juce/source/src/audio/audio_file_formats/flac/callback.h

   1 /* libFLAC - Free Lossless Audio Codec library
   2  * Copyright (C) 2004,2005,2006,2007  Josh Coalson
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  *
   8  * - Redistributions of source code must retain the above copyright
   9  * notice, this list of conditions and the following disclaimer.
  10  *
  11  * - Redistributions in binary form must reproduce the above copyright
  12  * notice, this list of conditions and the following disclaimer in the
  13  * documentation and/or other materials provided with the distribution.
  14  *
  15  * - Neither the name of the Xiph.org Foundation nor the names of its
  16  * contributors may be used to endorse or promote products derived from
  17  * this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  21  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  22  * A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR
  23  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  24  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  25  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  26  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  27  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  28  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  29  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #ifndef FLAC__CALLBACK_H
  33 #define FLAC__CALLBACK_H
  34
  35 #include "ordinals.h"
  36 #include <stdlib.h> /* for size_t */
  37
  38 /** \file include/FLAC/callback.h
  39  *
  40  *  \brief
  41  *  This module defines the structures for describing I/O callbacks
  42  *  to the other FLAC interfaces.
  43  *
  44  *  See the detailed documentation for callbacks in the
  45  *  \link flac_callbacks callbacks \endlink module.
  46  */
  47
  48 /** \defgroup flac_callbacks FLAC/callback.h: I/O callback structures
  49  *  \ingroup flac
  50  *
  51  *  \brief
  52  *  This module defines the structures for describing I/O callbacks
  53  *  to the other FLAC interfaces.
  54  *
  55  *  The purpose of the I/O callback functions is to create a common way
  56  *  for the metadata interfaces to handle I/O.
  57  *
  58  *  Originally the metadata interfaces required filenames as the way of
  59  *  specifying FLAC files to operate on.  This is problematic in some
  60  *  environments so there is an additional option to specify a set of
  61  *  callbacks for doing I/O on the FLAC file, instead of the filename.
  62  *
  63  *  In addition to the callbacks, a FLAC__IOHandle type is defined as an
  64  *  opaque structure for a data source.
  65  *
  66  *  The callback function prototypes are similar (but not identical) to the
  67  *  stdio functions fread, fwrite, fseek, ftell, feof, and fclose.  If you use
  68  *  stdio streams to implement the callbacks, you can pass fread, fwrite, and
  69  *  fclose anywhere a FLAC__IOCallback_Read, FLAC__IOCallback_Write, or
  70  *  FLAC__IOCallback_Close is required, and a FILE* anywhere a FLAC__IOHandle
  71  *  is required.  \warning You generally CANNOT directly use fseek or ftell
  72  *  for FLAC__IOCallback_Seek or FLAC__IOCallback_Tell since on most systems
  73  *  these use 32-bit offsets and FLAC requires 64-bit offsets to deal with
  74  *  large files.  You will have to find an equivalent function (e.g. ftello),
  75  *  or write a wrapper.  The same is true for feof() since this is usually
  76  *  implemented as a macro, not as a function whose address can be taken.
  77  *
  78  * \{
  79  */
  80
  81 #ifdef __cplusplus
  82 extern "C" {
  83 #endif
  84
  85 /** This is the opaque handle type used by the callbacks.  Typically
  86  *  this is a \c FILE* or address of a file descriptor.
  87  */
  88 typedef void* FLAC__IOHandle;
  89
  90 /** Signature for the read callback.
  91  *  The signature and semantics match POSIX fread() implementations
  92  *  and can generally be used interchangeably.
  93  *
  94  * \param  ptr      The address of the read buffer.
  95  * \param  size     The size of the records to be read.
  96  * \param  nmemb    The number of records to be read.
  97  * \param  handle   The handle to the data source.
  98  * \retval size_t
  99  *    The number of records read.
 100  */
 101 typedef size_t (*FLAC__IOCallback_Read) (void *ptr, size_t size, size_t nmemb, FLAC__IOHandle handle);
 102
 103 /** Signature for the write callback.
 104  *  The signature and semantics match POSIX fwrite() implementations
 105  *  and can generally be used interchangeably.
 106  *
 107  * \param  ptr      The address of the write buffer.
 108  * \param  size     The size of the records to be written.
 109  * \param  nmemb    The number of records to be written.
 110  * \param  handle   The handle to the data source.
 111  * \retval size_t
 112  *    The number of records written.
 113  */
 114 typedef size_t (*FLAC__IOCallback_Write) (const void *ptr, size_t size, size_t nmemb, FLAC__IOHandle handle);
 115
 116 /** Signature for the seek callback.
 117  *  The signature and semantics mostly match POSIX fseek() WITH ONE IMPORTANT
 118  *  EXCEPTION: the offset is a 64-bit type whereas fseek() is generally 'long'
 119  *  and 32-bits wide.
 120  *
 121  * \param  handle   The handle to the data source.
 122  * \param  offset   The new position, relative to \a whence
 123  * \param  whence   \c SEEK_SET, \c SEEK_CUR, or \c SEEK_END
 124  * \retval int
 125  *    \c 0 on success, \c -1 on error.
 126  */
 127 typedef int (*FLAC__IOCallback_Seek) (FLAC__IOHandle handle, FLAC__int64 offset, int whence);
 128
 129 /** Signature for the tell callback.
 130  *  The signature and semantics mostly match POSIX ftell() WITH ONE IMPORTANT
 131  *  EXCEPTION: the offset is a 64-bit type whereas ftell() is generally 'long'
 132  *  and 32-bits wide.
 133  *
 134  * \param  handle   The handle to the data source.
 135  * \retval FLAC__int64
 136  *    The current position on success, \c -1 on error.
 137  */
 138 typedef FLAC__int64 (*FLAC__IOCallback_Tell) (FLAC__IOHandle handle);
 139
 140 /** Signature for the EOF callback.
 141  *  The signature and semantics mostly match POSIX feof() but WATCHOUT:
 142  *  on many systems, feof() is a macro, so in this case a wrapper function
 143  *  must be provided instead.
 144  *
 145  * \param  handle   The handle to the data source.
 146  * \retval int
 147  *    \c 0 if not at end of file, nonzero if at end of file.
 148  */
 149 typedef int (*FLAC__IOCallback_Eof) (FLAC__IOHandle handle);
 150
 151 /** Signature for the close callback.
 152  *  The signature and semantics match POSIX fclose() implementations
 153  *  and can generally be used interchangeably.
 154  *
 155  * \param  handle   The handle to the data source.
 156  * \retval int
 157  *    \c 0 on success, \c EOF on error.
 158  */
 159 typedef int (*FLAC__IOCallback_Close) (FLAC__IOHandle handle);
 160
 161 /** A structure for holding a set of callbacks.
 162  *  Each FLAC interface that requires a FLAC__IOCallbacks structure will
 163  *  describe which of the callbacks are required.  The ones that are not
 164  *  required may be set to NULL.
 165  *
 166  *  If the seek requirement for an interface is optional, you can signify that
 167  *  a data sorce is not seekable by setting the \a seek field to \c NULL.
 168  */
 169 typedef struct {
 170         FLAC__IOCallback_Read read;
 171         FLAC__IOCallback_Write write;
 172         FLAC__IOCallback_Seek seek;
 173         FLAC__IOCallback_Tell tell;
 174         FLAC__IOCallback_Eof eof;
 175         FLAC__IOCallback_Close close;
 176 } FLAC__IOCallbacks;
 177
 178 /* \} */
 179
 180 #ifdef __cplusplus
 181 }
 182 #endif
 183
 184 #endif