Ethiopian multiplication: Difference between revisions

=={{header|Objective-C}}==

Using class methods except for the generic useful function <tt>iseven</tt>.

<lang objc>#import <stdio.h>

#import <objc/Object.h>

BOOL iseven(int x)

{

return (x&1) == 0;

}

@interface EthiopicMult : Object

+ (int)mult: (int)plier by: (int)plicand;

+ (int)halve: (int)a;

+ (int)double: (int)a;

@end

@implementation EthiopicMult

+ (int)mult: (int)plier by: (int)plicand

{

int r = 0;

while(plier >= 1) {

if ( !iseven(plier) ) r += plicand;

plier = [EthiopicMult halve: plier];

plicand = [EthiopicMult double: plicand];

}

return r;

}

+ (int)halve: (int)a

{

return (a>>1);

}

+ (int)double: (int)a

{

return (a<<1);

}

@end

int main()

{

printf("%d\n", [EthiopicMult mult: 17 by: 34]);

return 0;

}</lang>