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https://github.com/logos-storage/logos-storage-nim.git
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43 lines
1.4 KiB
Nim
43 lines
1.4 KiB
Nim
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## Nim-Codex
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## Copyright (c) 2025 Status Research & Development GmbH
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## Licensed under either of
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## * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
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## * MIT license ([LICENSE-MIT](LICENSE-MIT))
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## at your option.
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## This file may not be copied, modified, or distributed except according to
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## those terms.
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import pkg/questionable/results
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import std/math
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import ../manifest
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const maxBlocks = 2147483648.uint64 # 2^31 - maximum for 2D grid
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func calculate2DErasureParams*(numBlocks: uint64): ?!(int, int) =
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## Calculate K and M for 2D erasure coding for ~2x output with GF(2^16) constraint
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if numBlocks > maxBlocks:
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return failure(
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"Dataset too large: " & $numBlocks & " blocks exceeds maximum of " & $maxBlocks &
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" blocks for 2D erasure coding"
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)
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let
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totalDim = min(round(sqrt(2.0 * numBlocks.float)).int, 65536)
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minK = ceil(sqrt(numBlocks.float)).int
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k = max(minK, round(totalDim.float / sqrt(2.0)).int)
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m = max(1, min(totalDim - k, 65536 - k))
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success (k, m)
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func calculate2DSlotBlocks*(manifest: Manifest): ?!Natural =
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## Calculate number of blocks per slot for 2D encoding
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if not manifest.protected:
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return failure("2D encoding requires a protected manifest")
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let numSlotBlocks = manifest.numSlotBlocks
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without (ecK, ecM) =? calculate2DErasureParams(numSlotBlocks.uint64), err:
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return failure(err)
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success ((ecK + ecM) * (ecK + ecM)).Natural
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