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/* $Id$ */ |
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/* |
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* FreeBob Streaming API |
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* FreeBob = Firewire (pro-)audio for linux |
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* |
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* http://freebob.sf.net |
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* |
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* Copyright (C) 2005,2006 Pieter Palmers <pieterpalmers@users.sourceforge.net> |
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* |
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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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* |
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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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* |
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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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* |
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* |
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*/ |
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#include "AmdtpPort.h" |
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#include <assert.h> |
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namespace FreebobStreaming { |
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AmdtpMidiPort::AmdtpMidiPort(std::string name, |
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enum E_Direction direction, |
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int position, |
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int location, |
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enum E_Formats format, |
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int type) |
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: MidiPort(name, direction), |
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AmdtpPortInfo(name, position, location, format, type) |
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, m_countdown(0) |
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{ |
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m_ringbuffer=freebob_ringbuffer_create(m_buffersize * getEventSize()); |
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if(!m_ringbuffer) { |
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debugFatal("Could not allocate ringbuffer\n"); |
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m_buffersize=0; |
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} |
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} |
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AmdtpMidiPort::~AmdtpMidiPort() { |
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if (m_ringbuffer) freebob_ringbuffer_free(m_ringbuffer); |
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} |
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/** |
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* The problem with MIDI ports is that there is no guaranteed availability of data. |
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* This function will return true if: |
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* (1) there is a byte ready in the buffer |
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* (2) we are allowed to send a byte |
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* |
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* it will also assume that you actually are sending a byte, and it will reset |
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* the countdown |
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* |
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* note on (2): the midi over 1394 spec limits the speed of sending midi data bytes. |
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* For every (time muxed) channel, you can send only one midi byte every |
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* 320 microseconds. The packet rate is 8000pkt/sec, or 125us. Therefore |
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* we wait (at least) two packets before sending another byte. This comes |
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* down to 375us, so there is a slight limiting of the bandwidth. |
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* |
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* \todo fix the too long delay (375us instead of 320us) |
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* |
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* @return true if you can send a midi byte |
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*/ |
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bool AmdtpMidiPort::canSend() { |
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bool byte_present_in_buffer; |
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assert(m_ringbuffer); |
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byte_present_in_buffer=(freebob_ringbuffer_read_space(m_ringbuffer)>=sizeof(char)); |
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if(byte_present_in_buffer && (m_countdown < 0)) { |
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m_countdown=2; |
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return true; |
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} |
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return false; |
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} |
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|
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} // end of namespace FreebobStreaming |
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