/* mp6test.c */
/* a heap exerciser */

#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include "mymalloc.h"

/* number of malloc/free trials to run */
#define TRIALS 10000

/* number of pointers to allocate (average heap use will be 1/2 this) */
#define POINTERS 1000

/* average block size for allocation, in bytes */
#define SIZES 1000

/* pointers to objects on the heap */
static int * pointer[ POINTERS ] = {NULL};

/* each object begins with its size (an intptr_t) */

main(){
	int trial; /* for loop counter */

	/* record of the demand on the heap */
	long int maxdemand = 0; /* maximum encountered */
	long int curdemand = 0; /* current value*/
	long int sumdemand = 0; /* integrated current demand */
	int mallocs = 0;        /* count malloc calls */
	long int summallocs = 0;/* integrated amount allocated */

	srandom( 12 ); /* make things repeatable */

	for (trial = 0; trial < TRIALS; trial++) {
		int item = random() % POINTERS;
		int * p = pointer[item];

		if (p == NULL) { /* we allocate */
			int size; /* block size to allocate */
			int i; /* index for initializing block */

			/* work in words, not bytes, make a long-tail */
			#define WORDS (SIZES / sizeof( int ))
			#define PEAK ((WORDS * 400)/ 100)
			/* make long-tail on size distribution */
			size = (random() % PEAK) + 1;
			size = (random() % size) + 1;

			/* now we get a block */
			p = mymalloc( size * sizeof( int ) );

			if (p != NULL) { /* expected case */
				mallocs = mallocs + 1;
				p[0] = size;
				for (i = 1; i < size; i++) {
					p[i] = i;
				}
				curdemand = curdemand
						+ (size * sizeof( int ));
				summallocs = summallocs
						+ (size * sizeof( int ));

			} else { /* should never occur */
				printf( "allocate failure\n" );
				fflush( stdout );
			}
			pointer[item] = p;

		} else { /* we deallocate */
			int i = 0; /* index for checking block */
			int size = p[0]; 
			for (i = 1; i < size; i++) {
				if (p[i] != i) printf( "bad at %d\n", trial );
			}
			myfree( p );
			pointer[item] = NULL;

			curdemand = curdemand - (size * sizeof( int ));
		}

		/* gather statistics */
		if (curdemand > maxdemand) maxdemand = curdemand;
		sumdemand = sumdemand + curdemand;
	}

	printf( "completed %d trials\n", TRIALS );
	printf( "          %d mallocs\n", mallocs );
	printf( "          %d frees\n", TRIALS-mallocs );
	printf( "maximum demand was %d bytes\n", maxdemand);
	printf( "average demand was %d bytes\n", sumdemand / TRIALS );
	printf( "average block size %d bytes\n", summallocs / mallocs );
}