#include #include // prinf, scanf, puts, NULL #include // sqrt #include // srand, rand #include #include // DWORD #include using namespace std; #pragma pack(push, 1) struct badpack { char a; DWORD badint1; // misaligned char b; DWORD badint2; short c; short d; }; #pragma pack(pop) struct okpack { short a; // 2 // two padding bytes DWORD okint1; // 4 short c; // 2 DWORD okint2; short d; // 2 }; struct betterpack { short a; // 2 short b; // 2 DWORD betterint1; // 4 DWORD betterint2; short d; // 2 }; class timeit { public: struct timeval start, end; timeit(): start(), end() { gettimeofday(&start, 0); end = start; } void reset() { gettimeofday(&start, 0); end = start; } int elapsed() { //cout << end.tv_usec << endl; return(end.tv_sec*1000 + end.tv_usec/1000) - (start.tv_sec*1000 + start.tv_usec/1000); } int split() { gettimeofday(&end, 0); return elapsed(); } }; int main() { struct badpack badpacked; struct okpack okpacked; struct betterpack betterpacked; timeit timer; DWORD runover[1000]; // random data srand(time(NULL)); int badtime = 0; int oktime = 0; int bettertime = 0; int elements=1000; int outeriters=5; int inneriters=60000; for(int i=0; i<1000; i++){ runover[i] = rand() % 1000000 + 1; // 1 to a million // outputs[i] = static_cast(sqrt(runover[j])); } for(int i=0; i

packed struct