root/trunk/libffado/src/libstreaming/MotuStreamProcessor.cpp

/*
 * Copyright (C) 2005-2007 by Jonathan Woithe
 * Copyright (C) 2005-2007 by Pieter Palmers
 *
 * This file is part of FFADO
 * FFADO = Free Firewire (pro-)audio drivers for linux
 *
 * FFADO is based upon FreeBoB.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License version 2.1, as published by the Free Software Foundation;
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301 USA
 */

#include "MotuStreamProcessor.h"
#include "Port.h"
#include "MotuPort.h"

#include <math.h>

#include <netinet/in.h>

#include "cycletimer.h"

// in ticks
#define TRANSMIT_TRANSFER_DELAY 6000U
// the number of cycles to send a packet in advance of it's timestamp
#define TRANSMIT_ADVANCE_CYCLES 1U

namespace Streaming {

IMPL_DEBUG_MODULE( MotuTransmitStreamProcessor, MotuTransmitStreamProcessor, DEBUG_LEVEL_NORMAL );
IMPL_DEBUG_MODULE( MotuReceiveStreamProcessor, MotuReceiveStreamProcessor, DEBUG_LEVEL_NORMAL );

// Set to 1 to enable the generation of a 1 kHz test tone in analog output 1
#define TESTTONE 1

// A macro to extract specific bits from a native endian quadlet
#define get_bits(_d,_start,_len) (((_d)>>((_start)-(_len)+1)) & ((1<<(_len))-1))

// Convert an SPH timestamp as received from the MOTU to a full timestamp in ticks.
static inline uint32_t sphRecvToFullTicks(uint32_t sph, uint32_t ct_now) {

uint32_t timestamp = CYCLE_TIMER_TO_TICKS(sph & 0x1ffffff);
uint32_t now_cycles = CYCLE_TIMER_GET_CYCLES(ct_now);

uint32_t ts_sec = CYCLE_TIMER_GET_SECS(ct_now);
    // If the cycles have wrapped, correct ts_sec so it represents when timestamp
    // was received.  The timestamps sent by the MOTU are always 1 or two cycles
    // in advance of the cycle timer (reasons unknown at this stage).  In addition,
    // iso buffering can delay the arrival of packets for quite a number of cycles
    // (have seen a delay >12 cycles).
    // Every so often we also see sph wrapping ahead of ct_now, so deal with that
    // too.
    if (CYCLE_TIMER_GET_CYCLES(sph) > now_cycles + 1000) {
        if (ts_sec)
            ts_sec--;
        else
            ts_sec = 127;
    } else
    if (now_cycles > CYCLE_TIMER_GET_CYCLES(sph) + 1000) {
        if (ts_sec == 127)
            ts_sec = 0;
        else
            ts_sec++;
    }
    return timestamp + ts_sec*TICKS_PER_SECOND;
}

// Convert a full timestamp into an SPH timestamp as required by the MOTU
static inline uint32_t fullTicksToSph(int64_t timestamp) {
    return TICKS_TO_CYCLE_TIMER(timestamp) & 0x1ffffff;
}

/* transmit */
MotuTransmitStreamProcessor::MotuTransmitStreamProcessor(int port, int framerate,
        unsigned int event_size)
    : TransmitStreamProcessor(port, framerate), m_event_size(event_size),
    m_tx_dbc(0),
    m_startup_count(-1), m_closedown_count(-1), m_streaming_active(0) {
}

MotuTransmitStreamProcessor::~MotuTransmitStreamProcessor() {

}

bool MotuTransmitStreamProcessor::init() {

    debugOutput( DEBUG_LEVEL_VERBOSE, "Initializing (%p)...\n");
    // call the parent init
    // this has to be done before allocating the buffers,
    // because this sets the buffersizes from the processormanager
    if(!TransmitStreamProcessor::init()) {
        debugFatal("Could not do base class init (%p)\n",this);
        return false;
    }

    return true;
}

void MotuTransmitStreamProcessor::setVerboseLevel(int l) {
    setDebugLevel(l); // sets the debug level of the current object
    TransmitStreamProcessor::setVerboseLevel(l); // also set the level of the base class
}


enum raw1394_iso_disposition
MotuTransmitStreamProcessor::getPacket(unsigned char *data, unsigned int *length,
                  unsigned char *tag, unsigned char *sy,
                  int cycle, unsigned int dropped, unsigned int max_length) {

// FIXME: the actual delays in the system need to be worked out so
// we can get this thing synchronised.  For now this seems to work.
    int fc;
    int64_t ts_head;
    ffado_timestamp_t ts_tmp;
    quadlet_t *quadlet = (quadlet_t *)data;
    signed int i;

    // The number of events per packet expected by the MOTU is solely
    // dependent on the current sample rate.  An 'event' is one sample from
    // all channels plus possibly other midi and control data.
    signed n_events = m_framerate<=48000?8:(m_framerate<=96000?16:32);

    m_last_cycle=cycle;

    // determine if we want to send a packet or not
    // note that we can't use getCycleTimer directly here,
    // because packets are queued in advance. This means that
    // we the packet we are constructing will be sent out
    // on 'cycle', not 'now'.
    unsigned int ctr=m_handler->getCycleTimer();
    int now_cycles = (int)CYCLE_TIMER_GET_CYCLES(ctr);

    // the difference between the cycle this
    // packet is intended for and 'now'
    int cycle_diff = diffCycles(cycle, now_cycles);

//debugOutput(DEBUG_LEVEL_VERBOSE,"tx: enabled=%d, cycle=%d, now_cycles=%d, diff=%d\n",
//  !m_is_disabled,cycle, now_cycles, cycle_diff);

    // Signal that streaming is still active
    m_streaming_active = 1;

    // as long as the cycle parameter is not in sync with
    // the current time, the stream is considered not
    // to be 'running'
    // NOTE: this works only at startup
    if (!m_running && cycle_diff >= 0 && cycle >= 0) {
            debugOutput(DEBUG_LEVEL_VERBOSE, "Xmit StreamProcessor %p started running at cycle %d\n",this, cycle);
            m_running=true;
    }

    if (!m_disabled && m_is_disabled) {
        // this means that we are trying to enable

        // check if we are on or past the enable point
        signed int cycles_past_enable=diffCycles(cycle, m_cycle_to_enable_at);
        
        if (cycles_past_enable >= 0) {
            m_is_disabled=false;

            debugOutput(DEBUG_LEVEL_VERBOSE,"Enabling Tx StreamProcessor %p at %u\n", this, cycle);

            // initialize the buffer head & tail
            m_SyncSource->m_data_buffer->getBufferHeadTimestamp(&ts_tmp, &fc); // thread safe
            ts_head = (int64_t)ts_tmp;

            // the number of cycles the sync source lags (> 0)
            // or leads (< 0)
            int sync_lag_cycles=diffCycles(cycle, m_SyncSource->getLastCycle());

            // account for the cycle lag between sync SP and this SP
            // the last update of the sync source's timestamps was sync_lag_cycles
            // cycles before the cycle we are calculating the timestamp for.
            // if we were to use one-frame buffers, you would expect the
            // frame that is sent on cycle CT to have a timestamp T1.
            // ts_head however is for cycle CT-sync_lag_cycles, and lies
            // therefore sync_lag_cycles * TICKS_PER_CYCLE earlier than
            // T1.
            ts_head = addTicks(ts_head, sync_lag_cycles * TICKS_PER_CYCLE);

// These are just copied from AmdtpStreamProcessor.  At some point we should
// verify that they make sense for the MOTU.
            ts_head = substractTicks(ts_head, TICKS_PER_CYCLE);
            // account for the number of cycles we are too late to enable
            ts_head = addTicks(ts_head, cycles_past_enable * TICKS_PER_CYCLE);
            // account for one extra packet of frames
// For the MOTU this subtraction doesn't seem necessary, and in general just makes it take
// longer to achieve stable sync.
//            ts_head = substractTicks(ts_head,
//             (uint32_t)((float)n_events * m_SyncSource->m_data_buffer->getRate())); 
//            ts_head = substractTicks(ts_head,
//              (uint32_t)(m_SyncSource->m_data_buffer->getRate())); 
            m_data_buffer->setBufferTailTimestamp(ts_head);

            // Set up the startup count which keeps the output muted during
            // sync stabilisation at startup.  For now we go for about 2 seconds of
            // muting.  Note that this is a count of *packets*, not frames.
            m_startup_count = 2*m_framerate/n_events;

            #ifdef DEBUG
            if ((unsigned int)m_data_buffer->getFrameCounter() != m_data_buffer->getBufferSize()) {
                debugWarning("m_data_buffer->getFrameCounter() != m_data_buffer->getBufferSize()\n");
            }
            #endif
            debugOutput(DEBUG_LEVEL_VERBOSE,"XMIT TS SET: TS=%10lld, LAG=%03d, FC=%4d\n",
                            ts_head, sync_lag_cycles, m_data_buffer->getFrameCounter());
        } else {
            debugOutput(DEBUG_LEVEL_VERY_VERBOSE,
                        "will enable StreamProcessor %p at %u, now is %d\n",
                        this, m_cycle_to_enable_at, cycle);
        }
    } else if (m_disabled && !m_is_disabled) {
        // trying to disable
        debugOutput(DEBUG_LEVEL_VERBOSE,"disabling StreamProcessor %p at %u\n",
                    this, cycle);
        m_is_disabled=true;
        m_startup_count = -1;
    }

    // Do housekeeping expected for all packets sent to the MOTU, even
    // for packets containing no audio data.
    *sy = 0x00;
    *tag = 1;      // All MOTU packets have a CIP-like header

    // the base timestamp is the one of the next sample in the buffer
    m_data_buffer->getBufferHeadTimestamp(&ts_tmp, &fc); // thread safe
    ts_head = (int64_t)ts_tmp;
    int64_t timestamp = ts_head;

//debugOutput(DEBUG_LEVEL_VERBOSE,"tx cycle %d, base timestamp %lld\n",cycle, ts_head);

    // we send a packet some cycles in advance, to avoid the
    // following situation:
    // suppose we are only a few ticks away from
    // the moment to send this packet. therefore we decide
    // not to send the packet, but send it in the next cycle.
    // This means that the next time point will be 3072 ticks
    // later, making that the timestamp will be expired when the
    // packet is sent, unless TRANSFER_DELAY > 3072.
    // this means that we need at least one cycle of extra buffering.
    int64_t ticks_to_advance = TICKS_PER_CYCLE * TRANSMIT_ADVANCE_CYCLES;

    // if cycle lies cycle_diff cycles in the future, we should
    // queue this packet cycle_diff * TICKS_PER_CYCLE earlier than
    // we would if it were to be sent immediately.
    ticks_to_advance += (int64_t)cycle_diff * TICKS_PER_CYCLE;

    // determine the 'now' time in ticks
//    uint64_t cycle_timer=CYCLE_TIMER_TO_TICKS(ctr);

    // time until the packet is to be sent (if <= 0: send packet)
    // For Amdtp this looked like
    //   int32_t until_next=diffTicks(timestamp, cycle_timer + ticks_to_advance);
    // However, this didn't seem to work well with the MOTU's buffer structure.
    // For now we'll revert to the "send trigger" we used earlier since this
    // seems to work.
    int32_t until_next = (cycle >= TICKS_TO_CYCLES(timestamp))?-1:1;

    // Size of a single data frame in quadlets
    unsigned dbs = m_event_size / 4;

    // don't process the stream when it is not enabled, not running
    // or when the next sample is not due yet.
    if((until_next>0) || m_is_disabled || !m_running) {
        // send dummy packet

        // construct the packet CIP-like header.  Even if this is a data-less
        // packet the dbs field is still set as if there were data blocks
        // present.  For data-less packets the dbc is the same as the previously
        // transmitted block.
        *quadlet = htonl(0x00000400 | ((getNodeId()&0x3f)<<24) | m_tx_dbc | (dbs<<16));
        quadlet++;
        *quadlet = htonl(0x8222ffff);
        quadlet++;
        *length = 8;

        return RAW1394_ISO_DEFER;
    }

    // add the transmit transfer delay to construct the playout time
    ffado_timestamp_t ts=addTicks(timestamp, TRANSMIT_TRANSFER_DELAY);

    // Only read frames from the tx buffer when we're not in the process of
    // stopping.  When preparing for stop the buffer isn't necessarily being
    // replinished so it's possible to cause a buffer underflow during
    // shutdown if the buffer is read during this time.
    if (m_closedown_count!=-1 || m_data_buffer->readFrames(n_events, (char *)(data + 8))) {

#if TESTTONE
        // FIXME: remove this hacked in 1 kHz test signal to
        // analog-1 when testing is complete.  Note that the tone is
        // *never* added during closedown.
        if (m_closedown_count<0) {
            for (i=0; i<n_events; i++) {
                static signed int a_cx = 0;
                signed int val;
                val = (int)(0x7fffff*sin(1000.0*2.0*M_PI*(a_cx/24576000.0)));
                if ((a_cx+=512) >= 24576000) {
                    a_cx -= 24576000;
                }
                *(data+8+i*m_event_size+16) = (val >> 16) & 0xff;
                *(data+8+i*m_event_size+17) = (val >> 8) & 0xff;
                *(data+8+i*m_event_size+18) = val & 0xff;
            }
        }
#endif
        // Increment the dbc (data block count).  This is only done if the
        // packet will contain events - that is, we are due to send some
        // data.  Otherwise a pad packet is sent which contains the DBC of
        // the previously sent packet.  This regime also means that the very
        // first packet containing data will have a DBC of n_events, which
        // matches what is observed from other systems.
        m_tx_dbc += n_events;
        if (m_tx_dbc > 0xff)
            m_tx_dbc -= 0x100;

        // construct the packet CIP-like header.  Even if this is a data-less
        // packet the dbs field is still set as if there were data blocks
        // present.  For data-less packets the dbc is the same as the previously
        // transmitted block.
        *quadlet = htonl(0x00000400 | ((getNodeId()&0x3f)<<24) | m_tx_dbc | (dbs<<16));
        quadlet++;
        *quadlet = htonl(0x8222ffff);
        quadlet++;

        *length = n_events*m_event_size + 8;

        // Zero out data if we're in closedown or startup
        if (m_closedown_count>=0 || m_startup_count>=0) {
            memset(data+8,0,n_events*m_event_size);
        }

        // Account for this packet's frames during startup / closedown.  Note:
        //  * m_startup_count: -1 = not in startup delay, >-1 = in startup delay.
        //  * m_closedown_count: -1 = not in closedown mode, 0 = closedown
        //    preparation now finished, >0 = closedown preparation in
        //    progress.
        if (m_closedown_count > 0)
            m_closedown_count--;
        if (m_startup_count >= 0)
            m_startup_count--;

        // Set up each frames's SPH.  Note that the (int) typecast
        // appears to do rounding.

        float ticks_per_frame = m_SyncSource->m_data_buffer->getRate();
        for (i=0; i<n_events; i++, quadlet += dbs) {
//FIXME: not sure which is best for the MOTU
//            int64_t ts_frame = addTicks(ts, (unsigned int)(i * ticks_per_frame));
            int64_t ts_frame = addTicks(timestamp, (unsigned int)(i * ticks_per_frame));
            *quadlet = htonl(fullTicksToSph(ts_frame));
        }

        // Process all ports that should be handled on a per-packet base
        // this is MIDI for AMDTP (due to the need of DBC, which is lost
        // when putting the events in the ringbuffer)
        // for motu this might also be control data, however as control
        // data isn't time specific I would also include it in the period
        // based processing

        // FIXME: m_tx_dbc probably needs to be initialised to a non-zero
        // value somehow so MIDI sync is possible.  For now we ignore
        // this issue.
        if (!encodePacketPorts((quadlet_t *)(data+8), n_events, m_tx_dbc)) {
            debugWarning("Problem encoding Packet Ports\n");
        }

        return RAW1394_ISO_OK;

    } else if (now_cycles<cycle) {
        // we can still postpone the queueing of the packets
        return RAW1394_ISO_AGAIN;
    } else { // there is no more data in the ringbuffer

        debugWarning("Transmit buffer underrun (now %d, queue %d, target %d)\n",
                 now_cycles, cycle, TICKS_TO_CYCLES((int64_t)ts));

        // signal underrun
        m_xruns++;

        // disable the processing, will be re-enabled when
        // the xrun is handled
        m_disabled=true;
        m_is_disabled=true;

        // compose a no-data packet, we should always
        // send a valid packet

        // send dummy packet

        // construct the packet CIP-like header.  Even if this is a data-less
        // packet the dbs field is still set as if there were data blocks
        // present.  For data-less packets the dbc is the same as the previously
        // transmitted block.
        *quadlet = htonl(0x00000400 | ((getNodeId()&0x3f)<<24) | m_tx_dbc | (dbs<<16));
        quadlet++;
        *quadlet = htonl(0x8222ffff);
        quadlet++;
        *length = 8;

        return RAW1394_ISO_DEFER;
    }

    // we shouldn't get here
    return RAW1394_ISO_ERROR;

}

int MotuTransmitStreamProcessor::getMinimalSyncDelay() {
    return 0;
}

bool MotuTransmitStreamProcessor::prefill() {
    // this is needed because otherwise there is no data to be
    // sent when the streaming starts

    int i = m_nb_buffers;
    while (i--) {
        if(!transferSilence(m_period)) {
            debugFatal("Could not prefill transmit stream\n");
            return false;
        }
    }
    return true;
}

bool MotuTransmitStreamProcessor::reset() {

    debugOutput( DEBUG_LEVEL_VERBOSE, "Resetting...\n");

    // we have to make sure that the buffer HEAD timestamp
    // lies in the future for every possible buffer fill case.
    int offset=(int)(m_data_buffer->getBufferSize()*m_ticks_per_frame);

    m_data_buffer->setTickOffset(offset);

    // reset all non-device specific stuff
    // i.e. the iso stream and the associated ports
    if (!TransmitStreamProcessor::reset()) {
        debugFatal("Could not do base class reset\n");
        return false;
    }

    // we should prefill the event buffer
    if (!prefill()) {
        debugFatal("Could not prefill buffers\n");
        return false;
    }

    return true;
}

bool MotuTransmitStreamProcessor::prepare() {

    debugOutput( DEBUG_LEVEL_VERBOSE, "Preparing...\n");

    // prepare all non-device specific stuff
    // i.e. the iso stream and the associated ports
    if (!TransmitStreamProcessor::prepare()) {
        debugFatal("Could not prepare base class\n");
        return false;
    }

    m_PeriodStat.setName("XMT PERIOD");
    m_PacketStat.setName("XMT PACKET");
    m_WakeupStat.setName("XMT WAKEUP");

    debugOutput( DEBUG_LEVEL_VERBOSE, "Event size: %d\n", m_event_size);

    // allocate the event buffer
    unsigned int ringbuffer_size_frames=m_nb_buffers * m_period;

    // allocate the internal buffer
    m_ticks_per_frame = (TICKS_PER_SECOND*1.0) / ((float)m_framerate);

    assert(m_data_buffer);
    // Note: terminology is slightly confused here.  From the point of view
    // of the buffer the event size is the size of a single complete "event"
    // in the MOTU datastream, which consists of one sample from each audio
    // channel plus a timestamp and other control data.  Almost by
    // definition then, the buffer's "events per frame" must be 1.  With
    // these values, data copies to/from the MOTU data stream can be handled
    // by the generic copying functions.
    m_data_buffer->setBufferSize(ringbuffer_size_frames);
    m_data_buffer->setEventSize(m_event_size);
    m_data_buffer->setEventsPerFrame(1);

    m_data_buffer->setUpdatePeriod(m_period);
    m_data_buffer->setNominalRate(m_ticks_per_frame);

    // FIXME: check if the timestamp wraps at one second
    m_data_buffer->setWrapValue(128L*TICKS_PER_SECOND);

    m_data_buffer->prepare();

    // Set the parameters of ports we can: we want the audio ports to be
    // period buffered, and the midi ports to be packet buffered.
    for ( PortVectorIterator it = m_Ports.begin();
      it != m_Ports.end();
      ++it ) {
        debugOutput(DEBUG_LEVEL_VERBOSE, "Setting up port %s\n",(*it)->getName().c_str());
        if(!(*it)->setBufferSize(m_period)) {
            debugFatal("Could not set buffer size to %d\n",m_period);
            return false;
            }

        switch ((*it)->getPortType()) {
        case Port::E_Audio:
            if (!(*it)->setSignalType(Port::E_PeriodSignalled)) {
                debugFatal("Could not set signal type to PeriodSignalling");
                return false;
            }
            break;

        case Port::E_Midi:
            if (!(*it)->setSignalType(Port::E_PacketSignalled)) {
                debugFatal("Could not set signal type to PacketSignalling");
                return false;
            }
            if (!(*it)->setBufferType(Port::E_RingBuffer)) {
                debugFatal("Could not set buffer type");
                return false;
            }
            if (!(*it)->setDataType(Port::E_MidiEvent)) {
                debugFatal("Could not set data type");
                return false;
            }
            // FIXME: probably need rate control too.  See
            // Port::useRateControl() and AmdtpStreamProcessor.
            break;

        case Port::E_Control:
            if (!(*it)->setSignalType(Port::E_PeriodSignalled)) {
                debugFatal("Could not set signal type to PeriodSignalling");
                return false;
            }
            break;

        default:
            debugWarning("Unsupported port type specified\n");
            break;
        }
    }

    // The API specific settings of the ports are already set before
    // this routine is called, therefore we can init&prepare the ports
    if (!initPorts()) {
        debugFatal("Could not initialize ports!\n");
        return false;
    }

    if(!preparePorts()) {
        debugFatal("Could not initialize ports!\n");
        return false;
    }

    return true;
}

bool MotuTransmitStreamProcessor::prepareForStop() {

    // If the stream is disabled or isn't running there's no need to
    // wait since the MOTU *should* still be in a "zero data" state.
    //
    // If the m_streaming_active flag is 0 it indicates that the
    // transmit callback hasn't been called since a closedown was
    // requested when this function was last called.  This effectively
    // signifies that the streaming thread has been exitted due to an
    // xrun in either the receive or transmit handlers.  In this case
    // there's no point in waiting for the closedown count to hit zero
    // because it never will; the zero data will never get to the MOTU.
    // It's best to allow an immediate stop and let the xrun handler
    // proceed as best it can.
    //
    // The ability to detect the lack of streaming also prevents the
    // "wait for stop" in the stream processor manager's stop() method
    // from hitting its timeout which in turn seems to increase the
    // probability of a successful recovery.
    if (m_is_disabled || !isRunning() || !m_streaming_active)
        return true;

    if (m_closedown_count < 0) {
        // No closedown has been initiated, so start one now.  Set
        // the closedown count to the number of zero packets which
        // will be sent to the MOTU before closing off the iso
        // streams.  FIXME: 128 packets (each containing 8 frames at
        // 48 kHz) is the experimentally-determined figure for 48
        // kHz with a period size of 1024.  It seems that at least
        // one period of zero samples need to be sent to allow for
        // inter-thread communication occuring on period boundaries.
        // This needs to be confirmed for other rates and period
        // sizes.
        signed n_events = m_framerate<=48000?8:(m_framerate<=96000?16:32);
        m_closedown_count = m_period / n_events;

        // Set up a test to confirm that streaming is still active.
        // If the streaming function hasn't been called by the next
        // iteration through this function there's no point in
        // continuing since it means the zero data will never get to
        // the MOTU.
        m_streaming_active = 0;
        return false;
    }

    // We are "go" for closedown once all requested zero packets
    // (initiated by a previous call to this function) have been sent to
    // the MOTU.
    return m_closedown_count == 0;
}

bool MotuTransmitStreamProcessor::prepareForStart() {
// Reset some critical variables required so the stream starts cleanly. This
// method is called once on every stream restart. Initialisations which should
// be done once should be placed in the init() method instead.
    m_running = 0;
    m_closedown_count = -1;
    m_streaming_active = 0;

    // At this point we'll also disable the stream processor here.
    // At this stage stream processors are always explicitly re-enabled
    // after being started, so by starting in the disabled state we
    // ensure that every start will be exactly the same.
    disable();

    return true;
}

bool MotuTransmitStreamProcessor::prepareForEnable(uint64_t time_to_enable_at) {

    debugOutput(DEBUG_LEVEL_VERBOSE,"Preparing to enable...\n");

    // for the transmit SP, we have to initialize the
    // buffer timestamp to something sane, because this timestamp
    // is used when it is SyncSource

    // the time we initialize to will determine the time at which
    // the first sample in the buffer will be sent, so we should
    // make it at least 'time_to_enable_at'

    uint64_t now=m_handler->getCycleTimer();
    unsigned int now_secs=CYCLE_TIMER_GET_SECS(now);

    // check if a wraparound on the secs will happen between
    // now and the time we start
    int until_enable=(int)time_to_enable_at - (int)CYCLE_TIMER_GET_CYCLES(now);

    if(until_enable>4000) {
        // wraparound on CYCLE_TIMER_GET_CYCLES(now)
        // this means that we are late starting up,
        // and that the start lies in the previous second
        if (now_secs==0) now_secs=127;
        else now_secs--;
    } else if (until_enable<-4000) {
        // wraparound on time_to_enable_at
        // this means that we are early and that the start
        // point lies in the next second
        now_secs++;
        if (now_secs>=128) now_secs=0;
    }

////    uint64_t ts_head= now_secs*TICKS_PER_SECOND;
//    uint64_t ts_head = time_to_enable_at*TICKS_PER_CYCLE;
    uint64_t ts_head= now_secs*TICKS_PER_SECOND;
    ts_head+=time_to_enable_at*TICKS_PER_CYCLE; 

    // we also add the nb of cycles we transmit in advance
    ts_head=addTicks(ts_head, TRANSMIT_ADVANCE_CYCLES*TICKS_PER_CYCLE);

    m_data_buffer->setBufferTailTimestamp(ts_head);

    if (!StreamProcessor::prepareForEnable(time_to_enable_at)) {
        debugError("StreamProcessor::prepareForEnable failed\n");
        return false;
    }

    return true;
}

bool MotuTransmitStreamProcessor::transferSilence(unsigned int size) {
    bool retval;

    // This function should tranfer 'size' frames of 'silence' to the event buffer
    char *dummybuffer=(char *)calloc(size,m_event_size);

    transmitSilenceBlock(dummybuffer, size, 0);

    // add the silence data to the ringbuffer
    if(m_data_buffer->writeFrames(size, dummybuffer, 0)) {
        retval=true;
    } else {
        debugWarning("Could not write to event buffer\n");
        retval=false;
    }

    free(dummybuffer);

    return retval;
}

bool MotuTransmitStreamProcessor::putFrames(unsigned int nbframes, int64_t ts) {
    m_PeriodStat.mark(m_data_buffer->getBufferFill());

    debugOutput(DEBUG_LEVEL_VERY_VERBOSE, "MotuTransmitStreamProcessor::putFrames(%d, %llu)\n", nbframes, ts);

    // transfer the data
#if 0
debugOutput(DEBUG_LEVEL_VERBOSE, "1 - timestamp is %d\n", ts);
#endif
    m_data_buffer->blockProcessWriteFrames(nbframes, ts);
#if 0
debugOutput(DEBUG_LEVEL_VERBOSE, "  done\n");
#endif
    debugOutput(DEBUG_LEVEL_VERY_VERBOSE, " New timestamp: %llu\n", ts);

    return true;
}

/*
 * write received events to the stream ringbuffers.
 */

bool MotuTransmitStreamProcessor::processWriteBlock(char *data,
                       unsigned int nevents, unsigned int offset) {
    bool no_problem=true;
    unsigned int i;

    // FIXME: ensure the MIDI and control streams are all zeroed until
    // such time as they are fully implemented.
    for (i=0; i<nevents; i++) {
        memset(data+4+i*m_event_size, 0x00, 6);
    }

    for ( PortVectorIterator it = m_PeriodPorts.begin();
      it != m_PeriodPorts.end();
      ++it ) {
        // If this port is disabled, don't process it
        if((*it)->isDisabled()) {continue;};

        //FIXME: make this into a static_cast when not DEBUG?
        Port *port=dynamic_cast<Port *>(*it);

        switch(port->getPortType()) {

        case Port::E_Audio:
            if (encodePortToMotuEvents(static_cast<MotuAudioPort *>(*it), (quadlet_t *)data, offset, nevents)) {
                debugWarning("Could not encode port %s to MBLA events",(*it)->getName().c_str());
                no_problem=false;
            }
            break;
        // midi is a packet based port, don't process
        //    case MotuPortInfo::E_Midi:
        //        break;

        default: // ignore
            break;
        }
    }
    return no_problem;
}

int MotuTransmitStreamProcessor::transmitSilenceBlock(char *data,
                       unsigned int nevents, unsigned int offset) {
    // This is the same as the non-silence version, except that is
    // doesn't read from the port buffers.

    int problem=0;

    for ( PortVectorIterator it = m_PeriodPorts.begin();
      it != m_PeriodPorts.end();
      ++it ) {
        //FIXME: make this into a static_cast when not DEBUG?
        Port *port=dynamic_cast<Port *>(*it);

        switch(port->getPortType()) {

        case Port::E_Audio:
            if (encodeSilencePortToMotuEvents(static_cast<MotuAudioPort *>(*it), (quadlet_t *)data, offset, nevents)) {
                debugWarning("Could not encode port %s to MBLA events",(*it)->getName().c_str());
                problem=1;
            }
            break;
        // midi is a packet based port, don't process
        //    case MotuPortInfo::E_Midi:
        //        break;

        default: // ignore
            break;
        }
    }
    return problem;
}

/**
 * @brief decode a packet for the packet-based ports
 *
 * @param data Packet data
 * @param nevents number of events in data (including events of other ports & port types)
 * @param dbc DataBlockCount value for this packet
 * @return true if all successfull
 */
bool MotuTransmitStreamProcessor::encodePacketPorts(quadlet_t *data, unsigned int nevents,
        unsigned int dbc) {
    bool ok=true;
    char byte;

    // Use char here since the target address won't necessarily be
    // aligned; use of an unaligned quadlet_t may cause issues on
    // certain architectures.  Besides, the target for MIDI data going
    // directly to the MOTU isn't structured in quadlets anyway; it is a
    // sequence of 3 unaligned bytes.
    unsigned char *target = NULL;

    for ( PortVectorIterator it = m_PacketPorts.begin();
        it != m_PacketPorts.end();
        ++it ) {

        Port *port=static_cast<Port *>(*it);
         assert(port); // this should not fail!!

        // Currently the only packet type of events for MOTU
        // is MIDI in mbla.  However in future control data
        // might also be sent via "packet" events.
        // assert(pinfo->getFormat()==MotuPortInfo::E_Midi);

        // FIXME: MIDI output is completely untested at present.
        switch (port->getPortType()) {
            case Port::E_Midi: {
                MotuMidiPort *mp=static_cast<MotuMidiPort *>(*it);

                // Send a byte if we can. MOTU MIDI data is
                // sent using a 3-byte sequence starting at
                // the port's position.  For now we'll
                // always send in the first event of a
                // packet, but this might need refinement
                // later.
                if (mp->canRead()) {
                    mp->readEvent(&byte);
                    target = (unsigned char *)data + mp->getPosition();
                    *(target++) = 0x01;
                    *(target++) = 0x00;
                    *(target++) = byte;
                }
                break;
            }
            default:
                debugOutput(DEBUG_LEVEL_VERBOSE, "Unknown packet-type port type %d\n",port->getPortType());
                return ok;
              }
    }

    return ok;
}

int MotuTransmitStreamProcessor::encodePortToMotuEvents(MotuAudioPort *p, quadlet_t *data,
                       unsigned int offset, unsigned int nevents) {
// Encodes nevents worth of data from the given port into the given buffer.  The
// format of the buffer is precisely that which will be sent to the MOTU.
// The basic idea:
//   iterate over the ports
//     * get port buffer address
//     * loop over events
//         - pick right sample in event based upon PortInfo
//         - convert sample from Port format (E_Int24, E_Float, ..) to MOTU
//           native format
//
// We include the ability to start the transfer from the given offset within
// the port (expressed in frames) so the 'efficient' transfer method can be
// utilised.

    unsigned int j=0;

    // Use char here since the target address won't necessarily be
    // aligned; use of an unaligned quadlet_t may cause issues on certain
    // architectures.  Besides, the target (data going directly to the MOTU)
    // isn't structured in quadlets anyway; it mainly consists of packed
    // 24-bit integers.
    unsigned char *target;
    target = (unsigned char *)data + p->getPosition();

    switch(p->getDataType()) {
        default:
        case Port::E_Int24:
            {
                quadlet_t *buffer=(quadlet_t *)(p->getBufferAddress());

                assert(nevents + offset <= p->getBufferSize());

                // Offset is in frames, but each port is only a single
                // channel, so the number of frames is the same as the
                // number of quadlets to offset (assuming the port buffer
                // uses one quadlet per sample, which is the case currently).
                buffer+=offset;

                for(j = 0; j < nevents; j += 1) { // Decode nsamples
                    *target = (*buffer >> 16) & 0xff;
                    *(target+1) = (*buffer >> 8) & 0xff;
                    *(target+2) = (*buffer) & 0xff;

                    buffer++;
                    target+=m_event_size;
                }
            }
            break;
        case Port::E_Float:
            {
                const float multiplier = (float)(0x7FFFFF);
                float *buffer=(float *)(p->getBufferAddress());

                assert(nevents + offset <= p->getBufferSize());

                buffer+=offset;

                for(j = 0; j < nevents; j += 1) { // decode max nsamples
                    unsigned int v = (int)(*buffer * multiplier);
                    *target = (v >> 16) & 0xff;
                    *(target+1) = (v >> 8) & 0xff;
                    *(target+2) = v & 0xff;

                    buffer++;
                    target+=m_event_size;
                }
            }
            break;
    }

    return 0;
}

int MotuTransmitStreamProcessor::encodeSilencePortToMotuEvents(MotuAudioPort *p, quadlet_t *data,
                       unsigned int offset, unsigned int nevents) {
    unsigned int j=0;
    unsigned char *target = (unsigned char *)data + p->getPosition();

    switch (p->getDataType()) {
    default:
        case Port::E_Int24:
        case Port::E_Float:
        for (j = 0; j < nevents; j++) {
            *target = *(target+1) = *(target+2) = 0;
            target += m_event_size;
        }
        break;
    }

    return 0;
}

/* --------------------- RECEIVE ----------------------- */

MotuReceiveStreamProcessor::MotuReceiveStreamProcessor(int port, int framerate,
    unsigned int event_size)
    : ReceiveStreamProcessor(port, framerate), m_event_size(event_size),
    m_closedown_active(0) {

}

MotuReceiveStreamProcessor::~MotuReceiveStreamProcessor() {

}

bool MotuReceiveStreamProcessor::init() {

    // call the parent init
    // this has to be done before allocating the buffers,
    // because this sets the buffersizes from the processormanager
    if(!ReceiveStreamProcessor::init()) {
        debugFatal("Could not do base class init (%d)\n",this);
        return false;
    }

    return true;
}

enum raw1394_iso_disposition
MotuReceiveStreamProcessor::putPacket(unsigned char *data, unsigned int length,
                  unsigned char channel, unsigned char tag, unsigned char sy,
                  unsigned int cycle, unsigned int dropped) {

    enum raw1394_iso_disposition retval=RAW1394_ISO_OK;
    // this is needed for the base class getLastCycle() to work.
    // this avoids a function call like StreamProcessor::updateLastCycle()
    m_last_cycle=cycle;

    // check our enable status
    if (!m_disabled && m_is_disabled) {
        // this means that we are trying to enable

        // check if we are on or past the enable point
        int cycles_past_enable=diffCycles(cycle, m_cycle_to_enable_at);

        if (cycles_past_enable >= 0) {
            m_is_disabled=false;
            debugOutput(DEBUG_LEVEL_VERBOSE,"Enabling Rx StreamProcessor %p at %d\n",
                this, cycle);

            // the previous timestamp is the one we need to start with
            // because we're going to update the buffer again this loop
            // using writeframes
            m_data_buffer->setBufferTailTimestamp(m_last_timestamp);

debugOutput(DEBUG_LEVEL_VERBOSE,"On enable: last ts=%lld, ts2=%lld = %lld (%p)\n",
  m_last_timestamp, m_last_timestamp2, m_last_timestamp-m_last_timestamp2,
  m_data_buffer);

        } else {
            debugOutput(DEBUG_LEVEL_VERY_VERBOSE,
                "will enable StreamProcessor %p at %u, now is %d\n",
                    this, m_cycle_to_enable_at, cycle);
        }
    } else if (m_disabled && !m_is_disabled) {
        // trying to disable
        debugOutput(DEBUG_LEVEL_VERBOSE,"disabling StreamProcessor %p at %u\n", this, cycle);
        m_is_disabled=true;
    }

    // If the packet length is 8 bytes (ie: just a CIP-like header)
    // there is no isodata.
    if (length > 8) {
        // The iso data blocks from the MOTUs comprise a CIP-like
        // header followed by a number of events (8 for 1x rates, 16
        // for 2x rates, 32 for 4x rates).
        quadlet_t *quadlet = (quadlet_t *)data;
        unsigned int dbs = get_bits(ntohl(quadlet[0]), 23, 8);  // Size of one event in terms of fdf_size
        unsigned int fdf_size = get_bits(ntohl(quadlet[1]), 23, 8) == 0x22 ? 32:0; // Event unit size in bits

        // Don't even attempt to process a packet if it isn't what
        // we expect from a MOTU.  Yes, an FDF value of 32 bears
        // little relationship to the actual data (24 bit integer)
        // sent by the MOTU - it's one of those areas where MOTU
        // have taken a curious detour around the standards.
        if (tag!=1 || fdf_size!=32) {
            return RAW1394_ISO_OK;
        }

        // put this after the check because event_length can become 0 on invalid packets
        unsigned int event_length = (fdf_size * dbs) / 8;       // Event size in bytes
        unsigned int n_events = (length-8) / event_length;

        //=> store the previous timestamp
        m_last_timestamp2=m_last_timestamp;

        // Acquire the timestamp of the last frame in the packet just
        // received.  Since every frame from the MOTU has its own timestamp
        // we can just pick it straight from the packet.
        uint32_t last_sph = ntohl(*(quadlet_t *)(data+8+(n_events-1)*event_length));
        m_last_timestamp = sphRecvToFullTicks(last_sph, m_handler->getCycleTimer());
                                                         
        // Signal that we're running
        if(!m_running && n_events && m_last_timestamp2 && m_last_timestamp) {
            debugOutput(DEBUG_LEVEL_VERBOSE,"Receive StreamProcessor %p started running at %d\n", this, cycle);
            m_running=true;
        }

        //=> don't process the stream samples when it is not enabled.
        if(m_is_disabled) {

            // we keep track of the timestamp here
            // this makes sure that we will have a somewhat accurate
            // estimate as to when a period might be ready. i.e. it will not
            // be ready earlier than this timestamp + period time

            // Set the timestamp as if a sample was put into the buffer by
            // this present packet.  This means we use the timestamp
            // corresponding to the last frame which would have been added
            // to the buffer this cycle if we weren't disabled - that is,
            // m_last_timestamp.
            m_data_buffer->setBufferTailTimestamp(m_last_timestamp);

            return RAW1394_ISO_DEFER;
        }

        debugOutput( DEBUG_LEVEL_VERY_VERBOSE, "put packet...\n");
//debugOutput(DEBUG_LEVEL_VERBOSE,"rx cycle=%d, last ts=%lld\n",cycle, m_last_timestamp);

        //=> process the packet
        // add the data payload to the ringbuffer
        // Note: the last argument to writeFrames is the timestamp of the *last sample* being
        // added.
        if(m_data_buffer->writeFrames(n_events, (char *)(data+8), m_last_timestamp)) {
            retval=RAW1394_ISO_OK;
            int dbc = get_bits(ntohl(quadlet[0]), 8, 8);

            // process all ports that should be handled on a per-packet base
            // this is MIDI for AMDTP (due to the need of DBC)
            if (!decodePacketPorts((quadlet_t *)(data+8), n_events, dbc)) {
                debugWarning("Problem decoding Packet Ports\n");
                retval=RAW1394_ISO_DEFER;
            }

        } else {

            debugWarning("Receive buffer overrun (cycle %d, FC=%d, PC=%d)\n",
                 cycle, m_data_buffer->getFrameCounter(), m_handler->getPacketCount());

            m_xruns++;

            // disable the processing, will be re-enabled when
            // the xrun is handled
            m_disabled=true;
            m_is_disabled=true;

            retval=RAW1394_ISO_DEFER;
        }
    }

    return retval;
}

// returns the delay between the actual (real) time of a timestamp as received,
// and the timestamp that is passed on for the same event. This is to cope with
// ISO buffering
int MotuReceiveStreamProcessor::getMinimalSyncDelay() {
    unsigned int n_events = m_framerate<=48000?8:(m_framerate<=96000?16:32);

    return (int)(m_handler->getWakeupInterval() * n_events * m_ticks_per_frame);
}

bool MotuReceiveStreamProcessor::reset() {

    debugOutput( DEBUG_LEVEL_VERBOSE, "Resetting...\n");

    m_data_buffer->setTickOffset(0);

    // reset all non-device specific stuff
    // i.e. the iso stream and the associated ports
    if(!ReceiveStreamProcessor::reset()) {
        debugFatal("Could not do base class reset\n");
        return false;
    }

    return true;
}

bool MotuReceiveStreamProcessor::prepare() {

    // prepare all non-device specific stuff
    // i.e. the iso stream and the associated ports
    if(!ReceiveStreamProcessor::prepare()) {
        debugFatal("Could not prepare base class\n");
        return false;
    }

    debugOutput( DEBUG_LEVEL_VERBOSE, "Preparing...\n");

    m_PeriodStat.setName("RCV PERIOD");
    m_PacketStat.setName("RCV PACKET");
    m_WakeupStat.setName("RCV WAKEUP");

    // setup any specific stuff here
    // FIXME: m_frame_size would be a better name
    debugOutput( DEBUG_LEVEL_VERBOSE, "Event size: %d\n", m_event_size);

    // prepare the framerate estimate
    m_ticks_per_frame = (TICKS_PER_SECOND*1.0) / ((float)m_framerate);

    // initialize internal buffer
    unsigned int ringbuffer_size_frames=m_nb_buffers * m_period;

    unsigned int events_per_frame = m_framerate<=48000?8:(m_framerate<=96000?16:32);

    assert(m_data_buffer);
    m_data_buffer->setBufferSize(ringbuffer_size_frames);
    m_data_buffer->setEventSize(m_event_size);
    m_data_buffer->setEventsPerFrame(1);

// JMW: The rx buffer receives a new timestamp once per received frame so I think the
// buffer update period is events_per_frame, not events per period.
//    m_data_buffer->setUpdatePeriod(m_period);
    m_data_buffer->setUpdatePeriod(events_per_frame);
    m_data_buffer->setNominalRate(m_ticks_per_frame);

    m_data_buffer->setWrapValue(128L*TICKS_PER_SECOND);

    m_data_buffer->prepare();

    // set the parameters of ports we can:
    // we want the audio ports to be period buffered,
    // and the midi ports to be packet buffered
    for ( PortVectorIterator it = m_Ports.begin();
          it != m_Ports.end();
          ++it )
    {
        debugOutput(DEBUG_LEVEL_VERBOSE, "Setting up port %s\n",(*it)->getName().c_str());

        if(!(*it)->setBufferSize(m_period)) {
            debugFatal("Could not set buffer size to %d\n",m_period);
            return false;
        }

        switch ((*it)->getPortType()) {
            case Port::E_Audio:
                if(!(*it)->setSignalType(Port::E_PeriodSignalled)) {
                    debugFatal("Could not set signal type to PeriodSignalling");
                    return false;
                }
                break;
            case Port::E_Midi:
                if(!(*it)->setSignalType(Port::E_PacketSignalled)) {
                    debugFatal("Could not set signal type to PacketSignalling");
                    return false;
                }
                if (!(*it)->setBufferType(Port::E_RingBuffer)) {
                    debugFatal("Could not set buffer type");
                    return false;
                }
                if (!(*it)->setDataType(Port::E_MidiEvent)) {
                    debugFatal("Could not set data type");
                    return false;
                }
                // FIXME: probably need rate control too.  See
                // Port::useRateControl() and AmdtpStreamProcessor.
                break;
            case Port::E_Control:
                if(!(*it)->setSignalType(Port::E_PeriodSignalled)) {
                    debugFatal("Could not set signal type to PeriodSignalling");
                    return false;
                }
                break;
            default:
                debugWarning("Unsupported port type specified\n");
                break;
        }

    }

    // The API specific settings of the ports are already set before
    // this routine is called, therefore we can init&prepare the ports
    if(!initPorts()) {
        debugFatal("Could not initialize ports!\n");
        return false;
    }

    if(!preparePorts()) {
        debugFatal("Could not initialize ports!\n");
        return false;
    }

    return true;

}


bool MotuReceiveStreamProcessor::prepareForStop() {

    // A MOTU receive stream can stop at any time.  However, signify
    // that stopping is in progress because other streams (notably the
    // transmit stream) may keep going for some time and cause an
    // overflow in the receive buffers.  If a closedown is in progress
    // the receive handler simply throws all incoming data away so
    // no buffer overflow can occur.
    m_closedown_active = 1;
    return true;
}

bool MotuReceiveStreamProcessor::prepareForStart() {
// Reset some critical variables required so the stream starts cleanly. This
// method is called once on every stream restart, including those during
// xrun recovery.  Initialisations which should be done once should be
// placed in the init() method instead.
    m_running = 0;
    m_closedown_active = 0;

    // At this point we'll also disable the stream processor here.
    // At this stage stream processors are always explicitly re-enabled
    // after being started, so by starting in the disabled state we
    // ensure that every start will be exactly the same.
    disable();

    return true;
}

bool MotuReceiveStreamProcessor::getFrames(unsigned int nbframes, int64_t ts) {

    m_PeriodStat.mark(m_data_buffer->getBufferFill());

    // ask the buffer to process nbframes of frames
    // using it's registered client's processReadBlock(),
    // which should be ours
    m_data_buffer->blockProcessReadFrames(nbframes);

    return true;
}

/**
 * \brief write received events to the port ringbuffers.
 */
bool MotuReceiveStreamProcessor::processReadBlock(char *data,
                       unsigned int nevents, unsigned int offset)
{
    bool no_problem=true;
    for ( PortVectorIterator it = m_PeriodPorts.begin();
          it != m_PeriodPorts.end();
          ++it ) {
        if((*it)->isDisabled()) {continue;};

        //FIXME: make this into a static_cast when not DEBUG?
        Port *port=dynamic_cast<Port *>(*it);

        switch(port->getPortType()) {

        case Port::E_Audio:
            if(decodeMotuEventsToPort(static_cast<MotuAudioPort *>(*it), (quadlet_t *)data, offset, nevents)) {
                debugWarning("Could not decode packet MBLA to port %s",(*it)->getName().c_str());
                no_problem=false;
            }
            break;
        // midi is a packet based port, don't process
        //    case MotuPortInfo::E_Midi:
        //        break;

        default: // ignore
            break;
        }
    }
    return no_problem;
}

/**
 * @brief decode a packet for the packet-based ports
 *
 * @param data Packet data
 * @param nevents number of events in data (including events of other ports & port types)
 * @param dbc DataBlockCount value for this packet
 * @return true if all successfull
 */
bool MotuReceiveStreamProcessor::decodePacketPorts(quadlet_t *data, unsigned int nevents,
        unsigned int dbc) {
    bool ok=true;

    // Use char here since the source address won't necessarily be
    // aligned; use of an unaligned quadlet_t may cause issues on
    // certain architectures.  Besides, the source for MIDI data going
    // directly to the MOTU isn't structured in quadlets anyway; it is a
    // sequence of 3 unaligned bytes.
    unsigned char *src = NULL;

    for ( PortVectorIterator it = m_PacketPorts.begin();
        it != m_PacketPorts.end();
        ++it ) {

        Port *port=dynamic_cast<Port *>(*it);
        assert(port); // this should not fail!!

        // Currently the only packet type of events for MOTU
        // is MIDI in mbla.  However in future control data
        // might also be sent via "packet" events, so allow
        // for this possible expansion.

        // FIXME: MIDI input is completely untested at present.
        switch (port->getPortType()) {
            case Port::E_Midi: {
                MotuMidiPort *mp=static_cast<MotuMidiPort *>(*it);
                signed int sample;
                unsigned int j = 0;
                // Get MIDI bytes if present anywhere in the
                // packet.  MOTU MIDI data is sent using a
                // 3-byte sequence starting at the port's
                // position.  It's thought that there can never
                // be more than one MIDI byte per packet, but
                // for completeness we'll check the entire packet
                // anyway.
                src = (unsigned char *)data + mp->getPosition();
                while (j < nevents) {
                    if (*src==0x01 && *(src+1)==0x00) {
                        sample = *(src+2);
                        if (!mp->writeEvent(&sample)) {
                            debugWarning("MIDI packet port events lost\n");
                            ok = false;
                        }
                    }
                    j++;
                    src += m_event_size;
                }
                break;
            }
            default:
                debugOutput(DEBUG_LEVEL_VERBOSE, "Unknown packet-type port format %d\n",port->getPortType());
                return ok;
              }
    }

    return ok;
}

signed int MotuReceiveStreamProcessor::decodeMotuEventsToPort(MotuAudioPort *p,
        quadlet_t *data, unsigned int offset, unsigned int nevents)
{
    unsigned int j=0;

    // Use char here since a port's source address won't necessarily be
    // aligned; use of an unaligned quadlet_t may cause issues on
    // certain architectures.  Besides, the source (data coming directly
    // from the MOTU) isn't structured in quadlets anyway; it mainly
    // consists of packed 24-bit integers.

    unsigned char *src_data;
    src_data = (unsigned char *)data + p->getPosition();

    switch(p->getDataType()) {
        default:
        case Port::E_Int24:
            {
                quadlet_t *buffer=(quadlet_t *)(p->getBufferAddress());

                assert(nevents + offset <= p->getBufferSize());

                // Offset is in frames, but each port is only a single
                // channel, so the number of frames is the same as the
                // number of quadlets to offset (assuming the port buffer
                // uses one quadlet per sample, which is the case currently).
                buffer+=offset;

                for(j = 0; j < nevents; j += 1) { // Decode nsamples
                    *buffer = (*src_data<<16)+(*(src_data+1)<<8)+*(src_data+2);
                    // Sign-extend highest bit of 24-bit int.
                    // FIXME: this isn't strictly needed since E_Int24 is a 24-bit,
                    // but doing so shouldn't break anything and makes the data
                    // easier to deal with during debugging.
                    if (*src_data & 0x80)
                        *buffer |= 0xff000000;

                    buffer++;
                    src_data+=m_event_size;
                }
            }
            break;
        case Port::E_Float:
            {
                const float multiplier = 1.0f / (float)(0x7FFFFF);
                float *buffer=(float *)(p->getBufferAddress());

                assert(nevents + offset <= p->getBufferSize());

                buffer+=offset;

                for(j = 0; j < nevents; j += 1) { // decode max nsamples

                    unsigned int v = (*src_data<<16)+(*(src_data+1)<<8)+*(src_data+2);

                    // sign-extend highest bit of 24-bit int
                    int tmp = (int)(v << 8) / 256;

                    *buffer = tmp * multiplier;

                    buffer++;
                    src_data+=m_event_size;
                }
            }
            break;
    }

    return 0;
}

signed int MotuReceiveStreamProcessor::setEventSize(unsigned int size) {
    m_event_size = size;
    return 0;
}

unsigned int MotuReceiveStreamProcessor::getEventSize(void) {
//
// Return the size of a single event sent by the MOTU as part of an iso
// data packet in bytes.
//
    return m_event_size;
}

void MotuReceiveStreamProcessor::setVerboseLevel(int l) {
    setDebugLevel(l);
    ReceiveStreamProcessor::setVerboseLevel(l);
}

} // end of namespace Streaming