blockchain v0.1.7 BitHelper
Helpers for common operations on the blockchain.
Link to this section Summary
Functions
Similar to :binary.decode_unsigned/1, except we decode <<>> back to 0,
which is a common practice in Ethereum, since we cannot have any leading
zeros
Similar to :binary.encode_unsigned/1, except we encode 0 as
<<>>, the empty string. This is because the specification says that
we cannot have any leading zeros, and so having <<0>> by itself is
leading with a zero and prohibited
Simple wrapper for decoding hex data
Returns the keccak sha256 of a given input
Simply returns the rightmost n bits of a binary
Simply returns the rightmost n bits of a binary
Returned a binary padded to given length in bytes. Fails if binary is longer than desired length
Simple wrapper to generate hex
Link to this section Types
Link to this section Functions
Similar to :binary.decode_unsigned/1, except we decode <<>> back to 0,
which is a common practice in Ethereum, since we cannot have any leading
zeros.
Examples
iex> BitHelper.decode_unsigned(<<>>)
0
iex> BitHelper.decode_unsigned(<<5>>)
5
iex> BitHelper.decode_unsigned(<<76, 75, 64>>)
5_000_000Similar to :binary.encode_unsigned/1, except we encode 0 as
<<>>, the empty string. This is because the specification says that
we cannot have any leading zeros, and so having <<0>> by itself is
leading with a zero and prohibited.
Examples
iex> BitHelper.encode_unsigned(0)
<<>>
iex> BitHelper.encode_unsigned(5)
<<5>>
iex> BitHelper.encode_unsigned(5_000_000)
<<76, 75, 64>>Simple wrapper for decoding hex data.
Examples
iex> BitHelper.from_hex("aabbcc")
<<0xaa, 0xbb, 0xcc>>Returns the keccak sha256 of a given input.
Examples
iex> BitHelper.kec("hello world")
<<71, 23, 50, 133, 168, 215, 52, 30, 94, 151, 47, 198, 119, 40, 99,
132, 248, 2, 248, 239, 66, 165, 236, 95, 3, 187, 250, 37, 76, 176,
31, 173>>
iex> BitHelper.kec(<<0x01, 0x02, 0x03>>)
<<241, 136, 94, 218, 84, 183, 160, 83, 49, 140, 212, 30, 32, 147, 34,
13, 171, 21, 214, 83, 129, 177, 21, 122, 54, 51, 168, 59, 253, 92,
146, 57>>Simply returns the rightmost n bits of a binary.
Examples
iex> BitHelper.mask(0b111101111, 6)
0b101111
iex> BitHelper.mask(0b101101, 3)
0b101
iex> BitHelper.mask(0b011, 1)
1
iex> BitHelper.mask(0b011, 0)
0
iex> BitHelper.mask(0b010, 1)
0
iex> BitHelper.mask(0b010, 20)
0b010Simply returns the rightmost n bits of a binary.
Examples
iex> BitHelper.mask_bitstring(<<0b111101111>>, 6)
<<0b101111::size(6)>>
iex> BitHelper.mask_bitstring(<<0b101101>>, 3)
<<0b101::size(3)>>
iex> BitHelper.mask_bitstring(<<0b011>>, 1)
<<1::size(1)>>
iex> BitHelper.mask_bitstring(<<0b011>>, 0)
<<>>
iex> BitHelper.mask_bitstring(<<0b010>>, 1)
<<0::size(1)>>
iex> BitHelper.mask_bitstring(<<0b010>>, 20)
<<0, 0, 2::size(4)>>
iex> BitHelper.mask_bitstring(<<0b010>>, 3)
<<0b010::size(3)>>
iex> BitHelper.mask_bitstring(<<>>, 3)
<<0b000::size(3)>>Returned a binary padded to given length in bytes. Fails if binary is longer than desired length.
Examples
iex> BitHelper.pad(<<9>>, 5)
<<0, 0, 0, 0, 9>>
iex> BitHelper.pad(<<9>>, 1)
<<9>>
iex> BitHelper.pad(<<9, 9>>, 1)
** (RuntimeError) Binary too long for padding