path: root/pd/src/s_audio_alsa.c

/* Copyright (c) 1997-2003 Guenter Geiger, Miller Puckette, Larry Troxler,
* Winfried Ritsch, Karl MacMillan, and others.
* For information on usage and redistribution, and for a DISCLAIMER OF ALL
* WARRANTIES, see the file, "LICENSE.txt," in this distribution.  */

/* this file inputs and outputs audio using the ALSA API available on linux. */

#include <alsa/asoundlib.h>

#include "m_pd.h"
#include "s_stuff.h"
#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <sched.h>
#include <sys/mman.h>

typedef int16_t t_alsa_sample16;
typedef int32_t t_alsa_sample32;
#define ALSA_SAMPLEWIDTH_16 sizeof(t_alsa_sample16)
#define ALSA_SAMPLEWIDTH_32 sizeof(t_alsa_sample32)
#define ALSA_XFERSIZE16  (signed int)(sizeof(t_alsa_sample16) * DEFDACBLKSIZE)
#define ALSA_XFERSIZE32  (signed int)(sizeof(t_alsa_sample32) * DEFDACBLKSIZE)
#define ALSA_MAXDEV 1
#define ALSA_JITTER 1024
#define ALSA_EXTRABUFFER 2048
#define ALSA_DEFFRAGSIZE 64
#define ALSA_DEFNFRAG 12

#ifndef INT32_MAX
#define INT32_MAX 0x7fffffff
#endif

#if (SND_LIB_MAJOR < 1)
#define ALSAAPI9
#endif

typedef struct _alsa_dev
{
    snd_pcm_t *inhandle;
    snd_pcm_t *outhandle;
    int innoninterleave;    /* true if we're set for noninterleaved read */
    int outnoninterleave;   /* same for write */
} t_alsa_dev;

t_alsa_dev alsa_device;
static void *alsa_snd_buf = 0;
static void **alsa_buf_ptrs;
static int alsa_samplewidth;
static snd_pcm_status_t* in_status;
static snd_pcm_status_t* out_status;

static int alsa_mode;
static int alsa_buf_samps;  /* believed actual ALSA bufsize in sample frames */
static int alsa_inchannels;
static int alsa_outchannels;

/* Defines */
#define DEBUG(x) x
#define DEBUG2(x) {x;}

static void alsa_checkiosync( void);
static void alsa_numbertoname(int devno, char *devname, int nchar);

    /* don't assume we can turn all 31 bits when doing float-to-fix; 
    otherwise some audio drivers (e.g. Midiman/ALSA) wrap around. */
#define FMAX 0x7ffff000
#define CLIP32(x) (((x)>FMAX)?FMAX:((x) < -FMAX)?-FMAX:(x))

/* support for ALSA pcmv2 api by Karl MacMillan<karlmac@peabody.jhu.edu> */ 

static void check_error(int err, const char *why)
{
    if (err < 0)
	fprintf(stderr, "%s: %s\n", why, snd_strerror(err));
}

/* was: alsa_open_audio(int wantinchans, int wantoutchans, int srate) */

int alsa_open_audio(int naudioindev, int *audioindev, int nchindev,
    int *chindev, int naudiooutdev, int *audiooutdev, int nchoutdev,
    int *choutdev, int rate)
{
    int err, inchans = 0, outchans = 0, subunitdir;
    char devname[512];
    snd_pcm_hw_params_t* hw_params;
    snd_pcm_sw_params_t* sw_params;
    snd_output_t* out;
    int frag_size = (sys_blocksize ? sys_blocksize : ALSA_DEFFRAGSIZE);
    int nfrags, i;
    short* tmp_buf;
    unsigned int tmp_uint;
    snd_pcm_uframes_t tmp_snd_pcm_uframes;
    int wantinchans, wantoutchans, devno;

    if (naudioindev >= 2 || naudiooutdev >= 2)
    	post("alsa: only one input and output device allowed (extras ignored");
    if (naudioindev >= 1 && naudiooutdev >= 1 &&
    	audioindev[0] != audiooutdev[0])
    	    post("alsa: changing output device to agree with input device");
    if (nchindev)
    	wantinchans = chindev[0];
    else wantinchans = (naudioindev ? 2 : 0);
    if (nchoutdev)
    	wantoutchans = choutdev[0];
    else wantoutchans = (naudiooutdev ? 2 : 0);
    devno = (naudioindev > 0 ? audioindev[0] :
    	(naudiooutdev > 0 ? audiooutdev[0] : 0));

    alsa_numbertoname(devno, devname, 512);

    if (sys_verbose)
    	post("device name %s; channels in %d, out %d", devname, wantinchans,
	    wantoutchans);
    
    nfrags = sys_schedadvance * (float)rate / (1e6 * frag_size);
    	/* save our belief as to ALSA's buffer size for later */
    alsa_buf_samps = nfrags * frag_size;

    if (sys_verbose)
    	post("audio buffer set to %d", (int)(0.001 * sys_schedadvance));
    
    alsa_device.innoninterleave = alsa_device.outnoninterleave = 0;
    if (wantinchans)
    {
	err = snd_pcm_open(&alsa_device.inhandle, devname,
			   SND_PCM_STREAM_CAPTURE, SND_PCM_NONBLOCK);

	check_error(err, "snd_pcm_open (input)");
	if (err < 0)
	    inchans = 0;
	else
	{
	    inchans = wantinchans;
	    snd_pcm_nonblock(alsa_device.inhandle, 1);
	}
    }
    if (wantoutchans)
    {
	err = snd_pcm_open(&alsa_device.outhandle, devname,
			   SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK);

	check_error(err, "snd_pcm_open (output)");
	if (err < 0)
	    outchans = 0;
	else
	{
	    outchans = wantoutchans;
	    snd_pcm_nonblock(alsa_device.outhandle, 1);
	}
    }
    if (inchans)
    {
    	if (sys_verbose)
	    post("opening sound input...");
	err = snd_pcm_hw_params_malloc(&hw_params);
	check_error(err, "snd_pcm_hw_params_malloc (input)");
    
	// get the default params
	err = snd_pcm_hw_params_any(alsa_device.inhandle, hw_params);
	check_error(err, "snd_pcm_hw_params_any (input)");

	/* try to set interleaved access */
	err = snd_pcm_hw_params_set_access(alsa_device.inhandle,
	    hw_params, SND_PCM_ACCESS_RW_INTERLEAVED);
	if (err < 0)
	{
	    	/* OK, so try non-interleaved */
	    err = snd_pcm_hw_params_set_access(alsa_device.inhandle,
	    	hw_params, SND_PCM_ACCESS_RW_NONINTERLEAVED);
	    if (err >= 0)
	    {
	    	post("using non-interleaved audio input");
	    	alsa_device.innoninterleave = 1;
	    }
	}
	check_error(err, "snd_pcm_hw_params_set_access (input)");
	// Try to set 32 bit format first
	err = snd_pcm_hw_params_set_format(alsa_device.inhandle, hw_params,
					   SND_PCM_FORMAT_S32);
	if (err < 0)
	{
	    /* fprintf(stderr,
	    	"PD-ALSA: 32 bit format not available - using 16\n"); */
	    err = snd_pcm_hw_params_set_format(alsa_device.inhandle, hw_params,
					       SND_PCM_FORMAT_S16);
	    check_error(err, "snd_pcm_hw_params_set_format (input)");
	    alsa_samplewidth = 2;
	}
	else
	{
	    alsa_samplewidth = 4;
	}
	post("Sample width set to %d bytes", alsa_samplewidth);
	// set the subformat
	err = snd_pcm_hw_params_set_subformat(alsa_device.inhandle, hw_params,
					      SND_PCM_SUBFORMAT_STD);
	check_error(err, "snd_pcm_hw_params_set_subformat (input)");
	// set the number of channels
	tmp_uint = inchans;
	err = snd_pcm_hw_params_set_channels_min(alsa_device.inhandle,
						 hw_params, &tmp_uint);
	check_error(err, "snd_pcm_hw_params_set_channels (input)");
	if (tmp_uint != (unsigned)inchans)
	    post("ALSA: set input channels to %d", tmp_uint);
	inchans = tmp_uint;
	// set the sampling rate
	err = snd_pcm_hw_params_set_rate_min(alsa_device.inhandle, hw_params,
					     &rate, 0);
	check_error(err, "snd_pcm_hw_params_set_rate_min (input)");
#if 0
    	err = snd_pcm_hw_params_get_rate(hw_params, &subunitdir);
	post("input sample rate %d", err);
#endif
	// set the period - ie frag size
	// post("fragsize a %d", frag_size);

    	    /* LATER try this to get a recommended period size...
	     right now, it trips an assertion failure in ALSA lib */
#if 0
    	post("input period was %d, min %d, max %d\n",
	    snd_pcm_hw_params_get_period_size(hw_params, 0),
	    snd_pcm_hw_params_get_period_size_min(hw_params, 0),
	    snd_pcm_hw_params_get_period_size_max(hw_params, 0));
#endif
#ifdef ALSAAPI9
	err = snd_pcm_hw_params_set_period_size_near(alsa_device.inhandle,
						    hw_params, 
						    (snd_pcm_uframes_t)
						    frag_size, 0);
#else
    	tmp_snd_pcm_uframes = frag_size;
	err = snd_pcm_hw_params_set_period_size_near(alsa_device.inhandle,
	    hw_params, &tmp_snd_pcm_uframes, 0);
#endif
	check_error(err, "snd_pcm_hw_params_set_period_size_near (input)");
	// post("fragsize b %d", frag_size);
	// set the number of periods - ie numfrags
	// post("nfrags a %d", nfrags);
#ifdef ALSAAPI9
	err = snd_pcm_hw_params_set_periods_near(alsa_device.inhandle,
						hw_params, nfrags, 0);
#else
    	tmp_uint = nfrags;
	err = snd_pcm_hw_params_set_periods_near(alsa_device.inhandle,
    	    hw_params, &tmp_uint, 0);
#endif
	check_error(err, "snd_pcm_hw_params_set_periods_near (input)");
	// set the buffer size
#ifdef ALSAAPI9
	err = snd_pcm_hw_params_set_buffer_size_near(alsa_device.inhandle,
						hw_params, nfrags * frag_size);
#else
    	tmp_snd_pcm_uframes = nfrags * frag_size;
	err = snd_pcm_hw_params_set_buffer_size_near(alsa_device.inhandle,
    	    hw_params, &tmp_snd_pcm_uframes);
#endif
	check_error(err, "snd_pcm_hw_params_set_buffer_size_near (input)");

	err = snd_pcm_hw_params(alsa_device.inhandle, hw_params);
	check_error(err, "snd_pcm_hw_params (input)");
	
	snd_pcm_hw_params_free(hw_params);
	
	err = snd_pcm_sw_params_malloc(&sw_params);
	check_error(err, "snd_pcm_sw_params_malloc (input)");
	err = snd_pcm_sw_params_current(alsa_device.inhandle, sw_params);
	check_error(err, "snd_pcm_sw_params_current (input)");
	err = snd_pcm_sw_params_set_start_threshold(alsa_device.inhandle,
	    sw_params, nfrags * frag_size);
	check_error(err, "snd_pcm_sw_params_set_start_threshold (input)");
	err = snd_pcm_sw_params_set_stop_threshold(alsa_device.inhandle,
	    sw_params, 0x7fffffff);
	check_error(err, "snd_pcm_sw_params_set_stop_threshold (input)");
	err = snd_pcm_sw_params_set_avail_min(alsa_device.inhandle, sw_params,
					      frag_size);
	check_error(err, "snd_pcm_sw_params_set_avail_min (input)");
	err = snd_pcm_sw_params(alsa_device.inhandle, sw_params);
	check_error(err, "snd_pcm_sw_params (input)");
	
	snd_pcm_sw_params_free(sw_params);
	
	snd_output_stdio_attach(&out, stderr, 0);
#if 0
	if (sys_verbose)
	{
	    snd_pcm_dump_hw_setup(alsa_device.inhandle, out);
	    snd_pcm_dump_sw_setup(alsa_device.inhandle, out);
    	}
#endif
    }

    if (outchans)
    {
    	int foo;
    	if (sys_verbose)
	    post("opening sound output...");
	err = snd_pcm_hw_params_malloc(&hw_params);
	check_error(err, "snd_pcm_sw_params (output)");

	// get the default params
	err = snd_pcm_hw_params_any(alsa_device.outhandle, hw_params);
	check_error(err, "snd_pcm_hw_params_any (output)");
	// set interleaved access - FIXME deal with other access types
	err = snd_pcm_hw_params_set_access(alsa_device.outhandle, hw_params,
					   SND_PCM_ACCESS_RW_INTERLEAVED);
	check_error(err, "snd_pcm_hw_params_set_access (output)");

	    /* try to set interleaved access */
	err = snd_pcm_hw_params_set_access(alsa_device.outhandle,
	    hw_params, SND_PCM_ACCESS_RW_INTERLEAVED);
	if (err < 0)
	{
	    	/* OK, so try non-interleaved */
	    err = snd_pcm_hw_params_set_access(alsa_device.outhandle,
	    	hw_params, SND_PCM_ACCESS_RW_NONINTERLEAVED);
	    if (err >= 0)
	    {
	    	post("using non-interleaved audio");
	    	alsa_device.outnoninterleave = 1;
	    }
	}
	check_error(err, "snd_pcm_hw_params_set_access (output)");


	// Try to set 32 bit format first
	err = snd_pcm_hw_params_set_format(alsa_device.outhandle, hw_params,
					     SND_PCM_FORMAT_S32);
	if (err < 0)
	{
	    err = snd_pcm_hw_params_set_format(alsa_device.outhandle,
					       hw_params,SND_PCM_FORMAT_S16);
	    check_error(err, "snd_pcm_hw_params_set_format (output)");
	    /* fprintf(stderr,
	    	"PD-ALSA: 32 bit format not available - using 16\n"); */
	    alsa_samplewidth = 2;
	}
	else
	{
	    alsa_samplewidth = 4;
	}
	// set the subformat
	err = snd_pcm_hw_params_set_subformat(alsa_device.outhandle, hw_params,
					      SND_PCM_SUBFORMAT_STD);
	check_error(err, "snd_pcm_hw_params_set_subformat (output)");
	// set the number of channels
	tmp_uint = outchans;
	err = snd_pcm_hw_params_set_channels_min(alsa_device.outhandle,
						 hw_params, &tmp_uint);
	check_error(err, "snd_pcm_hw_params_set_channels (output)");
	if (tmp_uint != (unsigned)outchans)
    	    post("alsa: set output channels to %d", tmp_uint);
    	outchans = tmp_uint;
	// set the sampling rate
	err = snd_pcm_hw_params_set_rate_min(alsa_device.outhandle, hw_params,
					     &rate, 0);
	check_error(err, "snd_pcm_hw_params_set_rate_min (output)");
#if 0
    	err = snd_pcm_hw_params_get_rate(hw_params, &subunitdir);
	post("output sample rate %d", err);
#endif
	// set the period - ie frag size
#if 0
    	post("output period was %d, min %d, max %d\n",
	    snd_pcm_hw_params_get_period_size(hw_params, 0),
	    snd_pcm_hw_params_get_period_size_min(hw_params, 0),
	    snd_pcm_hw_params_get_period_size_max(hw_params, 0));
#endif
	// post("fragsize c %d", frag_size);
#ifdef ALSAAPI9
	err = snd_pcm_hw_params_set_period_size_near(alsa_device.outhandle,
						    hw_params,
						    (snd_pcm_uframes_t)
						    frag_size, 0);
#else
    	tmp_snd_pcm_uframes = frag_size;
	err = snd_pcm_hw_params_set_period_size_near(alsa_device.outhandle,
	    hw_params, &tmp_snd_pcm_uframes, 0);
#endif
	// post("fragsize d %d", frag_size);
	check_error(err, "snd_pcm_hw_params_set_period_size_near (output)");
	// set the number of periods - ie numfrags
#ifdef ALSAAPI9
	err = snd_pcm_hw_params_set_periods_near(alsa_device.outhandle,
						hw_params, nfrags, 0);
#else
    	tmp_uint = nfrags;
	err = snd_pcm_hw_params_set_periods_near(alsa_device.outhandle,
	    hw_params, &tmp_uint, 0);
#endif
	check_error(err, "snd_pcm_hw_params_set_periods_near (output)");
	// set the buffer size
#ifdef ALSAAPI9
	err = snd_pcm_hw_params_set_buffer_size_near(alsa_device.outhandle,
	    hw_params, nfrags * frag_size);
#else
    	tmp_snd_pcm_uframes = nfrags * frag_size;
	err = snd_pcm_hw_params_set_buffer_size_near(alsa_device.outhandle,
	    hw_params, &tmp_snd_pcm_uframes);
#endif
	check_error(err, "snd_pcm_hw_params_set_buffer_size_near (output)");

	err = snd_pcm_hw_params(alsa_device.outhandle, hw_params);
	check_error(err, "snd_pcm_hw_params (output)");

	snd_pcm_hw_params_free(hw_params);

	err = snd_pcm_sw_params_malloc(&sw_params);
	check_error(err, "snd_pcm_sw_params_malloc (output)");
	err = snd_pcm_sw_params_current(alsa_device.outhandle, sw_params);
	check_error(err, "snd_pcm_sw_params_current (output)");
	err = snd_pcm_sw_params_set_start_threshold(alsa_device.outhandle,
	    sw_params, nfrags * frag_size);
	check_error(err, "snd_pcm_sw_params_set_start_threshold (output)");
	err = snd_pcm_sw_params_set_stop_threshold(alsa_device.outhandle,
	    sw_params, 0x7fffffff);
	check_error(err, "snd_pcm_sw_params_set_stop_threshold (output)");
	err = snd_pcm_sw_params_set_avail_min(alsa_device.outhandle, sw_params,
	    frag_size);
	check_error(err, "snd_pcm_sw_params_set_avail_min (output)");
	err = snd_pcm_sw_params(alsa_device.outhandle, sw_params);
	check_error(err, "snd_pcm_sw_params (output)");
	snd_pcm_sw_params_free(sw_params);
	
	snd_output_stdio_attach(&out, stderr, 0);
#if 0
	if (sys_verbose)
	{
	    snd_pcm_dump_hw_setup(alsa_device.outhandle, out);
	    snd_pcm_dump_sw_setup(alsa_device.outhandle, out);
    	}
#endif
    }

    if (inchans)
      snd_pcm_prepare(alsa_device.inhandle);
    if (outchans)
      snd_pcm_prepare(alsa_device.outhandle);

    // if duplex we can link the channels so they start together
    if (inchans && outchans)
      snd_pcm_link(alsa_device.inhandle, alsa_device.outhandle);

    // set up the status variables
    err = snd_pcm_status_malloc(&in_status);
    check_error(err, "snd_pcm_status_malloc");
    err = snd_pcm_status_malloc(&out_status);
    check_error(err, "snd_pcm_status_malloc");

    // set up the buffer
    if (alsa_snd_buf)
    	free(alsa_snd_buf);
    alsa_snd_buf = (void *)malloc(
	sizeof(char) * alsa_samplewidth * DEFDACBLKSIZE *
	    (outchans > inchans ? outchans : inchans));
    memset(alsa_snd_buf, 0, sizeof(char) * alsa_samplewidth * DEFDACBLKSIZE *
	    (outchans > inchans ? outchans : inchans));
    	/* make an array of pointers too in case we need them */
    if (alsa_buf_ptrs)
    	free(alsa_buf_ptrs);
    alsa_buf_ptrs = (void **)malloc(
	sizeof(void *) * (outchans > inchans ? outchans : inchans));
    for (i = 0; i < (outchans > inchans ? outchans : inchans); i++)
    	alsa_buf_ptrs[i] = (t_alsa_sample32 *)alsa_snd_buf + i * DEFDACBLKSIZE;

    // fill the buffer with silence
    if (outchans)
    {
	i = (frag_size * nfrags)/DEFDACBLKSIZE + 1;
	while (i--)
	{
	    if (alsa_device.outnoninterleave)
	    	snd_pcm_writen(alsa_device.outhandle, alsa_buf_ptrs,
		    DEFDACBLKSIZE);
	    else snd_pcm_writei(alsa_device.outhandle, alsa_snd_buf,
		    DEFDACBLKSIZE);
    	}
	    	/* confused about this: */
	/* if ((err = snd_pcm_start(alsa_device.outhandle) < 0))
	    check_error(err, "output start failed\n"); */
    }
    else if (inchans)
    {
    	if (snd_pcm_start(alsa_device.inhandle) < 0)
	    check_error(err, "input start failed\n");
    }
    alsa_outchannels = outchans;
    alsa_inchannels = inchans;
	    
    return (!(inchans || outchans));
}

void alsa_close_audio(void)
{
    int err;
    if (alsa_inchannels)
    {
	err = snd_pcm_close(alsa_device.inhandle);
	check_error(err, "snd_pcm_close (input)");
    }
    if (alsa_outchannels)
    {
	err = snd_pcm_close(alsa_device.outhandle);
	check_error(err, "snd_pcm_close (output)");
    }
}

// #define DEBUG_ALSA_XFER

int alsa_send_dacs(void)
{
    static int16_t *sp;
    static int xferno = 0;
    static int callno = 0;
    static double timenow;
    double timelast;
    t_sample *fp, *fp1, *fp2;
    int i, j, k, err, devno = 0;
    int inputcount = 0, outputcount = 0, inputlate = 0, outputlate = 0;
    int result; 
    int inchannels = (sys_inchannels > alsa_inchannels ?
    	alsa_inchannels : sys_inchannels);
    int outchannels = (sys_outchannels > alsa_outchannels ?
	    alsa_outchannels : sys_outchannels);
    unsigned int intransfersize = DEFDACBLKSIZE;
    unsigned int outtransfersize = DEFDACBLKSIZE;

    // get the status
    if (!inchannels && !outchannels)
    {
	return SENDDACS_NO;
    }
    
    timelast = timenow;
    timenow = sys_getrealtime();

#ifdef DEBUG_ALSA_XFER
    if (timenow - timelast > 0.050)
    	fprintf(stderr, "(%d)",
	    (int)(1000 * (timenow - timelast))), fflush(stderr);
#endif

    callno++;

    alsa_checkiosync();     /* check I/O are in sync and data not late */

    if (alsa_inchannels)
    {
	snd_pcm_status(alsa_device.inhandle, in_status);
	if (snd_pcm_status_get_avail(in_status) < intransfersize)
	    return SENDDACS_NO;
    }
    if (alsa_outchannels)
    {
	snd_pcm_status(alsa_device.outhandle, out_status);
	if (snd_pcm_status_get_avail(out_status) < outtransfersize)
	    return SENDDACS_NO;
    }

    /* do output */
    if (alsa_outchannels)
    {
	fp = sys_soundout;
	if (alsa_samplewidth == 4)
	{
	    if (alsa_device.outnoninterleave)
	    {
	    	int n = outchannels * DEFDACBLKSIZE;
		for (i = 0, fp1 = fp; i < n; i++)
		{
		    float s1 = *fp1 * INT32_MAX;
		    ((t_alsa_sample32 *)alsa_snd_buf)[i] = CLIP32(s1);
		}
		n = alsa_outchannels * DEFDACBLKSIZE;
		for (; i < n; i++)
		    ((t_alsa_sample32 *)alsa_snd_buf)[i] = 0;
	    }
	    else
	    {
		for (i = 0, fp1 = fp; i < outchannels; i++,
		    fp1 += DEFDACBLKSIZE)
		{
		    for (j = i, k = DEFDACBLKSIZE, fp2 = fp1; k--;
			 j += alsa_outchannels, fp2++)
		    {
			float s1 = *fp2 * INT32_MAX;
			((t_alsa_sample32 *)alsa_snd_buf)[j] = CLIP32(s1);
		    } 
		}
	    }
	}
	else
	{
	    for (i = 0, fp1 = fp; i < outchannels; i++, fp1 += DEFDACBLKSIZE)
	    {
		for (j = i, k = DEFDACBLKSIZE, fp2 = fp1; k--;
		     j += alsa_outchannels, fp2++)
		{
		    int s = *fp2 * 32767.;
		    if (s > 32767)
			s = 32767;
		    else if (s < -32767)
			s = -32767;
		    ((t_alsa_sample16 *)alsa_snd_buf)[j] = s;
		}
	    }
	}

	if (alsa_device.outnoninterleave)
	    result = snd_pcm_writen(alsa_device.outhandle, alsa_buf_ptrs,
		outtransfersize);
	else result = snd_pcm_writei(alsa_device.outhandle, alsa_snd_buf,
		outtransfersize);

	if (result != (int)outtransfersize)
	{
    #ifdef DEBUG_ALSA_XFER
	    if (result >= 0 || errno == EAGAIN)
		fprintf(stderr, "ALSA: write returned %d of %d\n",
			result, outtransfersize);
	    else fprintf(stderr, "ALSA: write: %s\n",
			 snd_strerror(errno));
	    fprintf(stderr,
		    "inputcount %d, outputcount %d, outbufsize %d\n",
		    inputcount, outputcount, 
		    (ALSA_EXTRABUFFER + sys_advance_samples)
		    * alsa_samplewidth * outchannels);
    #endif
	    sys_log_error(ERR_DACSLEPT);
	    return (SENDDACS_NO);
	}

	/* zero out the output buffer */
	memset(sys_soundout, 0, DEFDACBLKSIZE * sizeof(*sys_soundout) *
	       sys_outchannels);
	if (sys_getrealtime() - timenow > 0.002)
	{
    #ifdef DEBUG_ALSA_XFER
    	    fprintf(stderr, "output %d took %d msec\n",
		    callno, (int)(1000 * (timenow - timelast))), fflush(stderr);
    #endif
    	    timenow = sys_getrealtime();
    	    sys_log_error(ERR_DACSLEPT);
	}
    }
    /* do input */
    if (alsa_inchannels)
    {
    	if (alsa_device.innoninterleave)
	    result = snd_pcm_readn(alsa_device.inhandle, alsa_buf_ptrs,
	    	intransfersize);
	else result = snd_pcm_readi(alsa_device.inhandle, alsa_snd_buf,
	    	intransfersize);
	if (result < (int)intransfersize)
	{
#ifdef DEBUG_ALSA_XFER
	    if (result < 0)
    	    	fprintf(stderr,
			"snd_pcm_read %d %d: %s\n", 
			callno, xferno, snd_strerror(errno));
	    else fprintf(stderr,
			 "snd_pcm_read %d %d returned only %d\n", 
			 callno, xferno, result);
	    fprintf(stderr,
		    "inputcount %d, outputcount %d, inbufsize %d\n",
		    inputcount, outputcount, 
	    	    (ALSA_EXTRABUFFER + sys_advance_samples)
		    * alsa_samplewidth * inchannels);
#endif
    	    sys_log_error(ERR_ADCSLEPT);
	    return (SENDDACS_NO);
	}
	fp = sys_soundin;
	if (alsa_samplewidth == 4)
	{
	    if (alsa_device.innoninterleave)
	    {
	    	int n = inchannels * DEFDACBLKSIZE;
		for (i = 0, fp1 = fp; i < n; i++)
	    	    *fp1 = (float) ((t_alsa_sample32 *)alsa_snd_buf)[i]
		    	    * (1./ INT32_MAX);
	    }
	    else
	    {
		for (i = 0, fp1 = fp; i < inchannels;
		    i++, fp1 += DEFDACBLKSIZE)
		{
		    for (j = i, k = DEFDACBLKSIZE, fp2 = fp1; k--;
			 j += alsa_inchannels, fp2++)
	    		*fp2 = (float) ((t_alsa_sample32 *)alsa_snd_buf)[j]
		    	    * (1./ INT32_MAX);
	    	}
	    }
	}
	else
	{
	    for (i = 0, fp1 = fp; i < inchannels; i++, fp1 += DEFDACBLKSIZE)
	    {
		for (j = i, k = DEFDACBLKSIZE, fp2 = fp1; k--;
		    j += alsa_inchannels, fp2++)
	    	    	*fp2 = (float) ((t_alsa_sample16 *)alsa_snd_buf)[j]
		    	    * 3.051850e-05;
	    }
    	}
    }
    xferno++;
    if (sys_getrealtime() - timenow > 0.002)
    {
#ifdef DEBUG_ALSA_XFER
    	fprintf(stderr, "routine took %d msec\n",
	    (int)(1000 * (sys_getrealtime() - timenow)));
#endif
    	sys_log_error(ERR_ADCSLEPT);
    }
    return SENDDACS_YES;
}

void alsa_printstate( void)
{
    int i, result;
    snd_pcm_sframes_t indelay, outdelay;
    if (sys_audioapi != API_ALSA)
    {
    	error("restart-audio: implemented for ALSA only.");
	return;
    }
    if (sys_inchannels)
    {
    	result = snd_pcm_delay(alsa_device.inhandle, &indelay);
	if (result < 0)
	    post("snd_pcm_delay 1 failed");
	else post("in delay %d", indelay);
    }
    if (sys_outchannels)
    {
    	result = snd_pcm_delay(alsa_device.outhandle, &outdelay);
	if (result < 0)
	    post("snd_pcm_delay 2 failed");
	else post("out delay %d", outdelay);
    }
    post("sum %d (%d mod 64)\n", indelay + outdelay, (indelay+outdelay)%64);

    post("buf samples %d", alsa_buf_samps);
}


void alsa_resync( void)
{
    int i, result;
    if (sys_audioapi != API_ALSA)
    {
    	error("restart-audio: implemented for ALSA only.");
	return;
    }
    memset(alsa_snd_buf, 0,
    	sizeof(char) * alsa_samplewidth * DEFDACBLKSIZE * sys_outchannels);
    for (i = 0; i < 1000000; i++)
    {
	if (alsa_device.outnoninterleave)
	    result = snd_pcm_writen(alsa_device.outhandle, alsa_buf_ptrs,
		DEFDACBLKSIZE);
	else result = snd_pcm_writei(alsa_device.outhandle, alsa_snd_buf,
		DEFDACBLKSIZE);
	if (result != (int)DEFDACBLKSIZE)
	    break;
    }
    post("%d written", i);
}

void alsa_putzeros(int n)
{
    int i, result;
    memset(alsa_snd_buf, 0,
    	sizeof(char) * alsa_samplewidth * DEFDACBLKSIZE * alsa_outchannels);
    for (i = 0; i < n; i++)
    {
	if (alsa_device.outnoninterleave)
	    result = snd_pcm_writen(alsa_device.outhandle, alsa_buf_ptrs,
		DEFDACBLKSIZE);
	else result = snd_pcm_writei(alsa_device.outhandle, alsa_snd_buf,
		DEFDACBLKSIZE);
#if 0
	if (result != DEFDACBLKSIZE)
	    post("result %d", result);
#endif
    }
    /* post ("putzeros %d", n); */
}

void alsa_getzeros(int n)
{
    int i, result;
    for (i = 0; i < n; i++)
    {
	result = snd_pcm_readi(alsa_device.inhandle, alsa_snd_buf,
	    DEFDACBLKSIZE);
#if 0
	if (result != DEFDACBLKSIZE)
	    post("result %d", result);
#endif
    }
    /* post ("getzeros %d", n); */
}

    /* call this only if both input and output are open */
static void alsa_checkiosync( void)
{
    int i, result, checkit = 1, giveup = 1000, alreadylogged = 0;
    snd_pcm_sframes_t indelay, outdelay, defect;

    if (!(alsa_outchannels && alsa_inchannels))
    	return;
    while (checkit)
    {
    	checkit = 0;
	if (giveup-- <= 0)
	    return;
	result = snd_pcm_delay(alsa_device.outhandle, &outdelay);
	if (result < 0)
	{
	    post("output snd_pcm_delay failed: %s", snd_strerror(result));
	    if (snd_pcm_status(alsa_device.outhandle, out_status) < 0)
	    	post("output snd_pcm_status failed");
	    else post("astate %d",
	    	 snd_pcm_status_get_state(out_status));
    	    return;
	}
	if (outdelay < 0)
	    sys_log_error(ERR_DATALATE), alreadylogged = 1;

    	if (sys_inchannels)
	{
	    result = snd_pcm_delay(alsa_device.inhandle, &indelay);
	    if (result < 0)
	    {
		post("input snd_pcm_delay failed");
    		return;
	    }
	    defect = indelay + outdelay - alsa_buf_samps;
	    if (defect < -(3 * DEFDACBLKSIZE / 2) )
    	    {
		checkit = 1;
    		alsa_putzeros(1);
		if (!alreadylogged)
	    	    sys_log_error(ERR_RESYNC), alreadylogged = 1;
	    }
	    else if (defect > 0)
	    {
		checkit = 1;
    		alsa_getzeros(1);	    
		if (!alreadylogged)
	    	    sys_log_error(ERR_RESYNC), alreadylogged = 1;
	    }
	    /* if (alreadylogged)
	    	post("in %d out %d defect %d", indelay, outdelay, defect); */
    	}
    }
}

static int alsa_nnames = 0;
static char **alsa_names = 0;

void alsa_adddev(char *name)
{
    if (alsa_nnames)
    	alsa_names = (char **)t_resizebytes(alsa_names,
	    alsa_nnames * sizeof(char *),
	    (alsa_nnames+1) * sizeof(char *));
    else alsa_names = (char **)t_getbytes(sizeof(char *));
    alsa_names[alsa_nnames] = gensym(name)->s_name;
    alsa_nnames++;
}

static void alsa_numbertoname(int devno, char *devname, int nchar)
{
    int ndev = 0, cardno = -1;
    while (!snd_card_next(&cardno) && cardno >= 0)
    	ndev++;
    if (devno < 2*ndev)
    {
    	if (devno & 1)
    	    snprintf(devname, nchar, "plughw:%d", devno/2);
    	else snprintf(devname, nchar, "hw:%d", devno/2);
    }
    else if (devno <2*ndev + alsa_nnames)
    	snprintf(devname, nchar, "%s", alsa_names[devno - 2*ndev]);
    else snprintf(devname, nchar, "???");
}

    /* For each hardware card found, we list two devices, the "hard" and
    "plug" one.  The card scan is derived from portaudio code. */
void alsa_getdevs(char *indevlist, int *nindevs,
    char *outdevlist, int *noutdevs, int *canmulti, 
    	int maxndev, int devdescsize)
{
    int ndev = 0, cardno = -1, i, j;
    *canmulti = 0;  /* only one device; must be the same for input&output */
    while (!snd_card_next(&cardno) && cardno >= 0)
    {
    	snd_ctl_t *ctl;
    	snd_ctl_card_info_t *info;
        char devname[80];
    	const char *desc;
    	if (2 * ndev + 2  > maxndev)
	    break;
	    /* apparently, "cardno" is just a counter; but check that here */
	if (ndev != cardno)
	    fprintf(stderr, "oops: ALSA cards not reported in order?\n");
        sprintf(devname, "hw:%d", cardno );
        /* fprintf(stderr, "\ntry %s...\n", devname); */
        if (snd_ctl_open(&ctl, devname, 0) >= 0)
	{
            snd_ctl_card_info_malloc(&info);
            snd_ctl_card_info(ctl, info);
	    desc = snd_ctl_card_info_get_name(info);
	    snd_ctl_card_info_free(info);
    	}
    	else
	{
	    fprintf(stderr, "ALSA card scan error\n");
	    desc = "???";
	}
        /* fprintf(stderr, "name: %s\n", snd_ctl_card_info_get_name(info)); */
        sprintf(indevlist + 2*ndev * devdescsize, "%s (hardware)", desc);
        sprintf(indevlist + (2*ndev + 1) * devdescsize, "%s (plug-in)", desc);
        sprintf(outdevlist + 2*ndev * devdescsize, "%s (hardware)", desc);
        sprintf(outdevlist + (2*ndev + 1) * devdescsize, "%s (plug-in)", desc);
	ndev++;
    }
    for (i = 0, j = 2*ndev; i < alsa_nnames; i++, j++)
    {
    	if (j >= maxndev)
	    break;
        snprintf(indevlist + j * devdescsize, devdescsize, "%s", 
	    alsa_names[i]);
    }
    *nindevs = *noutdevs = j;
}