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