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adds heapsort
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@toddtreece
toddtreece committed Mar 27, 2015
1 parent ea4cc11 commit b7a6903
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Showing 2 changed files with 108 additions and 122 deletions.
227 changes: 105 additions & 122 deletions FifteenStep.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -345,9 +345,6 @@ void FifteenStep::setStepHandler(StepCallback cb)
// step position. If there is already a note on value at this
// position, the note will be turned off.
//
// TODO: this function could/should probably be simplified by
// sorting first. maybe an in-place merge sort?
//
// @access public
// @param note on or off message
// @param pitch of note
Expand All @@ -361,15 +358,10 @@ void FifteenStep::setNote(byte channel, byte pitch, byte velocity)
if(! _running)
return;

int i = 0;
int position = _quantizedPosition();
bool existing_on = false;
bool existing_off = false;
bool added = false;
int toggle_note = 0;

// find a new slot to use
for(i=0; i < _sequence_size; ++i)
for(int i=0; i < _sequence_size; ++i)
{

// used by another pitch, keep going
Expand All @@ -388,99 +380,28 @@ void FifteenStep::setNote(byte channel, byte pitch, byte velocity)
if(_sequence[i].pitch == pitch && _sequence[i].step == position && _sequence[i].channel == channel)
{

// this is a note on
if(_sequence[i].velocity > 0)
{

// check if there's already a note on at this step
if(existing_on)
{

// free this one since we don't need two at this step
_sequence[i] = DEFAULT_NOTE;

// turn toggle note off since this step already had a note on
_sequence[toggle_note].velocity = 0;

// now there's an existing off
existing_off = true;

}
else // no note on
{
// this is the first on at this step
existing_on = true;
// mark the location of this note on so we can toggle it if needed
toggle_note = i;
}

}
else // this is a note off
{

// if there is already a note off at this step, we can free this slot.
// if not, then mark this as the existing off note
if(existing_off)
_sequence[i] = DEFAULT_NOTE;
else
existing_off = true;

}
if(velocity > 0 && _sequence[i].velocity > 0)
_sequence[i] = DEFAULT_NOTE;

}

// not a match, but there's a free slot and we haven't saved the new note yet.
// use the free slot
if(_sequence[i].pitch == 0 && _sequence[i].step == 0 && _sequence[i].channel == 0 && !added)
{

// make sure there already isn't a note on at this step
if(existing_on && velocity > 0)
{

// turn toggle note off since this step already had a note on
_sequence[toggle_note].velocity = 0;

// now there's an existing off
existing_off = true;

// we don't need to add anything, so mark it as complete
added = true;
continue;

}

// make sure there already isn't a note off at this step
if(existing_off && velocity == 0)
{
// we don't need to add anything, so mark it as complete
added = true;
continue;
}

// free slot. use it
_sequence[i].channel = channel;
_sequence[i].pitch = pitch;
_sequence[i].velocity = velocity;
_sequence[i].step = position;

// mark this as the appropriate message
if(velocity > 0)
{
existing_on = true;
toggle_note = i;
}
else
{
existing_off = true;
}

// mark as added
added = true;

}

}

_heapSort();

}

// pause
Expand Down Expand Up @@ -713,75 +634,137 @@ void FifteenStep::_loopPosition()

}

// _triggerNotes
// _heapSort
//
// Calls the user defined MIDI callback with
// all of the note on and off messages at the
// current step position.
// Sort the sequence based on the heapsort algorithm
//
// TODO: simplify so it only has to loop through
// the sequence once. this probably will be fixed
// once setNote is simplified.
// Based on pseudocode found here: http://en.wikipedia.org/wiki/Heapsort
//
// @access private
// @return void
//
void FifteenStep::_triggerNotes()
void FifteenStep::_heapSort()
{

int i;
FifteenStepNote tmp;

// bail if the midi callback isn't set
if(! _midi_cb)
return;
for(i = _sequence_size / 2; i >= 0; i--)
_siftDown(i, _sequence_size - 1);

// loop through the sequence and trigger note offs at the current position.
// they should be sent first.
for(i=0; i < _sequence_size; ++i)
for(i = _sequence_size - 1; i >= 1; i--)
{

// ignore if it's not the current position
if(_sequence[i].step != _position)
continue;
tmp = _sequence[0];
_sequence[0] = _sequence[i];
_sequence[i] = tmp;

// ignore if not a note off for this loop
if(_sequence[i].velocity > 0)
continue;
_siftDown(0, i - 1);

// if this position is in the default state, ignore it
if(_sequence[i].pitch == 0 && _sequence[i].velocity == 0 && _sequence[i].step == 0)
continue;
}

// send note off values to callback
_midi_cb(
_sequence[i].channel,
0x8,
_sequence[i].pitch,
_sequence[i].velocity
);
}

}
// _siftDown
//
// Used by heapsort to shift note positions
//
// Based on pseudocode found here: http://en.wikipedia.org/wiki/Heapsort
//
// @access private
// @return void
//
void FifteenStep::_siftDown(int root, int bottom)
{

int max = root * 2 + 1;

if(max < bottom)
max = _greater(max, max + 1) == max ? max : max + 1;
else if(max > bottom)
return;

if(_greater(root, max) == root || _greater(root, max) == -1)
return;

FifteenStepNote tmp = _sequence[root];
_sequence[root] = _sequence[max];
_sequence[max] = tmp;

_siftDown(max, bottom);

}

// _greater
//
// Used by heapsort to compare two notes so we
// know where they should be placed in the sorted
// array. Will return -1 if they are equal
//
// @access private
// @param first position to compare
// @param second position to compare
// @return int
//
int FifteenStep::_greater(int first, int second)
{

if(_sequence[first].velocity > _sequence[second].velocity)
return first;
else if(_sequence[second].velocity > _sequence[first].velocity)
return second;

if(_sequence[first].pitch > _sequence[second].pitch)
return first;
else if(_sequence[second].pitch > _sequence[first].pitch)
return second;

if(_sequence[first].step > _sequence[second].step)
return first;
else if(_sequence[second].step > _sequence[first].step)
return second;

if(_sequence[first].channel > _sequence[second].channel)
return first;
else if(_sequence[second].channel > _sequence[first].channel)
return second;

return - 1;

}

// _triggerNotes
//
// Calls the user defined MIDI callback with
// all of the note on and off messages at the
// current step position.
//
// @access private
// @return void
//
void FifteenStep::_triggerNotes()
{

// bail if the midi callback isn't set
if(! _midi_cb)
return;

// loop through the sequence again and trigger note ons at the current position
for(i=0; i < _sequence_size; ++i)
for(int i=0; i < _sequence_size; ++i)
{

// ignore if it's not the current position
if(_sequence[i].step != _position)
continue;

// ignore if not a note off for this loop
if(_sequence[i].velocity == 0)
continue;

// if this position is in the default state, ignore it
if(_sequence[i].pitch == 0 && _sequence[i].velocity == 0 && _sequence[i].step == 0)
continue;

// send note on values to callback
_midi_cb(
_sequence[i].channel,
0x9,
_sequence[i].velocity > 0 ? 0x9 : 0x8,
_sequence[i].pitch,
_sequence[i].velocity
);
Expand Down
3 changes: 3 additions & 0 deletions FifteenStep.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -104,7 +104,10 @@ class FifteenStep
unsigned long _next_clock;
unsigned long _shuffleDivision();
int _quantizedPosition();
int _greater(int first, int second);
void _init(int memory);
void _heapSort();
void _siftDown(int root, int bottom);
void _resetSequence();
void _loopPosition();
void _tick();
Expand Down

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