write.h

   1 /*
   2  * Copyright (C) 2006-2011 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         /** The number of this writer. */
  17         int writer_num;
  18         /** Writer-specific data. */
  19         void *private_data;
  20         /** The writer-specific configuration of this node. */
  21         void *conf;
  22         /** The buffer tree node associated with this writer node. */
  23         struct btr_node *btrn;
  24         /** The task of this writer node. */
  25         struct task task;
  26         /** The minimal input queue size (size of one audio sample). */
  27         size_t min_iqs;
  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         void (*init)(struct writer *w);
  39         /**
  40          * The command line parser of the writer.
  41          *
  42          * It should check whether the command line options given by \a options
  43          * are valid and return a pointer to the writer-specific configuration
  44          * data determined by \a options. This function must either succeed or
  45          * call exit(). Note that parse_config_or_die() might be called more
  46          * than once with different values of \a options. \sa \ref
  47          * free_config().
  48          */
  49         void *(*parse_config_or_die)(const char *options);
  50         /**
  51          * Dellocate all configuration resources.
  52          *
  53          * This should free whatever was allocated by \ref parse_config_or_die().
  54          */
  55         void (*free_config)(void *config);
  56         /**
  57          * Prepare the fd sets for select.
  58          *
  59          * This is called from scheduler. It may use the sched pointer to add
  60          * any file descriptors or to decrease the select timeout.
  61          */
  62         void (*pre_select)(struct sched *s, struct task *t);
  63         /**
  64          * Write audio data.
  65          *
  66          * Called from the post_select function of the writer node's task.
  67          */
  68         void (*post_select)(struct sched *s, struct task *t);
  69         /**
  70          * Close one instance of the writer.
  71          *
  72          * This function is assumed to succeed.
  73          */
  74         void (*close)(struct writer_node *);
  75         /**
  76          * Shutdown the writer.
  77          *
  78          * This is a optional function pointer used for cleaning up.
  79          */
  80         void (*shutdown)(struct writer_node *);
  81         /** The short and the log help text of this writer. */
  82         struct ggo_help help;
  83         /**
  84          * The callback handler.
  85          *
  86          * Each writer may provide an ->execute callback which can be used for
  87          * inter-node communication.
  88          */
  89         btr_command_handler execute;
  90 };
  91
  92 /** Loop over each supported writer. */
  93 #define FOR_EACH_WRITER(i) for (i = 0; i < NUM_SUPPORTED_WRITERS; i++)
  94
  95 /** Declare the init functions of all supported writers. */
  96 DECLARE_WRITER_INITS;
  97
  98 /** Array containing the name of each writer. */
  99 extern const char *writer_names[];
 100
 101 /** The writer structure for each supported writer. */
 102 extern struct writer writers[NUM_SUPPORTED_WRITERS];