class Integer

Constants

ROUNDING

rosettacode.org/wiki/Nth_root#Ruby (with modifications)

Public Instance Methods

invmod(n) click to toggle source

From Wikipedia: en.wikipedia.org/wiki/Extended_Euclidean_algorithm#Pseudocode

# File lib/crypto_toolchain/extensions/integer_extensions.rb, line 31
def invmod(n)
  a = self
  t = 0
  new_t = 1
  r = n
  new_r = a
  while new_r != 0
      quotient = r / new_r
      t, new_t = new_t, (t - quotient * new_t)
      r, new_r = new_r, (r - quotient * new_r)
  end
  raise ArgumentError.new("#{self} is not invertible") if r > 1
  t += n if t < 0
  t
end
Also aliased as: mod_inverse, modinv
lrot(num) click to toggle source
# File lib/crypto_toolchain/extensions/integer_extensions.rb, line 19
def lrot(num)
  ((self << num) & 0xffffffff) |
    ((self & 0xffffffff) >> (32 - num))
end
mod_inverse(n)
Alias for: invmod
modexp(exponent, mod) click to toggle source
# File lib/crypto_toolchain/extensions/integer_extensions.rb, line 76
def modexp(exponent, mod)
  raise ArgumentError.new("Exponent must be non-negative") if exponent < 0
  product = 1
  base = self % mod
  while exponent > 0
    if exponent & 0x01 == 1
      product = (product * base) % mod
    end
    exponent = exponent >> 1
    base = (base**2) % mod
  end
  product
end
Also aliased as: modpow
modinv(n)
Alias for: invmod
modpow(exponent, mod)
Alias for: modexp
root(n, round: :down) click to toggle source
# File lib/crypto_toolchain/extensions/integer_extensions.rb, line 52
def root(n, round: :down)
  raise ArgumentError.new("round must be in [#{ROUNDING.join(', ')}]") unless ROUNDING.include?(round)
  raise ArgumentError.new("Can't be called on 0") if self == 0
  x = self
  loop do
    prev = x
    x = ((n - 1) * prev) + (self / (prev ** (n - 1)))
    x /= n
    break if (prev - x) <= 0
  end
  if x**n == self
    x
  else
    case round
    when :up
      x+1
    when :down
      x
    when :none
      raise ArgumentError.new("#{self} has no #{n}th root")
    end
  end
end
rrot(num) click to toggle source
# File lib/crypto_toolchain/extensions/integer_extensions.rb, line 24
def rrot(num)
  ((self & 0xffffffff) >> num) |
    ((self << (32 - num)) & 0xffffffff)
end
to_bin_string() click to toggle source
# File lib/crypto_toolchain/extensions/integer_extensions.rb, line 11
def to_bin_string
  to_hex_string.from_hex
end
to_bits(pack_arg = "L>") click to toggle source
# File lib/crypto_toolchain/extensions/integer_extensions.rb, line 15
def to_bits(pack_arg = "L>")
  [self].pack(pack_arg).to_bits
end
to_hex_string() click to toggle source
# File lib/crypto_toolchain/extensions/integer_extensions.rb, line 3
def to_hex_string
  ret = to_s(16)
  if ret.length.odd?
    ret = "0#{ret}"
  end
  ret
end
updiv(other) click to toggle source
# File lib/crypto_toolchain/extensions/integer_extensions.rb, line 91
def updiv(other)
  quot, remainder = self.divmod(other)
  if remainder == 0
    quot
  else
    quot + 1
  end
end