_curpos] = inputs[0].get(sampindex);
m_curpos = (m_curpos + 1) % Entries;
for (int sampindex = 0; sampindex < outputs[0].samples(); sampindex++)
{
for (int outnum = 0; outnum < Outputs; outnum++)
outputs[outnum].put(sampindex, m_buffer[(m_curpos + (Outputs - 1) - outnum) % Entries]);
m_buffer[m_curpos] = inputs[0].get(sampindex);
m_curpos = (m_curpos + 1) % Entries;
}
}
else
{
read_stream_view in(inputs[0], m_next_bbdtime);
attotime intime = in.start_time();
attotime outtime = outputs[0].start_time();
int inpos = 0;
// loop until all outputs generated
for (int sampindex = 0; sampindex < outputs[0].samples(); sampindex++)
{
// we need to process some more BBD input
while (outtime >= m_next_bbdtime)
{
// find the input sample that overlaps our start time
while (intime + in.sample_period() < m_next_bbdtime)
{
inpos++;
intime += in.sample_period();
}
// copy that to the buffer
m_buffer[m_curpos] = in.get(inpos);
m_curpos = (m_curpos + 1) % std::size(m_buffer);
// advance the end time of this BBD sample
m_next_bbdtime += attotime(0, m_cv_handler(m_next_bbdtime));
}
// copy the most recently-generated BBD data
for (int outnum = 0; outnum < Outputs; outnum++)
outputs[outnum].put(sampindex, outputval(outnum - (Outputs - 1)));
outtime += outputs[0].sample_period();
}
}
}

20
src/devices/sound/bbd.h
View File

@ -14,13 +14,19 @@
template<int Entries, int Outputs>
class bbd_device_base : public device_t, public device_sound_interface
{
public:
// configuration
template <typename... T> void set_cv_handler(T &&... args)
{
m_cv_handler.set(std::forward<T>(args)...);
}
protected:
using cv_delegate = device_delegate<attoseconds_t (attotime const &)>;
// internal constructor
bbd_device_base(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock, device_type type);
// override to convert clock to sample rate
virtual u32 sample_rate() const { return clock(); }
// device-level overrides
virtual void device_start() override;
virtual void device_clock_changed() override;
@ -29,9 +35,15 @@ protected:
virtual void sound_stream_update(sound_stream &stream, std::vector<read_stream_view> const &inputs, std::vector<write_stream_view> &outputs) override;
protected:
// override to convert clock to sample rate
stream_buffer::sample_t outputval(s32 index) const { return m_buffer[m_curpos + Entries + index]; }
virtual u32 sample_rate() const { return clock(); }
sound_stream * m_stream;
u32 m_curpos;
stream_buffer::sample_t m_buffer[Entries];
cv_delegate m_cv_handler;
attotime m_next_bbdtime;
stream_buffer::sample_t m_buffer[Entries + 1];
};