text: #include "stdio.h"
  #ifndef mips
  #include "stdlib.h"
  #endif
  #include "xlisp.h"
  #include "sound.h"
  
  #include "falloc.h"
  #include "cext.h"
  #include "allpoles.h"
  
  void allpoles_free(snd_susp_type a_susp);
  
  
  typedef struct allpoles_susp_struct {
      snd_susp_node susp;
      long terminate_cnt;
      boolean logically_stopped;
      sound_type x_snd;
      long x_snd_cnt;
      sample_block_values_type x_snd_ptr;
  
      long ak_len;
      LVAL ak_array;
      double gain;
      double *ak_coefs;
      double *zk_buf;
      long index;
  } allpoles_susp_node, *allpoles_susp_type;
  
  
  void allpoles_s_fetch(snd_susp_type a_susp, snd_list_type snd_list)
  {
      allpoles_susp_type susp = (allpoles_susp_type) a_susp;
      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 long ak_len_reg;
      register double gain_reg;
      register double * ak_coefs_reg;
      register double * zk_buf_reg;
      register long index_reg;
      register sample_type x_snd_scale_reg = susp->x_snd->scale;
      register sample_block_values_type x_snd_ptr_reg;
      falloc_sample_block(out, "allpoles_s_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 x_snd input sample block: */
  	susp_check_term_log_samples(x_snd, x_snd_ptr, x_snd_cnt);
  	togo = min(togo, susp->x_snd_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) togo = 0;  /* avoids rounding errros */
  	    if (togo == 0) break;
  	}
  
  
  	/* don't run past logical stop time */
  	if (!susp->logically_stopped && susp->susp.log_stop_cnt != UNKNOWN) {
  	    int to_stop = susp->susp.log_stop_cnt - (susp->susp.current + cnt);
  	    /* break if to_stop == 0 (we're at the logical stop)
  	     * AND cnt > 0 (we're not at the beginning of the
  	     * output block).
  	     */
  	    if (to_stop < 0) to_stop = 0; /* avoids rounding errors */
  	    if (to_stop < togo) {
  		if (to_stop == 0) {
  		    if (cnt) {
  			togo = 0;
  			break;
  		    } else /* keep togo as is: since cnt == 0, we
  		            * can set the logical stop flag on this
  		            * output block
  		            */
  			susp->logically_stopped = true;
  		} else /* limit togo so we can start a new
  		        * block at the LST
  		        */
  		    togo = to_stop;
  	    }
  	}
  
  
        if (susp->ak_array == NULL) {
               togo = 0; /* indicate termination */
               break;    /* we're done */
        }
        else if (!vectorp(susp->ak_array))
             xlerror("array expected", susp->ak_array);
        else if (susp->ak_coefs == NULL)
             {
                 long i;
                 susp->ak_len = getsize(susp->ak_array);
                 if (susp->ak_len < 1) xlerror("array has not elements", susp->ak_array);
                 susp->ak_coefs = (double *) calloc(susp->ak_len, sizeof(double));
                 susp->zk_buf   = (double *) calloc(susp->ak_len, sizeof(double));
   
                /* at this point we have a new array and a place to put ak coefs */
                for(i=0; i < susp->ak_len; i++) {
                   LVAL elem = getelement(susp->ak_array,i);
                   if (ntype(elem) != FLONUM) {
                        xlerror("flonum expected", elem);
                   }
                   susp->ak_coefs[i] = getflonum(elem);
                }
  
              }
  
  	n = togo;
  	ak_len_reg = susp->ak_len;
  	gain_reg = susp->gain;
  	ak_coefs_reg = susp->ak_coefs;
  	zk_buf_reg = susp->zk_buf;
  	index_reg = susp->index;
  	x_snd_ptr_reg = susp->x_snd_ptr;
  	out_ptr_reg = out_ptr;
  	if (n) do { /* the inner sample computation loop */
              double z0; long xi; long xj;            z0 = (x_snd_scale_reg * *x_snd_ptr_reg++)*gain_reg;
              for (xi=0; xi < ak_len_reg ; xi++) {
                  xj = index_reg + xi; if (xj >= ak_len_reg) xj -= ak_len_reg;
                  z0 +=  ak_coefs_reg[xi] * zk_buf_reg[xj];
              }
              zk_buf_reg[index_reg] = z0;
              index_reg++; if (index_reg == ak_len_reg) index_reg = 0;
              *out_ptr_reg++ = (sample_type) z0;
  	} while (--n); /* inner loop */
  
  	susp->zk_buf = zk_buf_reg;
  	susp->index = index_reg;
  	/* using x_snd_ptr_reg is a bad idea on RS/6000: */
  	susp->x_snd_ptr += togo;
  	out_ptr += togo;
  	susp_took(x_snd_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;
      }
      /* test for logical stop */
      if (susp->logically_stopped) {
  	snd_list->logically_stopped = true;
      } else if (susp->susp.log_stop_cnt == susp->susp.current) {
  	susp->logically_stopped = true;
      }
  } /* allpoles_s_fetch */
  
  
  void allpoles_toss_fetch(snd_susp_type a_susp, snd_list_type snd_list)
      {
      allpoles_susp_type susp = (allpoles_susp_type) a_susp;
      time_type final_time = susp->susp.t0;
      long n;
  
      /* fetch samples from x_snd up to final_time for this block of zeros */
      while ((ROUNDBIG((final_time - susp->x_snd->t0) * susp->x_snd->sr)) >=
  	   susp->x_snd->current)
  	susp_get_samples(x_snd, x_snd_ptr, x_snd_cnt);
      /* convert to normal processing when we hit final_count */
      /* we want each signal positioned at final_time */
      n = ROUNDBIG((final_time - susp->x_snd->t0) * susp->x_snd->sr -
           (susp->x_snd->current - susp->x_snd_cnt));
      susp->x_snd_ptr += n;
      susp_took(x_snd_cnt, n);
      susp->susp.fetch = susp->susp.keep_fetch;
      (*(susp->susp.fetch))(a_susp, snd_list);
  }
  
  
  void allpoles_mark(snd_susp_type a_susp)
  {
      allpoles_susp_type susp = (allpoles_susp_type) a_susp;
      if (susp->ak_array) mark(susp->ak_array);
      sound_xlmark(susp->x_snd);
  }
  
  
  void allpoles_free(snd_susp_type a_susp)
  {
      allpoles_susp_type susp = (allpoles_susp_type) a_susp;
  
       free(susp->zk_buf);
       free(susp->ak_coefs);
       susp->ak_array = NULL;  /* free array */
      sound_unref(susp->x_snd);
      ffree_generic(susp, sizeof(allpoles_susp_node), "allpoles_free");
  }
  
  
  void allpoles_print_tree(snd_susp_type a_susp, int n)
  {
      allpoles_susp_type susp = (allpoles_susp_type) a_susp;
      indent(n);
      stdputstr("x_snd:");
      sound_print_tree_1(susp->x_snd, n);
  }
  
  
  sound_type snd_make_allpoles(sound_type x_snd, LVAL ak_array, double gain)
  {
      register allpoles_susp_type susp;
      rate_type sr = x_snd->sr;
      time_type t0 = x_snd->t0;
      sample_type scale_factor = 1.0F;
      time_type t0_min = t0;
      falloc_generic(susp, allpoles_susp_node, "snd_make_allpoles");
      susp->ak_len = 0;
      susp->ak_array = ak_array;
      susp->gain = gain;
      susp->ak_coefs = NULL;
      susp->zk_buf = NULL;
      susp->index = 0;
      susp->susp.fetch = allpoles_s_fetch;
      susp->terminate_cnt = UNKNOWN;
      /* handle unequal start times, if any */
      if (t0 < x_snd->t0) sound_prepend_zeros(x_snd, t0);
      /* minimum start time over all inputs: */
      t0_min = min(x_snd->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 = allpoles_toss_fetch;
      }
  
      /* initialize susp state */
      susp->susp.free = allpoles_free;
      susp->susp.sr = sr;
      susp->susp.t0 = t0;
      susp->susp.mark = allpoles_mark;
      susp->susp.print_tree = allpoles_print_tree;
      susp->susp.name = "allpoles";
      susp->logically_stopped = false;
      susp->susp.log_stop_cnt = logical_stop_cnt_cvt(x_snd);
      susp->susp.current = 0;
      susp->x_snd = x_snd;
      susp->x_snd_cnt = 0;
      return sound_create((snd_susp_type)susp, t0, sr, scale_factor);
  }
  
  
  sound_type snd_allpoles(sound_type x_snd, LVAL ak_array, double gain)
  {
      sound_type x_snd_copy = sound_copy(x_snd);
      return snd_make_allpoles(x_snd_copy, ak_array, gain);
  }
  