How to properly handle incoming TCP/UDP data

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•

indianajones

No, it's not in the data stream. The code snipped I copied from you is in a function that's called on a setInterval(), called long after I know I've received all the data. That error occurs on the console.log() of the attempt to dump the whole array.

I assume the CTRL-C was some interrupt or something going on in the microcontroller when it encounters a fatal memory error. I assume that because I've seen that exact message so many times while I was coding up my data processing code (which allocates memory). But none of that processing code is in use right now, only the attempt to dump data.

So I have to issue a correction, embarrassingly. The dumpArray() doesn't strictly allocate memory (as in new XXX()), but it creates a string that it appends the entire buffer to, and returns that string (to be printed to console). So there's absolutely another big buffer allocation going on when I try to dump the data.

My problem is that if I just loop through the array, and console.log() each byte, I get newlines after each byte:
0xb0
0x63
0x20
...and so on. It becomes unreadable. Any ideas on how to print to the console without the newline?

•

Robin in reply to @indianajones

'Any ideas on how to print to the console without the newline?'

Not off hand. I've usually built new strings just concatenating each byte, then console.log() say 32 bytes at a time generating a table. I've done some code stripping the leading '0x' let me see if I can locate that snippet. . . .

EDIT: (truncate the leading '0x')

https://www.w3schools.com/jsref/jsref_parseint.asp
https://www.w3schools.com/jsref/tryit.asp?filename=tryjsref_parseint
var byte = 0x??;
parseInt( byte, 16 );

build a columnar table of hex values

  for( var j=0; j<bytes; j++ ) {

    var decbyte = sread[j];
    //var schar = String.fromCharCode( decbyte );
    var soutcvrt = parseInt( decbyte, 16 );
    soutequiv+= " ";
    soutequiv+= ( j == nNumSepHexBytes ) ? " " : "";    // Separate each eight byte block
    soutequiv+= soutcvrt;

//  08 52 ff ff ff ff ff ff   31 32 33 61 00 ff ff ff

substitute a period marker for known value

soutequiv+= "|";
  for( var k=0; k<bytes; k++ ) {

    var decbyte = sread[k];
    if( decbyte == 255 ) decbyte = 46;  // . Period marker
    var schar = ( decbyte > dASCIICtrlCharEnd ) ? String.fromCharCode( decbyte ) : " ";

    if( bDebugPrint ) {
      if( decbyte == 0 ) {
        console.log( "[L242] schar [ " + schar + " ]" );
      }
      if( sChar == "00" ) {
        console.log( "[L242] schar [ " + schar + " ]" );
      }
    }

    soutequiv+= ( k == nNumSepHexBytes ) ? " " : "";    // Separate each eight byte block
    soutequiv+= schar;
  }
soutequiv+= "|";

    if( bDebugPrint ) {

    console.log( "[L120] str read " + sread );
    console.log( "[L121] " + sread.toString() );

    // https://www.w3schools.com/jsref/jsref_fromcharcode.asp
    // var str = String.fromCharCode(sread);

    // https://stackoverflow.com/questions/40142324/how-to-convert-an-array-of-character-codes-to-string-in-javascript

    // https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/apply

    var str = String.fromCharCode.apply(null,sread);
    console.log( "[L126] " + str );
    }

end EDIT

Here is a similar issue (Ctrl+C error) and explanation with setInterval():

http://forum.espruino.com/conversations/321778/

How to properly handle incoming TCP/UDP data

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