Previously the current iterator bbt was moved to p->bbt().
From then on, no grid line is reached if the point p is not on
a bar and mod_bar != 0 or the point is not on an expected beat_div.
e.g. when using bbt += mod_bar, and a tempo-change is at 5|2|0.
iterations continues 6|2|0 7|2|0 is_bar() is always false
and no more grid-lines were added.
Rather than trying
bbt = round-up-to-next-grid-mod-div
and then finding the metric for that position, this
approach only does the latter using the already incremented
BBT position.
We cannot call TempoMetric::superclock_at (BBT_Time) if the BBT time is beyond
the range of the current TempoMetric. We must discover that *before* we make
that call, not as part of the test to see if we've exceeded the range.
There were many logical errors in the previous implementation. This one is
simpler to read, and appears to work much better.
It also allows the caller to specify the quarter-note subdivision to use when
generating the grid, rather than choosing only between some bar modulo or
quarter notes.
introducing a new time signature that uses non-quarter notes as the denominator
will move the beat position a given BBT time (since the middle "B" of BBT
refers to "beats" given by the denominator, not quarters).
This is never for inline references to parameters, only for starting parameter
documentation blocks. The "@p" command is for this, although unfortunately
Doxygen doesn't actually do anything with it and it's just an alias for code
text.
MIDI clock start at the next beat (round_up_to_beat), so
here we have to round the current tick, rather than fall
back to a tick that is not yet complete, as 14da117bc8 does.
Reproduced with the Session from #9027
Start loop at bar 40 with MClk generator enabled.
```
#3 in __GI___assert_fail (assertion=0x7fedd86c4fd5 "clk_pos >= pos", file=0x7fedd86c38b7 "../libs/temporal/tempo.cc", line=3336, function=0x7fedd86c4f60 "void Temporal::TempoMap::midi_clock_beat_at_or_after(Temporal::samplepos_t, Temporal::samplepos_t&, uint32_t&) const") at assert.c:101
#4 in Temporal::TempoMap::midi_clock_beat_at_or_after(long, long&, unsigned int&) const (this= 0x560187e92c00, pos=20691033, clk_pos=@0x7fedc02178b8: 20691032, clk_beat=@0x7fedc02178c4: 11472) at ../libs/temporal/tempo.cc:3336
#5 in ARDOUR::MidiClockTicker::tick(long, long, unsigned int, long) (this=0x56018eed6db0, start_sample=20691033, end_sample=20692057, n_samples=1024, pre_roll=0) at ../libs/ardour/ticker.cc:170
#6 in ARDOUR::Session::send_mclk_for_cycle(long, long, unsigned int, long) (this=0x56018a216340, start_sample=20691033, end_sample=20692057, n_samples=1024, pre_roll=0) at ../libs/ardour/session.cc:7495
#7 in ARDOUR::AudioEngine::process_callback(unsigned int) (this=0x5601881a4f20, nframes=1024) at ../libs/ardour/audioengine.cc:563
```
