out_oss.c

   1 /*
   2
   3     Ann Hell Ex Machina - Music Software
   4     Copyright (C) 2003/2004 Angel Ortega <angel@triptico.com>
   5
   6     out_oss.c - Output driver for Linux Open Sound System
   7
   8     This program is free software; you can redistribute it and/or
   9     modify it under the terms of the GNU General Public License
  10     as published by the Free Software Foundation; either version 2
  11     of the License, or (at your option) any later version.
  12
  13     This program is distributed in the hope that it will be useful,
  14     but WITHOUT ANY WARRANTY; without even the implied warranty of
  15     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16     GNU General Public License for more details.
  17
  18     You should have received a copy of the GNU General Public License
  19     along with this program; if not, write to the Free Software
  20     Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  21
  22     http://www.triptico.com
  23
  24 */
  25
  26 #include "config.h"
  27 #include <stdio.h>
  28 #include "output.h"
  29
  30 #ifdef CONFOPT_LINUX_OSS
  31
  32 #include <string.h>
  33 #include <stdlib.h>
  34 #include <fcntl.h>
  35 #include <sys/ioctl.h>
  36 #include <sys/types.h>
  37 #include <unistd.h>
  38 #include <errno.h>
  39 #include <signal.h>
  40
  41 #include <linux/soundcard.h>
  42
  43 #include "core.h"
  44
  45
  46 /*******************
  47         Data
  48 ********************/
  49
  50 static int _audio_fd=-1;
  51
  52 #define OSS_BUFFER_BITS 10
  53 #define OSS_BUFFER_SIZE (1<<OSS_BUFFER_BITS)
  54
  55
  56 /*******************
  57         Code
  58 ********************/
  59
  60 static int detect_endianess(void)
  61 /* is this machine big or little endian? */
  62 {
  63         short s;
  64         unsigned char * c;
  65
  66         s=1;
  67         c=(unsigned char *) &s;
  68
  69         if(*c==1) return(AFMT_S16_LE);
  70         return(AFMT_S16_BE);
  71 }
  72
  73
  74 static int _out_open_oss(char * devfile)
  75 {
  76         int n;
  77
  78         /* OSS does not support more than stereo output */
  79         if(_n_channels > 2)
  80                 _n_channels=2;
  81
  82         if((_audio_fd=open(devfile, O_WRONLY))==-1)
  83                 return(-100);
  84
  85         n=(2<<16)|OSS_BUFFER_BITS;
  86         if(ioctl(_audio_fd, SNDCTL_DSP_SETFRAGMENT, &n)==-1)
  87                 return(-101);
  88
  89         if(ioctl(_audio_fd, SNDCTL_DSP_RESET, 0)==-1)
  90                 return(-102);
  91
  92         if(ioctl(_audio_fd, SNDCTL_DSP_SPEED, &_frequency)==-1)
  93                 return(-103);
  94
  95         n=_n_channels == 2 ? 1 : 0;
  96         if(ioctl(_audio_fd, SNDCTL_DSP_STEREO, &n)==-1)
  97                 return(-104);
  98
  99         n=detect_endianess();
 100         if(ioctl(_audio_fd, SNDCTL_DSP_SETFMT, &n)==-1)
 101         {
 102                 /* do I really want 8 bit output? */
 103                 n=AFMT_U8;
 104                 if(ioctl(_audio_fd, SNDCTL_DSP_SETFMT, &n)==-1)
 105                         return(-105);
 106         }
 107
 108         return(OSS_BUFFER_SIZE);
 109 }
 110
 111
 112 static int _out_write_oss(short int * buffer, int size)
 113 {
 114         return(write(_audio_fd, buffer, size * sizeof(short int)));
 115 }
 116
 117
 118 static int _out_close_oss(void)
 119 {
 120         close(_audio_fd);
 121         return(0);
 122 }
 123
 124
 125 /* driver */
 126
 127 struct _output_driver _out_driver_oss=
 128 { "oss", "/dev/dsp", _out_open_oss, _out_write_oss, _out_close_oss };
 129
 130 #else /* CONFOPT_LINUX_OSS */
 131
 132 struct _output_driver _out_driver_oss=
 133 { "oss", NULL, NULL, NULL, NULL };
 134
 135 #endif /* #ifdef CONFOPT_LINUX_OSS */