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temporal: add clarification on why the non-ramped ::quarters@superclock is so complex

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Paul Davis 2023-09-20 13:38:15 -06:00
parent c5e7e5c4df
commit ad7bcd2ebe
1 changed files with 14 additions and 0 deletions
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14
libs/temporal/tempo.cc
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@ -575,9 +575,23 @@ TempoPoint::quarters_at_superclock (superclock_t sc) const
if (!actually_ramped()) {
/* The simple expression of the math we're computing here is
* (if we could use floating point):
*
* double sc_delta = sc - _sclock; // how far in superclocks from this point's superclock position?
* double seconds = sc_delta / superclock_ticks_per_second; // how long is that in seconds?
* double note_types_per_second = npm / 60.; // how many note types in 1 second ?
* double quarter_delta = note_types_per_second * (4. / * _note_type); // how many quarters is that?
* return _quarters + Beats (floor (quarter_delta), fmod (quarter_delta, 1.)); // add to this point's position in quarters
*
* But we can't use doubles, so this gets quite a bit more complex.
*/
// TEMPO_MAP_ASSERT (sc >= _sclock);
superclock_t sc_delta = sc - _sclock;
/* convert sc into superbeats, given that sc represents some number of seconds */
const superclock_t whole_seconds = sc_delta / superclock_ticks_per_second();
const superclock_t remainder = sc_delta - (whole_seconds * superclock_ticks_per_second());