Add google-endpoints to third_party/.

third_party/google-endpoints/Crypto/Util/_number_new.py

+# -*- coding: ascii -*-
+#
+#  Util/_number_new.py : utility functions
+#
+# Written in 2008 by Dwayne C. Litzenberger <dlitz@dlitz.net>
+#
+# ===================================================================
+# The contents of this file are dedicated to the public domain.  To
+# the extent that dedication to the public domain is not available,
+# everyone is granted a worldwide, perpetual, royalty-free,
+# non-exclusive license to exercise all rights associated with the
+# contents of this file for any purpose whatsoever.
+# No rights are reserved.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+# ===================================================================
+
+## NOTE: Do not import this module directly.  Import these functions from Crypto.Util.number.
+
+__revision__ = "$Id$"
+__all__ = ['ceil_shift', 'ceil_div', 'floor_div', 'exact_log2', 'exact_div']
+
+import sys
+if sys.version_info[0] == 2 and sys.version_info[1] == 1:
+    from Crypto.Util.py21compat import *
+
+def ceil_shift(n, b):
+    """Return ceil(n / 2**b) without performing any floating-point or division operations.
+
+    This is done by right-shifting n by b bits and incrementing the result by 1
+    if any '1' bits were shifted out.
+    """
+    if not isinstance(n, (int, long)) or not isinstance(b, (int, long)):
+        raise TypeError("unsupported operand type(s): %r and %r" % (type(n).__name__, type(b).__name__))
+
+    assert n >= 0 and b >= 0    # I haven't tested or even thought about negative values
+    mask = (1L << b) - 1
+    if n & mask:
+        return (n >> b) + 1
+    else:
+        return n >> b
+
+def ceil_div(a, b):
+    """Return ceil(a / b) without performing any floating-point operations."""
+
+    if not isinstance(a, (int, long)) or not isinstance(b, (int, long)):
+        raise TypeError("unsupported operand type(s): %r and %r" % (type(a).__name__, type(b).__name__))
+
+    (q, r) = divmod(a, b)
+    if r:
+        return q + 1
+    else:
+        return q
+
+def floor_div(a, b):
+    if not isinstance(a, (int, long)) or not isinstance(b, (int, long)):
+        raise TypeError("unsupported operand type(s): %r and %r" % (type(a).__name__, type(b).__name__))
+
+    (q, r) = divmod(a, b)
+    return q
+
+def exact_log2(num):
+    """Find and return an integer i >= 0 such that num == 2**i.
+
+    If no such integer exists, this function raises ValueError.
+    """
+
+    if not isinstance(num, (int, long)):
+        raise TypeError("unsupported operand type: %r" % (type(num).__name__,))
+
+    n = long(num)
+    if n <= 0:
+        raise ValueError("cannot compute logarithm of non-positive number")
+
+    i = 0
+    while n != 0:
+        if (n & 1) and n != 1:
+            raise ValueError("No solution could be found")
+        i += 1
+        n >>= 1
+    i -= 1
+
+    assert num == (1L << i)
+    return i
+
+def exact_div(p, d, allow_divzero=False):
+    """Find and return an integer n such that p == n * d
+
+    If no such integer exists, this function raises ValueError.
+
+    Both operands must be integers.
+
+    If the second operand is zero, this function will raise ZeroDivisionError
+    unless allow_divzero is true (default: False).
+    """
+
+    if not isinstance(p, (int, long)) or not isinstance(d, (int, long)):
+        raise TypeError("unsupported operand type(s): %r and %r" % (type(p).__name__, type(d).__name__))
+
+    if d == 0 and allow_divzero:
+        n = 0
+        if p != n * d:
+            raise ValueError("No solution could be found")
+    else:
+        (n, r) = divmod(p, d)
+        if r != 0:
+            raise ValueError("No solution could be found")
+
+    assert p == n * d
+    return n
+
+# vim:set ts=4 sw=4 sts=4 expandtab: