How to handle nodejs buffer (uncertain length)

Question

Here is the example data stream (in buffer). The 0x81 is the end of each block, need to process the logic until next 0x81.

00:15:04:00:00:30:04:54:52:55:45:05:14:00:00:00:04:4b:30:01:00:64:81:00:14:04:00:00:10:03:42:57:47:03:0c:00:14:00:04:4b:31:01:01:f4:81:00:1a:04:00:00:14:07:44:43:4f:4e:2d:57:32:00:80:00:03:00:04:4b:33:02:07:08:20:08:81:00:15:04:00:00:20:04:49:52:50:43:01:ba:00:00:00:04:4b:34:01:00:64:81:00:15:04:00:00:00:04:42:44:4d:53:07:e4:00:1e:00:04:4b:35:01:03:20:81

I need to process the complete streams but don't know how to handle with uncertain length of each block.

Answer 1

You can try with something like :

var bytes = "00:15:04:00:00:81:00:01:81:51:81".split(":");
var buffer = new Buffer(bytes);

function getNextBlock(buffer, pos) {
    if (pos >= buffer.length)
        return false;

    var block = [];
    while (pos < buffer.length && buffer[pos] != "81")
        block.push(buffer[pos++]);

    return block.length ? block : false;

}

var block;
var pos = 0;
while(block = getNextBlock(buffer, pos)) {
    console.log(block);
    pos += 1 + block.length;
}