es5506.c

十七种模拟器源代码 非常有用的作课程设计不可缺少的

/**********************************************************************************************
 *
 *   Ensoniq ES5505/6 driver
 *   by Aaron Giles
 *
 **********************************************************************************************/


#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include "sasound.h"

#include "driver.h"
#include "adpcm.h"

//#define DUMP 1
/**********************************************************************************************

     CONSTANTS

***********************************************************************************************/

#define BACKEND_INTERPOLATE		1
#define LOG_COMMANDS			0


#define MAX_SAMPLE_CHUNK		10000
#define ULAW_MAXBITS			8

#define FRAC_BITS				14
#define FRAC_ONE				(1 << FRAC_BITS)
#define FRAC_MASK				(FRAC_ONE - 1)


#define CONTROL_BS1				0x8000
#define CONTROL_BS0				0x4000
#define CONTROL_CMPD			0x2000
#define CONTROL_CA2				0x1000
#define CONTROL_CA1				0x0800
#define CONTROL_CA0				0x0400
#define CONTROL_LP4				0x0200
#define CONTROL_LP3				0x0100
#define CONTROL_IRQ				0x0080
#define CONTROL_DIR				0x0040
#define CONTROL_IRQE			0x0020
#define CONTROL_BLE				0x0010
#define CONTROL_LPE				0x0008
#define CONTROL_LEI				0x0004
#define CONTROL_STOP1			0x0002
#define CONTROL_STOP0			0x0001

#define CONTROL_BSMASK			(CONTROL_BS1 | CONTROL_BS0)
#define CONTROL_CAMASK			(CONTROL_CA2 | CONTROL_CA1 | CONTROL_CA0)
#define CONTROL_LPMASK			(CONTROL_LP4 | CONTROL_LP3)
#define CONTROL_LOOPMASK		(CONTROL_BLE | CONTROL_LPE)
#define CONTROL_STOPMASK		(CONTROL_STOP1 | CONTROL_STOP0)



/**********************************************************************************************

     INTERNAL DATA STRUCTURES

***********************************************************************************************/

/* struct describing a single playing voice */
struct ES5506Voice
{
	/* external state */
	UINT32		control;				/* control register */
	UINT32		freqcount;				/* frequency count register */
	UINT32		start;					/* start register */
	UINT32		lvol;					/* left volume register */
	UINT32		end;					/* end register */
	UINT32		lvramp;					/* left volume ramp register */
	UINT32		accum;					/* accumulator register */
	UINT32		rvol;					/* right volume register */
	UINT32		rvramp;					/* right volume ramp register */
	UINT32		ecount;					/* envelope count register */
	UINT32		k2;						/* k2 register */
	UINT32		k2ramp;					/* k2 ramp register */
	UINT32		k1;						/* k1 register */
	UINT32		k1ramp;					/* k1 ramp register */
	INT32		o4n1;					/* filter storage O4(n-1) */
	INT32		o3n1;					/* filter storage O3(n-1) */
	INT32		o3n2;					/* filter storage O3(n-2) */
	INT32		o2n1;					/* filter storage O2(n-1) */
	INT32		o2n2;					/* filter storage O2(n-2) */
	INT32		o1n1;					/* filter storage O1(n-1) */
	UINT32		exbank;					/* external address bank */

	/* internal state */
	UINT8		index;					/* index of this voice */
	UINT8		filtcount;				/* filter count */
};

struct ES5506Chip
{
	int			stream;					/* which stream are we using */
	UINT16 *	region_base[4];			/* pointer to the base of the region */
	UINT32 		write_latch;			/* currently accumulated data for write */
	UINT32 		read_latch;				/* currently accumulated data for read */
	double 		master_clock;			/* master clock frequency */
	void 		(*irq_callback)(int);	/* IRQ callback */
	UINT16		(*port_read)(void);		/* input port read */

	UINT8 		current_page;			/* current register page */
	UINT8		active_voices;			/* number of active voices */
	UINT8		mode;					/* MODE register */
	UINT8		wst;					/* W_ST register */
	UINT8		wend;					/* W_END register */
	UINT8		lrend;					/* LR_END register */
	UINT8		irqv;					/* IRQV register */

	INT32		output_step;			/* step value for frequency conversion */
	INT32		output_pos;				/* current fractional position */
	INT32		last_lsample;			/* last sample output */
	INT32		last_rsample;			/* last sample output */
	INT32		curr_lsample;			/* current sample target */
	INT32		curr_rsample;			/* current sample target */

	struct 		ES5506Voice voice[32];	/* the 32 voices */
};



/**********************************************************************************************

     GLOBALS

***********************************************************************************************/

static struct ES5506Chip es5506[MAX_ES5506];
static INT32 *accumulator;
static INT32 *scratch;

static INT16 *ulaw_lookup;
static UINT16 *volume_lookup;

static FILE *eslog;



/**********************************************************************************************

     update_irq_state -- update the IRQ state

***********************************************************************************************/

INLINE static void update_irq_state(struct ES5506Chip *chip)
{
#if 0
	int irq_bits = chip->status_register & chip->irq_mask;

	/* always off if the enable is off */
	if (!chip->irq_enable)
		irq_bits = 0;

	/* update the state if changed */
	if (irq_bits && !chip->irq_state)
	{
		chip->irq_state = 1;
		if (chip->irq_callback)
			(*chip->irq_callback)(1);
	}
	else if (!irq_bits && chip->irq_state)
	{
		chip->irq_state = 0;
		if (chip->irq_callback)
			(*chip->irq_callback)(0);
	}
#endif
}



/**********************************************************************************************

     compute_tables -- compute static tables

***********************************************************************************************/

static int compute_tables(void)
{
	int i;
	
	/* allocate ulaw lookup table */
	if (!ulaw_lookup)
		ulaw_lookup = malloc(sizeof(ulaw_lookup[0]) << ULAW_MAXBITS);
	if (!ulaw_lookup)
		return 0;
	
	/* generate ulaw lookup table */
	for (i = 0; i < (1 << ULAW_MAXBITS); i++)
	{
		UINT16 rawval = (i << (16 - ULAW_MAXBITS)) | (1 << (15 - ULAW_MAXBITS));
		UINT8 exponent = rawval >> 13;
		UINT32 mantissa = (rawval << 3) & 0xffff;
		
		if (exponent == 0)
			ulaw_lookup[i] = (INT16)mantissa >> 7;
		else
		{
			mantissa = (mantissa >> 1) | (~mantissa & 0x8000);
			ulaw_lookup[i] = (INT16)mantissa >> (7 - exponent);
		}
	}

	/* allocate volume lookup table */
	if (!volume_lookup)
		volume_lookup = malloc(sizeof(volume_lookup[0]) * 4096);
	if (!volume_lookup)
		return 0;
	
	/* generate ulaw lookup table */
	for (i = 0; i < 4096; i++)
	{
		UINT8 exponent = i >> 8;
		UINT32 mantissa = (i & 0xff) | 0x100;
		
		volume_lookup[i] = (mantissa << 11) >> (20 - exponent);
	}

	return 1;
}



/**********************************************************************************************

     interpolate
     backend_interpolate -- interpolate between two samples

***********************************************************************************************/

#define interpolate(sample1, sample2, accum)										\
		(sample1 * (INT32)(0x800 - (voice->accum & 0x7ff)) + 						\
		 sample2 * (INT32)(voice->accum & 0x7ff)) >> 11;

#if BACKEND_INTERPOLATE
#define backend_interpolate(sample1, sample2, position)								\
		(sample1 * (INT32)(FRAC_ONE - position) + 									\
		 sample2 * (INT32)position) >> FRAC_BITS;
#else
#define backend_interpolate(sample1, sample2, position)	sample1
#endif



/**********************************************************************************************

     apply_filters -- apply the 4-pole digital filter to the sample

***********************************************************************************************/

#define apply_filters(voice, sample)															\
do																								\
{																								\
	/* pole 1 is always low-pass using K1 */													\
	sample = ((INT32)(voice->k1 >> 2) * (sample - voice->o1n1) / 16384) + voice->o1n1;			\
	voice->o1n1 = sample;																		\
																								\
	/* pole 2 is always low-pass using K1 */													\
	sample = ((INT32)(voice->k1 >> 2) * (sample - voice->o2n1) / 16384) + voice->o2n1;			\
	voice->o2n2 = voice->o2n1;																	\
	voice->o2n1 = sample;																		\
																								\
	/* remaining poles depend on the current filter setting */									\
	switch (voice->control & CONTROL_LPMASK)													\
	{																							\
		case 0:																					\
			/* pole 3 is high-pass using K2 */													\
			sample = sample - voice->o2n2 + ((INT32)(voice->k2 >> 2) * voice->o3n1) / 32768 + voice->o3n1 / 2; \
			voice->o3n2 = voice->o3n1;															\
			voice->o3n1 = sample;																\
																								\
			/* pole 4 is high-pass using K2 */													\
			sample = sample - voice->o3n2 + ((INT32)(voice->k2 >> 2) * voice->o4n1) / 32768 + voice->o4n1 / 2; \
			voice->o4n1 = sample;																\
			break;																				\
																								\
		case CONTROL_LP3:																		\
			/* pole 3 is low-pass using K1 */													\
			sample = ((INT32)(voice->k1 >> 2) * (sample - voice->o3n1) / 16384) + voice->o3n1;	\
			voice->o3n2 = voice->o3n1;															\
			voice->o3n1 = sample;																\
																								\
			/* pole 4 is high-pass using K2 */													\
			sample = sample - voice->o3n2 + ((INT32)(voice->k2 >> 2) * voice->o4n1) / 32768 + voice->o4n1 / 2; \
			voice->o4n1 = sample;																\
			break;																				\
																								\
		case CONTROL_LP4:																		\
			/* pole 3 is low-pass using K2 */													\
			sample = ((INT32)(voice->k2 >> 2) * (sample - voice->o3n1) / 16384) + voice->o3n1;	\
			voice->o3n2 = voice->o3n1;															\
			voice->o3n1 = sample;																\
																								\
			/* pole 4 is low-pass using K2 */													\
			sample = ((INT32)(voice->k2 >> 2) * (sample - voice->o4n1) / 16384) + voice->o4n1;	\
			voice->o4n1 = sample;																\
			break;																				\
																								\
		case CONTROL_LP4 | CONTROL_LP3:															\
			/* pole 3 is low-pass using K1 */													\
			sample = ((INT32)(voice->k1 >> 2) * (sample - voice->o3n1) / 16384) + voice->o3n1;	\
			voice->o3n2 = voice->o3n1;															\
			voice->o3n1 = sample;																\
																								\
			/* pole 4 is low-pass using K2 */													\
			sample = ((INT32)(voice->k2 >> 2) * (sample - voice->o4n1) / 16384) + voice->o4n1;	\
			voice->o4n1 = sample;																\
			break;																				\
	}																							\
} while (0)



/**********************************************************************************************

     update_envelopes -- update the envelopes

***********************************************************************************************/

#define update_envelopes(voice, samples)											\
do																					\
{																					\
	int count = (samples > 1 && samples > voice->ecount) ? voice->ecount : samples;	\
																					\
	/* decrement the envelope counter */											\
	voice->ecount -= count;															\
																					\
	/* ramp left volume */															\
	if (voice->lvramp)																\
	{																				\
		voice->lvol += (INT8)voice->lvramp * count;									\
		if ((INT32)voice->lvol < 0) voice->lvol = 0;								\
		else if (voice->lvol > 0xffff) voice->lvol = 0xffff;						\
	}																				\
																					\
	/* ramp right volume */															\
	if (voice->rvramp)																\
	{																				\
		voice->rvol += (INT8)voice->rvramp * count;									\
		if ((INT32)voice->rvol < 0) voice->rvol = 0;								\
		else if (voice->rvol > 0xffff) voice->rvol = 0xffff;						\
	}																				\
																					\
	/* ramp k1 filter constant */													\
	if (voice->k1ramp && ((INT32)voice->k1ramp >= 0 || !(voice->filtcount & 7)))	\
	{																				\
		voice->k1 += (INT8)voice->k1ramp * count;									\
		if ((INT32)voice->k1 < 0) voice->k1 = 0;									\
		else if (voice->k1 > 0xffff) voice->k1 = 0xffff;							\
	}																				\
																					\
	/* ramp k2 filter constant */													\
	if (voice->k2ramp && ((INT32)voice->k2ramp >= 0 || !(voice->filtcount & 7)))	\
	{																				\
		voice->k2 += (INT8)voice->k2ramp * count;									\
		if ((INT32)voice->k2 < 0) voice->k2 = 0;									\
		else if (voice->k2 > 0xffff) voice->k2 = 0xffff;							\
	}																				\
																					\
	/* update the filter constant counter */										\
	voice->filtcount += count;														\
																					\
} while (0)



/**********************************************************************************************

     check_for_end_forward
     check_for_end_reverse -- check for loop end and loop appropriately

***********************************************************************************************/

#define check_for_end_forward(voice, accum)											\
do																					\
{																					\
	/* are we past the end? */														\
	if (accum > voice->end && !(voice->control & CONTROL_LEI))					\
	{																				\
		/* generate interrupt */													\
		voice->control |= CONTROL_IRQ;												\
																					\
		/* handle the different types of looping */									\
		switch (voice->control & CONTROL_LOOPMASK)									\
		{																			\
			/* non-looping */														\
			case 0:																	\
				voice->control |= CONTROL_STOP0;									\
				goto alldone;														\
																					\
			/* uni-directional looping */											\
			case CONTROL_LPE:														\
				accum = voice->start + (accum - voice->end);						\
				break;																\
																					\
			/* trans-wave looping */												\
			case CONTROL_BLE:														\
				accum = voice->start + (accum - voice->end);						\
				voice->control = (voice->control & ~CONTROL_LOOPMASK) | CONTROL_LEI;\
				break;																\
																					\
			/* bi-directional looping */											\
			case CONTROL_LPE | CONTROL_BLE:											\
				accum = voice->end - (accum - voice->end);							\
				voice->control ^= CONTROL_DIR;										\
				goto reverse;														\
		}																			\
	}																				\
} while (0)


#define check_for_end_reverse(voice, accum)											\
do																					\
{																					\
	/* are we past the end? */														\
	if (accum < voice->start && !(voice->control & CONTROL_LEI))					\
	{																				\
		/* generate interrupt */													\
		voice->control |= CONTROL_IRQ;												\
																					\
		/* handle the different types of looping */									\
		switch (voice->control & CONTROL_LOOPMASK)									\
		{																			\
			/* non-looping */														\
			case 0:																	\
				voice->control |= CONTROL_STOP0;									\
				goto alldone;														\
																					\
			/* uni-directional looping */											\
			case CONTROL_LPE:														\
				accum = voice->end - (voice->start - accum);						\
				break;																\
																					\
			/* trans-wave looping */												\
			case CONTROL_BLE:														\
				accum = voice->end - (voice->start - accum);						\
				voice->control = (voice->control & ~CONTROL_LOOPMASK) | CONTROL_LEI;\
				break;																\
																					\
			/* bi-directional looping */											\
			case CONTROL_LPE | CONTROL_BLE:											\
				accum = voice->start + (voice->start - accum);						\
				voice->control ^= CONTROL_DIR;										\
				goto reverse;														\
		}																			\
	}																				\
} while (0)



/**********************************************************************************************

     generate_dummy -- generate nothing, just apply envelopes

***********************************************************************************************/

static void generate_dummy(struct ES5506Voice *voice, UINT16 *base, INT32 *lbuffer, INT32 *rbuffer, int samples)
{
	UINT32 freqcount = voice->freqcount;
	UINT32 accum = voice->accum;

	/* outer loop, in case we switch directions */
	while (samples > 0 && !(voice->control & CONTROL_STOPMASK))
	{
reverse:
		/* two cases: first case is forward direction */
		if (!(voice->control & CONTROL_DIR))
		{
			/* loop while we still have samples to generate */
			while (samples--)
			{
				/* fetch two samples */
				accum += freqcount;

				/* update filters/volumes */
				if (voice->ecount != 0)
					update_envelopes(voice, 1);
				
				/* check for loop end */
				check_for_end_forward(voice, accum);
			}
		}

		/* two cases: second case is backward direction */
		else
		{
			/* loop while we still have samples to generate */
			while (samples--)
			{
				/* fetch two samples */
				accum -= freqcount;
				
				/* update filters/volumes */
				if (voice->ecount != 0)
					update_envelopes(voice, 1);
				
				/* check for loop end */
				check_for_end_reverse(voice, accum);
			}
		}
	}

	/* if we stopped, process any additional envelope */