/***
 * CopyPolicy: GNU Public License 2 applies
 * Copyright (C) by Monty (xiphmont@mit.edu)
 *
 * sorted vector abstraction for paranoia
 *
 ***/

/* Old isort got a bit complex.  This re-constrains complexity to
   give a go at speed through a more alpha-6-like mechanism. */

#include <stdlib.h>
#include <string.h>
#include "p_block.h"
#include "isort.h"

sort_info *sort_alloc(long size){
  sort_info *ret=calloc(1,sizeof(sort_info));

  ret->vector=NULL;
  ret->sortbegin=-1;
  ret->size=-1;
  ret->maxsize=size;

  ret->head=calloc(65536,sizeof(sort_link **));
  ret->bucketusage=malloc(65536*sizeof(long));
  ret->revindex=calloc(size,sizeof(sort_link *));
  ret->lastbucket=0;

  return(ret);
}

void sort_unsortall(sort_info *i){
  if(i->lastbucket>2000){ /* a guess */
    memset(i->head,0,65536*sizeof(sort_link *));
  }else{
    long b;
    for(b=0;b<i->lastbucket;b++)
      i->head[i->bucketusage[b]]=NULL;
  }

  i->lastbucket=0;
  i->sortbegin=-1;
}

void sort_free(sort_info *i){
  free(i->revindex);
  free(i->head);
  free(i->bucketusage);
  free(i);
}
 
static void sort_sort(sort_info *i,long sortlo,long sorthi){
  long j;

  for(j=sorthi-1;j>=sortlo;j--){
    sort_link **hv=i->head+i->vector[j]+32768;
    sort_link *l=i->revindex+j;

    if(*hv==NULL){
      i->bucketusage[i->lastbucket]=i->vector[j]+32768;
      i->lastbucket++;
    }
    l->next=*hv;    
    *hv=l;
  }
  i->sortbegin=0;
}

/* size *must* be less than i->maxsize */
void sort_setup(sort_info *i,size16 *vector,long *abspos,
		long size,long sortlo,long sorthi){
  if(i->sortbegin!=-1)sort_unsortall(i);

  i->vector=vector;
  i->size=size;
  i->abspos=abspos;

  i->lo=min(size,max(sortlo-*abspos,0));
  i->hi=max(0,min(sorthi-*abspos,size));
}

sort_link *sort_getmatch(sort_info *i,long post,long overlap,int value){
  sort_link *ret;

  if(i->sortbegin==-1)sort_sort(i,i->lo,i->hi);
  /* Now we reuse lo and hi */
  
  post=max(0,min(i->size,post));
  i->val=value+32768;
  i->lo=max(0,post-overlap);       /* absolute position */
  i->hi=min(i->size,post+overlap); /* absolute position */

  ret=i->head[i->val];
  while(ret){
    if(ipos(i,ret)<i->lo){
      ret=ret->next;
    }else{
      if(ipos(i,ret)>=i->hi)
	ret=NULL;
      break;
    }
  }
  /*i->head[i->val]=ret;*/
  return(ret);
}

sort_link *sort_nextmatch(sort_info *i,sort_link *prev){
  sort_link *ret=prev->next;

  if(!ret || ipos(i,ret)>=i->hi)return(NULL); 
  return(ret);
}

