How does JS use hexadecimal to save 100-bit state

Now the development encounters a requirement,需要保存100个状态,状态只有0和1两种状态,If using string save100个0和1,Then it will be very long, Then I thought of turning it into16进制

思考

但是在JS里最大的安全整数 Number.MAX_SAFE_INTEGER The maximum can only be9007199254740991这么大.

// Convert the largest safe integer to 16进制
(Number.MAX_SAFE_INTEGER).toString(16)
// 0x1FFFFFFFFFFFFF

结果发现只有13个F,一个F可以表示4位(1111),即13*4=52Normally only save52位

// 转成二进制
parseInt('0xFFFFFFFFFFFFF').toString(2)
// 1111111111111111111111111111111111111111111111111111

// 计算下长度
parseInt('0xFFFFFFFFFFFFF').toString(2).length
// 52

If so, add one moreF呢？14个F（Found that there seems to be no problem？！真的没问题吗？？）

parseInt('0xFFFFFFFFFFFFFF')	// 72057594037927940

Now do the down conversion to binary and calculate the down length

// 转成二进制
parseInt('0xFFFFFFFFFFFFFF').toString(2)
// '100000000000000000000000000000000000000000000000000000000'

// 计算下长度
parseInt('0xFFFFFFFFFFFFFF').toString(2).length
// 57

It can be seen that there is a problem,The converted binary is incorrect,wrong length.
那么没办法了,Only within safe limits52位可以用（It is also necessary to pay attention to safety when writing code,不然出错了,I don't know why）

然后就想到了,There is no need to use two 52 * 2 = 104个了,Then it suffices

实现

保存数据的格式,我使用的是 . 进行数据分割,即 整数.小数 的数据格式.
Then it can be dealt with separately,I'm using the integer part first,即 [0-49].[50-99]这种方式保存
Later found a problem not to use bitwise operations directly,Because bit operations are only supported32位以内的,这样就麻烦了
I did it by converting hex to binary string,Then convert to hexadecimal,This does not involve bit operations

Regarding the preservation of the location,Since the array is on the left side is0位,We change directly0位,Then the initial data will be very large,所以我们要反过来,Change from the highest bit of the array.

// 第一位为1
1 '1000' => 8   '0001' => 1
// 第二位为1
3 '1100' => 8   '0011' => 3
// 第三位为1
7 '1110' => 8   '0111' => 7

We use the latter save method,In this way, the data will be changed from small to large after conversion,Also in line with our habits.

Basic version conversion

Now this is only supported50位以内的

/** * Binary increment operation * @param {String} data 十六进制 * @param {Number} pos 位 * @return {String} Calculated hexadecimal value */
function addBinaryVal(data, pos) {
    
	// 超过50Bits are not converted
	if (pos >= 50){
    
        return data;
    }
	// Convert hexadecimal to binary first,Fill in the front 0,Then split into arrays,Then replace the state at the specified location,Finally, convert to hexadecimal
    let binaryData = parseInt(data, 16).toString(2).padStart(50, '0').split('');
    // Change the specified location
    binaryData[49-pos] = '1';

    return '0x' + parseInt(binaryData.join(''), 2).toString(16)
}

Enhanced conversion

可以支持100位或者150位甚至更高,我这里只是100位,It can be expanded as needed
Encapsulates a method to make state changes

/** * Sets the hexadecimal string specified position value to 1 * Calculated separately for the two hex strings,然后再还原 * @param {String} data 数据 Two hexadecimal strings * @param {Number} pos 位置 范围限制[0,99] * @return {String} 改变后的字符串 */
function replaceBinaryValByPos(data, pos){
    
    if (pos > 100 || pos < 0){
    
        logger.error("getBinaryValByPos data: %j pos: %j is invalid");
        return data;
    }
    let tempData = data.split('.');
    if(pos < 50){
    
        tempData[0] = addBinaryVal(tempData[0], pos);
    }else{
    
        tempData[1] = addBinaryVal(tempData[1], pos-50);
    }
    return tempData.join('.');
}


let val = '0xa.0xa' // '1010.1010'
val = replaceBinaryValByPos(val, 0) // '1011.1010'
console.log(val) // '0xb.0xa'

val = replaceBinaryValByPos(val, 50) // '1010.1011'
console.log(val) // '0xa.0xb'

Get the state of the corresponding bit

Encapsulates a method fixed method to obtain the state of the data

/** * The hexadecimal string specifies the status of the location * Convert the largest safe integer to binary 可以有53位 只取用50位,Two strings can be there100位 * @param {String} data 数据 Two hexadecimal strings * @param {Number}pos 位置 范围限制[0,99] * @return {boolean} 状态 [true,false] */
function getBinaryValByPos(data, pos){
    
    if (pos > 100 || pos < 0){
    
        logger.error("getBinaryValByPos data: %j pos: %j is invalid");
        // Invalid status returnedtrue Indicates that it has taken effect,Prevent repeated operations due to ineffectiveness
        return true;
    }

    if(pos < 50){
    
        let val = parseInt(data.split('.')[0], 16).toString(2).padStart(50, '0');
        return val.charAt((50-1) - pos) === '1';
    }else{
    
        let val = parseInt(data.split('.')[1] || '0x0', 16).toString(2).padStart(50, '0');
        return val.charAt((100-1) - pos) === '1';
    }
}

let val = '0xa.0xb' // ==> '1010.1011'
console.log(getBinaryValByPos(val,0))   // false
console.log(getBinaryValByPos(val,1))   // true
console.log(getBinaryValByPos(val,2))   // false

Convert hexadecimal data to binary string

Here is the conversion of hexadecimal data to binary string,However, the data state is saved from left to right
这样方便使用

/** * Get the binary format string * 反向组合 从左往右算 * @param data 数据 Two hexadecimal strings * @return {string} 二进制字符串 */
function getBinaryStr(data) {
    
    let tempData = data.split('.');
    let len = 50;
    let strArr = [];
    strArr[0] = parseInt(tempData[0], 16).toString(2).padStart(len, '0').split('').reverse().join('');
    strArr[1] = parseInt(tempData[1], 16).toString(2).padStart(len, '0').split('').reverse().join('');
    return strArr.join('');
}


let val = '0xa.0xb'  // 1010 1011 翻转=> 01011101
val = getBinaryStr(val);
console.log(val)  // '0101000...0001101000...000' =>总长度100

结束

Here is just the way I came up with it,如果有更好的方法,可以一起探讨交流
I'll update if I find something better,加油！