write.h

   1 /*
   2  * Copyright (C) 2006-2009 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         /** Pointer to the group this node belongs to. */
  21         struct writer_node_group *wng;
  22         /** The writer-specific configuration of this node. */
  23         void *conf;
  24         /** How much of the wng's buffer is already written. */
  25         size_t written;
  26         struct btr_node *btrn;
  27         struct task task;
  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 are
  43          * valid.  On success, it should return a pointer to the writer-specific
  44          * configuration data determined by \a options.  Note that this might be called
  45          * more than once with different values of \a options.
  46          */
  47         void *(*parse_config)(const char *options);
  48         /**
  49          * Open one instance of this writer.
  50          *
  51          * This function should perform any work necessary to write the incoming
  52          * stream. To this aim, it may allocate its private data structure and store
  53          * a pointer to that structure via the given writer_node parameter.
  54          */
  55         int (*open)(struct writer_node *);
  56         /**
  57          * Prepare the fd sets for select.
  58          *
  59          * This is called from the writer node group task's pre_select(). It
  60          * may use the sched pointer to add any file descriptors or to decrease
  61          * the select timeout. It must return positive on success and negative
  62          * on errors.
  63          */
  64         int (*pre_select)(struct sched *s, struct writer_node *wn);
  65         void (*pre_select_btr)(struct sched *s, struct task *t);
  66         /**
  67          * Write audio data.
  68          *
  69          * Called from the post_select function of the wng task. It must keep
  70          * track of the number of bytes consumed from the wng's buffer via
  71          * the \p wn->written variable (which may be modified by the wng handling
  72          * functions). This function must return positive on success and
  73          * negative on errors.
  74          */
  75         int (*post_select)(struct sched *s, struct writer_node *wn);
  76         void (*post_select_btr)(struct sched *s, struct task *t);
  77         /**
  78          * Close one instance of the writer.
  79          *
  80          * This function is assumed to succeed.
  81          */
  82         void (*close)(struct writer_node *);
  83         /**
  84          * Shutdown the writer
  85          *
  86          * This is a optional function pointer used for cleaning up.
  87          */
  88         void (*shutdown)(struct writer_node *);
  89         struct ggo_help help;
  90         btr_command_handler execute;
  91 };
  92
  93 /**
  94  * Describes a set of writer nodes that all write the same stream.
  95  */
  96 struct writer_node_group {
  97         /** Number of nodes belonging to this group. */
  98         unsigned num_writers;
  99         /** Array of pointers to the corresponding writer nodes. */
 100         struct writer_node *writer_nodes;
 101         /** Non-zero if an error or end of file was encountered by the feeding task. */
 102         int *input_error;
 103         /** Current output buffer. */
 104         char **bufp;
 105         /** Number of bytes loaded in the output buffer. */
 106         size_t *loaded;
 107         /** Number of audio channels of the current stream. */
 108         unsigned int *channels;
 109         /** Sample rate of the current stream. */
 110         unsigned int *samplerate;
 111         /** The task associated to this group. */
 112         struct task task;
 113         /** Whether the group is open, i.e. wng_open() was called. */
 114         int open;
 115         /** Max number of bytes written in the previous post_select() call. */
 116         int last_written;
 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];