How to write a large int as as bytes

donuan

Hi, I need to send the value 115200 over serial to an external device that accepts the format 0x00, 0x00, 0x00, 0x00, and I have no idea how to convert it into that format. Any advice would be much appriciated. Thanks

KevinWorkman

Step one would be to understand exactly how that format maps to the value. Does the documentation for the device explain what that format means?

GoToLoop

Converting 1 int to 4 byte (big-endian) values is like extracting aRGB properties from 1 color: :ar!

/**
 * aRGB_Shifting_Conversion (v1.0)
 * GoToLoop (2015-Nov-05)
 *
 * forum.Processing.org/two/discussion/13411/how-to-write-a-large-int-as-as-bytes
 * forum.Processing.org/two/discussion/13792/color-bit-shifting
 * forum.Processing.org/two/discussion/14814/how-to-translate-byte-to-pimage
 */

final byte[] output = new byte[4];
int input = 115200;

void setup() {
  println(input, binary(input));
  to_aRGB_array(input, output);
  println(output);
  exit();
}

static final byte[] to_aRGB_array(color c, byte... target) {
  byte a = (byte) (c >>> 030);
  byte r = (byte) (c >>  020 & 0xff);
  byte g = (byte) (c >>  010 & 0xff);
  byte b = (byte) (c         & 0xff);

  if (target == null || target.length < 4)  return new byte[] {a, r, g, b};

  target[0] = a;
  target[1] = r;
  target[2] = g;
  target[3] = b;

  return target;
}

donuan

Thank you! this helped a lot!

KevinWorkman

Please link between crossposts: http://stackoverflow.com/questions/33550618/how-to-convert-a-large-integer-to-bytes