二进制转浮点数
单精度
binary_to_float(data){
let buf = new Uint8Array(data);
buf.reverse();
let buf32 = new Float32Array(buf.buffer);
return buf32[0];
}
双精度
binary_to_double(data) {
let buf = new Uint8Array(data);
buf.reverse();
let buf64 = new Float64Array(buf.buffer);
return buf64[0];
}
浮点数转二进制
单精度
float_to_binary(data)
{
var str = Number(data).toString(); //单精度浮点数转为字符串表示（十进制）
var hexStr = this.get_float_hex(str); //十进制字符串表示转为十六进制字符串表示
var bin = new Uint8Array(4);
for(let i=0,j=0;i<4;i++,j+=2)
{
//将每个字节中的二进制数换算成十进制数，存到ArrayBuffer中
let dec = parseInt(hexStr[j],16)*16 + parseInt(hexStr[j+1],16);
bin[i] = dec;
}
return bin;
}
get_float_hex(decString)
{
var dec = decString; //浮点数的十进制字符串
var sign;
var signString;
var decValue = parseFloat(Math.abs(decString)); //获取浮点数的绝对值
if (decString.toString().charAt(0) == '-')
{
sign = 1; //若为负数，符号位为1
signString = "1";
}
else
{
sign = 0; //若为正数，符号位为0
signString = "0";
}
if (decValue==0) //对于0的特殊处理
{
fraction = 0;
exponent = 0;
}
else
{
var exponent = 127; //单精度浮点数的偏移值为127
if (decValue>=2) //若浮点数>=2，就不断除2，同时指数不断增加，直到浮点数小于2
{
while (decValue>=2)
{
exponent++;
decValue /= 2;
}
}
else if (decValue<1) //若浮点数<1，就不断乘2，同时指数不断减少，直到浮点数大于1或指数为0
{
while (decValue < 1)
{
exponent--;
decValue *= 2;
if (exponent ==0)
break;
}
}
if (exponent!=0) decValue-=1; else decValue /= 2; //若指数不为0，取小数部分，否则除以2
}
var fractionString = this.DecToBinTail(decValue, 23); //取23位尾数
var exponentString = this.DecToBinHead(exponent, 8); //取8位阶码
return this.Right('00000000'+parseInt(signString + exponentString + fractionString, 2).toString(16),8);
}
DecToBinTail(dec, pad)
{
var bin = "";
var i;
for (i = 0; i < pad; i++)
{
dec *= 2;
if (dec>= 1)
{
dec -= 1;
bin += "1";
}
else
{
bin += "0";
}
}
return bin;
}
DecToBinHead(dec,pad)
{
var bin="";
var i;
for (i = 0; i < pad; i++)
{
bin = (parseInt(dec % 2).toString()) + bin;
dec /= 2;
}
return bin;
}
Right(String, Length)
{
if (String == null)
return (false);
var dest = '';
for (var i = (String.length - 1); i >= 0; i--)
dest = dest + String.charAt(i);
String = dest;
String = String.substr(0, Length);
dest = '';
for (var i = (String.length - 1); i >= 0; i--)
dest = dest + String.charAt(i);
return dest;
}
双精度
double_to_binary(data)
{
var str = Number(data).toString();
var hexStr = this.get_double_hex(str);
var bin = new Uint8Array(8);
for(let i=0,j=0;i<8;i++,j+=2)
{
let dec = parseInt(hexStr[j],16)*16 + parseInt(hexStr[j+1],16);
bin[i] = dec;
}
return bin;
}
get_double_hex(decString)
{
var dec = decString;
var sign;
var signString;
var decValue = parseFloat(Math.abs(decString));
if (decString.toString().charAt(0) == '-')
{
sign = 1;
signString = "1";
}
else
{
sign = 0;
signString = "0";
}
if (decValue==0)
{
fraction = 0;
exponent = 0;
}
else
{
var exponent = 1023; //双精度浮点数偏移值为1023
if (decValue>=2)
{
while (decValue>=2)
{
exponent++;
decValue /= 2;
}
}
else if (decValue<1)
{
while (decValue < 1)
{
exponent--;
decValue *= 2;
if (exponent ==0)
break;
}
}
if (exponent!=0) decValue-=1; else decValue /= 2;
}
var fractionString = this.DecToBinTail(decValue, 52); //取52位尾数
var exponentString = this.DecToBinHead(exponent, 11); //取11位阶码
var doubleBinStr = signString + exponentString + fractionString;
var doubleHexStr = "";
for(let i=0,j=0;i<8;i++,j+=8)
{
let m = 3-(j%4);
let hexUnit = doubleBinStr[j]*Math.pow(2,m) + doubleBinStr[j+1]*Math.pow(2,m-1) + doubleBinStr[j+2]*Math.pow(2,m-2) + doubleBinStr[j+3]*Math.pow(2,m-3);
let hexDecade = doubleBinStr[j+4]*Math.pow(2,m) + doubleBinStr[j+5]*Math.pow(2,m-1) + doubleBinStr[j+6]*Math.pow(2,m-2) + doubleBinStr[j+7]*Math.pow(2,m-3);
doubleHexStr = doubleHexStr + hexUnit.toString(16) + hexDecade.toString(16);
}
return doubleHexStr;
}
DecToBinTail(dec, pad)
{
var bin = "";
var i;
for (i = 0; i < pad; i++)
{
dec *= 2;
if (dec>= 1)
{
dec -= 1;
bin += "1";
}
else
{
bin += "0";
}
}
return bin;
}
DecToBinHead(dec,pad)
{
var bin="";
var i;
for (i = 0; i < pad; i++)
{
bin = (parseInt(dec % 2).toString()) + bin;
dec /= 2;
}
return bin;
}
Right(String, Length)
{
if (String == null)
return (false);
var dest = '';
for (var i = (String.length - 1); i >= 0; i--)
dest = dest + String.charAt(i);
String = dest;
String = String.substr(0, Length);
dest = '';
for (var i = (String.length - 1); i >= 0; i--)
dest = dest + String.charAt(i);
return dest;
}
【参考文章】
JavaScript实现浮点数转十六进制
