GNU Radio 3.5.1 C++ API
audio_alsa_sink.h
Go to the documentation of this file.
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  * \ingroup audio_blk
00038  *
00039  * The sink has N input streams of floats, where N depends
00040  * on the hardware characteristics of the selected device.
00041  *
00042  * Input samples must be in the range [-1,1].
00043  */
00044 class audio_alsa_sink : public audio_sink {
00045   // typedef for pointer to class work method
00046   typedef int (audio_alsa_sink::*work_t)(int noutput_items,
00047                                          gr_vector_const_void_star &input_items,
00048                                          gr_vector_void_star &output_items);
00049 
00050   unsigned int          d_sampling_rate;
00051   std::string           d_device_name;
00052   snd_pcm_t            *d_pcm_handle;
00053   snd_pcm_hw_params_t  *d_hw_params;
00054   snd_pcm_sw_params_t  *d_sw_params;
00055   snd_pcm_format_t      d_format;
00056   unsigned int          d_nperiods;
00057   unsigned int          d_period_time_us;       // microseconds
00058   snd_pcm_uframes_t     d_period_size;          // in frames
00059   unsigned int          d_buffer_size_bytes;    // sizeof of d_buffer
00060   char                 *d_buffer;
00061   work_t                d_worker;               // the work method to use
00062   bool                  d_special_case_mono_to_stereo;
00063 
00064   // random stats
00065   int                   d_nunderuns;            // count of underruns
00066   int                   d_nsuspends;            // count of suspends
00067   bool                  d_ok_to_block;      // defaults to "true", controls blocking/non-block I/O
00068 
00069   void output_error_msg (const char *msg, int err);
00070   void bail (const char *msg, int err) throw (std::runtime_error);
00071 
00072 public:
00073   audio_alsa_sink (int sampling_rate, const std::string device_name,
00074                    bool ok_to_block);
00075 
00076   ~audio_alsa_sink ();
00077   
00078   bool check_topology (int ninputs, int noutputs);
00079 
00080   int work (int noutput_items,
00081             gr_vector_const_void_star &input_items,
00082             gr_vector_void_star &output_items);
00083 
00084 
00085 protected:
00086   bool write_buffer (const void *buffer, unsigned nframes, unsigned sizeof_frame);
00087 
00088   int work_s16 (int noutput_items,
00089                 gr_vector_const_void_star &input_items,
00090                 gr_vector_void_star &output_items);
00091 
00092   int work_s16_1x2 (int noutput_items,
00093                     gr_vector_const_void_star &input_items,
00094                     gr_vector_void_star &output_items);
00095 
00096   int work_s32 (int noutput_items,
00097                 gr_vector_const_void_star &input_items,
00098                 gr_vector_void_star &output_items);
00099 
00100   int work_s32_1x2 (int noutput_items,
00101                     gr_vector_const_void_star &input_items,
00102                     gr_vector_void_star &output_items);
00103 };
00104 
00105 #endif /* INCLUDED_AUDIO_ALSA_SINK_H */