new bitwise module [was Re: Discussion: new operators ...]

[Alex Martelli]

"Huaiyu Zhu" <hzhu at localhost.localdomain> wrote in message
news:slrn8obed7.17f.hzhu at rocket.knowledgetrack.com...
    [snip]
> Excellent.  So let's put them in.  I don't know what they do as I don't
use
> bitwise operations, but I suppose they are simple to write on top of
current
> bitwise operators.  Would you do it?

Why, sure.  Also reposting your original stuff for completeness:

""" bitwise.py - replaces builtin bitwise operations with named functions
"""

def bitleft(x, bits):
    return x << bits

def bitright(x, bits):
    return x >> bits

def bitshift(x, bits):
    "shift left (positive bits) or right (negative bits)."
    if bits >= 0:
        return x << bits
    else:
        return x >> -bits

def bitnot(x):
    return ~x

def bitxor(x1, x2):
    return x1 ^ x2

def bitor(*args):
    y = 0
    for x in args:
        y = y | x
    return y

def bitand(*args):
    y = ~0
    for x in args:
        y = y & x
    return y

def bitset(x, bitoff, value=1):
    "return an int with a specified bit set"
    if value:
        return x|(1<<bitoff)
    else:
        return x&~(1<<bitoff)

def bitclear(x, bitoff):
    "return an int with a specified bit zeroed"
    return x&~(1<<bitoff)

def bitget(x, bitoff):
    "get a specified bit from an int as 0 or 1"
    return (x>>bitoff)&1

def bitflip(x, bitoff):
    "return an int with a specified bit inverted"
    return x^(1<<bitoff)

def bitfieldget(x, bitoff, nbits):
    "get a specified bitfield from an int"
    mask=(1<<nbits)-1
    return (x>>bitoff) & mask

def bitfieldset(x, bitoff, nbits, value):
    "return an int with a specified bitfield set"
    mask=(1<<nbits)-1
    return (x&~(mask<<bitoff))|((value&mask)<<bitoff)


if __name__ == "__main__":
    assert bitleft(16,2) == 64
    assert bitright(16,3) == 2
    assert bitshift(16,2) == 64
    assert bitshift(16,-3) == 2

    assert bitnot(7) == -8
    assert bitxor(6,7) == 1
    assert bitand(6,7) == 6
    assert bitor(6,7) == 7
    assert bitand(4,5,6) == 4
    assert bitor(4,5,6) == 7

    assert bitset(16,2) == 20
    assert bitset(7,1,0) == 5
    assert bitget(5,1) == 0
    assert bitflip(5,1) == 7
    assert bitfieldget(0xf0,4,2) == 3
    assert bitfieldset(0xf0,0,2,2) == 0xf2

    print "Tests passed"



> >Maybe it could get into the Standard Distribution, and it would be
trivial
> >to supply a C implementation of course (cBitfield perhaps?).  No way to
    [snip]
> That's the idea.  So let's have it.   That would make adding new math
> operators a little easier to swallow as well. :-)

OK, so, how does one proceed now?  We have a new simple and general
purpose module that we believe might be beneficial to include in the
standard distribution -- what do we send were to submit it? Anybody knows?


Alex