🚀 go-pugleaf

John:

That's just the way Java works.  Doesn't have "unsigned" types,
either.

Here's a routine that I use for the same basic work.  It takes a
byte[], but since you are reading from a stream you shouldn't have to
change it:

 // convert two bytes into an int, least significant bit first
  static final int toInt(byte[] bStreamIn){
     if(bStreamIn.length != 2)
        throw new IllegalArgumentException("int assumes 2 bytes");
     int part1 = (int)bStreamIn[0];
     int part2 = (int)bStreamIn[1];

     if( part1 < 0 )
        part1 += 256;

     return( part1 + (part2 << 8) );

  } // end of method toInt(byte[])


I have a similar routine for moving from 4 bytes to a long, in case
you need to work with floating point values at some point.  It looks
like:

 // convert 4 bytes into a long, least significant bit first
  static final long toLong(byte[] bStreamIn){
     if(bStreamIn.length != 4)
        throw new IllegalArgumentException("long assumes 4 bytes");

        int part1 = (int)bStreamIn[0];
        int part2 = (int)bStreamIn[1];
        int part3 = (int)bStreamIn[2];
        int part4 = (int)bStreamIn[3];

        if(part1 < 0) part1 += 256;
        if(part2 < 0) part2 += 256;
        if(part3 < 0) part3 += 256;

        return( part1 + (part2 << 8) + (part3 << 16) + (part4 << 24)
);

  } // end of method toLong(byte[])

-Rich

John F. Dutcher wrote:
> 
> Java users: Can any comment on the following integer problem ?
> I am converting a system from DOS written in Microsoft Quick
> Basic (compiled). I have had to discover that the 2 byte integer
> in DOS based files use a reverse byte format from those used
> in JAVA. This is the big endian, little endian dilema for those
> acquainted with those terms. When reading the DOS files for
> conversion with JAVA the integer values are, of course, all wrong.
> I tried simply 'byte switching' which seemed like the appropriate
> and simple solution to getting JAVA integers in the 'endian' format
> it wants. This does not produce good values however. (I don't
> know why). Has anyone seen or used a solution that will covert
> these DOS, Basic integers to true valued JAVA integers ??

-- 

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Rich Wilkman
Senior Quality Assurance Engineer
Borland JBuilder Team

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