How to convert between floats and decimal twos complement numbers in Python?

Question

I want to convert decimal float numbers in python into twos complement decimal binary numbers. For example 1.5 in twos complement decimal 2.6 (8 bits) would be 0b011000.

Is there a module that can do this for me?

Answer 1

Well, I couldnt find anything so I wrote some code and tested it.Should work...

def floatToTwosComplementDecimal(intBits,decBits,number):
    if decBits == 0:
        mx = pow(2,intBits-1) - 1 # maximum number
    else:
        mx = pow(2,intBits-1) - pow(2,-1*decBits) # maximum number
    mn = -1*pow(2,intBits-1) # minimum number
    if number > mx:
        print "number:" + str(number) + " has been truncated to: " + str(mx)
        number = mx
    elif number < mn:
        print "number:" + str(number) + " has been truncated to: " + str(mn)
        number = mn
    n = []
    m = 0
    if number < 0:
        n.append(1)
        m = -1*pow(2,intBits-1)
    else:
        n.append(0)
        m = 0
    for i in reversed(range(intBits-1)):
        m1 = m + pow(2,i)
        if number < m1:
            n.append(0)
        else:
            n.append(1)
            m = m1
    for i in range(1,decBits+1):
        m1 = m + pow(2,-1*i)
        if number < m1:
            n.append(0)
        else:
            n.append(1)
            m = m1
    return string.join([str(i) for i in n], '')

def twosComplementDecimalToFloat(intBits,decBits,binString):
    n = 0.0
    if binString[0] == "1":
        n = -1*pow(2,intBits-1)
    for i in range(intBits-1):
        n += int(binString[intBits-1-i])*pow(2,i)
    for i in range(1,decBits+1):
        n += int(binString[intBits-1+i])*pow(2,-1*i)
    return n