Thread: Port mixer from oss to alsa

Hello
I'm new in c programming and my requirement is as follows.
I make a code for oss mixer and now when new systems, throwing the OSS, and there is no /dev/mixer I want to port my code to alsa but my skills are minimal.
Any help would be welcome.

Code:

static int mixer_fd = -1, mixer_src = -1;
static char *devices[] = SOUND_DEVICE_NAMES;

int mixer_init(char *mixer_device, char *mixer_source)
{
    int i;
    
    mixer_src = -1;
    
    for (i=0;i<SOUND_MIXER_NRDEVICES;i++)
        if (strcmp(mixer_source, devices[i]) == 0) 
            mixer_src = i;

    mixer_fd = open(mixer_device, O_RDWR);

    if (mixer_src < 0)    
        return -1;
            
    if (mixer_fd < 0)
        return 0;
    return 1;
}

char* mixer_get_sndcard_name(void)
{
    mixer_info info;
    char *result = NULL;

    if (ioctl(mixer_fd, SOUND_MIXER_INFO, &info) == -1)
        return NULL;

    result = strdup(info.name);    
    
    return result;
}

char** mixer_get_rec_devices(void)
{
    int i, o, devmask, res;
    char** result;
    
    if ((ioctl(mixer_fd, SOUND_MIXER_READ_RECMASK, &devmask)) == -1)
        return NULL;
    else
    {
        result = malloc(sizeof(char*)*SOUND_MIXER_NRDEVICES);
        o = 0;
        for (i=0;i<SOUND_MIXER_NRDEVICES;i++)
            {
                res = (devmask >> i)%2;
                if (res)
                {
                    result[o] = malloc(strlen(devices[i])+1);
                    sprintf(result[o], "%s", devices[i]); 
                    o++;
                }
                result[o] = NULL;    
            }
    }
    return result;
}

int mixer_set_rec_device(void)
{
    int devmask, recmask;

    if (mixer_fd <= 0)
        return 0;

    if (mixer_src < 0)
        return 0;

    if ((ioctl(mixer_fd, SOUND_MIXER_READ_RECMASK, &devmask)) == -1)
        return 0;
    
    recmask = 1 << mixer_src;
    if (!(recmask & devmask))
        return 0;

    if ((ioctl(mixer_fd, SOUND_MIXER_WRITE_RECSRC, &recmask)) == -1)
        return 0;

    return 1;
}            

int mixer_close(void)
{
    if (mixer_fd > 0)
        close(mixer_fd);
    
    return 1;
}
        
int mixer_set_volume(int volume)
{
    int i_vol;
    if (mixer_fd<0)
        return -1;

    assert(volume <= 100);
    assert(volume >= 0);


    if (mixer_src<0) 
        return -1;
    
    i_vol = volume;  
    i_vol += volume << 8;

    if ((ioctl(mixer_fd, MIXER_WRITE(mixer_src), &i_vol)) < 0)
        return 0;
        
    return 1;
}

int mixer_get_volume(void)
{
    int i_vol = 0, r, l, volume;
    
    if (mixer_fd<0)
        return -1;

    if (mixer_src<0) 
        return -1;
    
    if ((ioctl(mixer_fd, MIXER_READ(mixer_src), &i_vol)) < 0)
        return 0;

    r = i_vol >> 8;
    l = i_vol % (1 << 8);
    volume = (r + l)/2;
    
    assert((volume >= 0) && (volume <= 100));
    
    return volume;
}

Coexistance with OSS would be nice, so both could be
used depending on users choice. Perhaps: if this first
part of the mixer name is a valid device file, try OSS,
otherwise try ALSA?