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

#define HEAP_SIZE 64
#define FREE 0
#define ALLOCATED 1

void* my_malloc(size_t size);
void my_free(void *p);
char* header();
char* footer();
char* previous_header();
char* previous_footer();
char* next_header();
char* next_footer();

struct header {
  unsigned int length :29;
  unsigned int NOT_USED :2;
  unsigned int allocated :1;
};

struct footer {
  unsigned int length :29;
  unsigned int NOT_USED :2;
  unsigned int allocated :1;
};

static char* myHeap = FREE;

void *my_malloc(size_t size)
{
  if(size <=0)
    return NULL;

  if(myHeap){
    char* temp = myHeap;
    int allocated = 0;
    while(!allocated && temp!=(myHeap+(HEAP_SIZE-1))){
    if(temp)
      {
	struct header *hpTemp = temp;
	if(hpTemp->allocated==ALLOCATED)
	  {
	    int move = hpTemp->length;
	    int i;
	    for(i=0;i<move;i++)
		temp++;
	  }
      }
    else
      {
	allocated = 1;
      }
    }
    errno=ENOMEM;
    printf("Unable to Allocate\n");
    return NULL;
  }
  else{
    myHeap = calloc(HEAP_SIZE,1);
    struct header *hp;
    hp=&myHeap[0];
    if(size>HEAP_SIZE){
      return NULL;
    }
    else
      {
	while(size%8!=0)
	  {
	    size++;
	  }
	hp->length=(size+8);
	hp->allocated=ALLOCATED;
	struct footer *fp;
	fp = hp+(size+4);
	fp->length=(size+8);
	fp->allocated=ALLOCATED;
	return hp+4;
      }
    }

  return NULL;
}

void my_free(void *p)
{
  struct header *temp = p-4;
  temp->allocated=FREE;
  if(temp-4->allocated==FREE&&temp!=myHeap)
    {
      int tempLength = temp->length;
      int leftTempLen = temp-4->length;
      temp-(8+leftTempLen)->length=(tempLength+leftTempLen+8);
      (footer)temp+tempLength->length=(tempLength+leftTempLen+8);
      temp+tempLength->allocated=FREE;
      temp-=(8+leftTempLen);
    }
  if(temp+4->allocated==FREE&&temp!=(myHeap+HEAP_SIZE))
    {
      int tempLength = temp->length;
      int rightTempLen = temp+(tempLength+4)->length;
      temp-(8+leftTempLen)->length=(tempLength+leftTempLen+8);
      (header)temp->length=(tempLength+leftTempLen+8);
      (footer)temp+(tempLength+rightTempLen+8)->allocated=FREE;
    }

}

char *header()
{
  return NULL;
}
char *footer()
{
  return NULL;
}
char *previous_header()
{
  return NULL;
}
char *previous_footer()
{
  return NULL;
}
char *next_header()
{
  return NULL;
}
char *next_footer()
{
  return NULL;
}