32 lines
790 B
Go
32 lines
790 B
Go
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package fr32
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import (
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"math/bits"
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"github.com/filecoin-project/specs-actors/actors/abi"
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)
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func subPieces(in abi.UnpaddedPieceSize) []abi.UnpaddedPieceSize {
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// Convert to in-sector bytes for easier math:
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//
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// (we convert to sector bytes as they are nice round binary numbers)
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w := uint64(in.Padded())
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out := make([]abi.UnpaddedPieceSize, bits.OnesCount64(w))
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for i := range out {
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// Extract the next lowest non-zero bit
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next := bits.TrailingZeros64(w)
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psize := uint64(1) << next
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// e.g: if the number is 0b010100, psize will be 0b000100
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// set that bit to 0 by XORing it, so the next iteration looks at the
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// next bit
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w ^= psize
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// Add the piece size to the list of pieces we need to create
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out[i] = abi.PaddedPieceSize(psize).Unpadded()
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}
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return out
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}
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