102 lines
2.6 KiB
Nim
102 lines
2.6 KiB
Nim
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# Fluffy
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# Copyright (c) 2023-2024 Status Research & Development GmbH
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# Licensed and distributed under either of
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# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
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# * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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# As per spec:
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# https://github.com/ethereum/portal-network-specs/blob/master/state-network.md#content-keys-and-content-ids
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{.push raises: [].}
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import
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nimcrypto/hash,
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results,
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stint,
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eth/common/eth_types,
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ssz_serialization,
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../../../common/common_types
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export ssz_serialization, common_types, hash, results
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const
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MAX_PACKED_NIBBLES_LEN = 33
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MAX_UNPACKED_NIBBLES_LEN = 64
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type Nibbles* = List[byte, MAX_PACKED_NIBBLES_LEN]
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func init*(T: type Nibbles, packed: openArray[byte], isEven: bool): T =
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doAssert(packed.len() <= MAX_PACKED_NIBBLES_LEN)
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var output = newSeqOfCap[byte](packed.len() + 1)
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if isEven:
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output.add(0x00)
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else:
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doAssert(packed.len() > 0)
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# set the first nibble to 1 and copy the second nibble from the input
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output.add((packed[0] and 0x0F) or 0x10)
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let startIdx = if isEven: 0 else: 1
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for i in startIdx ..< packed.len():
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output.add(packed[i])
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Nibbles(output)
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func encode*(nibbles: Nibbles): seq[byte] =
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SSZ.encode(nibbles)
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func decode*(T: type Nibbles, bytes: openArray[byte]): Result[T, string] =
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decodeSsz(bytes, T)
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func packNibbles*(unpacked: openArray[byte]): Nibbles =
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doAssert(
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unpacked.len() <= MAX_UNPACKED_NIBBLES_LEN, "Can't pack more than 64 nibbles"
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)
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if unpacked.len() == 0:
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return Nibbles(@[byte(0x00)])
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let isEvenLength = unpacked.len() mod 2 == 0
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var
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output = newSeqOfCap[byte](unpacked.len() div 2 + 1)
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highNibble = isEvenLength
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currentByte: byte = 0
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if isEvenLength:
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output.add(0x00)
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else:
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currentByte = 0x10
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for i, nibble in unpacked:
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if highNibble:
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currentByte = nibble shl 4
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else:
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output.add(currentByte or nibble)
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currentByte = 0
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highNibble = not highNibble
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Nibbles(output)
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func unpackNibbles*(packed: Nibbles): seq[byte] =
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doAssert(packed.len() <= MAX_PACKED_NIBBLES_LEN, "Packed nibbles length is too long")
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var output = newSeqOfCap[byte](packed.len() * 2)
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for i, pair in packed:
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if i == 0 and pair == 0x00:
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continue
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let
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first = (pair and 0xF0) shr 4
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second = pair and 0x0F
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if i == 0 and first == 0x01:
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output.add(second)
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else:
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output.add(first)
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output.add(second)
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output
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