Module refinery.units.blockwise.bitrev

Expand source code Browse git 
#!/usr/bin/env python3
# -*- coding: utf-8 -*-
from refinery.units.blockwise import UnaryOperation


class bitrev(UnaryOperation):
    """
    Reverse the bits of every block. Any excess bytes at the end of the input that are not
    an integer multiple of the block size are ignored.
    """
    @staticmethod
    def operate(arg):
        raise RuntimeError('operate was called before the unit was initialized')

    def __init__(self, bigendian=False, blocksize=None):
        """
        Unreadable bit reversal operations due to:
        https://graphics.stanford.edu/~seander/bithacks.html#ReverseByteWith64BitsDiv
        https://graphics.stanford.edu/~seander/bithacks.html#ReverseParallel
        """
        super().__init__(bigendian=bigendian, blocksize=blocksize, _truncate=1)

        if self.bytestream:
            def operate(v):
                return ((v * 0x202020202) & 0x10884422010) % 1023
        elif self.blocksize in (2, 4, 8):
            def operate(v):
                s = self.fbits
                m = self.fmask
                w = v
                while s > 1:
                    s >>= 1
                    m = m ^ (m << s)
                    w = ((w << s) & ~m) | ((w >> s) & m)
                return w
        else:
            def operate(v):
                w = v & 0
                for s in range(self.fbits):
                    w |= ((v >> s) & 1) << (self.fbits - s - 1)
                return w
        self.operate = operate

Classes

class bitrev (bigendian=False, blocksize=None)

Reverse the bits of every block. Any excess bytes at the end of the input that are not an integer multiple of the block size are ignored.

Unreadable bit reversal operations due to: https://graphics.stanford.edu/~seander/bithacks.html#ReverseByteWith64BitsDiv https://graphics.stanford.edu/~seander/bithacks.html#ReverseParallel

Expand source code Browse git 
class bitrev(UnaryOperation):
    """
    Reverse the bits of every block. Any excess bytes at the end of the input that are not
    an integer multiple of the block size are ignored.
    """
    @staticmethod
    def operate(arg):
        raise RuntimeError('operate was called before the unit was initialized')

    def __init__(self, bigendian=False, blocksize=None):
        """
        Unreadable bit reversal operations due to:
        https://graphics.stanford.edu/~seander/bithacks.html#ReverseByteWith64BitsDiv
        https://graphics.stanford.edu/~seander/bithacks.html#ReverseParallel
        """
        super().__init__(bigendian=bigendian, blocksize=blocksize, _truncate=1)

        if self.bytestream:
            def operate(v):
                return ((v * 0x202020202) & 0x10884422010) % 1023
        elif self.blocksize in (2, 4, 8):
            def operate(v):
                s = self.fbits
                m = self.fmask
                w = v
                while s > 1:
                    s >>= 1
                    m = m ^ (m << s)
                    w = ((w << s) & ~m) | ((w >> s) & m)
                return w
        else:
            def operate(v):
                w = v & 0
                for s in range(self.fbits):
                    w |= ((v >> s) & 1) << (self.fbits - s - 1)
                return w
        self.operate = operate

Ancestors

Class variables

var required_dependencies
var optional_dependencies

Static methods

def operate(arg)
Expand source code Browse git 
@staticmethod
def operate(arg):
    raise RuntimeError('operate was called before the unit was initialized')

Inherited members