write.h

   1 /*
   2  * Copyright (C) 2006-2007 Andre Noll <maan@systemlinux.org>
   3  *
   4  * Licensed under the GPL v2. For licencing details see COPYING.
   5  */
   6
   7 /** \file write.h writer-related structures */
   8
   9 /** the list of supported writers */
  10 enum writer_enum {WRITER_ENUM};
  11
  12 /**
  13  * Describes one running instance of a writer.
  14  */
  15 struct writer_node {
  16         /** points to the writer structure associated with this node */
  17         struct writer *writer; /* FIXME: Should better be only the number */
  18         /** writer-specific data */
  19         void *private_data;
  20         /** send that many bytes in one go */
  21         int chunk_bytes;
  22         /** pointer to the group this node belongs to */
  23         struct writer_node_group *wng;
  24         /** the writer-specific configuration of this node */
  25         void *conf;
  26         /** how much of the wng's buffer is already written */
  27         size_t written;
  28 };
  29
  30 /** describes one supported writer */
  31 struct writer {
  32         /**
  33          * the init function of the writer
  34          *
  35          * It must fill in all other function pointers of the given
  36          * writer structure.
  37          *
  38          */
  39         void (*init)(struct writer *w);
  40         /**
  41          *
  42          *
  43          * the command line parser of the writer
  44          *
  45          * It should check whether the command line options given by \a options are
  46          * valid.  On success, it should return a pointer to the writer-specific
  47          * configuration data determined by \a options.  Note that this might be called
  48          * more than once with different values of \a options.
  49          *
  50          */
  51                 void * (*parse_config)(const char *options);
  52         /**
  53          *
  54          * open one instance of this writer
  55          *
  56          * This function should perform any work necessary to write the incoming
  57          * stream. If To this aim, it may allocate its private data structure and store
  58          * a pointer to that structure via the given writer_node parameter.
  59          */
  60         int (*open)(struct writer_node *);
  61         /**
  62          *
  63          * write a chunk of audio data
  64          *
  65          * This is called from the writer node group task's pre_select(). It
  66          * may use the sched pointer to add any file descriptors or to decrease
  67          * the select timeout. It must return positive on success and negative
  68          * on errors.
  69          */
  70         int (*pre_select)(struct sched *s, struct writer_node *wn);
  71         /**
  72          * Called from the post_select function of the wng task. It must keep
  73          * track of the number of bytes consumed from the wng's buffer via
  74          * the wn->written variable (which may be modified by the wng handling
  75          * functions). This function must return positive on success and
  76          * negative on errors.
  77          */
  78         int (*post_select)(struct sched *s, struct writer_node *wn);
  79         /**
  80          * close one instance of the writer
  81          *
  82          * This function is assumed to succeed.
  83          */
  84         void (*close)(struct writer_node *);
  85         /**
  86          * shutdown the writer
  87          *
  88          * This is a optional function pointer used for cleaning
  89          * up.
  90          */
  91         void (*shutdown)(struct writer_node *);
  92 };
  93
  94 /**
  95  * describes a set of writer nodes that all write the same stream.
  96  */
  97 struct writer_node_group {
  98         /** number of nodes belonging to this group */
  99         unsigned num_writers;
 100         /** array of pointers to the corresponding writer nodes */
 101         struct writer_node *writer_nodes;
 102         /** the maximum of the chunk_bytes values of the writer nodes in this group */
 103         size_t max_chunk_bytes;
 104         /** Non-zero if an error or end of file was encountered by the feeding task. */
 105         int *input_error;
 106         /** Non-zero if an error occurred or end of file was encountered. */
 107         int error;
 108         /** current output buffer */
 109         char *buf;
 110         /** number of bytes loaded in the output buffer */
 111         size_t *loaded;
 112         /** number of audio channels of the current stream */
 113         unsigned int *channels;
 114         /** sample rate of the current stream */
 115         unsigned int *samplerate;
 116         /** the task associated to this group */
 117         struct task task;
 118 };
 119
 120 /** loop over each writer node in a writer group */
 121 #define FOR_EACH_WRITER_NODE(i, wng) for (i = 0; i < (wng)->num_writers; i++)
 122 /** loop over each supported writer */
 123 #define FOR_EACH_WRITER(i) for (i = 0; i < NUM_SUPPORTED_WRITERS; i++)
 124
 125 /** declare the init functions of all supported writers */
 126 DECLARE_WRITER_INITS;
 127
 128 /** array containing the name of each writer */
 129 extern const char *writer_names[];
 130
 131 /** the writer structure for each supported writer */
 132 extern struct writer writers[NUM_SUPPORTED_WRITERS];