Request to Add Function for Converting Two's Complement HEX to Decimal (Support for Multi-byte Length)

[volodymyr-babak]

Currently, there is no built-in function in TBEL to convert Two's Complement HEX values to Decimal.
I would like to propose adding a function that supports this conversion, specifically for HEX values with multiple bytes in length.

As a starting point, I've provided a sample code that is capable of converting a single byte HEX value to a Decimal number.
This sample was developed by @rekcaiot and currently only handles single-byte conversions, but the goal is to expand this functionality to support multiple-byte HEX values.

Here’s the sample code that works for converting single byte HEX to Decimal:

function twoComplementOneByte(hex){
    var signed = parseInt(hex,16) & 0x80; //is first bit signed? 0 = positive number; >0 = negative number
    if(signed > 0){
        var binaryString = Integer.toString(parseInt(hex, 16), 2);  //convert hex to binary string
        var binaryStringInverted = "";
        for(var k=0; k<binaryString.length; k++){  //invert all bits of string
            if(binaryString[k] == "0"){
                binaryStringInverted = binaryStringInverted + "1";
            }else{
                binaryStringInverted = binaryStringInverted + "0";
            }
        }
        return (parseInt(binaryStringInverted, 2) + 1) * -1;
    }else{
        return parseInt(hex, 16);
    }
}

Output:

0xDB -> -37 // 11011011
0x69 -> 105 // 01101001
0xF2 -> -14 // 11110010
0x9C -> -100 // 10011100
0x57 -> 87 // 01010111

Results can be double checked here:
https://sandbox.mc.edu/~bennet/cs110/tc/tctod.html

[nickAS21]

var a1 = 0x69;          // 106
var a1_bit_to_int = parseBinaryArrayToInt(parseByteToBinaryArray(a1)); // 105
var a2 = 0xDB;          // 219 
var a2_bit_to_int = parseBinaryArrayToInt(parseByteToBinaryArray(a2)); // -37
var a3 = 0xEB4D;        // 60237
var a3_bit = parseByteToBinaryArray(0xEBDB);    // [1, 1, 0, 1, 1, 0, 1, 1]
var a3_lastBit_to_int = parseBinaryArrayToInt(parseByteToBinaryArray(0xEBDB)); // only last as 0xDB == -37
var aa3 = [0xEB, 0x4D]; // [235, 77]
var aa3_bit = parseBytesToBinaryArray(aa3); // [1, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1]
var aa3_bit_to_int = parseBinaryArrayToInt(aa3_bit); // 60237 == aa3
var a4 = 0xFFEB4D;          // 16771917    
var aa4 = [0xFF, 0xEB, 0x4D]; // [255, 235, 77]
var aa4_bit = parseBytesToBinaryArray(aa4); // [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1]
var aa4_bit_to_int = parseBinaryArrayToInt(aa4_bit); // 16771917 == aa4

var result = {
    a1: a1,
    a1_bit_to_int: a1_bit_to_int,
    a2: a2,
    a2_bit_to_int: a2_bit_to_int,
    a3: a3,
    a3_bit: a3_bit,
    a3_lastBit_to_int: a3_lastBit_to_int,
    aa3: aa3,
    aa3_bit: aa3_bit,
    aa3_bit_to_int: aa3_bit_to_int,
    a4: a4,
    aa4: aa4,
    aa4_bit: aa4_bit,
    aa4_bit_to_int: aa4_bit_to_int
}; 

result:

{
    "a1": 105,
    "a1_bit_to_int": 105,
    "a2": 219,
    "a2_bit_to_int": -37,
    "a3": 60237,
    "a3_bit": [1, 1, 0, 1, 1, 0, 1, 1],
    "a3_lastBit_to_int": -37,
    "aa3": [235, 77],
    "aa3_bit": [1, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1],
    "aa3_bit_to_int": 60237,
    "a4": 16771917,
    "aa4": [255, 235, 77],
    "aa4_bit": [1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1],
    "aa4_bit_to_int": 16771917
}