write.h

   1 /*
   2  * Copyright (C) 2006 Andre Noll <maan@systemlinux.org>
   3  *
   4  *     This program is free software; you can redistribute it and/or modify
   5  *     it under the terms of the GNU General Public License as published by
   6  *     the Free Software Foundation; either version 2 of the License, or
   7  *     (at your option) any later version.
   8  *
   9  *     This program is distributed in the hope that it will be useful,
  10  *     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *     GNU General Public License for more details.
  13  *
  14  *     You should have received a copy of the GNU General Public License
  15  *     along with this program; if not, write to the Free Software
  16  *     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA.
  17  */
  18
  19 /** \file write.h writer-related structures */
  20
  21 /** the list of supported writers */
  22 enum writer_enum {WRITER_ENUM};
  23
  24 /**
  25  * decbribes one running instance of a writer
  26  */
  27 struct writer_node {
  28 /** points to the writer structure associated with this node */
  29         struct writer *writer;
  30 /** writer-specific data */
  31         void *private_data;
  32 /** send that many bytes in one go */
  33         int chunk_bytes;
  34         struct task task;
  35         struct writer_node_group *wng;
  36 };
  37
  38 /** describes one supported writer */
  39 struct writer {
  40 /**
  41  * the init function of the writer
  42  *
  43  * It must fill in all other function pointers of the given
  44  * writer structure.
  45  *
  46  */
  47 void (*init)(struct writer *w);
  48 /**
  49  *
  50  * open one instance of this writer
  51  *
  52  * This function should perform any work necessary to write the incoming
  53  * stream. If To this aim, it may allocate its private data structure and store
  54  * a pointer to that structure via the given writer_node paramenter.
  55  */
  56 int (*open)(struct writer_node *);
  57 /**
  58  *
  59  * write a chunk of audio data
  60  *
  61  * This is called from the driving application whenever a data block of \a
  62  * chunk_bytes is available. It must return the number of bytes consumed from
  63  * \a data on success, and negative on errors.
  64  *
  65  */
  66 int (*write)(char *data, size_t nbytes, struct writer_node *);
  67 void (*pre_select)(struct sched *s, struct task *t);
  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
  79  * up.
  80  */
  81 void (*shutdown)(struct writer_node *);
  82 };
  83
  84 /**
  85  * describes a set of writer nodes that all write the same stream.
  86  */
  87 struct writer_node_group {
  88 /** number of nodes belonging to this group */
  89 unsigned num_writers;
  90 /** array of pointers to the corresponding writer nodes */
  91 struct writer_node *writer_nodes;
  92 /** keeps track of how many bytes have been written by each node */
  93 int *written;
  94 /** the maximum of the chunk_bytes values of the writer nodes in this group */
  95 size_t max_chunk_bytes;
  96 /** non-zero if end of file was encountered */
  97 int *eof;
  98 char *buf;
  99 size_t *loaded;
 100 struct task task;
 101 };
 102
 103 /** loop over each writer node in a writer group */
 104 #define FOR_EACH_WRITER_NODE(i, wng) for (i = 0; i < (wng)->num_writers; i++)
 105 /** loop over each supported writer */
 106 #define FOR_EACH_WRITER(i) for (i = 0; i < NUM_SUPPORTED_WRITERS; i++)
 107
 108 /** declare the init functions of all supported writers */
 109 DECLARE_WRITER_INITS;
 110
 111 /** array containing the name of each writer */
 112 extern const char *writer_names[];
 113
 114 /** the writer structure for each supported writer */
 115 extern struct writer writers[NUM_SUPPORTED_WRITERS];