Here is a converter, based on this theory. Use at your own risk. I'm not
sure there is really enough data about how the exponent works.

public class WeirdFloat {

/*
HEX:830d4000 BIN:10000011000011010100000000000000 Should be: -2
HEX:838f7500 BIN:10000011100011110111010100000000 Should be: -2.3333
HEX:8493e000 BIN:10000100100100111110000000000000 Should be: -3
HEX:8a2c2a81 BIN:10001010001011000010101010000001 Should be -.66666
 */
  public static void main(String[] args) {
    long[] inputs = {0x830d4000L, 0x838f7500L, 0x8493e000L, 0x8a2c2a81L};
    for(long in: inputs){
      System.out.printf("%xl %f\n",in,toDouble(in));
    }
  }
  static double toDouble(long in){
    long signBit = 0x80000000L;
    long mantissaBits = 0x4fffffffL;
    long expSignBit = 0x80L;
    long expBits = 0x4fL;

    boolean isNegative = (in & signBit)==signBit;
    double result = (in & mantissaBits)>>8;
    boolean negativeExponent = (in & expSignBit)==expSignBit;
    int exponent = (int)(in & expBits);
    if(negativeExponent){
      exponent = -exponent;
    }
    exponent -= 5;
    result *= Math.pow(10,exponent);
    if(isNegative){
      return -result;
    }else{
      return result;
    }
  }
}