二进制转十进制整数及浮点数lua实现

local function BinIntToHexInt(b1,b2,b3,b4)  --二进制转十进制整数
    local x = 0
    x = x*0x100 + b4
    x = x*0x100 + b3
    x = x*0x100 + b2
    x = x*0x100 + b1
    return x
end

local function BinFloatToHexFloat(b1, b2, b3, b4)   --二进制转十进制浮点数（传入参数从低到高位的四个字节）
    local sign = b4 > 0x7F  --符号位
    local expo = (b4 % 0x80) * 0x02 + math.floor(b3 / 0x80)  --整数部分
    local mant =  ((b3%0x80)*0x100+b2)*0x100+b1 --小数部分
    if sign then
        sign = -1
    else
        sign = 1
    end
    local n
    if mant == 0 and expo == 0 then
        n = sign * 0.0
    elseif expo == 0xFF then
        if mant == 0 then
            n = sign * math.huge
        else
            n = 0.0/0.0
        end
    else
        if (expo>0) and (expo<0xFF) then
            n = sign * math.ldexp(1.0 + mant / 8388608, expo - 0x7F)
        else
            n = sign * math.ldexp(0.0 + mant / 8388608, - 0x7E)
        end
    end
    return n
end