from math import frexp, copysign, isnan, isinf

def hex_float(x):
    # special-case infinities, nans and zeros
    if isnan(x) or isinf(x):
        return str(x)
    sign = '-' if copysign(1.0, x) < 0 else ''
    if not x:
        return sign + '0x0p+0'

    m, e = frexp(x)
    m = 2.0*abs(m)
    if m == 1.0:
        # no (hexa)decimal point required
        return "%s0x1p%+d" % (sign, e-1)
    while m != int(m):
        m *= 16.0
    return "%s0x1.%sp%+d" % (sign, ("%x" % int(m))[1:], e-1)