plain C versus Java performance.

this is follow up on Objective C vs Java performance

In plain C:

#include <stdio.h>
#include <stdlib.h>
#include <CoreServices/CoreServices.h>
#include <mach/mach.h>
#include <mach/mach_time.h>
#include <unistd.h>

typedef struct {
    int x;
    int y;
    int w;
    int h;
} Rectangle;

int intersect(Rectangle* t, Rectangle* r)
{
    int tw = t->w;
    int th = t->h;
    int rw = r->w;
    int rh = r->h;
    if (rw <= 0 || rh <= 0 || tw <= 0 || th <= 0) {
        return 0;
    }
    int tx = t->x;
    int ty = t->y;
    int rx = r->x;
    int ry = r->y;
    rw += rx;
    rh += ry;
    tw += tx;
    th += ty;
    //      overflow || intersect
    return ((rw < rx || rw > tx) &&
            (rh < ry || rh > ty) &&
            (tw < tx || tw > rx) &&
            (th < ty || th > ry));
}


int main (int argc, const char * argv[]) {
    Rectangle* r1 = malloc(sizeof(Rectangle));
    Rectangle* r2 = malloc(sizeof(Rectangle));
 int i;
 uint64_t start, stop, elapsed;
 Nanoseconds nano;
 double duration;
 start = mach_absolute_time();
    for (i = 0; i < 500*1000000; i++) {
        r1->x = i;
        r1->y = i;
        r1->w = i / 4;
        r1->h = i / 4;
        r2->x = i + i / 8;
        r2->y = i + i / 8;
        r2->w = i / 2;
        r2->h = i / 2;
        int b = intersect(r1, r2);
    }
 stop = mach_absolute_time();
 elapsed = stop - start;
 nano = AbsoluteToNanoseconds( *(AbsoluteTime *) &elapsed );
    duration = (*(uint64_t*)&nano) / 1000000000.;
    printf("time: %g\n", duration);
    return 0;
}

run on iMac
Model Name: iMac
Model Identifier: iMac10,1
Processor Name: Intel Core 2 Duo
Processor Speed: 3.06 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 3 MB
Memory: 4 GB
Bus Speed: 1.07 GHz

Yield:
ObjectiveC: 7.73261 seconds
Java: 2.303848 seconds
Plain C: 1.39241 seconds
wall time.

Objective C versus Java performance.

Objective C:

#import <Foundation/Foundation.h>
#include <stdio.h>


@interface Rectangle : NSObject {
@public
    int x;
    int y;
    int w;
    int h;
}
-(int)intersect:(Rectangle*)r1;
@end


@implementation Rectangle
-(int)intersect:(Rectangle*)r
{
    int tw = w;
    int th = h;
    int rw = r->w;
    int rh = r->h;
    if (rw <= 0 || rh <= 0 || tw <= 0 || th <= 0) {
        return 0;
    }
    int tx = x;
    int ty = y;
    int rx = r->x;
    int ry = r->y;
    rw += rx;
    rh += ry;
    tw += tx;
    th += ty;
    //      overflow || intersect
    return ((rw < rx || rw > tx) &&
            (rh < ry || rh > ty) &&
            (tw < tx || tw > rx) &&
            (th < ty || th > ry));
}
@end


int main (int argc, const char * argv[]) {
    Rectangle* r1 = [Rectangle new];
    Rectangle* r2 = [Rectangle new];
    NSDate *start = [NSDate date];
    for (int i = 0; i < 500*1000000; i++) {
        r1->x = i;
        r1->y = i;
        r1->w = i / 4;
        r1->h = i / 4;
        r2->x = i + i / 8;
        r2->y = i + i / 8;
        r2->w = i / 2;
        r2->h = i / 2;
        int b = [r1 intersect: r2];
    }
    NSDate *stop = [NSDate date];
    NSTimeInterval duration = [stop timeIntervalSinceDate:start];
    printf("time: %g\n", duration);
    return 0;
}

---

Java:

public class Test {

    static class Rectangle {
        int x;
        int y;
        int w;
        int h;

        public boolean intersects(Rectangle r) {
            int tw = this.w;
            int th = this.h;
            int rw = r.w;
            int rh = r.h;
            if (rw <= 0 || rh <= 0 || tw <= 0 || th <= 0) {
                return false;
            }
            int tx = this.x;
            int ty = this.y;
            int rx = r.x;
            int ry = r.y;
            rw += rx;
            rh += ry;
            tw += tx;
            th += ty;
            //      overflow || intersect
            return ((rw < rx || rw > tx) &&
                    (rh < ry || rh > ty) &&
                    (tw < tx || tw > rx) &&
                    (th < ty || th > ry));
        }
    }

    public static void main(String[] a) {
        Rectangle r1 = new Rectangle();
        Rectangle r2 = new Rectangle();

        long start = System.nanoTime();
        for (int i = 0; i < 500*1000000; i++) {
                r1.x = i;
                r1.y = i;
                r1.w = i / 4;
                r1.h = i / 4;
                r2.x = i + i / 8;
                r2.y = i + i / 8;
                r2.w = i / 2;
                r2.h = i / 2;
                boolean b = r1.intersects(r2);
        }
        long stop = System.nanoTime();
        double duration = (stop - start) / 1000000000.;
        System.out.println("time: " + duration);
    }

}

---

both run on iMac
Model Name: iMac
Model Identifier: iMac10,1
Processor Name: Intel Core 2 Duo
Processor Speed: 3.06 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 3 MB
Memory: 4 GB
Bus Speed: 1.07 GHz

Yield:
ObjectiveC: 7.73261 seconds
Java: 2.303848 seconds
wall time.