JS浮点数16进制与10进制之间的转换

JS浮点数16进制与10进制之间的转换

天猫精灵IoT平台自定义脚本时,需要将浮点数在16进制与10进制之间进行转换.设备端发过来的浮点数是16进制的,而显示到网页上的浮点数是10进制的.

使用ArrayBuffer DataView TypeArray进行转换

var aa = 123.45;

// 打印16进制buffer
var floatArr1 = new Float32Array([aa]);
var buffer1 = floatArr1.buffer;
var intArr1 = new Int8Array(buffer1);
intArr1.forEach(function(val){
    console.log((val & 0xFF).toString(16).toUpperCase());
});

// buffer转10进制
var intArr2 = new Int8Array([0x42, 0xF6, 0xE6, 0x66]);
var buffer2 = intArr2.buffer;
var dv2 = new DataView(buffer2);
var bb = dv2.getFloat32();

// 打印16进制buffer
var buffer3 = new ArrayBuffer(4);
var dv3 = new DataView(buffer3);
dv3.setFloat32(0, aa, false);
// dv3.setFloat32(0, aa, true);
var intArr1 = new Int8Array(buffer3);
intArr1.forEach(function(val){
    console.log((val & 0xFF).toString(16).toUpperCase());
});

以下是网上搜到的写法

//需要用到的函数
function InsertString(t, c, n) {
    var r = [];
    for (var i = 0; i * 2 < t.length; i++) {
        r.push(t.substr(i * 2, n));
    }
    return r.join(c);
}
//需要用到的函数
function FillString(t, c, n, b) {
    if ((t === "") || (c.length != 1) || (n <= t.length)) {
        return t;
    }
    var l = t.length;
    for (var i = 0; i < n - l; i++) {
        if (b === true) {
            t = c + t;
        } else {
            t += c;
        }
    }
    return t;
}
//16进制转浮点数
function HexToSingle(t) {
    t = t.replace(/\s+/g, "");
    if (t === "") {
        return "";
    }
    if (t == "00000000") {
        return "0";
    }
    if ((t.length > 8) || (isNaN(parseInt(t, 16)))) {
        return "Error";
    }
    if (t.length < 8) {
        t = FillString(t, "0", 8, true);
    }
    t = parseInt(t, 16).toString(2);
    t = FillString(t, "0", 32, true);
    var s = t.substring(0, 1);
    var e = t.substring(1, 9);
    var m = t.substring(9);
    e = parseInt(e, 2) - 127;
    m = "1" + m;
    if (e >= 0) {
        m = m.substr(0, e + 1) + "." + m.substring(e + 1);
    }
     else {
        m = "0." + FillString(m, "0", m.length - e - 1, true);
    }
    if (m.indexOf(".") == -1) {
        m = m + ".0";
    }
    var a = m.split(".");
    var mi = parseInt(a[0], 2);
    var mf = 0;
    for (var i = 0; i < a[1].length; i++) {
        mf += parseFloat(a[1].charAt(i)) * Math.pow(2, -(i + 1));
    }
    m = parseInt(mi) + parseFloat(mf);
    if (s == 1) {
        m = 0 - m;
    }
    return m;
}
//浮点数转16进制
function SingleToHex(t) {
    if (t === "") {
        return "";
    }
    t = parseFloat(t);
    if (isNaN(t) === true) {
        return "Error";
    }
    if (t === 0) {
        return "00000000";
    }
    var s,
    e,
    m;
    if (t > 0) {
        s = 0;
    }
     else {
        s = 1;
        t = 0 - t;
    }
    m = t.toString(2);
    if (m >= 1) {
        if (m.indexOf(".") == -1) {
            m = m + ".0";
        }
        e = m.indexOf(".") - 1;
    }
     else {
        e = 1 - m.indexOf("1");
    }
    if (e >= 0) {
        m = m.replace(".", "");
    }
     else {
        m = m.substring(m.indexOf("1"));
    }
    if (m.length > 24) {
        m = m.substr(0, 24);
    }
     else {
        m = FillString(m, "0", 24, false);
    }
    m = m.substring(1);
    e = (e + 127).toString(2);
    e = FillString(e, "0", 8, true);
    var r = parseInt(s + e + m, 2).toString(16);
    r = FillString(r, "0", 8, true);
    return InsertString(r, " ", 2).toUpperCase();
}