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amisound.c

/*
 * linux/arch/m68k/amiga/amisound.c
 *
 * amiga sound driver for Linux/m68k
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details.
 */

#include <linux/jiffies.h>
#include <linux/timer.h>
#include <linux/init.h>
#include <linux/string.h>

#include <asm/system.h>
#include <asm/amigahw.h>

static unsigned short *snd_data;
static const signed char sine_data[] = {
      0,  39,  75,  103,  121,  127,  121,  103,  75,  39,
      0, -39, -75, -103, -121, -127, -121, -103, -75, -39
};
#define DATA_SIZE (sizeof(sine_data)/sizeof(sine_data[0]))

#define custom amiga_custom

    /*
     * The minimum period for audio may be modified by the frame buffer
     * device since it depends on htotal (for OCS/ECS/AGA)
     */

volatile unsigned short amiga_audio_min_period = 124; /* Default for pre-OCS */

#define MAX_PERIOD      (65535)


    /*
     *      Current period (set by dmasound.c)
     */

unsigned short amiga_audio_period = MAX_PERIOD;

static unsigned long clock_constant;

void __init amiga_init_sound(void)
{
      static struct resource beep_res = { .name = "Beep" };

      snd_data = amiga_chip_alloc_res(sizeof(sine_data), &beep_res);
      if (!snd_data) {
            printk (KERN_CRIT "amiga init_sound: failed to allocate chipmem\n");
            return;
      }
      memcpy (snd_data, sine_data, sizeof(sine_data));

      /* setup divisor */
      clock_constant = (amiga_colorclock+DATA_SIZE/2)/DATA_SIZE;

      /* without amifb, turn video off and enable high quality sound */
#ifndef CONFIG_FB_AMIGA
      amifb_video_off();
#endif
}

static void nosound( unsigned long ignored );
static DEFINE_TIMER(sound_timer, nosound, 0, 0);

void amiga_mksound( unsigned int hz, unsigned int ticks )
{
      unsigned long flags;

      if (!snd_data)
            return;

      local_irq_save(flags);
      del_timer( &sound_timer );

      if (hz > 20 && hz < 32767) {
            unsigned long period = (clock_constant / hz);

            if (period < amiga_audio_min_period)
                  period = amiga_audio_min_period;
            if (period > MAX_PERIOD)
                  period = MAX_PERIOD;

            /* setup pointer to data, period, length and volume */
            custom.aud[2].audlc = snd_data;
            custom.aud[2].audlen = sizeof(sine_data)/2;
            custom.aud[2].audper = (unsigned short)period;
            custom.aud[2].audvol = 32; /* 50% of maxvol */

            if (ticks) {
                  sound_timer.expires = jiffies + ticks;
                  add_timer( &sound_timer );
            }

            /* turn on DMA for audio channel 2 */
            custom.dmacon = DMAF_SETCLR | DMAF_AUD2;

      } else
            nosound( 0 );

      local_irq_restore(flags);
}


static void nosound( unsigned long ignored )
{
      /* turn off DMA for audio channel 2 */
      custom.dmacon = DMAF_AUD2;
      /* restore period to previous value after beeping */
      custom.aud[2].audper = amiga_audio_period;
}

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