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feat: support ints in TypeEncoder #49

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feat: support ints in TypeEncoder #49

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8f5b7cc
feat: support ints in TypeEncoder
fluffywaffles Jan 16, 2025
4def8bb
chore: increment minor version to include integer encoder
fluffywaffles Jan 17, 2025
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1 change: 1 addition & 0 deletions lib/abi/function_selector.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@ defmodule ABI.FunctionSelector do
| :bytes
| :string
| :address
| {:int, integer()}
| {:array, type}
| {:array, type, non_neg_integer}
| {:tuple, [argument_type]}
Expand Down
44 changes: 41 additions & 3 deletions lib/abi/type_encoder.ex
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Original file line number Diff line number Diff line change
Expand Up @@ -195,6 +195,11 @@ defmodule ABI.TypeEncoder do
...> )
...> |> Base.encode16(case: :lower)
"19c9d90a00000000000000000000000000000000000000000000000000000000000000010000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000000300000000000000000000000000000000000000000000000000000000000000e00000000000000000000000000000000000000000000000000000000000000009000000000000000000000000000000000000000000000000000000000000000a000000000000000000000000000000000000000000000000000000000000000b0000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000500000000000000000000000000000000000000000000000000000000000000a000000000000000000000000000000000000000000000000000000000000000e0000000000000000000000000000000000000000000000000000000000000000800000000000000000000000000000000000000000000000000000000000000010600000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000007"

iex> [-255]
...> |> ABI.TypeEncoder.encode(%ABI.FunctionSelector{function: nil, types: [%{type: {:int, 16}}]})
...> |> Base.encode16(case: :lower)
"ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff01"
"""
def encode(data, function_selector) do
encode_method_id(function_selector) <> do_encode_data(data, function_selector)
Expand Down Expand Up @@ -255,6 +260,10 @@ defmodule ABI.TypeEncoder do
{encode_uint(data, size), rest}
end

defp encode_type({:int, size}, [data | rest]) do
{encode_int(data, size), rest}
end

defp encode_type(:address, data), do: encode_type({:uint, 160}, data)

defp encode_type(:bool, [data | rest]) do
Expand Down Expand Up @@ -342,6 +351,29 @@ defmodule ABI.TypeEncoder do
bytes |> pad(byte_size(bytes), :right)
end

defp encode_int(int, desired_size_bits) when rem(desired_size_bits, 8) == 0 and is_integer(int) do
desired_size_bytes = ceil(desired_size_bits / 8)

sign_byte = if(int < 0, do: <<0xFF>>, else: <<0x00>>)

significant_bytes =
if int >= 0 do
maybe_encode_unsigned(abs(int))
else
# two's complement encoding: 2**(integer_bit_size) - abs(integer)
actual_bit_size = :binary.encode_unsigned(-1 * int) |> bit_size()
maybe_encode_unsigned(2 ** actual_bit_size + int)
end

if byte_size(significant_bytes) > desired_size_bytes - 1 do
raise(
"Data overflow encoding int, data `#{int}` cannot fit in #{(desired_size_bytes - 1) * 8} bits"
)
end

pad(significant_bytes, desired_size_bytes, :left, fill_byte: sign_byte)
end

# Note, we'll accept a binary or an integer here, so long as the
# binary is not longer than our allowed data size
defp encode_uint(data, size_in_bits) when rem(size_in_bits, 8) == 0 do
Expand All @@ -357,12 +389,18 @@ defmodule ABI.TypeEncoder do
bin |> pad(size_in_bytes, :left)
end

defp pad(bin, size_in_bytes, direction) do
defp pad(bin, size_in_bytes, direction, opts \\ []) do
fill_byte = Keyword.get(opts, :fill_byte, <<0x00>>)

# TODO: Create `left_pad` repo, err, add to `ABI.Math`
total_size = size_in_bytes + ABI.Math.mod(32 - ABI.Math.mod(size_in_bytes, 32), 32)

padding_size_bits = (total_size - byte_size(bin)) * 8
padding = <<0::size(padding_size_bits)>>
padding_size_bytes = total_size - byte_size(bin)

padding =
Stream.duplicate(fill_byte, padding_size_bytes)
|> Enum.to_list()
|> :binary.list_to_bin()

case direction do
:left -> padding <> bin
Expand Down