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Made an attempt fully to implement PCMPatchedTrack. Which now requires tests.

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This commit is contained in:
Thomas Harte 2016-12-20 07:30:57 -05:00
parent 1ef1f6ec69
commit ec624eaab1
2 changed files with 52 additions and 35 deletions
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85
Storage/Disk/PCMPatchedTrack.cpp
View File

@ -13,10 +13,11 @@ using namespace Storage::Disk;
PCMPatchedTrack::PCMPatchedTrack(std::shared_ptr<Track> underlying_track) :
underlying_track_(underlying_track)
{
Time zero(0);
Time one(1);
const Time zero(0);
const Time one(1);
periods_.emplace_back(zero, one, zero, nullptr);
active_period_ = &periods_.back();
active_period_ = periods_.begin();
underlying_track_->seek_to(zero);
}
void PCMPatchedTrack::add_segment(const Time &start_time, const PCMSegment &segment)
@ -42,14 +43,8 @@ void PCMPatchedTrack::add_segment(const Time &start_time, const PCMSegment &segm
// the vector may have been resized, potentially invalidating active_period_ even if
// the thing it pointed to is still the same thing. So work it out afresh.
for(auto period : periods_)
{
if(period.start_time <= current_time_ && period.end_time > current_time_)
{
active_period_ = &period;
break;
}
}
active_period_ = periods_.begin();
while(active_period_->start_time > current_time_) active_period_++;
}
void PCMPatchedTrack::insert_period(const Period &period)
@ -94,44 +89,66 @@ void PCMPatchedTrack::insert_period(const Period &period)
Track::Event PCMPatchedTrack::get_next_event()
{
const Time one(1);
const Time zero(0);
Time extra_time(0);
Time period_error(0);
while(1)
{
// get the next event from the current active period
Track::Event event;
if(active_period_->event_source) event = active_period_->event_source->get_next_event();
else event = underlying_track_->get_next_event();
// see what time that gets us to. If it's still within the current period, return the found event
current_time_ += event.length;
if(current_time_ >= active_period_->end_time)
if(current_time_ < active_period_->end_time)
{
current_time_ -= active_period_->end_time;
active_period_++;
// if(active_period_
event.length += extra_time - period_error;
return event;
}
// otherwise move time back to the end of the outgoing period, accumulating the error into
// extra_time, and advance the extra period
extra_time += (current_time_ - active_period_->end_time);
current_time_ = active_period_->end_time;
active_period_++;
// test for having reached the end of the track
if(active_period_ == periods_.end())
{
// if this is the end of the track then jump the active pointer back to the beginning
// of the list of periods and reset current_time_ to zero
active_period_ = periods_.begin();
if(active_period_->event_source) active_period_->event_source->reset();
else underlying_track_->seek_to(zero);
current_time_ = zero;
// then return an index hole that is the aggregation of accumulated extra_time away
event.type = Storage::Disk::Track::Event::IndexHole;
event.length = extra_time;
return event;
}
else
{
// if this is not the end of the track then move to the next period and note how much will need
// to be subtracted if an event is found here
if(active_period_->event_source) period_error = active_period_->segment_start_time - active_period_->event_source->seek_to(active_period_->segment_start_time);
else period_error = underlying_track_->seek_to(current_time_) - current_time_;
}
}
// return active_period_->event_source->seek_to(zero);
return underlying_track_->get_next_event();
}
Storage::Time PCMPatchedTrack::seek_to(const Time &time_since_index_hole)
{
for(auto period : periods_)
{
if(period.start_time <= time_since_index_hole && period.end_time > time_since_index_hole)
{
active_period_ = &period;
if(period.event_source)
return period.event_source->seek_to(time_since_index_hole - period.start_time) + period.start_time;
else
return underlying_track_->seek_to(time_since_index_hole);
}
}
// start at the beginning and continue while segments start after the time sought
active_period_ = periods_.begin();
while(active_period_->start_time > time_since_index_hole) active_period_++;
// this should never be reached
Time zero(0);
active_period_ = &periods_[0];
// allow whatever storage represents the period found to perform its seek
if(active_period_->event_source)
return active_period_->event_source->seek_to(zero);
return active_period_->event_source->seek_to(time_since_index_hole - active_period_->start_time) + active_period_->start_time;
else
return underlying_track_->seek_to(zero);
return underlying_track_->seek_to(time_since_index_hole);
}

2
Storage/Disk/PCMPatchedTrack.hpp
View File

@ -49,7 +49,7 @@ class PCMPatchedTrack: public Track {
start_time(start_time), end_time(end_time), segment_start_time(segment_start_time), event_source(event_source) {}
};
std::vector<Period> periods_;
Period *active_period_;
std::vector<Period>::iterator active_period_;
Time current_time_;
void insert_period(const Period &period);