alsa_a.c

MIDI解码程序(用VC编写)

/* -*- c-file-style: "gnu" -*-
    TiMidity++ -- MIDI to WAVE converter and player
    Copyright (C) 1999-2002 Masanao Izumo <[e-mail]>
    Copyright (C) 1995 Tuukka Toivonen <[e-mail]>
    ALSA 0.[56] support by Katsuhiro Ueno <[e-mail]>
                rewritten by Takashi Iwai <[e-mail]>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    alsa_a.c

    Functions to play sound on the ALSA audio driver

*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif /* HAVE_CONFIG_H */
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>

#ifndef NO_STRING_H
#include <string.h>
#else
#include <strings.h>
#endif

/*ALSA header file*/
#if HAVE_ALSA_ASOUNDLIB_H
#define ALSA_PCM_OLD_HW_PARAMS_API
#define ALSA_PCM_OLD_SW_PARAMS_API
#include <alsa/asoundlib.h>
#else
#include <sys/asoundlib.h>
#endif

#if SND_LIB_MAJOR > 0
#define ALSA_LIB  9
#elif defined(SND_LIB_MINOR)
#define ALSA_LIB  SND_LIB_MINOR
#else
#define ALSA_LIB  3
#endif

#if ALSA_LIB < 4
typedef void  snd_pcm_t;
#endif

#include "timidity.h"
#include "common.h"
#include "output.h"
#include "controls.h"
#include "timer.h"
#include "instrum.h"
#include "playmidi.h"
#include "miditrace.h"

static int open_output(void); /* 0=success, 1=warning, -1=fatal error */
static void close_output(void);
static int output_data(char *buf, int32 nbytes);
static int acntl(int request, void *arg);
#if ALSA_LIB >= 5
static int detect(void);
#endif

/* export the playback mode */

#define dpm alsa_play_mode

PlayMode dpm = {
  DEFAULT_RATE, PE_16BIT|PE_SIGNED, PF_PCM_STREAM|PF_CAN_TRACE|PF_BUFF_FRAGM_OPT,
  -1,
  {0}, /* default: get all the buffer fragments you can */
  "ALSA pcm device", 's',
  "", /* here leave it empty so that the pcm device name can be given
       * via command line option.
       */
  open_output,
  close_output,
  output_data,
  acntl,
#if ALSA_LIB >= 5
  detect
#endif
};

/*************************************************************************/
/* We currently only honor the PE_MONO bit, the sample rate, and the
   number of buffer fragments. We try 16-bit signed data first, and
   then 8-bit unsigned if it fails. If you have a sound device that
   can't handle either, let me know. */


/*ALSA PCM handler*/
static snd_pcm_t* handle = NULL;
#if ALSA_LIB <= 5
static int card = 0;
static int device = 0;
#endif
static int total_bytes = -1;
static int frag_size = 0;
static int sample_shift = 0;
static int output_counter;

#if ALSA_LIB > 5
static char *alsa_device_name(void)
{
  if (dpm.name && *dpm.name)
    return dpm.name;
  else
    return "alsa pcm";
}
#else
static char *alsa_device_name(void)
{
  static char name[32];
  sprintf(name, "card%d/device%d", card, device);
  return name;
}
#endif

static void error_report (int snd_error)
{
  ctl->cmsg(CMSG_ERROR, VERB_NORMAL, "%s: %s",
	    alsa_device_name(), snd_strerror (snd_error));
}


#if ALSA_LIB < 6
/*return value == 0 sucess
               == -1 fails
 */
static int check_sound_cards (int* card__, int* device__,
			      const int32 extra_param[5])
{
  /*Search sound cards*/
  struct snd_ctl_hw_info ctl_hw_info;
  snd_pcm_info_t pcm_info;
  snd_ctl_t* ctl_handle;
  const char* env_sound_card = getenv ("TIMIDITY_SOUND_CARD");
  const char* env_pcm_device = getenv ("TIMIDITY_PCM_DEVICE");
  int tmp;

  /*specify card*/
  *card__ = 0;
  if (env_sound_card != NULL)
    *card__ = atoi (env_sound_card);
  /*specify device*/
  *device__ = 0;
  if (env_pcm_device != NULL)
    *device__ = atoi (env_pcm_device);

  tmp = snd_cards ();
  if (tmp == 0)
    {
      ctl->cmsg(CMSG_ERROR, VERB_NORMAL, "No sound card found.");
      return -1;
    }
  if (tmp < 0)
    {
      error_report (tmp);
      return -1;
    }

  if (*card__ < 0 || *card__ >= tmp)
    {
      ctl->cmsg(CMSG_ERROR, VERB_NORMAL, "There is %d sound cards."
		" %d is invalid sound card. assuming 0.",
		tmp, *card__);
      *card__ = 0;
    }

  tmp = snd_ctl_open (&ctl_handle, *card__);
  if (tmp < 0)
    {
      error_report (tmp);
      return -1;
    }

  /*check whether sound card has pcm device(s)*/
  tmp = snd_ctl_hw_info (ctl_handle, & ctl_hw_info);
  if (ctl_hw_info.pcmdevs == 0)
    {
      ctl->cmsg(CMSG_ERROR, VERB_NORMAL,
		"%d-th sound card(%s) has no pcm device",
		ctl_hw_info.longname, *card__);
      snd_ctl_close (ctl_handle);
      return -1;
    }

  if (*device__ < 0 || *device__ >= ctl_hw_info.pcmdevs)
    {
      ctl->cmsg(CMSG_ERROR, VERB_NORMAL,
		"%d-th sound cards(%s) has %d pcm device(s)."
		" %d is invalid pcm device. assuming 0.",
		*card__, ctl_hw_info.longname, ctl_hw_info.pcmdevs, *device__);
      *device__ = 0;

      if (ctl_hw_info.pcmdevs == 0)
	{/*sound card has no pcm devices*/
	  snd_ctl_close (ctl_handle);
	  return -1;
	}
    }

  /*check whether pcm device is able to playback*/
  tmp = snd_ctl_pcm_info(ctl_handle, *device__, &pcm_info);
  if (tmp < 0)
    {
      error_report (tmp);
      snd_ctl_close (ctl_handle);
      return -1;
    }

  if ((pcm_info.flags & SND_PCM_INFO_PLAYBACK) == 0)
    {
      ctl->cmsg(CMSG_ERROR, VERB_NORMAL,
		"%d-th sound cards(%s), device=%d, "
		"type=%d, flags=%d, id=%s, name=%s,"
		" does not support playback",
		*card__, ctl_hw_info.longname, ctl_hw_info.pcmdevs,
		pcm_info.type, pcm_info.flags, pcm_info.id, pcm_info.name);
      snd_ctl_close (ctl_handle);
      return -1;
    }

  tmp = snd_ctl_close (ctl_handle);
  if (tmp < 0)
    {
      error_report (tmp);
      return -1;
    }

  return 0;
}
#endif


#if ALSA_LIB > 5
/*================================================================
 * ALSA API version 0.9.x
 *================================================================*/

static char *get_pcm_name(void)
{
  char *name;
  if (dpm.name && *dpm.name)
    return dpm.name;
  name = getenv("TIMIDITY_PCM_NAME");
  if (! name || ! *name)
    name = "default";
  return name;
}

static void error_handle(const char *file, int line, const char *func, int err, const char *fmt, ...)
{
}

static int detect(void)
{
  snd_pcm_t *pcm;
  snd_lib_error_set_handler(error_handle);
  if (snd_pcm_open(&pcm, get_pcm_name(), SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK) < 0)
    return 0;
  snd_pcm_close(pcm);
  return 1; /* found */
}

/*return value == 0 sucess
               == 1 warning
               == -1 fails
 */
static int open_output(void)
{
  int orig_rate = dpm.rate;
  int ret_val = 0;
  int tmp, frags, r, pfds;
  int rate;
  snd_pcm_hw_params_t *pinfo;
  snd_pcm_sw_params_t *swpinfo;

  dpm.name = get_pcm_name();
  snd_lib_error_set_handler(NULL);
  tmp = snd_pcm_open(&handle, dpm.name, SND_PCM_STREAM_PLAYBACK, SND_PCM_NONBLOCK); /* avoid blocking by open */
  if (tmp < 0) {
    ctl->cmsg(CMSG_ERROR, VERB_NORMAL, "Can't open pcm device '%s'.", dpm.name);
    return -1;
  }
  snd_pcm_nonblock(handle, 0); /* set back to blocking mode */

  snd_pcm_hw_params_alloca(&pinfo);
  snd_pcm_sw_params_alloca(&swpinfo);

  if (snd_pcm_hw_params_any(handle, pinfo) < 0) {
    ctl->cmsg(CMSG_ERROR, VERB_NORMAL,
	      "ALSA pcm '%s' can't initialize hw_params",
	      alsa_device_name());
    snd_pcm_close(handle);
    return -1;
  }

#ifdef LITTLE_ENDIAN
#define S16_FORMAT	SND_PCM_FORMAT_S16_LE
#define U16_FORMAT	SND_PCM_FORMAT_U16_LE
#else
#define S16_FORMAT	SND_PCM_FORMAT_S16_BE
#define U16_FORMAT	SND_PCM_FORMAT_U16_LE
#endif

  dpm.encoding &= ~(PE_ULAW|PE_ALAW|PE_BYTESWAP);
  /*check sample bit*/
  if (snd_pcm_hw_params_test_format(handle, pinfo, S16_FORMAT) < 0 &&
      snd_pcm_hw_params_test_format(handle, pinfo, U16_FORMAT) < 0)
    dpm.encoding &= ~PE_16BIT; /*force 8bit samples*/
  if (snd_pcm_hw_params_test_format(handle, pinfo, SND_PCM_FORMAT_U8) < 0 &&
      snd_pcm_hw_params_test_format(handle, pinfo, SND_PCM_FORMAT_S8) < 0)
    dpm.encoding |= PE_16BIT; /*force 16bit samples*/

  /*check format*/
  if (dpm.encoding & PE_16BIT) {
    /*16bit*/
    if (snd_pcm_hw_params_set_format(handle, pinfo, S16_FORMAT) == 0)
      dpm.encoding |= PE_SIGNED;
    else if (snd_pcm_hw_params_set_format(handle, pinfo, U16_FORMAT) == 0)
      dpm.encoding &= ~PE_SIGNED;
    else {
      ctl->cmsg(CMSG_ERROR, VERB_NORMAL,
		"ALSA pcm '%s' doesn't support 16 bit sample width",
		alsa_device_name());
      snd_pcm_close(handle);
      return -1;
    }
  } else {
    /*8bit*/
    if (snd_pcm_hw_params_set_format(handle, pinfo, SND_PCM_FORMAT_U8) == 0)
      dpm.encoding &= ~PE_SIGNED;
    else if (snd_pcm_hw_params_set_format(handle, pinfo, SND_PCM_FORMAT_S8) == 0)
      dpm.encoding |= PE_SIGNED;
    else {
      ctl->cmsg(CMSG_ERROR, VERB_NORMAL,
		"ALSA pcm '%s' doesn't support 8 bit sample width",
		alsa_device_name());
      snd_pcm_close(handle);
      return -1;
    }
  }

  if (snd_pcm_hw_params_set_access(handle, pinfo,
				   SND_PCM_ACCESS_RW_INTERLEAVED) < 0) {
    ctl->cmsg(CMSG_ERROR, VERB_NORMAL,
	      "ALSA pcm '%s' doesn't support interleaved data",
	      alsa_device_name());
    snd_pcm_close(handle);
    return -1;
  }

  /*check rate*/
  r = snd_pcm_hw_params_get_rate_min(pinfo, NULL);
  if (r >= 0 && r > dpm.rate) {
    dpm.rate = r;
    ret_val = 1;
  }
  r = snd_pcm_hw_params_get_rate_max(pinfo, NULL);
  if (r >= 0 && r < dpm.rate) {
    dpm.rate = r;
    ret_val = 1;
  }
  if ((rate = snd_pcm_hw_params_set_rate_near(handle, pinfo, dpm.rate, 0)) < 0) {
    ctl->cmsg(CMSG_ERROR, VERB_NORMAL,
	      "ALSA pcm '%s' can't set rate %d",
	      alsa_device_name(), dpm.rate);
    snd_pcm_close(handle);
    return -1;
  }

  /*check channels*/
  if (dpm.encoding & PE_MONO) {
    if (snd_pcm_hw_params_test_channels(handle, pinfo, 1) < 0)
      dpm.encoding &= ~PE_MONO;
  } else {
    if (snd_pcm_hw_params_test_channels(handle, pinfo, 2) < 0)
      dpm.encoding |= PE_MONO;
  }
    
  if (dpm.encoding & PE_MONO) {
    if (snd_pcm_hw_params_set_channels(handle, pinfo, 1) < 0) {
      ctl->cmsg(CMSG_ERROR, VERB_NORMAL,
		"ALSA pcm '%s' can't set mono channel",
		alsa_device_name());
      snd_pcm_close(handle);
      return -1;
    }
  } else {
    if (snd_pcm_hw_params_set_channels(handle, pinfo, 2) < 0) {
      ctl->cmsg(CMSG_ERROR, VERB_NORMAL,
		"ALSA pcm '%s' can't set stereo channels",
		alsa_device_name());
      snd_pcm_close(handle);
      return -1;
    }
  }

  sample_shift = 0;
  if (!(dpm.encoding & PE_MONO))
    sample_shift++;
  if (dpm.encoding & PE_16BIT)
    sample_shift++;

  /* Set buffer fragment size (in extra_param[1]) */
  if (dpm.extra_param[1] != 0)
    frag_size = dpm.extra_param[1];
  else
    frag_size = audio_buffer_size << sample_shift;

  /* Set buffer fragments (in extra_param[0]) */
  if (dpm.extra_param[0] == 0)
    frags = 4;
  else
    frags = dpm.extra_param[0];