reverb.c

MIDI解码程序(用VC编写)

        /* R */
        LPFR = LPFR * lpflev + (buf2_R[spt2] + tb) * lpfinp + ta * width;
        ta = buf3_R[spt3];
        s  = buf3_R[spt3] = buf0_R[spt0];
        buf0_R[spt0] = LPFR;

        t = (HPFR + fixp) * hpflev;
        HPFR = t - fixp;

        buf2_R[spt2] = (s - fixp * fbklev) * nmixlev;
        tb = buf1_R[spt1];
        buf1_R[spt1] = t;

        EPFR = EPFR * epflev + ta * epfinp;
        buf[i] = (ta + EPFR) * wet + fixp;

		if (++spt0 == rpt0) {spt0 = 0;}
		if (++spt1 == rpt1) {spt1 = 0;}
		if (++spt2 == rpt2) {spt2 = 0;}
		if (++spt3 == rpt3) {spt3 = 0;}
	}
	memset(reverb_effect_buffer, 0, sizeof(int32) * count);
	info->spt0 = spt0, info->spt1 = spt1, info->spt2 = spt2, info->spt3 = spt3,
	info->ta = ta, info->tb = tb, info->HPFL = HPFL, info->HPFR = HPFR,
	info->LPFL = LPFL, info->LPFR = LPFR, info->EPFL = EPFL, info->EPFR = EPFR;
}

/* dummy */
void reverb_rc_event(int rc, int32 val)
{
    switch(rc)
    {
      case RC_CHANGE_REV_EFFB:
        break;
      case RC_CHANGE_REV_TIME:
        break;
    }
}

/*             */
/*  Freeverb   */
/*             */
static void set_freeverb_allpass(allpass *allpass, int32 size)
{
	if(allpass->buf != NULL) {
		free(allpass->buf);
		allpass->buf = NULL;
	}
	allpass->buf = (int32 *)safe_malloc(sizeof(int32) * size);
	if(allpass->buf == NULL) {return;}
	allpass->index = 0;
	allpass->size = size;
}

static void init_freeverb_allpass(allpass *allpass)
{
	memset(allpass->buf, 0, sizeof(int32) * allpass->size);
}

static void set_freeverb_comb(comb *comb, int32 size)
{
	if(comb->buf != NULL) {
		free(comb->buf);
		comb->buf = NULL;
	}
	comb->buf = (int32 *)safe_malloc(sizeof(int32) * size);
	if(comb->buf == NULL) {return;}
	comb->index = 0;
	comb->size = size;
	comb->filterstore = 0;
}

static void init_freeverb_comb(comb *comb)
{
	memset(comb->buf, 0, sizeof(int32) * comb->size);
}

#define scalewet 0.06f
#define scaledamp 0.4f
#define scaleroom 0.28f
#define offsetroom 0.7f
#define initialroom 0.5f
#define initialdamp 0.5f
#define initialwet 1 / scalewet
#define initialdry 0
#define initialwidth 0.5f
#define initialallpassfbk 0.65f
#define stereospread 23
static int combtunings[numcombs] = {1116, 1188, 1277, 1356, 1422, 1491, 1557, 1617};
static int allpasstunings[numallpasses] = {225, 341, 441, 556};
#define fixedgain 0.025f
#define combfbk 3.0f

static void realloc_freeverb_buf(InfoFreeverb *rev)
{
	int i;
	int32 tmpL, tmpR;
	double time, samplerate = play_mode->rate;

	time = reverb_time_table[reverb_status_gs.time] * gs_revchar_to_rt(reverb_status_gs.character) * combfbk
		/ (60 * combtunings[numcombs - 1] / (-20 * log10(rev->roomsize1) * 44100.0));

	for(i = 0; i < numcombs; i++)
	{
		tmpL = combtunings[i] * samplerate * time / 44100.0;
		tmpR = (combtunings[i] + stereospread) * samplerate * time / 44100.0;
		if(tmpL < 10) tmpL = 10;
		if(tmpR < 10) tmpR = 10;
		while(!isprime(tmpL)) tmpL++;
		while(!isprime(tmpR)) tmpR++;
		rev->combL[i].size = tmpL;
		rev->combR[i].size = tmpR;
		set_freeverb_comb(&rev->combL[i], rev->combL[i].size);
		set_freeverb_comb(&rev->combR[i], rev->combR[i].size);
	}

	for(i = 0; i < numallpasses; i++)
	{
		tmpL = allpasstunings[i] * samplerate * time / 44100.0;
		tmpR = (allpasstunings[i] + stereospread) * samplerate * time / 44100.0;
		if(tmpL < 10) tmpL = 10;
		if(tmpR < 10) tmpR = 10;
		while(!isprime(tmpL)) tmpL++;
		while(!isprime(tmpR)) tmpR++;
		rev->allpassL[i].size = tmpL;
		rev->allpassR[i].size = tmpR;
		set_freeverb_allpass(&rev->allpassL[i], rev->allpassL[i].size);
		set_freeverb_allpass(&rev->allpassR[i], rev->allpassR[i].size);
	}
}

static void update_freeverb(InfoFreeverb *rev)
{
	int i;
	double allpassfbk = 0.55, rtbase, rt;

	rev->wet = (double)reverb_status_gs.level / 127.0f * gs_revchar_to_level(reverb_status_gs.character) * fixedgain;
	rev->roomsize = gs_revchar_to_roomsize(reverb_status_gs.character) * scaleroom + offsetroom;
	rev->width = 0.5f;

	rev->wet1 = rev->width / 2.0f + 0.5f;
	rev->wet2 = (1.0f - rev->width) / 2.0f;
	rev->roomsize1 = rev->roomsize;
	rev->damp1 = rev->damp;

	realloc_freeverb_buf(rev);

	rtbase = 1.0 / (44100.0 * reverb_time_table[reverb_status_gs.time] * gs_revchar_to_rt(reverb_status_gs.character));

	for(i = 0; i < numcombs; i++)
	{
		rt = pow(10.0f, -combfbk * (double)combtunings[i] * rtbase);
		rev->combL[i].feedback = rt;
		rev->combR[i].feedback = rt;
		rev->combL[i].damp1 = rev->damp1;
		rev->combR[i].damp1 = rev->damp1;
		rev->combL[i].damp2 = 1 - rev->damp1;
		rev->combR[i].damp2 = 1 - rev->damp1;
		rev->combL[i].damp1i = TIM_FSCALE(rev->combL[i].damp1, 24);
		rev->combR[i].damp1i = TIM_FSCALE(rev->combR[i].damp1, 24);
		rev->combL[i].damp2i = TIM_FSCALE(rev->combL[i].damp2, 24);
		rev->combR[i].damp2i = TIM_FSCALE(rev->combR[i].damp2, 24);
		rev->combL[i].feedbacki = TIM_FSCALE(rev->combL[i].feedback, 24);
		rev->combR[i].feedbacki = TIM_FSCALE(rev->combR[i].feedback, 24);
	}

	for(i = 0; i < numallpasses; i++)
	{
		rev->allpassL[i].feedback = allpassfbk;
		rev->allpassR[i].feedback = allpassfbk;
		rev->allpassL[i].feedbacki = TIM_FSCALE(rev->allpassL[i].feedback, 24);
		rev->allpassR[i].feedbacki = TIM_FSCALE(rev->allpassR[i].feedback, 24);
	}

	rev->wet1i = TIM_FSCALE(rev->wet1, 24);
	rev->wet2i = TIM_FSCALE(rev->wet2, 24);

	set_delay(&(rev->pdelay), (int32)((double)reverb_status_gs.pre_delay_time * play_mode->rate / 1000.0f));
}

static void init_freeverb(InfoFreeverb *rev)
{
	int i;
	for(i = 0; i < numcombs; i++) {
		init_freeverb_comb(&rev->combL[i]);
		init_freeverb_comb(&rev->combR[i]);
	}
	for(i = 0; i < numallpasses; i++) {
		init_freeverb_allpass(&rev->allpassL[i]);
		init_freeverb_allpass(&rev->allpassR[i]);
	}
}

static void alloc_freeverb_buf(InfoFreeverb *rev)
{
	int i;
	if(rev->alloc_flag) {return;}
	for (i = 0; i < numcombs; i++) {
		set_freeverb_comb(&rev->combL[i], combtunings[i]);
		set_freeverb_comb(&rev->combR[i], combtunings[i] + stereospread);
	}
	for (i = 0; i < numallpasses; i++) {
		set_freeverb_allpass(&rev->allpassL[i], allpasstunings[i]);
		set_freeverb_allpass(&rev->allpassR[i], allpasstunings[i] + stereospread);
		rev->allpassL[i].feedback = initialallpassfbk;
		rev->allpassR[i].feedback = initialallpassfbk;
	}

	rev->wet = initialwet * scalewet;
	rev->damp = initialdamp * scaledamp;
	rev->width = initialwidth;
	rev->roomsize = initialroom * scaleroom + offsetroom;

	rev->alloc_flag = 1;
}

static void free_freeverb_buf(InfoFreeverb *rev)
{
	int i;
	
	for(i = 0; i < numcombs; i++)
	{
		if(rev->combL[i].buf != NULL) {
			free(rev->combL[i].buf);
			rev->combL[i].buf = NULL;
		}
		if(rev->combR[i].buf != NULL) {
			free(rev->combR[i].buf);
			rev->combR[i].buf = NULL;
		}
	}
	for(i = 0; i < numallpasses; i++)
	{
		if(rev->allpassL[i].buf != NULL) {
			free(rev->allpassL[i].buf);
			rev->allpassL[i].buf = NULL;
		}
		if(rev->allpassR[i].buf != NULL) {
			free(rev->allpassR[i].buf);
			rev->allpassR[i].buf = NULL;
		}
	}
	free_delay(&(rev->pdelay));
}

static inline void do_freeverb_allpass(int32 *stream, int32 *buf, int32 size, int32 *index, int32 feedback)
{
	int32 bufout, output;
	bufout = buf[*index];
	output = -*stream + bufout;
	buf[*index] = *stream + imuldiv24(bufout, feedback);
	if (++*index >= size) {*index = 0;}
	*stream = output;
}

static inline void do_freeverb_comb(int32 input, int32 *stream, int32 *buf, int32 size, int32 *index,
									int32 damp1, int32 damp2, int32 *fs, int32 feedback)
{
	int32 output;
	output = buf[*index];
	*fs = imuldiv24(output, damp2) + imuldiv24(*fs, damp1);
	buf[*index] = input + imuldiv24(*fs, feedback);
	if (++*index >= size) {*index = 0;}
	*stream += output;
}

static void do_ch_freeverb(int32 *buf, int32 count, InfoFreeverb *rev)
{
	int32 i, k = 0;
	int32 outl, outr, input;
	comb *combL = rev->combL, *combR = rev->combR;
	allpass *allpassL = rev->allpassL, *allpassR = rev->allpassR;
	delay *pdelay = &(rev->pdelay);

	if(count == MAGIC_INIT_EFFECT_INFO) {
		alloc_freeverb_buf(rev);
		update_freeverb(rev);
		init_freeverb(rev);
		return;
	} else if(count == MAGIC_FREE_EFFECT_INFO) {
		free_freeverb_buf(rev);
		return;
	}

	for (k = 0; k < count; k++)
	{
		input = reverb_effect_buffer[k] + reverb_effect_buffer[k + 1];
		outl = outr = reverb_effect_buffer[k] = reverb_effect_buffer[k + 1] = 0;

		do_delay(&input, pdelay->buf, pdelay->size, &pdelay->index);

		for (i = 0; i < numcombs; i++) {
			do_freeverb_comb(input, &outl, combL[i].buf, combL[i].size, &combL[i].index,
				combL[i].damp1i, combL[i].damp2i, &combL[i].filterstore, combL[i].feedbacki);
			do_freeverb_comb(input, &outr, combR[i].buf, combR[i].size, &combR[i].index,
				combR[i].damp1i, combR[i].damp2i, &combR[i].filterstore, combR[i].feedbacki);
		}
		for (i = 0; i < numallpasses; i++) {
			do_freeverb_allpass(&outl, allpassL[i].buf, allpassL[i].size, &allpassL[i].index, allpassL[i].feedbacki);
			do_freeverb_allpass(&outr, allpassR[i].buf, allpassR[i].size, &allpassR[i].index, allpassR[i].feedbacki);
		}
		buf[k] += imuldiv24(outl, rev->wet1i) + imuldiv24(outr, rev->wet2i);
		buf[k + 1] += imuldiv24(outr, rev->wet1i) + imuldiv24(outl, rev->wet2i);
		++k;
	}
}

/*                                 */
/*  Reverb: Delay & Panning Delay  */
/*                                 */
/*! initialize Reverb: Delay Effect; this implementation is specialized for system effect. */
static void init_ch_reverb_delay(InfoDelay3 *info)
{
	int32 x;
	info->size[0] = (double)reverb_status_gs.time * 3.75f * play_mode->rate / 1000.0f;
	x = info->size[0] + 1;	/* allowance */
	set_delay(&(info->delayL), x);
	set_delay(&(info->delayR), x);
	info->index[0] = x - info->size[0];
	info->level[0] = (double)reverb_status_gs.level * 1.82f / 127.0f;
	info->feedback = sqrt((double)reverb_status_gs.delay_feedback / 127.0f) * 0.98f;
	info->leveli[0] = TIM_FSCALE(info->level[0], 24);
	info->feedbacki = TIM_FSCALE(info->feedback, 24);
}

static void free_ch_reverb_delay(InfoDelay3 *info)
{
	free_delay(&(info->delayL));
	free_delay(&(info->delayR));
}

/*! Reverb: Panning Delay Effect; this implementation is specialized for system effect. */
static void do_ch_reverb_panning_delay(int32 *buf, int32 count, InfoDelay3 *info)
{
	int32 i, l, r;
	delay *delayL = &(info->delayL), *delayR = &(info->delayR);
	int32 *bufL = delayL->buf, *bufR = delayR->buf;
	int32 buf_index = delayL->index, buf_size = delayL->size;
	int32 index0 = info->index[0], level0i = info->leveli[0],
		feedbacki = info->feedbacki;

	if(count == MAGIC_INIT_EFFECT_INFO) {
		init_ch_reverb_delay(info);
		return;
	} else if(count == MAGIC_FREE_EFFECT_INFO) {
		free_ch_reverb_delay(info);
		return;
	}

	for (i = 0; i < count; i++)
	{
		bufL[buf_index] = reverb_effect_buffer[i] + imuldiv24(bufR[index0], feedbacki);
		l = imuldiv24(bufL[index0], level0i);
		bufR[buf_index] = reverb_effect_buffer[i + 1] + imuldiv24(bufL[index0], feedbacki);
		r = imuldiv24(bufR[index0], level0i);

		buf[i] += r;
		buf[++i] += l;

		if (++index0 == buf_size) {index0 = 0;}
		if (++buf_index == buf_size) {buf_index = 0;}
	}
	memset(reverb_effect_buffer, 0, sizeof(int32) * count);
	info->index[0] = index0;
	delayL->index = delayR->index = buf_index;
}

/*! Reverb: Normal Delay Effect; this implementation is specialized for system effect. */
static void do_ch_reverb_normal_delay(int32 *buf, int32 count, InfoDelay3 *info)
{
	int32 i;
	delay *delayL = &(info->delayL), *delayR = &(info->delayR);
	int32 *bufL = delayL->buf, *bufR = delayR->buf;
	int32 buf_index = delayL->index, buf_size = delayL->size;
	int32 index0 = info->index[0], level0i = info->leveli[0],
		feedbacki = info->feedbacki;

	if(count == MAGIC_INIT_EFFECT_INFO) {
		init_ch_reverb_delay(info);
		return;
	} else if(count == MAGIC_FREE_EFFECT_INFO) {
		free_ch_reverb_delay(info);
		return;
	}

	for (i = 0; i < count; i++)
	{
		bufL[buf_index] = reverb_effect_buffer[i] + imuldiv24(bufL[index0], feedbacki);
		buf[i] += imuldiv24(bufL[index0], level0i);

		bufR[buf_index] = reverb_effect_buffer[++i] + imuldiv24(bufR[index0], feedbacki);
		buf[i] += imuldiv24(bufR[index0], level0i);

		if (++index0 == buf_size) {index0 = 0;}
		if (++buf_index == buf_size) {buf_index = 0;}
	}
	memset(reverb_effect_buffer, 0, sizeof(int32) * count);
	info->index[0] = index0;
	delayL->index = delayR->index = buf_index;
}

/*                      */
/*  Plate Reverberator  */
/*                      */
#define PLATE_SAMPLERATE 29761.0
#define PLATE_DECAY 0.50
#define PLATE_DECAY_DIFFUSION1 0.70
#define PLATE_DECAY_DIFFUSION2 0.50
#define PLATE_INPUT_DIFFUSION1 0.750
#define PLATE_INPUT_DIFFUSION2 0.625
#define PLATE_BANDWIDTH 0.9955
#define PLATE_DAMPING 0.0005
#define PLATE_WET 0.25

/*! calculate delay sample in current sample-rate */
static inline int32 get_plate_delay(double delay, double t)
{
	return (int32)(delay * play_mode->rate * t / PLATE_SAMPLERATE);
}

/*! Plate Reverberator; this implementation is specialized for system effect. */