apps/buffering.h

   1 /***************************************************************************
   2  *             __________               __   ___.
   3  *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
   4  *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
   5  *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
   6  *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
   7  *                     \/            \/     \/    \/            \/
   8  * $Id$
   9  *
  10  * Copyright (C) 2007 Nicolas Pennequin
  11  *
  12  * This program is free software; you can redistribute it and/or
  13  * modify it under the terms of the GNU General Public License
  14  * as published by the Free Software Foundation; either version 2
  15  * of the License, or (at your option) any later version.
  16  *
  17  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
  18  * KIND, either express or implied.
  19  *
  20  ****************************************************************************/
  21
  22 #ifndef _BUFFERING_H_
  23 #define _BUFFERING_H_
  24
  25 #include <sys/types.h>
  26 #include <stdbool.h>
  27 #include "events.h"
  28
  29
  30 enum data_type {
  31     TYPE_CODEC,
  32     TYPE_PACKET_AUDIO,
  33     TYPE_ATOMIC_AUDIO,
  34     TYPE_ID3,
  35     TYPE_CUESHEET,
  36     TYPE_BITMAP,
  37     TYPE_BUFFER,
  38     TYPE_UNKNOWN,
  39 };
  40
  41 enum callback_event {
  42     EVENT_BUFFER_LOW = (EVENT_CLASS_BUFFERING|1),
  43     EVENT_HANDLE_REBUFFER,
  44     EVENT_HANDLE_CLOSED,
  45     EVENT_HANDLE_MOVED,
  46     EVENT_HANDLE_FINISHED,
  47 };
  48
  49 /* Error return values */
  50 #define ERR_HANDLE_NOT_FOUND    -1
  51 #define ERR_BUFFER_FULL         -2
  52 #define ERR_INVALID_VALUE       -3
  53 #define ERR_FILE_ERROR          -4
  54 #define ERR_HANDLE_NOT_DONE     -5
  55
  56
  57 /* Initialise the buffering subsystem */
  58 void buffering_init(void);
  59
  60 /* Reset the buffering system */
  61 bool buffering_reset(char *buf, size_t buflen);
  62
  63
  64 /***************************************************************************
  65  * MAIN BUFFERING API CALLS
  66  * ========================
  67  *
  68  * bufopen   : Reserve space in the buffer for a given file
  69  * bufalloc  : Open a new handle from data that needs to be copied from memory
  70  * bufclose  : Close an open handle
  71  * bufseek   : Set handle reading index, relatively to the start of the file
  72  * bufadvance: Move handle reading index, relatively to current position
  73  * bufread   : Copy data from a handle to a buffer
  74  * bufgetdata: Obtain a pointer for linear access to a "size" amount of data
  75  * bufgettail: Out-of-band get the last size bytes of a handle.
  76  * bufcuttail: Out-of-band remove the trailing 'size' bytes of a handle.
  77  *
  78  * NOTE: bufread and bufgetdata will block the caller until the requested
  79  * amount of data is ready (unless EOF is reached).
  80  * NOTE: Tail operations are only legal when the end of the file is buffered.
  81  ****************************************************************************/
  82
  83 #define BUF_MAX_HANDLES         256
  84
  85 int bufopen(const char *file, size_t offset, enum data_type type);
  86 int bufalloc(const void *src, size_t size, enum data_type type);
  87 bool bufclose(int handle_id);
  88 int bufseek(int handle_id, size_t newpos);
  89 int bufadvance(int handle_id, off_t offset);
  90 ssize_t bufread(int handle_id, size_t size, void *dest);
  91 ssize_t bufgetdata(int handle_id, size_t size, void **data);
  92 ssize_t bufgettail(int handle_id, size_t size, void **data);
  93 ssize_t bufcuttail(int handle_id, size_t size);
  94
  95
  96 /***************************************************************************
  97  * SECONDARY FUNCTIONS
  98  * ===================
  99  *
 100  * buf_get_offset: Get a handle offset from a pointer
 101  * buf_handle_offset: Get the offset of the first buffered byte from the file
 102  * buf_request_buffer_handle: Request buffering of a handle
 103  * buf_set_base_handle: Tell the buffering thread which handle is currently read
 104  * buf_used: Total amount of buffer space used (including allocated space)
 105  ****************************************************************************/
 106
 107 ssize_t buf_get_offset(int handle_id, void *ptr);
 108 ssize_t buf_handle_offset(int handle_id);
 109 void buf_request_buffer_handle(int handle_id);
 110 void buf_set_base_handle(int handle_id);
 111 size_t buf_used(void);
 112
 113
 114
 115 /* Settings */
 116 enum {
 117     BUFFERING_SET_WATERMARK = 1,
 118     BUFFERING_SET_CHUNKSIZE,
 119 };
 120 void buf_set_watermark(size_t bytes);
 121
 122
 123 /* Debugging */
 124 struct buffering_debug {
 125     int num_handles;
 126     size_t buffered_data;
 127     size_t wasted_space;
 128     size_t data_rem;
 129     size_t useful_data;
 130 };
 131 void buffering_get_debugdata(struct buffering_debug *dbgdata);
 132
 133 #endif