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BladeRF2 input: added details about the start and stop stream methods

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This commit is contained in:
f4exb 2018-09-26 14:56:33 +02:00
parent 96979e0c37
commit aa6834a6e9
1 changed files with 47 additions and 1 deletions
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48
plugins/samplesource/bladerf2input/bladerf2input.cpp
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@ -251,6 +251,36 @@ void BladeRF2Input::moveThreadToBuddy()
bool BladeRF2Input::start()
{
// There is a single thread per physical device (Rx side). This thread is unique and referenced by a unique
// buddy in the group of source buddies associated with this physical device.
//
// This start method is responsible for managing the thread and channel enabling when the streaming of a Rx channel is started
//
// It checks the following conditions
// - the thread is allocated or not (by itself or one of its buddies). If it is it grabs the thread pointer.
// - the requested channel is the first (0) or the following (just 1 in BladeRF 2 case)
//
// The BladeRF support library lets you work in two possible modes:
// - Single Input (SI) with only one channel streaming. This HAS to be channel 0.
// - Multiple Input (MI) with two channels streaming using interleaved samples. It MUST be in this configuration if channel 1
// is used irrespective of what you actually do with samples coming from channel 0. When we will run with only channel 1
// streaming from the client perspective the channel 0 will actually be enabled and streaming but its samples will
// just be disregarded.
//
// It manages the transition form SI where only one channel (the first or channel 0) should be running to the
// Multiple Input (MI) if the requested channel is 1. More generally it checks if the requested channel is within the current
// channel range allocated in the thread or past it. To perform the transition it stops the thread, deletes it and creates a new one.
// It marks the thread as needing start.
//
// If the requested channel is within the thread channel range (this thread being already allocated) it simply removes its FIFO reference
// so that the samples are not fed to the FIFO anymore and leaves the thread unchanged (no stop, no delete/new)
//
// If there is no thread allocated it creates a new one with a number of channels that fits the requested channel. That is
// 1 if channel 0 is requested (SI mode) and 2 if channel 1 is requested (MI mode). It marks the thread as needing start.
//
// Eventually it registers the FIFO in the thread. If the thread has to be started it enables the channels up to the number of channels
// allocated in the thread and starts the thread.
if (!m_deviceShared.m_dev)
{
qDebug("BladerfInput::start: no device object");
@ -347,6 +377,22 @@ bool BladeRF2Input::start()
void BladeRF2Input::stop()
{
// This stop method is responsible for managing the thread and channel disabling when the streaming of
// a Rx channel is stopped
//
// If the thread is currently managing only one channel (SI mode). The thread can be just stopped and deleted.
// Then the channel is closed (disabled).
//
// If the thread is currently managing many channels (MI mode) and we are removing the last channel. The transition
// from MI to SI or reduction of MI size is handled by stopping the thread, deleting it and creating a new one
// with one channel less. Then the channel is closed (disabled).
//
// If the thread is currently managing many channels (MI mode) but the channel being stopped is not the last
// channel then the FIFO reference is simply removed from the thread so that it will not stream into this FIFO
// anymore. In this case the channel is not closed (disabled) so that other channels can continue with the
// same configuration. The device continues streaming on this channel but the samples are simply dropped (by
// removing FIFO reference).
if (!m_running) {
return;
}
@ -416,7 +462,7 @@ void BladeRF2Input::stop()
}
else // remove channel from existing thread
{
qDebug("BladeRF2Input::stop: MI mode. Thread not owned by source. Just remove FIFO reference");
qDebug("BladeRF2Input::stop: MI mode. Not changing MI configuration. Just remove FIFO reference");
bladerf2InputThread->setFifo(requestedChannel, 0); // remove FIFO
}