Float value to Byte array

Processing Coding Questions
1

Hello there how to convert float val to byte array ? i have this function that work in oposite way, it converts Byte array to Float value:

public float byteArrayToFloat(byte test[]) {
  int MASK = 0xff;
  int bits = 0;
  int i = 3;
  for (int shifter = 3; shifter >= 0; shifter--) {
    bits |= ((int) test[i] & MASK) << (shifter * 8);
    i--;
  }
  println(bits);
  return Float.intBitsToFloat(bits);
}

So… How to make floatToByteArray function?

2

A search for " floatToByteArray" is a good start.

I did this a while back and was able to come up with solutions.

:slight_smile:

3

This is my take on it for both opposite conversion ways. :left_right_arrow:
You can also take a look at this site below in order to double-check results: :heavy_check_mark:

/**
 * Float As Bytes Array (v1.1.1)
 * GoToLoop (2019/Dec/29)
 * https://Discourse.Processing.org/t/float-value-to-byte-array/16698/3
 */

static final float MY_FLOAT = -PI;

byte[] floatBytes;
float convertedFloat;

void setup() {
  println(MY_FLOAT);

  floatBytes = floatToByteArr(MY_FLOAT);
  for (final byte b : floatBytes)  print(hex(b), TAB);
  println();

  convertedFloat = byteArrToFloat(floatBytes);
  println(convertedFloat, TAB, convertedFloat == MY_FLOAT);

  exit();
}

static final byte[] floatToByteArr(final float f) {
  return byte(floatToIntArr(f));
}

static final int[] floatToIntArr(final float f) {
  final int i = Float.floatToIntBits(f);
  return new int[] { i >>> 030, i >> 020 & 0xff, i >> 010 & 0xff, i & 0xff };
}

@SafeVarargs static final float byteArrToFloat(final byte... b) {
  return b != null? intArrToFloat(int(b)) : MIN_FLOAT;
}

@SafeVarargs static final float intArrToFloat(final int... i) {
  if (i == null || i.length < Float.BYTES)  return MIN_FLOAT;
  return Float.intBitsToFloat(i[0] << 030 | i[1] << 020 | i[2] << 010 | i[3]);
}
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4

Why is there @SafeVarargs ?

And difference between “>>” and “>>>” ?

… And why is the shifts written as “030”, “020” and “010” ? Maybe iam not the only one who wants to know :stuck_out_tongue:

5

ahh whe you place zero “0” before number, it is in the octal number system, thats it

6

:slight_smile:

1 Like
7

Docs.Oracle.com/en/java/javase/11/docs/api/java.base/java/lang/SafeVarargs.html

Bit-shift operator >>> shifts the most significant bit (negative bit), so the value isn’t negative anymore.

println(030, 020, 010); // 24, 16, 8 (Octal)

2 Likes