Mercurial > audio-send

     1 /**

     2  * OpenAL cross platform audio library

     3  * Copyright (C) 1999-2007 by authors.

     4  * This library is free software; you can redistribute it and/or

     5  *  modify it under the terms of the GNU Library General Public

     6  *  License as published by the Free Software Foundation; either

     7  *  version 2 of the License, or (at your option) any later version.

     8  *

     9  * This library 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 GNU

    12  *  Library General Public License for more details.

    13  *

    14  * You should have received a copy of the GNU Library General Public

    15  *  License along with this library; if not, write to the

    16  *  Free Software Foundation, Inc., 59 Temple Place - Suite 330,

    17  *  Boston, MA  02111-1307, USA.

    18  * Or go to http://www.gnu.org/copyleft/lgpl.html

    19  */

    20 

    21 #include "config.h"

    22 

    23 #include <string.h>

    24 #include <stdlib.h>

    25 

    26 #include "alMain.h"

    27 

    28 

    29 struct RingBuffer {

    30     ALubyte *mem;

    31 

    32     ALsizei frame_size;

    33     ALsizei length;

    34     ALint read_pos;

    35     ALint write_pos;

    36 

    37     CRITICAL_SECTION cs;

    38 };

    39 

    40 

    41 RingBuffer *CreateRingBuffer(ALsizei frame_size, ALsizei length)

    42 {

    43     RingBuffer *ring = calloc(1, sizeof(*ring) + ((length+1) * frame_size));

    44     if(ring)

    45     {

    46         ring->mem = (ALubyte*)(ring+1);

    47 

    48         ring->frame_size = frame_size;

    49         ring->length = length+1;

    50         ring->read_pos = 0;

    51         ring->write_pos = 0;

    52 

    53         InitializeCriticalSection(&ring->cs);

    54     }

    55     return ring;

    56 }

    57 

    58 void DestroyRingBuffer(RingBuffer *ring)

    59 {

    60     if(ring)

    61     {

    62         DeleteCriticalSection(&ring->cs);

    63         free(ring);

    64     }

    65 }

    66 

    67 ALsizei RingBufferSize(RingBuffer *ring)

    68 {

    69     ALsizei s;

    70 

    71     EnterCriticalSection(&ring->cs);

    72     s = (ring->write_pos-ring->read_pos+ring->length) % ring->length;

    73     LeaveCriticalSection(&ring->cs);

    74 

    75     return s;

    76 }

    77 

    78 void WriteRingBuffer(RingBuffer *ring, const ALubyte *data, ALsizei len)

    79 {

    80     int remain;

    81 

    82     EnterCriticalSection(&ring->cs);

    83 

    84     remain = (ring->read_pos-ring->write_pos-1+ring->length) % ring->length;

    85     if(remain < len) len = remain;

    86 

    87     if(len > 0)

    88     {

    89         remain = ring->length - ring->write_pos;

    90         if(remain < len)

    91         {

    92             memcpy(ring->mem+(ring->write_pos*ring->frame_size), data,

    93                    remain*ring->frame_size);

    94             memcpy(ring->mem, data+(remain*ring->frame_size),

    95                    (len-remain)*ring->frame_size);

    96         }

    97         else

    98             memcpy(ring->mem+(ring->write_pos*ring->frame_size), data,

    99                    len*ring->frame_size);

   100 

   101         ring->write_pos += len;

   102         ring->write_pos %= ring->length;

   103     }

   104 

   105     LeaveCriticalSection(&ring->cs);

   106 }

   107 

   108 void ReadRingBuffer(RingBuffer *ring, ALubyte *data, ALsizei len)

   109 {

   110     int remain;

   111 

   112     EnterCriticalSection(&ring->cs);

   113 

   114     remain = ring->length - ring->read_pos;

   115     if(remain < len)

   116     {

   117         memcpy(data, ring->mem+(ring->read_pos*ring->frame_size), remain*ring->frame_size);

   118         memcpy(data+(remain*ring->frame_size), ring->mem, (len-remain)*ring->frame_size);

   119     }

   120     else

   121         memcpy(data, ring->mem+(ring->read_pos*ring->frame_size), len*ring->frame_size);

   122 

   123     ring->read_pos += len;

   124     ring->read_pos %= ring->length;

   125 

   126     LeaveCriticalSection(&ring->cs);

   127 }
author	Robert McIntyre <rlm@mit.edu>
date	Fri, 18 Nov 2011 16:05:47 -0700
parents	f9476ff7637e
children