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/*
 * linux/amiga/amisound.c
 *
 * amiga sound driver for 680x0 Linux
 *
 * 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/sched.h>
#include <linux/timer.h>
 
#include <asm/system.h>
#include <asm/amigahw.h>
#include <asm/bootinfo.h>
 
static u_short *snd_data = NULL;
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]))
 
    /*
     * The minimum period for audio may be modified by the frame buffer
     * device since it depends on htotal (for OCS/ECS/AGA)
     */
 
volatile u_short amiga_audio_min_period = 124;	/* Default for pre-OCS */
 
#define MAX_PERIOD	(65535)
 
 
    /*
     *	Current period (set by dmasound.c)
     */
 
u_short amiga_audio_period = MAX_PERIOD;
 
static u_long clock_constant;
 
static void init_sound(void)
{
	snd_data = amiga_chip_alloc(sizeof(sine_data));
	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;
}
 
static void nosound( unsigned long ignored );
static struct timer_list sound_timer = { NULL, NULL, 0, 0, nosound };
 
void amiga_mksound( unsigned int hz, unsigned int ticks )
{
	static int inited = 0;
	unsigned long flags;
 
	if (!inited) {
		init_sound();
		inited = 1;
	}
 
	if (!snd_data)
		return;
 
	save_flags(flags);
	cli();
	del_timer( &sound_timer );
 
	if (hz > 20 && hz < 32767) {
		u_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 = (u_short)period;
		custom.aud[2].audvol = 64; /* 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;
 
		restore_flags(flags);
		return;
	} else {
		nosound( 0 );
		restore_flags(flags);
		return;
	}
}
 
 
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;
}