#include "stdio.h"
#ifndef mips
#include "stdlib.h"
#endif
#include "xlisp.h"
#include "sound.h"

#include "falloc.h"
#include "cext.h"
#include "alpassvv.h"

void alpassvv_free();


typedef struct alpassvv_susp_struct {
    snd_susp_node susp;
    long terminate_cnt;
    sound_type input;
    long input_cnt;
    sample_block_values_type input_ptr;
    sound_type delaysnd;
    long delaysnd_cnt;
    sample_block_values_type delaysnd_ptr;
    sound_type feedback;
    long feedback_cnt;
    sample_block_values_type feedback_ptr;

    float delay_scale_factor;
    long buflen;
    sample_type *delaybuf;
    sample_type *delayptr;
    sample_type *endptr;
} alpassvv_susp_node, *alpassvv_susp_type;


void alpassvv_nnn_fetch(register alpassvv_susp_type susp, snd_list_type snd_list)
{
    int cnt = 0; /* how many samples computed */
    int togo;
    int n;
    sample_block_type out;
    register sample_block_values_type out_ptr;

    register sample_block_values_type out_ptr_reg;

    register float delay_scale_factor_reg;
    register long buflen_reg;
    register sample_type * delayptr_reg;
    register sample_type * endptr_reg;
    register sample_block_values_type feedback_ptr_reg;
    register sample_block_values_type delaysnd_ptr_reg;
    register sample_block_values_type input_ptr_reg;
    falloc_sample_block(out, "alpassvv_nnn_fetch");
    out_ptr = out->samples;
    snd_list->block = out;

    while (cnt < max_sample_block_len) { /* outer loop */
	/* first compute how many samples to generate in inner loop: */
	/* don't overflow the output sample block: */
	togo = max_sample_block_len - cnt;

	/* don't run past the input input sample block: */
	susp_check_term_samples(input, input_ptr, input_cnt);
	togo = MIN(togo, susp->input_cnt);

	/* don't run past the delaysnd input sample block: */
	susp_check_samples(delaysnd, delaysnd_ptr, delaysnd_cnt);
	togo = MIN(togo, susp->delaysnd_cnt);

	/* don't run past the feedback input sample block: */
	susp_check_samples(feedback, feedback_ptr, feedback_cnt);
	togo = MIN(togo, susp->feedback_cnt);

	/* don't run past terminate time */
	if (susp->terminate_cnt != UNKNOWN &&
	    susp->terminate_cnt <= susp->susp.current + cnt + togo) {
	    togo = susp->terminate_cnt - (susp->susp.current + cnt);
	    if (togo == 0) break;
	}

	n = togo;
	delay_scale_factor_reg = susp->delay_scale_factor;
	buflen_reg = susp->buflen;
	delayptr_reg = susp->delayptr;
	endptr_reg = susp->endptr;
	feedback_ptr_reg = susp->feedback_ptr;
	delaysnd_ptr_reg = susp->delaysnd_ptr;
	input_ptr_reg = susp->input_ptr;
	out_ptr_reg = out_ptr;
	if (n) do { /* the inner sample computation loop */
        register sample_type y, z, delaysamp;
        register int delayi;
        register sample_type *yptr;

        /* compute where to read y, we want y to be delay_snd samples
         * after delay_ptr, where we write the new sample. First, 
         * conver from seconds to samples. Note: don't use actual sound_type
         * names in comments! The translator isn't smart enough.
         */
        register sample_type fb = *feedback_ptr_reg++;
        delaysamp = *delaysnd_ptr_reg++ * delay_scale_factor_reg;
        delayi = (int) delaysamp; /* get integer part */
        delaysamp = delaysamp - delayi; /* get phase */
        yptr = delayptr_reg + buflen_reg - (delayi + 1);
        if (yptr >= endptr_reg) yptr -= buflen_reg;
        /* now get y, the out-put of the delay, using interpolation */
        /* note that as phase increases, we use more of yptr[0] because
           positive phase means longer buffer means read earlier sample */
        y = (float) ((yptr[0] * delaysamp) + (yptr[1] * (1.0 - delaysamp)));
        /* WARNING: no check to keep delaysamp in range, so do this in LISP */

        *delayptr_reg++ = z = (sample_type) (fb * y + *input_ptr_reg++);
        /* Time out to update the buffer:
         * this is a tricky buffer: buffer[0] == buffer[bufflen]
         * the logical length is bufflen, but the actual length
         * is bufflen + 1 to allow for a repeated sample at the
         * end. This allows for efficient interpolation.
         */
        if (delayptr_reg > endptr_reg) {
            delayptr_reg = susp->delaybuf;
            *delayptr_reg++ = *endptr_reg;
        }
        *out_ptr_reg++ = (sample_type) (y - fb * z);;
	} while (--n); /* inner loop */

	susp->buflen = buflen_reg;
	susp->delayptr = delayptr_reg;
	/* using feedback_ptr_reg is a bad idea on RS/6000: */
	susp->feedback_ptr += togo;
	/* using delaysnd_ptr_reg is a bad idea on RS/6000: */
	susp->delaysnd_ptr += togo;
	/* using input_ptr_reg is a bad idea on RS/6000: */
	susp->input_ptr += togo;
	out_ptr += togo;
	susp_took(input_cnt, togo);
	susp_took(delaysnd_cnt, togo);
	susp_took(feedback_cnt, togo);
	cnt += togo;
    } /* outer loop */

    /* test for termination */
    if (togo == 0 && cnt == 0) {
	snd_list_terminate(snd_list);
    } else {
	snd_list->block_len = cnt;
	susp->susp.current += cnt;
    }
} /* alpassvv_nnn_fetch */


void alpassvv_nns_fetch(register alpassvv_susp_type susp, snd_list_type snd_list)
{
    int cnt = 0; /* how many samples computed */
    int togo;
    int n;
    sample_block_type out;
    register sample_block_values_type out_ptr;

    register sample_block_values_type out_ptr_reg;

    register float delay_scale_factor_reg;
    register long buflen_reg;
    register sample_type * delayptr_reg;
    register sample_type * endptr_reg;
    register sample_type feedback_scale_reg = susp->feedback->scale;
    register sample_block_values_type feedback_ptr_reg;
    register sample_block_values_type delaysnd_ptr_reg;
    register sample_block_values_type input_ptr_reg;
    falloc_sample_block(out, "alpassvv_nns_fetch");
    out_ptr = out->samples;
    snd_list->block = out;

    while (cnt < max_sample_block_len) { /* outer loop */
	/* first compute how many samples to generate in inner loop: */
	/* don't overflow the output sample block: */
	togo = max_sample_block_len - cnt;

	/* don't run past the input input sample block: */
	susp_check_term_samples(input, input_ptr, input_cnt);
	togo = MIN(togo, susp->input_cnt);

	/* don't run past the delaysnd input sample block: */
	susp_check_samples(delaysnd, delaysnd_ptr, delaysnd_cnt);
	togo = MIN(togo, susp->delaysnd_cnt);

	/* don't run past the feedback input sample block: */
	susp_check_samples(feedback, feedback_ptr, feedback_cnt);
	togo = MIN(togo, susp->feedback_cnt);

	/* don't run past terminate time */
	if (susp->terminate_cnt != UNKNOWN &&
	    susp->terminate_cnt <= susp->susp.current + cnt + togo) {
	    togo = susp->terminate_cnt - (susp->susp.current + cnt);
	    if (togo == 0) break;
	}

	n = togo;
	delay_scale_factor_reg = susp->delay_scale_factor;
	buflen_reg = susp->buflen;
	delayptr_reg = susp->delayptr;
	endptr_reg = susp->endptr;
	feedback_ptr_reg = susp->feedback_ptr;
	delaysnd_ptr_reg = susp->delaysnd_ptr;
	input_ptr_reg = susp->input_ptr;
	out_ptr_reg = out_ptr;
	if (n) do { /* the inner sample computation loop */
        register sample_type y, z, delaysamp;
        register int delayi;
        register sample_type *yptr;

        /* compute where to read y, we want y to be delay_snd samples
         * after delay_ptr, where we write the new sample. First, 
         * conver from seconds to samples. Note: don't use actual sound_type
         * names in comments! The translator isn't smart enough.
         */
        register sample_type fb = (feedback_scale_reg * *feedback_ptr_reg++);
        delaysamp = *delaysnd_ptr_reg++ * delay_scale_factor_reg;
        delayi = (int) delaysamp; /* get integer part */
        delaysamp = delaysamp - delayi; /* get phase */
        yptr = delayptr_reg + buflen_reg - (delayi + 1);
        if (yptr >= endptr_reg) yptr -= buflen_reg;
        /* now get y, the out-put of the delay, using interpolation */
        /* note that as phase increases, we use more of yptr[0] because
           positive phase means longer buffer means read earlier sample */
        y = (float) ((yptr[0] * delaysamp) + (yptr[1] * (1.0 - delaysamp)));
        /* WARNING: no check to keep delaysamp in range, so do this in LISP */

        *delayptr_reg++ = z = (sample_type) (fb * y + *input_ptr_reg++);
        /* Time out to update the buffer:
         * this is a tricky buffer: buffer[0] == buffer[bufflen]
         * the logical length is bufflen, but the actual length
         * is bufflen + 1 to allow for a repeated sample at the
         * end. This allows for efficient interpolation.
         */
        if (delayptr_reg > endptr_reg) {
            delayptr_reg = susp->delaybuf;
            *delayptr_reg++ = *endptr_reg;
        }
        *out_ptr_reg++ = (sample_type) (y - fb * z);;
	} while (--n); /* inner loop */

	susp->buflen = buflen_reg;
	susp->delayptr = delayptr_reg;
	/* using feedback_ptr_reg is a bad idea on RS/6000: */
	susp->feedback_ptr += togo;
	/* using delaysnd_ptr_reg is a bad idea on RS/6000: */
	susp->delaysnd_ptr += togo;
	/* using input_ptr_reg is a bad idea on RS/6000: */
	susp->input_ptr += togo;
	out_ptr += togo;
	susp_took(input_cnt, togo);
	susp_took(delaysnd_cnt, togo);
	susp_took(feedback_cnt, togo);
	cnt += togo;
    } /* outer loop */

    /* test for termination */
    if (togo == 0 && cnt == 0) {
	snd_list_terminate(snd_list);
    } else {
	snd_list->block_len = cnt;
	susp->susp.current += cnt;
    }
} /* alpassvv_nns_fetch */


void alpassvv_nsn_fetch(register alpassvv_susp_type susp, snd_list_type snd_list)
{
    int cnt = 0; /* how many samples computed */
    int togo;
    int n;
    sample_block_type out;
    register sample_block_values_type out_ptr;

    register sample_block_values_type out_ptr_reg;

    register float delay_scale_factor_reg;
    register long buflen_reg;
    register sample_type * delayptr_reg;
    register sample_type * endptr_reg;
    register sample_block_values_type feedback_ptr_reg;
    register sample_type delaysnd_scale_reg = susp->delaysnd->scale;
    register sample_block_values_type delaysnd_ptr_reg;
    register sample_block_values_type input_ptr_reg;
    falloc_sample_block(out, "alpassvv_nsn_fetch");
    out_ptr = out->samples;
    snd_list->block = out;

    while (cnt < max_sample_block_len) { /* outer loop */
	/* first compute how many samples to generate in inner loop: */
	/* don't overflow the output sample block: */
	togo = max_sample_block_len - cnt;

	/* don't run past the input input sample block: */
	susp_check_term_samples(input, input_ptr, input_cnt);
	togo = MIN(togo, susp->input_cnt);

	/* don't run past the delaysnd input sample block: */
	susp_check_samples(delaysnd, delaysnd_ptr, delaysnd_cnt);
	togo = MIN(togo, susp->delaysnd_cnt);

	/* don't run past the feedback input sample block: */
	susp_check_samples(feedback, feedback_ptr, feedback_cnt);
	togo = MIN(togo, susp->feedback_cnt);

	/* don't run past terminate time */
	if (susp->terminate_cnt != UNKNOWN &&
	    susp->terminate_cnt <= susp->susp.current + cnt + togo) {
	    togo = susp->terminate_cnt - (susp->susp.current + cnt);
	    if (togo == 0) break;
	}

	n = togo;
	delay_scale_factor_reg = susp->delay_scale_factor;
	buflen_reg = susp->buflen;
	delayptr_reg = susp->delayptr;
	endptr_reg = susp->endptr;
	feedback_ptr_reg = susp->feedback_ptr;
	delaysnd_ptr_reg = susp->delaysnd_ptr;
	input_ptr_reg = susp->input_ptr;
	out_ptr_reg = out_ptr;
	if (n) do { /* the inner sample computation loop */
        register sample_type y, z, delaysamp;
        register int delayi;
        register sample_type *yptr;

        /* compute where to read y, we want y to be delay_snd samples
         * after delay_ptr, where we write the new sample. First, 
         * conver from seconds to samples. Note: don't use actual sound_type
         * names in comments! The translator isn't smart enough.
         */
        register sample_type fb = *feedback_ptr_reg++;
        delaysamp = (delaysnd_scale_reg * *delaysnd_ptr_reg++) * delay_scale_factor_reg;
        delayi = (int) delaysamp; /* get integer part */
        delaysamp = delaysamp - delayi; /* get phase */
        yptr = delayptr_reg + buflen_reg - (delayi + 1);
        if (yptr >= endptr_reg) yptr -= buflen_reg;
        /* now get y, the out-put of the delay, using interpolation */
        /* note that as phase increases, we use more of yptr[0] because
           positive phase means longer buffer means read earlier sample */
        y = (float) ((yptr[0] * delaysamp) + (yptr[1] * (1.0 - delaysamp)));
        /* WARNING: no check to keep delaysamp in range, so do this in LISP */

        *delayptr_reg++ = z = (sample_type) (fb * y + *input_ptr_reg++);
        /* Time out to update the buffer:
         * this is a tricky buffer: buffer[0] == buffer[bufflen]
         * the logical length is bufflen, but the actual length
         * is bufflen + 1 to allow for a repeated sample at the
         * end. This allows for efficient interpolation.
         */
        if (delayptr_reg > endptr_reg) {
            delayptr_reg = susp->delaybuf;
            *delayptr_reg++ = *endptr_reg;
        }
        *out_ptr_reg++ = (sample_type) (y - fb * z);;
	} while (--n); /* inner loop */

	susp->buflen = buflen_reg;
	susp->delayptr = delayptr_reg;
	/* using feedback_ptr_reg is a bad idea on RS/6000: */
	susp->feedback_ptr += togo;
	/* using delaysnd_ptr_reg is a bad idea on RS/6000: */
	susp->delaysnd_ptr += togo;
	/* using input_ptr_reg is a bad idea on RS/6000: */
	susp->input_ptr += togo;
	out_ptr += togo;
	susp_took(input_cnt, togo);
	susp_took(delaysnd_cnt, togo);
	susp_took(feedback_cnt, togo);
	cnt += togo;
    } /* outer loop */

    /* test for termination */
    if (togo == 0 && cnt == 0) {
	snd_list_terminate(snd_list);
    } else {
	snd_list->block_len = cnt;
	susp->susp.current += cnt;
    }
} /* alpassvv_nsn_fetch */


void alpassvv_nss_fetch(register alpassvv_susp_type susp, snd_list_type snd_list)
{
    int cnt = 0; /* how many samples computed */
    int togo;
    int n;
    sample_block_type out;
    register sample_block_values_type out_ptr;

    register sample_block_values_type out_ptr_reg;

    register float delay_scale_factor_reg;
    register long buflen_reg;
    register sample_type * delayptr_reg;
    register sample_type * endptr_reg;
    register sample_type feedback_scale_reg = susp->feedback->scale;
    register sample_block_values_type feedback_ptr_reg;
    register sample_type delaysnd_scale_reg = susp->delaysnd->scale;
    register sample_block_values_type delaysnd_ptr_reg;
    register sample_block_values_type input_ptr_reg;
    falloc_sample_block(out, "alpassvv_nss_fetch");
    out_ptr = out->samples;
    snd_list->block = out;

    while (cnt < max_sample_block_len) { /* outer loop */
	/* first compute how many samples to generate in inner loop: */
	/* don't overflow the output sample block: */
	togo = max_sample_block_len - cnt;

	/* don't run past the input input sample block: */
	susp_check_term_samples(input, input_ptr, input_cnt);
	togo = MIN(togo, susp->input_cnt);

	/* don't run past the delaysnd input sample block: */
	susp_check_samples(delaysnd, delaysnd_ptr, delaysnd_cnt);
	togo = MIN(togo, susp->delaysnd_cnt);

	/* don't run past the feedback input sample block: */
	susp_check_samples(feedback, feedback_ptr, feedback_cnt);
	togo = MIN(togo, susp->feedback_cnt);

	/* don't run past terminate time */
	if (susp->terminate_cnt != UNKNOWN &&
	    susp->terminate_cnt <= susp->susp.current + cnt + togo) {
	    togo = susp->terminate_cnt - (susp->susp.current + cnt);
	    if (togo == 0) break;
	}

	n = togo;
	delay_scale_factor_reg = susp->delay_scale_factor;
	buflen_reg = susp->buflen;
	delayptr_reg = susp->delayptr;
	endptr_reg = susp->endptr;
	feedback_ptr_reg = susp->feedback_ptr;
	delaysnd_ptr_reg = susp->delaysnd_ptr;
	input_ptr_reg = susp->input_ptr;
	out_ptr_reg = out_ptr;
	if (n) do { /* the inner sample computation loop */
        register sample_type y, z, delaysamp;
        register int delayi;
        register sample_type *yptr;

        /* compute where to read y, we want y to be delay_snd samples
         * after delay_ptr, where we write the new sample. First, 
         * conver from seconds to samples. Note: don't use actual sound_type
         * names in comments! The translator isn't smart enough.
         */
        register sample_type fb = (feedback_scale_reg * *feedback_ptr_reg++);
        delaysamp = (delaysnd_scale_reg * *delaysnd_ptr_reg++) * delay_scale_factor_reg;
        delayi = (int) delaysamp; /* get integer part */
        delaysamp = delaysamp - delayi; /* get phase */
        yptr = delayptr_reg + buflen_reg - (delayi + 1);
        if (yptr >= endptr_reg) yptr -= buflen_reg;
        /* now get y, the out-put of the delay, using interpolation */
        /* note that as phase increases, we use more of yptr[0] because
           positive phase means longer buffer means read earlier sample */
        y = (float) ((yptr[0] * delaysamp) + (yptr[1] * (1.0 - delaysamp)));
        /* WARNING: no check to keep delaysamp in range, so do this in LISP */

        *delayptr_reg++ = z = (sample_type) (fb * y + *input_ptr_reg++);
        /* Time out to update the buffer:
         * this is a tricky buffer: buffer[0] == buffer[bufflen]
         * the logical length is bufflen, but the actual length
         * is bufflen + 1 to allow for a repeated sample at the
         * end. This allows for efficient interpolation.
         */
        if (delayptr_reg > endptr_reg) {
            delayptr_reg = susp->delaybuf;
            *delayptr_reg++ = *endptr_reg;
        }
        *out_ptr_reg++ = (sample_type) (y - fb * z);;
	} while (--n); /* inner loop */

	susp->buflen = buflen_reg;
	susp->delayptr = delayptr_reg;
	/* using feedback_ptr_reg is a bad idea on RS/6000: */
	susp->feedback_ptr += togo;
	/* using delaysnd_ptr_reg is a bad idea on RS/6000: */
	susp->delaysnd_ptr += togo;
	/* using input_ptr_reg is a bad idea on RS/6000: */
	susp->input_ptr += togo;
	out_ptr += togo;
	susp_took(input_cnt, togo);
	susp_took(delaysnd_cnt, togo);
	susp_took(feedback_cnt, togo);
	cnt += togo;
    } /* outer loop */

    /* test for termination */
    if (togo == 0 && cnt == 0) {
	snd_list_terminate(snd_list);
    } else {
	snd_list->block_len = cnt;
	susp->susp.current += cnt;
    }
} /* alpassvv_nss_fetch */


void alpassvv_toss_fetch(susp, snd_list)
  register alpassvv_susp_type susp;
  snd_list_type snd_list;
{
    long final_count = susp->susp.toss_cnt;
    time_type final_time = susp->susp.t0;
    long n;

    /* fetch samples from input up to final_time for this block of zeros */
    while ((round((final_time - susp->input->t0) * susp->input->sr)) >=
	   susp->input->current)
	susp_get_samples(input, input_ptr, input_cnt);
    /* fetch samples from delaysnd up to final_time for this block of zeros */
    while ((round((final_time - susp->delaysnd->t0) * susp->delaysnd->sr)) >=
	   susp->delaysnd->current)
	susp_get_samples(delaysnd, delaysnd_ptr, delaysnd_cnt);
    /* fetch samples from feedback up to final_time for this block of zeros */
    while ((round((final_time - susp->feedback->t0) * susp->feedback->sr)) >=
	   susp->feedback->current)
	susp_get_samples(feedback, feedback_ptr, feedback_cnt);
    /* convert to normal processing when we hit final_count */
    /* we want each signal positioned at final_time */
    n = round((final_time - susp->input->t0) * susp->input->sr -
         (susp->input->current - susp->input_cnt));
    susp->input_ptr += n;
    susp_took(input_cnt, n);
    n = round((final_time - susp->delaysnd->t0) * susp->delaysnd->sr -
         (susp->delaysnd->current - susp->delaysnd_cnt));
    susp->delaysnd_ptr += n;
    susp_took(delaysnd_cnt, n);
    n = round((final_time - susp->feedback->t0) * susp->feedback->sr -
         (susp->feedback->current - susp->feedback_cnt));
    susp->feedback_ptr += n;
    susp_took(feedback_cnt, n);
    susp->susp.fetch = susp->susp.keep_fetch;
    (*(susp->susp.fetch))(susp, snd_list);
}


void alpassvv_mark(alpassvv_susp_type susp)
{
    sound_xlmark(susp->input);
    sound_xlmark(susp->delaysnd);
    sound_xlmark(susp->feedback);
}


void alpassvv_free(alpassvv_susp_type susp)
{
free(susp->delaybuf);    sound_unref(susp->input);
    sound_unref(susp->delaysnd);
    sound_unref(susp->feedback);
    ffree_generic(susp, sizeof(alpassvv_susp_node), "alpassvv_free");
}


void alpassvv_print_tree(alpassvv_susp_type susp, int n)
{
    indent(n);
    stdputstr("input:");
    sound_print_tree_1(susp->input, n);

    indent(n);
    stdputstr("delaysnd:");
    sound_print_tree_1(susp->delaysnd, n);

    indent(n);
    stdputstr("feedback:");
    sound_print_tree_1(susp->feedback, n);
}


sound_type snd_make_alpassvv(sound_type input, sound_type delaysnd, sound_type feedback, double maxdelay)
{
    register alpassvv_susp_type susp;
    rate_type sr = MAX(MAX(input->sr, delaysnd->sr), feedback->sr);
    time_type t0 = MAX(input->t0, delaysnd->t0);
    int interp_desc = 0;
    sample_type scale_factor = 1.0F;
    time_type t0_min = t0;
    /* combine scale factors of linear inputs (INPUT) */
    scale_factor *= input->scale;
    input->scale = 1.0F;

    /* try to push scale_factor back to a low sr input */
    if (input->sr < sr) { input->scale = scale_factor; scale_factor = 1.0F; }

    falloc_generic(susp, alpassvv_susp_node, "snd_make_alpassvv");
    susp->delay_scale_factor = (float) (input->sr * delaysnd->scale);
    susp->buflen = MAX(2, (long) (input->sr * maxdelay + 2.5));
    susp->delaybuf = (sample_type *) calloc (susp->buflen + 1, sizeof(sample_type));
    susp->delayptr = susp->delaybuf;
    susp->endptr = susp->delaybuf + susp->buflen;

    /* select a susp fn based on sample rates */
    interp_desc = (interp_desc << 2) + interp_style(input, sr);
    interp_desc = (interp_desc << 2) + interp_style(delaysnd, sr);
    interp_desc = (interp_desc << 2) + interp_style(feedback, sr);
    switch (interp_desc) {
      case INTERP_nnn: susp->susp.fetch = alpassvv_nnn_fetch; break;
      case INTERP_nns: susp->susp.fetch = alpassvv_nns_fetch; break;
      case INTERP_nsn: susp->susp.fetch = alpassvv_nsn_fetch; break;
      case INTERP_nss: susp->susp.fetch = alpassvv_nss_fetch; break;
      default: snd_badsr(); break;
    }

    susp->terminate_cnt = UNKNOWN;
    /* handle unequal start times, if any */
    if (t0 < input->t0) sound_prepend_zeros(input, t0);
    if (t0 < delaysnd->t0) sound_prepend_zeros(delaysnd, t0);
    if (t0 < feedback->t0) sound_prepend_zeros(feedback, t0);
    /* minimum start time over all inputs: */
    t0_min = MIN(input->t0, MIN(delaysnd->t0, min(feedback->t0, t0)));
    /* how many samples to toss before t0: */
    susp->susp.toss_cnt = (long) ((t0 - t0_min) * sr + 0.5);
    if (susp->susp.toss_cnt > 0) {
	susp->susp.keep_fetch = susp->susp.fetch;
	susp->susp.fetch = alpassvv_toss_fetch;
    }

    /* initialize susp state */
    susp->susp.free = alpassvv_free;
    susp->susp.sr = sr;
    susp->susp.t0 = t0;
    susp->susp.mark = alpassvv_mark;
    susp->susp.print_tree = alpassvv_print_tree;
    susp->susp.name = "alpassvv";
    susp->susp.log_stop_cnt = UNKNOWN;
    susp->susp.current = 0;
    susp->input = input;
    susp->input_cnt = 0;
    susp->delaysnd = delaysnd;
    susp->delaysnd_cnt = 0;
    susp->feedback = feedback;
    susp->feedback_cnt = 0;
    return sound_create((snd_susp_type)susp, t0, sr, scale_factor);
}


sound_type snd_alpassvv(sound_type input, sound_type delaysnd, sound_type feedback, double maxdelay)
{
    sound_type input_copy = sound_copy(input);
    sound_type delaysnd_copy = sound_copy(delaysnd);
    sound_type feedback_copy = sound_copy(feedback);
    return snd_make_alpassvv(input_copy, delaysnd_copy, feedback_copy, maxdelay);
}