out_oss.c

   1 /*
   2
   3     Ann Hell Ex Machina - Music Software
   4     Copyright (C) 2003/2005 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 "ss_core.h"
  29 #include "ss_output.h"
  30
  31 #ifdef CONFOPT_LINUX_OSS
  32
  33 #include <string.h>
  34 #include <stdlib.h>
  35 #include <fcntl.h>
  36 #include <sys/ioctl.h>
  37 #include <sys/types.h>
  38 #include <unistd.h>
  39 #include <errno.h>
  40 #include <signal.h>
  41
  42 #include <linux/soundcard.h>
  43
  44 /*******************
  45         Data
  46 ********************/
  47
  48 static int _audio_fd=-1;
  49
  50 #define OSS_BUFFER_BITS 10
  51 #define OSS_BUFFER_SIZE (1<<OSS_BUFFER_BITS)
  52
  53
  54 /*******************
  55         Code
  56 ********************/
  57
  58 static int detect_endianess(void)
  59 /* is this machine big or little endian? */
  60 {
  61         short s;
  62         unsigned char * c;
  63
  64         s=1;
  65         c=(unsigned char *) &s;
  66
  67         if(*c==1) return(AFMT_S16_LE);
  68         return(AFMT_S16_BE);
  69 }
  70
  71
  72 static int _out_open_oss(char * devfile)
  73 {
  74         int n;
  75
  76         /* OSS does not support more than stereo output */
  77         if(ss_nchannels > 2)
  78                 ss_nchannels=2;
  79
  80         if((_audio_fd=open(devfile, O_WRONLY))==-1)
  81                 return(-100);
  82
  83         n=(2<<16)|OSS_BUFFER_BITS;
  84         if(ioctl(_audio_fd, SNDCTL_DSP_SETFRAGMENT, &n)==-1)
  85                 return(-101);
  86
  87         if(ioctl(_audio_fd, SNDCTL_DSP_RESET, 0)==-1)
  88                 return(-102);
  89
  90         if(ioctl(_audio_fd, SNDCTL_DSP_SPEED, &ss_frequency)==-1)
  91                 return(-103);
  92
  93         n=ss_nchannels == 2 ? 1 : 0;
  94         if(ioctl(_audio_fd, SNDCTL_DSP_STEREO, &n)==-1)
  95                 return(-104);
  96
  97         n=detect_endianess();
  98         if(ioctl(_audio_fd, SNDCTL_DSP_SETFMT, &n)==-1)
  99         {
 100                 /* do I really want 8 bit output? */
 101                 n=AFMT_U8;
 102                 if(ioctl(_audio_fd, SNDCTL_DSP_SETFMT, &n)==-1)
 103                         return(-105);
 104         }
 105
 106         return(OSS_BUFFER_SIZE);
 107 }
 108
 109
 110 static int _out_write_oss(short int * buffer, int size)
 111 {
 112         return(write(_audio_fd, buffer, size * sizeof(short int)));
 113 }
 114
 115
 116 static int _out_close_oss(void)
 117 {
 118         close(_audio_fd);
 119         return(0);
 120 }
 121
 122
 123 /* driver */
 124
 125 struct _output_driver _out_driver_oss=
 126 { "oss", "/dev/dsp", _out_open_oss, _out_write_oss, _out_close_oss };
 127
 128 #else /* CONFOPT_LINUX_OSS */
 129
 130 struct _output_driver _out_driver_oss=
 131 { "oss", NULL, NULL, NULL, NULL };
 132
 133 #endif /* #ifdef CONFOPT_LINUX_OSS */