type conversion - What is a the quickest way to bitwise convert two ints to a long in java? -

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i've been using images store data, since editing binary data through paint.net friendlier hex editors.

however, of data long integers. long integers twice size of 32-bit integer in java, 64-bits. how 1 long 2 integers, , more importantly, long when reading image? since java not have unsigned ints, top bit of integer or long negative sign bit, though bit 32 (the lower integer/pixel) ordinary bit in long integer.

most methods of converting long int discard upper bits, well, or may contain bitwise (binary) information!

what need

  1. transform single long 2 integers faithful contain bit data
  2. transform 2 integers long faithfully contains bit data.

no need use autoboxing (long, integer, etc.). primitives work fine. following best can in java programming language.

join

combining 2 ints long

int lo; // integer fill lower bits int hi; // integer fill upper bits long val = (((long) hi) << 32) | (lo & 0xffffffffl);

 

split

retrieving (upper) bits 31-16

int hi = (int) (val >> 32);

retrieving (lower) bits 15-0

int lo = (int) val;

 

note:

be aware of difference between:

  • n >> 32 (sign-extend right-shift)
  • n >>> 32 (zero-fill right-shift)

since java used signed bits, >>> operator introduced handle integers if "unsigned".


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