Re: Reading a unsigned 64bit integer from a buffer.

[Ben Short]

After searching this group I got it to work using the long class [1]

code snipit:

var Long = require('./long.js').Long;

var high = buffer.readUInt32BE(0);

var low = buffer.readUInt32BE(4); 

var l = Long.fromBits(low, high);

var timestamp = l.toNumber();

[1] https://github.com/mongodb/js-bson/blob/master/lib/bson/long.js

On Thursday, June 21, 2012 8:15:05 PM UTC+1, Ben Short wrote:

Hi, 

I'm trying out nodejs as a TCP server. The client server protocol is binary and the first value is a unsigned 64bit integer. The actual value in this 8 byte's is a unix epoch such as 1340304234643. The bytes are in network byte order/big endian.

Is there anyway that I'm going to be able to read this value in nodejs?

Thanks

Ben

[Tim Caswell]

Keep in mind that you'll lose precision when converting it to a native javascript number.  JS numbers are defined to be double floats. (though I head long type is coming in future JS)

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[Nathan Rajlich]

My "ref"[1] module can do this. It extends Buffer.prototype with the missing {read,write}{U}Int64{LE,BE] functions by calling into native functions. It can accept Strings with big integers inside of it and it will strtoll or strtoull the value in C-land. It also returns Strings when the value being returned is outside the range of a valid JS Number.

Cheers!

1: https://github.com/TooTallNate/ref

[Ben Short]

Thanks Nathan that looks like just what I'm after.

[Ben Short]

Nathan,

I'm trying this code:

   var eventTimeStamp = buffer.readUInt64BE(0);

but get the following error:

   var eventTimeStamp = buffer.readUInt64BE(0);

                                 ^

   TypeError: Object

What am I missing?

Ben

[Nathan Rajlich]

Ben, can you tell me what "ref.endianness" is reporting on your machine? If it's "LE" then I'll need to make an update to "ref" to support the non-native-endian read/write functions. It's been on my todo list, just haven't had a need yet. Gimme a minute...

[Nathan Rajlich]

Ok Ben, try out v0.0.18 of ref. It adds the "non-native-endianness" version of those read/write functions as well. Cheers!

[Ben Short]

Nathan, 

ref.endianness reports LE.

I upgraded to v 0.0.18 and the code works as expected.

Many thanks

Ben