Paul Davis
3900537fcf
Rounding to bar requires access to the tempo map, and we don't want this in the beats.h header
141 lines
4.0 KiB
C++
141 lines
4.0 KiB
C++
/*
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Copyright (C) 2017-2020 Paul Davis
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include "temporal/beats.h"
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#include "temporal/tempo.h"
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using namespace Temporal;
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Beats
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Beats::round_to_subdivision (int subdivision, RoundMode dir) const {
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if (subdivision == 0) {
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/* do not round */
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return *this;
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}
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if (subdivision < 0) {
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/* round to bar */
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TempoMap::SharedPtr map (TempoMap::use());
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const TempoMetric metric (map->metric_at (*this));
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BBT_Time bbt (metric.bbt_at (*this));
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if (dir < 0) {
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bbt = metric.meter().round_down_to_bar (bbt);
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} if (dir > 0) {
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bbt = metric.meter().round_up_to_bar (bbt);
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} else {
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bbt = metric.meter().round_to_bar (bbt);
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}
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return metric.quarters_at (bbt);
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}
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uint32_t ticks = to_ticks();
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const uint32_t ticks_one_subdivisions_worth = ticks_per_beat / subdivision;
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uint32_t mod = ticks % ticks_one_subdivisions_worth;
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uint32_t beats = _beats;
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if (dir > 0) {
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if (mod == 0 && dir == RoundUpMaybe) {
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/* right on the subdivision, which is fine, so do nothing */
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} else if (mod == 0) {
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/* right on the subdivision, so the difference is just the subdivision ticks */
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ticks += ticks_one_subdivisions_worth;
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} else {
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/* not on subdivision, compute distance to next subdivision */
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ticks += ticks_one_subdivisions_worth - mod;
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}
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// NOTE: this code intentionally limits the rounding so we don't advance to the next beat.
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// For the purposes of "jump-to-next-subdivision", we DO want to advance to the next beat.
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// And since the "prev" direction DOES move beats, I assume this code is unintended.
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// But I'm keeping it around, until we determine there are no terrible consequences.
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// if (ticks >= Temporal::ticks_per_beat) {
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// ticks -= Temporal::ticks_per_beat;
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// }
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} else if (dir < 0) {
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/* round to previous (or same iff dir == RoundDownMaybe) */
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uint32_t difference = ticks % ticks_one_subdivisions_worth;
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if (difference == 0 && dir == RoundDownAlways) {
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/* right on the subdivision, but force-rounding down,
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so the difference is just the subdivision ticks */
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difference = ticks_one_subdivisions_worth;
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}
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if (ticks < difference) {
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ticks = ticks_per_beat - ticks;
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} else {
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ticks -= difference;
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}
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} else {
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/* round to nearest */
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double rem;
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/* compute the distance to the previous and next subdivision */
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if ((rem = fmod ((double) ticks, (double) ticks_one_subdivisions_worth)) > ticks_one_subdivisions_worth/2.0) {
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/* closer to the next subdivision, so shift forward */
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ticks = lrint (ticks + (ticks_one_subdivisions_worth - rem));
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//DEBUG_TRACE (DEBUG::SnapBBT, string_compose ("moved forward to %1\n", ticks));
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if (ticks > ticks_per_beat) {
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++beats;
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ticks -= ticks_per_beat;
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//DEBUG_TRACE (DEBUG::SnapBBT, string_compose ("fold beat to %1\n", beats));
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}
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} else if (rem > 0) {
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/* closer to previous subdivision, so shift backward */
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if (rem > ticks) {
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if (beats == 0) {
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/* can't go backwards past zero, so ... */
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return *this;
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}
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/* step back to previous beat */
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--beats;
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ticks = lrint (ticks_per_beat - rem);
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//DEBUG_TRACE (DEBUG::SnapBBT, string_compose ("step back beat to %1\n", beats));
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} else {
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ticks = lrint (ticks - rem);
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//DEBUG_TRACE (DEBUG::SnapBBT, string_compose ("moved backward to %1\n", ticks));
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}
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} else {
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/* on the subdivision, do nothing */
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}
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}
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return Beats::ticks (ticks);
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}
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