Alc/null.c

   1 /**
   2  * OpenAL cross platform audio library
   3  * Copyright (C) 2010 by Chris Robinson
   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 <stdlib.h>
  24 #include "alMain.h"
  25 #include "AL/al.h"
  26 #include "AL/alc.h"
  27
  28
  29 typedef struct {
  30     ALvoid *buffer;
  31     ALuint size;
  32
  33     volatile int killNow;
  34     ALvoid *thread;
  35 } null_data;
  36
  37
  38 static const ALCchar nullDevice[] = "No Output";
  39
  40 static ALuint NullProc(ALvoid *ptr)
  41 {
  42     ALCdevice *Device = (ALCdevice*)ptr;
  43     null_data *data = (null_data*)Device->ExtraData;
  44     ALuint now, start;
  45     ALuint64 avail, done;
  46     const ALuint restTime = (ALuint64)Device->UpdateSize * 1000 /
  47                             Device->Frequency / 2;
  48
  49     done = 0;
  50     start = timeGetTime();
  51     while(!data->killNow && Device->Connected)
  52     {
  53         now = timeGetTime();
  54
  55         avail = (ALuint64)(now-start) * Device->Frequency / 1000;
  56         if(avail < done)
  57         {
  58             /* Timer wrapped. Add the remainder of the cycle to the available
  59              * count and reset the number of samples done */
  60             avail += 0xFFFFFFFFu*Device->Frequency/1000 - done;
  61             done = 0;
  62         }
  63         if(avail-done < Device->UpdateSize)
  64         {
  65             Sleep(restTime);
  66             continue;
  67         }
  68
  69         while(avail-done >= Device->UpdateSize)
  70         {
  71             aluMixData(Device, data->buffer, Device->UpdateSize);
  72             done += Device->UpdateSize;
  73         }
  74     }
  75
  76     return 0;
  77 }
  78
  79 static ALCboolean null_open_playback(ALCdevice *device, const ALCchar *deviceName)
  80 {
  81     null_data *data;
  82
  83     if(!deviceName)
  84         deviceName = nullDevice;
  85     else if(strcmp(deviceName, nullDevice) != 0)
  86         return ALC_FALSE;
  87
  88     data = (null_data*)calloc(1, sizeof(*data));
  89
  90     device->szDeviceName = strdup(deviceName);
  91     device->ExtraData = data;
  92     return ALC_TRUE;
  93 }
  94
  95 static void null_close_playback(ALCdevice *device)
  96 {
  97     null_data *data = (null_data*)device->ExtraData;
  98
  99     free(data);
 100     device->ExtraData = NULL;
 101 }
 102
 103 static ALCboolean null_reset_playback(ALCdevice *device)
 104 {
 105     null_data *data = (null_data*)device->ExtraData;
 106
 107     data->size = device->UpdateSize * aluFrameSizeFromFormat(device->Format);
 108     data->buffer = malloc(data->size);
 109     if(!data->buffer)
 110     {
 111         AL_PRINT("buffer malloc failed\n");
 112         return ALC_FALSE;
 113     }
 114     SetDefaultWFXChannelOrder(device);
 115
 116     data->thread = StartThread(NullProc, device);
 117     if(data->thread == NULL)
 118     {
 119         free(data->buffer);
 120         data->buffer = NULL;
 121         return ALC_FALSE;
 122     }
 123
 124     return ALC_TRUE;
 125 }
 126
 127 static void null_stop_playback(ALCdevice *device)
 128 {
 129     null_data *data = (null_data*)device->ExtraData;
 130
 131     if(!data->thread)
 132         return;
 133
 134     data->killNow = 1;
 135     StopThread(data->thread);
 136     data->thread = NULL;
 137
 138     data->killNow = 0;
 139
 140     free(data->buffer);
 141     data->buffer = NULL;
 142 }
 143
 144
 145 static ALCboolean null_open_capture(ALCdevice *device, const ALCchar *deviceName)
 146 {
 147     (void)device;
 148     (void)deviceName;
 149     return ALC_FALSE;
 150 }
 151
 152
 153 BackendFuncs null_funcs = {
 154     null_open_playback,
 155     null_close_playback,
 156     null_reset_playback,
 157     null_stop_playback,
 158     null_open_capture,
 159     NULL,
 160     NULL,
 161     NULL,
 162     NULL,
 163     NULL
 164 };
 165
 166 void alc_null_init(BackendFuncs *func_list)
 167 {
 168     *func_list = null_funcs;
 169 }
 170
 171 void alc_null_deinit(void)
 172 {
 173 }
 174
 175 void alc_null_probe(int type)
 176 {
 177     if(type == DEVICE_PROBE)
 178         AppendDeviceList(nullDevice);
 179     else if(type == ALL_DEVICE_PROBE)
 180         AppendAllDeviceList(nullDevice);
 181 }