nim-eth/eth/bloom.nim

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import stint, nimcrypto/[keccak, hash]
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type UInt2048 = StUint[2048]
iterator chunksForBloom(h: MDigest[256]): array[2, uint8] =
yield [h.data[0], h.data[1]]
yield [h.data[2], h.data[3]]
yield [h.data[4], h.data[5]]
proc chunkToBloomBits(chunk: array[2, uint8]): UInt2048 =
let h = chunk[0].int
let l = chunk[1].int
one(UInt2048) shl ((l + (h shl 8)) and 2047)
iterator bloomBits(h: MDigest[256]): UInt2048 =
for chunk in chunksForBloom(h):
yield chunkToBloomBits(chunk)
type BloomFilter* = object
value*: UInt2048
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proc incl*(f: var BloomFilter, h: MDigest[256]) =
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for bits in bloomBits(h):
f.value = f.value or bits
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proc init*(_: type BloomFilter, h: MDigest[256]): BloomFilter =
result.incl(h)
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# TODO: The following 2 procs should be one genric, but it doesn't compile. Nim bug?
proc incl*(f: var BloomFilter, v: string) = f.incl(keccak256.digest(v))
proc incl*(f: var BloomFilter, v: openArray[byte]) = f.incl(keccak256.digest(v))
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proc contains*(f: BloomFilter, h: MDigest[256]): bool =
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for bits in bloomBits(h):
if (f.value and bits).isZero: return false
return true
template contains*[T](f: BloomFilter, v: openArray[T]): bool =
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f.contains(keccak256.digest(v))