GNU Radio 3.4.0 C++ API
audio_alsa_sink.h
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00001 /* -*- c++ -*- */
00002 /*
00003  * Copyright 2004-2011 Free Software Foundation, Inc.
00004  * 
00005  * This file is part of GNU Radio
00006  * 
00007  * GNU Radio is free software; you can redistribute it and/or modify
00008  * it under the terms of the GNU General Public License as published by
00009  * the Free Software Foundation; either version 3, or (at your option)
00010  * any later version.
00011  * 
00012  * GNU Radio is distributed in the hope that it will be useful,
00013  * but WITHOUT ANY WARRANTY; without even the implied warranty of
00014  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
00015  * GNU General Public License for more details.
00016  * 
00017  * You should have received a copy of the GNU General Public License
00018  * along with GNU Radio; see the file COPYING.  If not, write to
00019  * the Free Software Foundation, Inc., 51 Franklin Street,
00020  * Boston, MA 02110-1301, USA.
00021  */
00022 
00023 #ifndef INCLUDED_AUDIO_ALSA_SINK_H
00024 #define INCLUDED_AUDIO_ALSA_SINK_H
00025 
00026 // use new ALSA API
00027 #define ALSA_PCM_NEW_HW_PARAMS_API
00028 #define ALSA_PCM_NEW_SW_PARAMS_API
00029 
00030 #include <gr_audio_sink.h>
00031 #include <string>
00032 #include <alsa/asoundlib.h>
00033 #include <stdexcept>
00034 
00035 /*!
00036  * \brief audio sink using ALSA
00037  *
00038  * The sink has N input streams of floats, where N depends
00039  * on the hardware characteristics of the selected device.
00040  *
00041  * Input samples must be in the range [-1,1].
00042  */
00043 class audio_alsa_sink : public audio_sink {
00044   // typedef for pointer to class work method
00045   typedef int (audio_alsa_sink::*work_t)(int noutput_items,
00046                                          gr_vector_const_void_star &input_items,
00047                                          gr_vector_void_star &output_items);
00048 
00049   unsigned int          d_sampling_rate;
00050   std::string           d_device_name;
00051   snd_pcm_t            *d_pcm_handle;
00052   snd_pcm_hw_params_t  *d_hw_params;
00053   snd_pcm_sw_params_t  *d_sw_params;
00054   snd_pcm_format_t      d_format;
00055   unsigned int          d_nperiods;
00056   unsigned int          d_period_time_us;       // microseconds
00057   snd_pcm_uframes_t     d_period_size;          // in frames
00058   unsigned int          d_buffer_size_bytes;    // sizeof of d_buffer
00059   char                 *d_buffer;
00060   work_t                d_worker;               // the work method to use
00061   bool                  d_special_case_mono_to_stereo;
00062 
00063   // random stats
00064   int                   d_nunderuns;            // count of underruns
00065   int                   d_nsuspends;            // count of suspends
00066   bool                  d_ok_to_block;      // defaults to "true", controls blocking/non-block I/O
00067 
00068   void output_error_msg (const char *msg, int err);
00069   void bail (const char *msg, int err) throw (std::runtime_error);
00070 
00071 public:
00072   audio_alsa_sink (int sampling_rate, const std::string device_name,
00073                    bool ok_to_block);
00074 
00075   ~audio_alsa_sink ();
00076   
00077   bool check_topology (int ninputs, int noutputs);
00078 
00079   int work (int noutput_items,
00080             gr_vector_const_void_star &input_items,
00081             gr_vector_void_star &output_items);
00082 
00083 
00084 protected:
00085   bool write_buffer (const void *buffer, unsigned nframes, unsigned sizeof_frame);
00086 
00087   int work_s16 (int noutput_items,
00088                 gr_vector_const_void_star &input_items,
00089                 gr_vector_void_star &output_items);
00090 
00091   int work_s16_1x2 (int noutput_items,
00092                     gr_vector_const_void_star &input_items,
00093                     gr_vector_void_star &output_items);
00094 
00095   int work_s32 (int noutput_items,
00096                 gr_vector_const_void_star &input_items,
00097                 gr_vector_void_star &output_items);
00098 
00099   int work_s32_1x2 (int noutput_items,
00100                     gr_vector_const_void_star &input_items,
00101                     gr_vector_void_star &output_items);
00102 };
00103 
00104 #endif /* INCLUDED_AUDIO_ALSA_SINK_H */