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 };
  27
  28 /** Describes one supported writer. */
  29 struct writer {
  30         /**
  31          * The init function of the writer.
  32          *
  33          * It must fill in all other function pointers of the given
  34          * writer structure.
  35          */
  36         void (*init)(struct writer *w);
  37         /**
  38          * The command line parser of the writer.
  39          *
  40          * It should check whether the command line options given by \a options are
  41          * valid.  On success, it should return a pointer to the writer-specific
  42          * configuration data determined by \a options.  Note that this might be called
  43          * more than once with different values of \a options.
  44          */
  45         void *(*parse_config)(const char *options);
  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 the writer node group task's pre_select(). It
  58          * may use the sched pointer to add any file descriptors or to decrease
  59          * the select timeout. It must return positive on success and negative
  60          * on errors.
  61          */
  62         int (*pre_select)(struct sched *s, struct writer_node *wn);
  63         /**
  64          * Write audio data.
  65          *
  66          * Called from the post_select function of the wng task. It must keep
  67          * track of the number of bytes consumed from the wng's buffer via
  68          * the \p wn->written variable (which may be modified by the wng handling
  69          * functions). This function must return positive on success and
  70          * negative on errors.
  71          */
  72         int (*post_select)(struct sched *s, struct writer_node *wn);
  73         /**
  74          * Close one instance of the writer.
  75          *
  76          * This function is assumed to succeed.
  77          */
  78         void (*close)(struct writer_node *);
  79         /**
  80          * Shutdown the writer
  81          *
  82          * This is a optional function pointer used for cleaning up.
  83          */
  84         void (*shutdown)(struct writer_node *);
  85         struct ggo_help help;
  86 };
  87
  88 /**
  89  * Describes a set of writer nodes that all write the same stream.
  90  */
  91 struct writer_node_group {
  92         /** Number of nodes belonging to this group. */
  93         unsigned num_writers;
  94         /** Array of pointers to the corresponding writer nodes. */
  95         struct writer_node *writer_nodes;
  96         /** Non-zero if an error or end of file was encountered by the feeding task. */
  97         int *input_error;
  98         /** Current output buffer. */
  99         char **bufp;
 100         /** Number of bytes loaded in the output buffer. */
 101         size_t *loaded;
 102         /** Number of audio channels of the current stream. */
 103         unsigned int *channels;
 104         /** Sample rate of the current stream. */
 105         unsigned int *samplerate;
 106         /** The task associated to this group. */
 107         struct task task;
 108         /** Whether the group is open, i.e. wng_open() was called. */
 109         int open;
 110         /** Max number of bytes written in the previous post_select() call. */
 111         int last_written;
 112 };
 113
 114 /** Loop over each writer node in a writer group. */
 115 #define FOR_EACH_WRITER_NODE(i, wng) for (i = 0; i < (wng)->num_writers; i++)
 116 /** Loop over each supported writer. */
 117 #define FOR_EACH_WRITER(i) for (i = 0; i < NUM_SUPPORTED_WRITERS; i++)
 118
 119 /** Declare the init functions of all supported writers. */
 120 DECLARE_WRITER_INITS;
 121
 122 /** Array containing the name of each writer. */
 123 extern const char *writer_names[];
 124
 125 /** The writer structure for each supported writer. */
 126 extern struct writer writers[NUM_SUPPORTED_WRITERS];