pas2_midi.c

LINUX1.0内核源代码,学习LINUX编程的一定要看。

/*
 * sound/pas2_midi.c
 * 
 * The low level driver for the PAS Midi Interface.
 * 
 * Copyright by Hannu Savolainen 1993
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met: 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer. 2.
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * 
 */

#include "sound_config.h"

#ifdef CONFIGURE_SOUNDCARD

#include "pas.h"

#if !defined(EXCLUDE_PAS) && !defined(EXCLUDE_MIDI) && defined(EXCLUDE_PRO_MIDI)

static int      midi_busy = 0, input_opened = 0;
static int      my_dev;
static volatile int ofifo_bytes = 0;

static unsigned char tmp_queue[256];
static volatile int qlen;
static volatile unsigned char qhead, qtail;

static void     (*midi_input_intr) (int dev, unsigned char data);

static int
pas_midi_open (int dev, int mode,
	       void            (*input) (int dev, unsigned char data),
	       void            (*output) (int dev)
)
{
  int             err;
  unsigned long   flags;
  unsigned char   ctrl;


  if (midi_busy)
    {
      printk ("PAS2: Midi busy\n");
      return RET_ERROR (EBUSY);
    }

  /* Reset input and output FIFO pointers */
  pas_write (M_C_RESET_INPUT_FIFO | M_C_RESET_OUTPUT_FIFO,
	     MIDI_CONTROL);

  DISABLE_INTR (flags);

  if ((err = pas_set_intr (I_M_MIDI_IRQ_ENABLE)) < 0)
    return err;

  /* Enable input available and output FIFO empty interrupts */

  ctrl = 0;
  input_opened = 0;
  midi_input_intr = input;

  if (mode == OPEN_READ || mode == OPEN_READWRITE)
    {
      ctrl |= M_C_ENA_INPUT_IRQ;/* Enable input */
      input_opened = 1;
    }

  if (mode == OPEN_WRITE || mode == OPEN_READWRITE)
    {
      ctrl |= M_C_ENA_OUTPUT_IRQ |	/* Enable output */
	M_C_ENA_OUTPUT_HALF_IRQ;
    }

  pas_write (ctrl,
	     MIDI_CONTROL);

  /* Acknowledge any pending interrupts */

  pas_write (0xff, MIDI_STATUS);
  ofifo_bytes = 0;

  RESTORE_INTR (flags);

  midi_busy = 1;
  qlen = qhead = qtail = 0;
  return 0;
}

static void
pas_midi_close (int dev)
{

  /* Reset FIFO pointers, disable intrs */
  pas_write (M_C_RESET_INPUT_FIFO | M_C_RESET_OUTPUT_FIFO, MIDI_CONTROL);

  pas_remove_intr (I_M_MIDI_IRQ_ENABLE);
  midi_busy = 0;
}

static int
dump_to_midi (unsigned char midi_byte)
{
  int             fifo_space, x;

  fifo_space = ((x = pas_read (MIDI_FIFO_STATUS)) >> 4) & 0x0f;

  if (fifo_space == 15 || (fifo_space < 2 && ofifo_bytes > 13))	/* Fifo full */
    {
      return 0;			/* Upper layer will call again */
    }

  ofifo_bytes++;

  pas_write (midi_byte, MIDI_DATA);

  return 1;
}

static int
pas_midi_out (int dev, unsigned char midi_byte)
{

  unsigned long   flags;

  /*
   * Drain the local queue first
   */

  DISABLE_INTR (flags);

  while (qlen && dump_to_midi (tmp_queue[qhead]))
    {
      qlen--;
      qhead++;
    }

  RESTORE_INTR (flags);

  /*
   * Output the byte if the local queue is empty.
   */

  if (!qlen)
    if (dump_to_midi (midi_byte))
      return 1;			/* OK */

  /*
   * Put to the local queue
   */

  if (qlen >= 256)
    return 0;			/* Local queue full */

  DISABLE_INTR (flags);

  tmp_queue[qtail] = midi_byte;
  qlen++;
  qtail++;

  RESTORE_INTR (flags);

  return 1;
}

static int
pas_midi_start_read (int dev)
{
  return 0;
}

static int
pas_midi_end_read (int dev)
{
  return 0;
}

static int
pas_midi_ioctl (int dev, unsigned cmd, unsigned arg)
{
  return RET_ERROR (EINVAL);
}

static void
pas_midi_kick (int dev)
{
  ofifo_bytes = 0;
}

static int
pas_buffer_status (int dev)
{
  return !qlen;
}

static struct midi_operations pas_midi_operations =
{
  {"Pro Audio Spectrum", 0, 0, SNDCARD_PAS},
  pas_midi_open,
  pas_midi_close,
  pas_midi_ioctl,
  pas_midi_out,
  pas_midi_start_read,
  pas_midi_end_read,
  pas_midi_kick,
  NULL,				/* command */
  pas_buffer_status
};

long
pas_midi_init (long mem_start)
{
  my_dev = num_midis;
  midi_devs[num_midis++] = &pas_midi_operations;
  return mem_start;
}

void
pas_midi_interrupt (void)
{
  unsigned char   stat;
  int             i, incount;
  unsigned long   flags;

  stat = pas_read (MIDI_STATUS);

  if (stat & M_S_INPUT_AVAIL)	/* Input byte available */
    {
      incount = pas_read (MIDI_FIFO_STATUS) & 0x0f;	/* Input FIFO count */
      if (!incount)
	incount = 16;

      for (i = 0; i < incount; i++)
	if (input_opened)
	  {
	    midi_input_intr (my_dev, pas_read (MIDI_DATA));
	  }
	else
	  pas_read (MIDI_DATA);	/* Flush */
    }

  if (stat & (M_S_OUTPUT_EMPTY | M_S_OUTPUT_HALF_EMPTY))
    {
      if (!(stat & M_S_OUTPUT_EMPTY))
	{
	  ofifo_bytes = 8;
	}
      else
	{
	  ofifo_bytes = 0;
	}

      DISABLE_INTR (flags);

      while (qlen && dump_to_midi (tmp_queue[qhead]))
	{
	  qlen--;
	  qhead++;
	}

      RESTORE_INTR (flags);
    }

  if (stat & M_S_FRAMING_ERROR)
    printk ("MIDI framing error\n");

  if (stat & M_S_OUTPUT_OVERRUN)
    {
      printk ("MIDI output overrun %x,%x,%d \n", pas_read (MIDI_FIFO_STATUS), stat, ofifo_bytes);
      ofifo_bytes = 100;
    }

  pas_write (stat, MIDI_STATUS);/* Acknowledge interrupts */
}

#endif

#endif