write.h

   1 /*
   2  * Copyright (C) 2006 Andre Noll <maan@systemlinux.org>
   3  *
   4  *     This program is free software; you can redistribute it and/or modify
   5  *     it under the terms of the GNU General Public License as published by
   6  *     the Free Software Foundation; either version 2 of the License, or
   7  *     (at your option) any later version.
   8  *
   9  *     This program is distributed in the hope that it will be useful,
  10  *     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *     GNU General Public License for more details.
  13  *
  14  *     You should have received a copy of the GNU General Public License
  15  *     along with this program; if not, write to the Free Software
  16  *     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  17  */
  18
  19 /** \file write.h writer-related structures */
  20
  21 /** the list of supported writers */
  22 enum writer_enum {WRITER_ENUM};
  23
  24 /**
  25  * decbribes one running instance of a writer
  26  */
  27 struct writer_node {
  28         /** points to the writer structure associated with this node */
  29         struct writer *writer; /* FIXME: Should better be only the number */
  30         /** writer-specific data */
  31         void *private_data;
  32         /** send that many bytes in one go */
  33         int chunk_bytes;
  34         struct writer_node_group *wng;
  35         /** the writer-specific configuration of this node */
  36         void *conf;
  37 };
  38
  39 /** describes one supported writer */
  40 struct writer {
  41         /**
  42          * the init function of the writer
  43          *
  44          * It must fill in all other function pointers of the given
  45          * writer structure.
  46          *
  47          */
  48         void (*init)(struct writer *w);
  49         /**
  50          *
  51          *
  52          * the command line parser of the writer
  53          *
  54          * It should check whether the command line options given by \a options are
  55          * valid.  On success, it should return a pointer to the writer-specific
  56          * configuration data determined by \a options.  Note that this might be called
  57          * more than once with different values of \a options.
  58          *
  59          */
  60                 void * (*parse_config)(char *options);
  61         /**
  62          *
  63          * open one instance of this writer
  64          *
  65          * This function should perform any work necessary to write the incoming
  66          * stream. If To this aim, it may allocate its private data structure and store
  67          * a pointer to that structure via the given writer_node paramenter.
  68          */
  69         int (*open)(struct writer_node *);
  70         /**
  71          *
  72          * write a chunk of audio data
  73          *
  74          * This is called from the driving application whenever a data block of \a
  75          * chunk_bytes is available. It must return the number of bytes consumed from
  76          * \a data on success, and negative on errors.
  77          *
  78          */
  79         int (*write)(char *data, size_t nbytes, struct writer_node *);
  80         int (*pre_select)(struct sched *s, struct writer_node *wn);
  81         int (*post_select)(struct sched *s, struct writer_node *wn);
  82         /**
  83          * close one instance of the writer
  84          *
  85          * This function is assumed to succeed.
  86          */
  87         void (*close)(struct writer_node *);
  88         /**
  89          * shutdown the writer
  90          *
  91          * This is a optional function pointer used for cleaning
  92          * up.
  93          */
  94         void (*shutdown)(struct writer_node *);
  95 };
  96
  97 /**
  98  * describes a set of writer nodes that all write the same stream.
  99  */
 100 struct writer_node_group {
 101         /** number of nodes belonging to this group */
 102         unsigned num_writers;
 103         /** array of pointers to the corresponding writer nodes */
 104         struct writer_node *writer_nodes;
 105         /** keeps track of how many bytes have been written by each node */
 106         int *written;
 107         /** the maximum of the chunk_bytes values of the writer nodes in this group */
 108         size_t max_chunk_bytes;
 109         /** non-zero if end of file was encountered */
 110         int *input_eof;
 111         int eof;
 112         char *buf;
 113         unsigned int *channels;
 114         unsigned int *samplerate;
 115         size_t *loaded;
 116         struct task task;
 117 };
 118
 119 /** loop over each writer node in a writer group */
 120 #define FOR_EACH_WRITER_NODE(i, wng) for (i = 0; i < (wng)->num_writers; i++)
 121 /** loop over each supported writer */
 122 #define FOR_EACH_WRITER(i) for (i = 0; i < NUM_SUPPORTED_WRITERS; i++)
 123
 124 /** declare the init functions of all supported writers */
 125 DECLARE_WRITER_INITS;
 126
 127 /** array containing the name of each writer */
 128 extern const char *writer_names[];
 129
 130 /** the writer structure for each supported writer */
 131 extern struct writer writers[NUM_SUPPORTED_WRITERS];