source: downloads/openal-0.0.8/src/backends/alc_backend_linux.c @ 17

/* -*- mode: C; tab-width:8; c-basic-offset:8 -*-
 * vi:set ts=8:
 *
 * lin_dsp.c
 *
 * functions related to the aquisition and management of /dev/dsp under
 * linux.
 *
 */
#include "al_siteconfig.h"

#include <AL/al.h>
#include <AL/alext.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/soundcard.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>

#include "al_config.h"
#include "al_main.h"
#include "al_debug.h"
#include "alc/alc_context.h"
#include "backends/alc_backend.h"

#ifdef WORDS_BIGENDIAN
#define AFMT_S16 AFMT_S16_BE
#else
#define AFMT_S16 AFMT_S16_LE
#endif /* WORDS_BIGENDIAN */

/*
 * DONTCARE was (1 << 16), but that breaks 4Front's commercial drivers.
 *  According to their reference manual, it musts be (2 << 16) or higher
 *  or it is ignored, which is not good. Thanks to 4Front for tracking this
 *  down.   --ryan.
 */
#define DONTCARE ( 8 << 16)

/* convert an alc channel to a linux dsp channel */
static int alcChannel_to_dsp_channel(ALCenum alcc);

/* /dev/dsp variables */
static fd_set dsp_fd_set;
static int mixer_fd    = -1; /* /dev/mixer file read/write descriptor */
static ALboolean use_select = AL_TRUE;

/* gets user prefered path */
static const char *lin_getwritepath(void);
static const char *lin_getreadpath(void);
static int aquire_read(void);
static int grab_mixerfd(void);
static int try_to_open(const char **paths, int n_paths, const char **used_path, int mode);

/* set the params associated with a file descriptor */
static int set_fd(int dsp_fd, ALboolean readable,
                              ALuint *bufsiz,
                              ALuint *fmt,
                              ALuint *speed,
                              ALuint *channels);


/* convert the format channel from /dev/dsp to openal format */
static int LIN2ALFMT(int fmt, int channels)
{
        switch(fmt)
        {
                case AFMT_U8:
                        switch(channels)
                        {
                                case 1: return AL_FORMAT_MONO8;
                                case 2: return AL_FORMAT_STEREO8;
                                case 4: return AL_FORMAT_QUAD8_LOKI;
                                default: return -1;
                        }
                case AFMT_S16:
                        switch(channels)
                        {
                                case 1: return AL_FORMAT_MONO16;
                                case 2: return AL_FORMAT_STEREO16;
                                case 4: return AL_FORMAT_QUAD16_LOKI;
                                default: return -1;
                        }
                default:
#ifdef DEBUG_MAXIMUS
                        fprintf(stderr, "unsupported dsp format\n");
#endif
                        return -1;
        }
}

/* convert the format channel from openal to /dev/dsp format */
static int AL2LINFMT(int fmt)
{
        switch(fmt) {
                case AL_FORMAT_MONO16:
                case AL_FORMAT_STEREO16:
                case AL_FORMAT_QUAD16_LOKI:
                        return AFMT_S16;
                        break;
                case AL_FORMAT_MONO8:
                case AL_FORMAT_STEREO8:
                case AL_FORMAT_QUAD8_LOKI:
                        return AFMT_U8;
                        break;
                default:
#ifdef DEBUG_MAXIMUS
                  fprintf(stderr, "unknown format 0x%x\n", fmt);
#endif
                  break;
        }

        return -1;
}


/*
 * Disable non-blocking on a file descriptor. Returns non-zero on
 *  success, zero on failure.  --ryan.
 */
static int toggle_nonblock(int fd, int state)
{
        int retval = 0;
        int flags = fcntl(fd, F_GETFL);
        if (flags != -1) {
                if (state) {
                        flags |= O_NONBLOCK;
                } else {
                        flags &= ~O_NONBLOCK;
                }

                if(fcntl(fd, F_SETFL, flags) != -1) {
                        retval = 1;
                }
        }

        if (!retval) {
                perror("fcntl");
        }

        return(retval);
}


/*
 *
 *  Format of divisor is bit field where:
 *
 *
 *         MSHW          LSHW
 *  [ some big value |     x  ]
 *
 *  where x is translated into 2^x, and used as the
 *  dma buffer size.
 *
 */
static void *grab_write_native(void)
{
        static int write_fd;
        Rcvar rc_use_select;
        const char *writepath = NULL;
        int divisor = DONTCARE | _alSpot( _ALC_DEF_BUFSIZ );
        const char *tried_paths[] = {
                "",
                "/dev/sound/dsp",
                "/dev/dsp"
        };
        tried_paths[0] = lin_getwritepath();
        write_fd = try_to_open(tried_paths, 3, &writepath, O_WRONLY | O_NONBLOCK);
        if(write_fd < 0) {
                perror("open /dev/[sound/]dsp");
                return NULL;
        }

        if(ioctl(write_fd, SNDCTL_DSP_SETFRAGMENT, &divisor) < 0) {
                perror("ioctl SETFRAGMENT grab");
        }

        toggle_nonblock(write_fd, 0);

        /* now get mixer_fd */
        mixer_fd = grab_mixerfd();

        /*
         * Some drivers, ie aurreal ones, don't implemented select.
         * I like to use select, as it ensures that we don't hang on
         * a bum write forever, but if you're in the unadmirable position
         * of having one of these cards I'm sure it's a small comfort.
         *
         * So, we have a special alrc var: native-use-select, that, if
         * set to #f, causes us to not do a select on the fd before
         * writing to it.
         */
        use_select = AL_TRUE;

        rc_use_select = rc_lookup("native-use-select");
        if(rc_use_select != NULL) {
                if(rc_type(rc_use_select) == ALRC_BOOL) {
                        use_select = rc_tobool(rc_use_select);
                }
        }

#ifdef DEBUG
        fprintf(stderr, "grab_native: (path %s fd %d)\n", writepath, write_fd);
#endif

        return &write_fd;
}

/*
 *
 *  Format of divisor is bit field where:
 *
 *
 *         MSHW          LSHW
 *  [ some big value |     x  ]
 *
 *  where x is translated into 2^x, and used as the
 *  dma buffer size.
 *
 */
static void *grab_read_native(void)
{
        static int read_fd;

        read_fd = aquire_read();
        if( read_fd < 0) {
                return NULL;
        }

        return &read_fd;
}

void *
alcBackendOpenNative_( ALC_OpenMode mode )
{
        return mode == ALC_OPEN_INPUT_ ? grab_read_native() : grab_write_native();
}

static int grab_mixerfd(void) {
        const char *tried_paths[] = {
                "/dev/sound/mixer",
                "/dev/mixer"
        };
        mixer_fd = try_to_open(tried_paths, 2, NULL, O_WRONLY | O_NONBLOCK);

        if(mixer_fd > 0) {
                toggle_nonblock(mixer_fd, 0);
                return mixer_fd;
        } else {
                perror("open /dev/[sound/]mixer");
        }

        return -1;
}

void release_native(void *handle) {
        int handle_fd;

        if(handle == NULL) {
                return;
        }

        handle_fd = *(int *) handle;

        if(ioctl(handle_fd, SNDCTL_DSP_RESET) < 0) {
#ifdef DEBUG
                fprintf(stderr, "Couldn't reset dsp\n");
#endif
        }

        ioctl(handle_fd, SNDCTL_DSP_SYNC, NULL);
        if((close(handle_fd) < 0) || (close(mixer_fd) < 0)) {
                return;
        }

        *(int *) handle = -1;
        mixer_fd        = -1;

        return;
}

ALfloat
get_nativechannel(UNUSED(void *handle), ALuint channel)
{
        int request = alcChannel_to_dsp_channel(channel);
        int retval;
        if(ioctl(mixer_fd, MIXER_READ(request), &retval) < 0) {
                return -1;
        }
        return (retval >> 8) / 100.0;
}


/*
 * Okay:
 *
 * Set audio channel expects an integer, in the range of
 * 0 - 100.  But wait!  It expects the integer to be
 * partitioned into a 16bit empty, L/R channel pair (high bits left,
 * low bits right), each 8 bit pair in the range 0 - 100.
 *
 * Kludgey, and obviously not the right way to do this
 */
int set_nativechannel(UNUSED(void *handle), ALuint channel, ALfloat volume) {
        int request = alcChannel_to_dsp_channel(channel);
        int unnormalizedvolume;

        unnormalizedvolume = volume * 100;
        unnormalizedvolume <<= 8;
        unnormalizedvolume += (volume * 100);

        if(ioctl(mixer_fd, MIXER_WRITE(request), &unnormalizedvolume) < 0) {
                return -1;
        }

        return 0;
}

/* convert the mixer channel from ALC to /dev/mixer format */
static int alcChannel_to_dsp_channel(ALCenum alcc) {
        switch(alcc) {
                case ALC_CHAN_MAIN_LOKI: return SOUND_MIXER_VOLUME;
                case ALC_CHAN_CD_LOKI:   return SOUND_MIXER_CD;
                case ALC_CHAN_PCM_LOKI:  return SOUND_MIXER_PCM;
                default: return -1;
        }
}

void pause_nativedevice(void *handle) {
        int fd;

        if(handle == NULL) {
                return;
        }

        fd = *(int *) handle;

        toggle_nonblock(fd, 1);

#if 0
        if(ioctl(fd, SNDCTL_DSP_POST, 0) == -1) {
                perror("ioctl");
        }
#endif

        return;
}

void resume_nativedevice(void *handle) {
        int fd;

        if(handle == NULL) {
                return;
        }

        fd = *(int *) handle;

        toggle_nonblock(fd, 0);

/*
        if(ioctl(fd, SNDCTL_DSP_SYNC, 0) == -1) {
                perror("ioctl");
        }
 */

        return;
}

static const char *lin_getwritepath(void) {
        Rcvar devdsp_path = rc_lookup("lin-dsp-path");
        static char retval[65]; /* FIXME */

        if(devdsp_path == NULL) {
                return NULL;
        }

        switch(rc_type(devdsp_path)) {
                case ALRC_STRING:
                        rc_tostr0(devdsp_path, retval, 64);
                        break;
                default:
                        return NULL;
        }

        return retval;
}

static const char *lin_getreadpath(void) {
        Rcvar devdsp_path = rc_lookup("lin-dsp-read-path");
        static char retval[65]; /* FIXME */

        if(devdsp_path == NULL) {
                /*
                 * no explicit read path?  try the default
                 * path.
                 */
                devdsp_path = rc_lookup("lin-dsp-path");
        }

        if(devdsp_path == NULL) {
                return NULL;
        }

        switch(rc_type(devdsp_path)) {
                case ALRC_STRING:
                        rc_tostr0(devdsp_path, retval, 64);
                        break;
                default:
                        return NULL;
        }


        /*
         * stupid.  /dev/dsp1 cannot be used for reading,
         * only /dev/dsp
         */
        if(retval[strlen(retval) - 1] == '1') {
                retval[strlen(retval) - 1] = '\0';
        }

        return retval;
}

/* capture data from the audio device */
ALsizei capture_nativedevice(void *handle,
                          void *capture_buffer,
                          int bufsiz) {
        int read_fd = *(int *)handle;
        int retval;

        retval = read(read_fd, capture_buffer, bufsiz);
        return retval > 0 ? retval : 0;
}

static int aquire_read(void) {
        int read_fd;
        const char *readpath = NULL;
        int divisor = _alSpot(_ALC_DEF_BUFSIZ) | (1<<16);
        const char *tried_paths[] = {
                "",
                "/dev/sound/dsp",
                "/dev/dsp"
        };
        tried_paths[0] = lin_getreadpath();
        read_fd = try_to_open(tried_paths, 3, &readpath, O_RDONLY | O_NONBLOCK);
        if(read_fd >= 0) {
#if 0 /* Reads should be non-blocking */
                toggle_nonblock(read_fd, 0);
#endif
                if(ioctl(read_fd, SNDCTL_DSP_SETFRAGMENT, &divisor) < 0) {
                        perror("ioctl SETFRAGMENT");
                }
        }

        return read_fd;
}

static ALboolean set_write_native(UNUSED(void *handle),
                                  ALuint *bufsiz,
                                  ALenum *fmt,
                                  ALuint *speed) {
        int write_fd = *(int *)handle;
        ALuint linformat;
        ALuint channels = _alGetChannelsFromFormat(*fmt);
        int err;

        if(write_fd < 0) {
                return AL_FALSE;
        }

        linformat = AL2LINFMT(*fmt);

        err = set_fd(write_fd, AL_FALSE, bufsiz, &linformat, speed, &channels);
        if(err < 0) {
#ifdef DEBUG
                fprintf(stderr, "Could not do write_fd\n");
#endif
                return AL_FALSE;
        }

        /* set format for caller */
        *fmt = LIN2ALFMT(linformat, channels);

        return AL_TRUE;
}

static ALboolean set_read_native(UNUSED(void *handle),
                                 ALuint *bufsiz,
                                 ALenum *fmt,
                                 ALuint *speed) {
        int read_fd = *(int *)handle;
        ALuint linformat;
        ALuint channels = 1;

        linformat = AL2LINFMT(*fmt);

        if(set_fd(read_fd, AL_TRUE, bufsiz, &linformat, speed, &channels) >= 0) {
                /* set format for caller */
                *fmt = LIN2ALFMT(linformat, channels);

                return AL_TRUE;
        }

        return AL_FALSE;
}

ALboolean
alcBackendSetAttributesNative_(ALC_OpenMode mode, void *handle, ALuint *bufsiz, ALenum *fmt, ALuint *speed)
{
        return mode == ALC_OPEN_INPUT_ ?
                set_read_native(handle, bufsiz, fmt, speed) :
                set_write_native(handle, bufsiz, fmt, speed);
}

void native_blitbuffer(void *handle, void *dataptr, int bytes_to_write) {
        struct timeval tv = { 0, 800000 }; /* at most .8 secs */
        int iterator = 0;
        int err;
        int fd;

        if(handle == NULL) {
                return;
        }

        fd = *(int *) handle;

        assert( fd >= 0 );

        for(iterator = bytes_to_write; iterator > 0; ) {
                FD_ZERO(&dsp_fd_set);
                FD_SET(fd, &dsp_fd_set);

                if(use_select == AL_TRUE) {
                        err = select(fd + 1, NULL, &dsp_fd_set, NULL, &tv);
                        if(FD_ISSET(fd, &dsp_fd_set) == 0) {
                                /*
                                 * error or timeout occured, don't try
                                 * and write.
                                 */
                                fprintf(stderr,
                                "native_blitbuffer: select error occured\n");
                                return;
                        }
                }

                assert(iterator > 0);
                assert(iterator <= bytes_to_write);

                err = write(fd,
                            (char *) dataptr + bytes_to_write - iterator,
                            iterator);

                if(err < 0) {
#ifdef DEBUG_MAXIMUS
                        fprintf( stderr, "write error: ( fd %d error %s )\n",
                                fd, strerror(err));
#endif
                        assert( 0 );
                        return;
                }

                iterator -= err;
        };

        return;
}

static int set_fd(int dsp_fd, ALboolean readable,
                     ALuint *bufsiz,
                     ALuint *fmt,
                     ALuint *speed,
                     ALuint *channels)
{
        struct audio_buf_info info;

        if(dsp_fd < 0) {
                return -1;
        }

#ifdef DEBUG
        fprintf( stderr, "set_fd in: bufsiz %d fmt 0x%x speed %d channels %d\n",
                 *bufsiz, *fmt, *speed, *channels );
#endif


#if 0 /* This code breaks 4Front's commercial drivers. Just say no. --ryan. */
{
        int divisor = DONTCARE | _alSpot( *bufsiz );
        if( ioctl(dsp_fd, SNDCTL_DSP_SETFRAGMENT, &divisor ) < 0) {
#ifdef DEBUG
                perror("ioctl SETFRAGMENT");
#endif
        }
}
#endif


        /* reset card defaults */
        if(ioctl(dsp_fd, SNDCTL_DSP_RESET, NULL) < 0) {
#ifdef DEBUG
                perror("set_devsp reset ioctl");
#endif
                return AL_FALSE;
        }

        if(ioctl(dsp_fd, SNDCTL_DSP_SETFMT, fmt) < 0) {
#ifdef DEBUG
                fprintf(stderr, "fmt %d\n", *fmt);
                perror("set_devsp format ioctl");
#endif
                return AL_FALSE;
        }

        if(ioctl(dsp_fd, SNDCTL_DSP_CHANNELS, channels)) {
#ifdef DEBUG
                fprintf(stderr, "channels %d\n", *channels);
                perror("set_devsp channels ioctl");
#endif
                return AL_FALSE;
        }

        if( readable == AL_TRUE ) {
                /*
                 * This is for reading.  Don't really use
                 * the speed argument.
                 */
                *speed = 16000;

                /* Try to set the speed (ignore value), then read it back */
                ioctl(dsp_fd, SNDCTL_DSP_SPEED, speed);
                if (ioctl(dsp_fd, SOUND_PCM_READ_RATE, speed) < 0) {
#ifdef DEBUG
                        char errbuf[256];

                        snprintf(errbuf, sizeof(errbuf), "(fd %d speed %d)", dsp_fd, *speed);

                        perror(errbuf);
                        return AL_FALSE;
#endif
                }
/*printf("Set recording rate: %d\n", *speed);*/

        } else {
                /* writable, set speed, otherwise no */
                if(ioctl(dsp_fd, SNDCTL_DSP_SPEED, speed) < 0) {
#ifdef DEBUG
                        char errbuf[256];

                        snprintf(errbuf, sizeof(errbuf), "(fd %d speed %d)", dsp_fd, *speed);

                        perror(errbuf);
                        return AL_FALSE;
#endif
                }

                if(ioctl(dsp_fd, SNDCTL_DSP_GETOSPACE, &info) < 0) {
#ifdef DEBUG
                        perror("ioctl SNDCTL_DSP_GETOSPACE");
#endif
                }

                /* set bufsiz correctly */

                *bufsiz = info.fragsize;

#ifdef DEBUG
                if( *bufsiz & (*bufsiz - 1) ) {
                        fprintf( stderr, "Non power-of-two bufsiz %d\n",
                                *bufsiz );
                }
#endif
        }

#ifdef DEBUG
        fprintf( stderr, "set_fd out: bufsiz %d fmt 0x%x speed %d channels %d\n",
                 *bufsiz, *fmt, *speed, *channels );
#endif

        return 0;
}

int try_to_open(const char **paths, int n_paths, const char **used_path, int mode)
{
        int i, fd = -1;
        for(i = 0; i != n_paths; ++i)
        {
                if(paths[i])
                {
                        if(used_path) *used_path = paths[i];
                        fd = open(paths[i], mode);
                        if(fd >= 0) return fd;
                }
        }
        return fd;
}