ASCII to HEX conversion

[Bengt Richter]

On 12 Apr 2002 04:56:27 -0700, westernsam at hotmail.com (sam) wrote:

>The following code will give binary from decimal. (N.B. I cannot claim
>credit for this as I didn't write it and just found it somewhere)
>
>import math, operator
>
>def binary_repr(self, number, max_length = 32):
>        assert number < 2L << max_length
>        shifts = map (operator.rshift, max_length * [number], range
>(max_length - 1, -1, -1))
>        digits = map (operator.mod, shifts, max_length * [2])
>        if not digits.count (1): return "00000000"
>        digits = digits [digits.index (1):]
>        returnString = string.join (map (repr, digits), '')
>        while (len(returnString) < 8):
>            returnString = "0%s" % returnString
>        return returnString

A little less importing etc:

 >>> def binstr(n, maxbits=None):
 ...     absn = abs(n)
 ...     s=[chr(((n>>b)&1)+48) for b in xrange(maxbits or len(hex(n))*4)
 ...         if maxbits or absn>>b or not b or (n<0 and absn>>(b-1))]
 ...     s.reverse()
 ...     return ''.join(s)
 ...
 >>> binstr(1)
 '1'
 >>> binstr(0)
 '0'
 >>> binstr(1,8)
 '00000001'
 >>> binstr(0xaaaaaaaa)
 '10101010101010101010101010101010'
 >>> binstr(0xcccc, 32)
 '00000000000000001100110011001100'
 >>> binstr(-1L<<55)
 '110000000000000000000000000000000000000000000000000000000'
 >>> binstr( 1L<<55,57)
 '010000000000000000000000000000000000000000000000000000000'
 >>> binstr(-5)
 '1011'
 >>> binstr(-5,8)
 '11111011'
 >>> binstr(-5,2)
 '11'

Note that I preserved a sign bit as such instead of generating the bits
of the absolute value with a minus sign. This makes an ambiguity, but it
shows the bits of the negative value. You can easily change it as desired.

Regards,
Bengt Richter