Left shift operator fails on int (not in real Java)

[jin...@tappytaps.com]

Hi,

I am implementing custom CRC algorithm and I have problem with bit shifts.

For example, this works in Java:

int i = 214502010;
System.out.println(i << 8);

but not in J2ObjC:

runtime error: left shift of 214502010 by 8 places cannot be represented in type 'jint' (aka 'int')
-922060288

Any workaround for this?

Thanks,

Jindrich

[jin...@tappytaps.com]

Hi,

I even was not successful with re-implementation as described at JLS spec, section 15.19. It looks like J2ObjC has stronger overflow checking, than Java:

int i = 214502010;
// i << 8
int i2 = i * (int)Math.pow(2, 8);

This works in Java, in j2objc again - overflow error.

However, in JLS specification is written clearly:

The value of n << s is n left-shifted s bit positions; this is equivalent (even if overflow occurs) to multiplication by two to the power s.

- so that it should not fail on overflow.

Jindrich


Dne pátek 5. dubna 2019 15:26:50 UTC+2 jin...@tappytaps.com napsal(a):

[Antonio Cortes Perez]

This is not a J2ObjC issue. It has to do with the clang flags that you are using. I was able to transpile, compile and run your provided example.

See: https://stackoverflow.com/questions/53566029/1-31-cannot-be-represented-by-type-int

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