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https://github.com/logos-storage/nim-poseidon2.git
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46 lines
1.7 KiB
Nim
46 lines
1.7 KiB
Nim
import ./types
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import constantine/math/arithmetic
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import constantine/math/io/io_bigints
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import constantine/math/io/io_fields
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import constantine/math/config/curves
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export curves
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func fromOpenArray(_: type F, bytes: openArray[byte]): F =
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F.fromBig(B.unmarshal(bytes, littleEndian))
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func fromBytes*(_: type F, bytes: array[31, byte]): F =
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## Converts bytes into a field element. The byte array is interpreted as a
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## canonical little-endian big integer.
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F.fromOpenArray(bytes)
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func toBytes*(element: F): array[32, byte] =
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## Converts a field element into its canonical representation in little-endian
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## byte order. Uses at most 254 bits, the remaining most-significant bits are
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## set to 0.
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assert marshal(result, element.toBig(), littleEndian)
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iterator elements*(bytes: openArray[byte], _: type F): F =
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## Converts bytes into field elements. The byte array is converted 31 bytes at
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## a time with the `F.fromBytes()` function. An end marker (0x1) and
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## padding (0x0's) are added to ensure unique field elements for byte
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## sequences that end with 0x0's.
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const chunkLen = 31
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const endMarker = @[1'u8]
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var chunkStart = 0
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while chunkStart + chunkLen <= bytes.len:
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let chunkEnd = chunkStart + chunkLen - 1
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let element = F.fromOpenArray(bytes.toOpenArray(chunkStart, chunkEnd))
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yield element
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chunkStart += chunkLen
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let finalChunk = bytes[chunkStart..<bytes.len] & endMarker
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let finalElement = F.fromOpenArray(finalChunk)
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yield finalElement
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# Remark: since `fromInt()` does not work at compile time, this doesn't either
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func toF*(a: SomeInteger | SomeUnsignedInt) : F =
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when a is SomeInteger:
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fromInt(result, a)
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else:
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fromUInt(result, a)
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