write.h

   1 /*
   2  * Copyright (C) 2006-2010 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         struct btr_node *btrn;
  23         struct task task;
  24         size_t min_iqs;
  25 };
  26
  27 /** Describes one supported writer. */
  28 struct writer {
  29         /**
  30          * The init function of the writer.
  31          *
  32          * It must fill in all other function pointers of the given
  33          * writer structure.
  34          */
  35         void (*init)(struct writer *w);
  36         /**
  37          * The command line parser of the writer.
  38          *
  39          * It should check whether the command line options given by \a options are
  40          * valid.  On success, it should return a pointer to the writer-specific
  41          * configuration data determined by \a options.  Note that this might be called
  42          * more than once with different values of \a options.
  43          */
  44         void *(*parse_config)(const char *options);
  45         void (*free_config)(void *conf);
  46         /**
  47          * Open one instance of this writer.
  48          *
  49          * This function should perform any work necessary to write the incoming
  50          * stream. To this aim, it may allocate its private data structure and store
  51          * a pointer to that structure via the given writer_node parameter.
  52          */
  53         int (*open)(struct writer_node *);
  54         /**
  55          * Prepare the fd sets for select.
  56          *
  57          * This is called from scheduler. It may use the sched pointer to add
  58          * any file descriptors or to decrease the select timeout.
  59          */
  60         void (*pre_select)(struct sched *s, struct task *t);
  61         /**
  62          * Write audio data.
  63          *
  64          * Called from the post_select function of the writer node's task.
  65          */
  66         void (*post_select)(struct sched *s, struct task *t);
  67         /**
  68          * Close one instance of the writer.
  69          *
  70          * This function is assumed to succeed.
  71          */
  72         void (*close)(struct writer_node *);
  73         /**
  74          * Shutdown the writer
  75          *
  76          * This is a optional function pointer used for cleaning up.
  77          */
  78         void (*shutdown)(struct writer_node *);
  79         struct ggo_help help;
  80         btr_command_handler execute;
  81 };
  82
  83 /** Loop over each supported writer. */
  84 #define FOR_EACH_WRITER(i) for (i = 0; i < NUM_SUPPORTED_WRITERS; i++)
  85
  86 /** Declare the init functions of all supported writers. */
  87 DECLARE_WRITER_INITS;
  88
  89 /** Array containing the name of each writer. */
  90 extern const char *writer_names[];
  91
  92 /** The writer structure for each supported writer. */
  93 extern struct writer writers[NUM_SUPPORTED_WRITERS];