packtest.cpp

#include <iostream>
#include <stdlib.h>
#include <time.h>
using namespace std;

#define ARRAY_SIZE 500000
#define ACCESS_AMOUNT 5000000

#ifdef packitbaby
#pragma pack(push, 1)
#endif
struct value {
	char type;
	float v;
};
#ifdef packitbaby
#pragma pack(pop)
#endif

struct dmlist {
	size_t num;
	value * values;
};

dmlist *listoflists[ARRAY_SIZE];

long counter = 0;
int main () {
	cout << "Hello world" << endl;
	srand ( time(NULL) ); //initialize the random seed
	cout << "value size: " << sizeof(value) << endl;
	cout << "dmlist size: " << sizeof(dmlist) << endl;
	#ifdef packitbaby
	cout << "Using packed format" << endl;
	#endif
	system( "PAUSE" );
	cout << "Generating array" << endl;
	clock_t t = clock();
	for (size_t i = 0; i < ARRAY_SIZE; i++) {
		dmlist * L = new dmlist;
		L->num = rand() % 500;
		L->values = new value[L->num];
		for (size_t o = 0; o < L->num; o++) {
			value entry = L->values[o];
			entry.type = (char)(rand() % 255);
			entry.v = (float)rand() * (float)rand() / (float)RAND_MAX;
			L->values[o] = entry;
		}
		listoflists[i] = L;
	}
	t = clock() - t;
	cout << "It took " << ((float)t)/CLOCKS_PER_SEC << " seconds to generate " << ARRAY_SIZE << " random lists" << endl;
	system( "PAUSE" );
	cout << "Accessing array" << endl;
	t = clock();
	for (size_t i = 0; i < ACCESS_AMOUNT; i++) {
		dmlist * L = listoflists[rand() % ARRAY_SIZE];
		for (size_t o = 0; o < L->num; o++) {
		value entry = L->values[rand() % L->num];
		if (((int)entry.type) % 2)
			counter++;
		if (((int)entry.v) % 2)
			counter++;
		}
	}
	t = clock() - t;
	cout << "It took " << ((float)t)/CLOCKS_PER_SEC << " seconds to access " << ACCESS_AMOUNT << " random lists" << endl;
	cout << "Counter:" << counter << endl;
	system( "PAUSE" );
	return 0;
}