/*-------------------------------------------------------------------*/
/* testsort.c                                                        */
/* A program to demonstrate execution profiling.                     */
/*-------------------------------------------------------------------*/

#include <string.h>
#include <stdio.h>
#include <stdlib.h>

enum {MAX_SIZE = 10000000};  /* That's 10 million. */

/* This large array doesn't fit on the stack, so place it in the
   bss section. */
static int piArray[MAX_SIZE];

/*-------------------------------------------------------------------*/

static void fillArray(int piArray[], int iSize)

/* Fill piArray with iSize random integers. */

{
   int i;
   for (i = 0; i < iSize; i++)
      piArray[i] = rand();
}

/*-------------------------------------------------------------------*/

static void swap(int piArray[], int iOne, int iTwo)

/* Swap piArray[iOne] and piArray[iTwo]. */

{
   int iTemp;
   iTemp = piArray[iOne];
   piArray[iOne] = piArray[iTwo];
   piArray[iTwo] = iTemp;
}

/*-------------------------------------------------------------------*/

static int partition(int piArray[], int iLeft, int iRight)

/* Divide piArray[iLeft...iRight] into two partitions so elements 
   in the first partition are <= elements in the second partition.
   Return the index of the element that marks the partition 
   boundary. */

{
   int iFirst = iLeft-1;
   int iLast = iRight;

   while (1)
   {
      while (piArray[++iFirst] < piArray[iRight])
         ;
      while (piArray[iRight] < piArray[--iLast])
         if (iLast == iLeft)
            break;
      if (iFirst >= iLast)
         break;
      swap(piArray, iFirst, iLast);
   }
   swap(piArray, iFirst, iRight);
   return iFirst;
}

/*-------------------------------------------------------------------*/

static void quicksort(int piArray[], int iLeft, int iRight)

/* Sort piArray[iLeft...iRight] in ascending order. */

{
   if (iRight > iLeft)
   {
      int iMid = partition(piArray, iLeft, iRight);
      quicksort(piArray, iLeft, iMid - 1);
      quicksort(piArray, iMid + 1, iRight);
   }
}

/*-------------------------------------------------------------------*/

static void printArray(int piArray[], int iSize)

/* Print the iSize elements of piArray to stdout. */

{
   int i;
   for (i = 0; i < iSize; i++)
      printf("%d\n", piArray[i]);
}

/*-------------------------------------------------------------------*/

int main(void)

/* Fill an array of MAX_SIZE random integers, sort the integers in 
   ascending order, and print the integers to stdout. */

{
   fillArray(piArray, MAX_SIZE);
   quicksort(piArray, 0, MAX_SIZE - 1);

/* printArray(piArray, MAX_SIZE); */

   return 0;
}