Big-Data-HPC-Platform/system/jlib/jsort.inc

/*##############################################################################

    HPCC SYSTEMS software Copyright (C) 2012 HPCC Systems®.

    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
############################################################################## */




//This function is included twice in order to common up the code....

/*
void * binary_add(const void *newitem, const void *base,
             size_t nmemb, 
             WIDTH_PROTOTYPE
             COMPARE_PROTOTYPE
             bool * ItemAdded)
{
*/
/*
 * Perform a binary search and add.  The entry is only added if it
 * does not already exist.
 * A pointer to the new entry is returned.

 */
   size_t      right;
   size_t      middle;
   size_t      left = 0;
   int         result;
   char *      CurEntry;

#ifndef ALWAYS_ADD
   *ItemAdded = false;
#endif

   if (nmemb == 0)
   {
      middle = 0;
      goto AddEntry;
   }

   right = nmemb-1;

   /*
    * Loop until we've narrowed down the search range to one or two
    * items.  This ensures that middle != 0, preventing 'right' from wrapping.
    */
   while (right - left > 1)
   {
      /* Calculate the middle entry in the array - NOT the middle offset */
      middle = (right + left) >> 1;

      CurEntry = (char *)base + middle * width;
      result = COMPARE(newitem, CurEntry);

      if (result < 0)
         right = middle - 1;
      else if (result > 0)
         left = middle + 1;
      else
         goto Done;
   }

   middle = left;
   /*
    * The range has been narrowed down to 1 or 2 items.
    * Perform an optimal check on these last two elements.
    */
   result = COMPARE(newitem, (char *)base + middle * width);
   if (result == 0)
      goto Done;

   if (result > 0)
   {
      ++middle;

      if (right == left + 1)
      {
         result = COMPARE(newitem, (char *)base + middle * width);
         if (result == 0)
            goto Done;
         if (result > 0)
            ++middle;
      }
   }

AddEntry:
#ifndef NEVER_ADD
#ifdef ALWAYS_ADD
Done:
#endif
   CurEntry = (char *)base + middle * width;
#ifdef SEEK_LAST_MATCH
   while((middle < nmemb) && (COMPARE(newitem, CurEntry) == 0))
   {
      ++middle;
      CurEntry += width;
   }
#endif
   memmove(CurEntry + width, CurEntry, (nmemb - middle) * width);
   INSERT(CurEntry, newitem);
#ifndef ALWAYS_ADD
   *ItemAdded = true;
Done:
#endif
#else
   *ItemAdded = true;
Done:
#endif
   return (char *)base + middle * width;
/*
}
*/