Initial impl

eth_bloom.nimble

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+# Package
+
+version       = "0.1.0"
+author        = "Status Research & Development GmbH"
+description   = "Ethereum Bloom Filter"
+license       = "Apache2"
+srcDir        = "src"
+
+# Dependencies
+
+requires "nim >= 0.17.0",
+         "https://github.com/status-im/nim-keccak-tiny.git >= 0.1.0",
+         "https://github.com/status-im/nim-ttmath >= 0.5.0"

src/eth_bloom.nim

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+import keccak_tiny, ttmath
+
+iterator chunksForBloom(h: Hash[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]): Int2048 =
+  let h = chunk[0].int
+  let l = chunk[1].int
+  1.i2048 shl ((l + (h shl 8)) and 2047)
+
+iterator bloomBits(h: Hash[256]): Int2048 =
+  for chunk in chunksForBloom(h):
+    yield chunkToBloomBits(chunk)
+
+type BloomFilter* = object
+  value*: Int2048
+
+proc incl(f: var BloomFilter, h: Hash[256]) = # Should this be public?
+  for bits in bloomBits(h):
+    f.value |= bits
+
+template incl*(f: var BloomFilter, v: typed) =
+  f.incl(keccak_256(v))
+
+proc contains(f: BloomFilter, h: Hash[256]): bool = # Should this be public?
+  for bits in bloomBits(h):
+    if isZero(f.value and bits): return false
+  return true
+
+template contains*(f: BloomFilter, v: typed): bool =
+  f.contains(keccak_256(v))

tests/test1.nim

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+import eth_bloom, ttmath, unittest
+
+suite "Simple Bloom Filter tests":
+  test "incl proc":
+    var f: BloomFilter
+    f.incl("hello")
+    check "hello" in f
+    check "hello1" notin f
+    f.incl("hello1")
+    check "hello" in f
+    check "hello1" in f
+
+  test "int value":
+    var f: BloomFilter
+    f.incl("value 1")
+    f.incl("value 2")
+    check f.value == i2048"1090215279796298345343057319992441901006450066263950115824040002588950485497113027143927523755823134941133023716890165043342811041924870874305880232180990464248298835944719578227183672673286106858273952584661686762419935928160959430409028732374024192153399763277382459194254234587232383494962731940352290891816707697788111127980409605093135659121120897102645250001200507634146244124778321795865777525978540960830042468420173693965828992647991129039043403835835590424035347457188427354145120006479590726476620907513681178254852999008485376"

tests/test1.nims

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+switch("path", "$projectDir/../src")