}

		// create some test data
		setup, err := newErasureTestSetup(t, test.dataBlocks, test.disks-test.dataBlocks, test.blocksize)
		if err != nil {
			t.Fatalf("Test %d: failed to setup Erasure environment: %v", i, err)
		}
		disks := setup.disks
		erasure, err := NewErasure(context.Background(), test.dataBlocks, test.disks-test.dataBlocks, test.blocksize)
		if err != nil {

var erasureEncodeDecodeTests = []struct {
	dataBlocks, parityBlocks   int
	missingData, missingParity int
	reconstructParity          bool
	shouldFail                 bool
}{
	{dataBlocks: 2, parityBlocks: 2, missingData: 0, missingParity: 0, reconstructParity: true, shouldFail: false},
	{dataBlocks: 3, parityBlocks: 3, missingData: 1, missingParity: 0, reconstructParity: true, shouldFail: false},

	for i, test := range erasureDecodeTests {
		setup, err := newErasureTestSetup(t, test.dataBlocks, test.onDisks-test.dataBlocks, test.blocksize)
		if err != nil {
			t.Fatalf("Test %d: failed to create test setup: %v", i, err)
		}
		erasure, err := NewErasure(context.Background(), test.dataBlocks, test.onDisks-test.dataBlocks, test.blocksize)
		if err != nil {
			t.Fatalf("Test %d: failed to create ErasureStorage: %v", i, err)
		}

	// Offset and out size cannot be negative.
	if offset < 0 || length < 0 {
		return 0, errUnexpected
	}

	// Do we have enough blocks?
	if len(enBlocks) < dataBlocks {
		return 0, reedsolomon.ErrTooFewShards
	}

	// Do we have enough data?
	if int64(getDataBlockLen(enBlocks, dataBlocks)) < length {

	{dataBlocks: 3, onDisks: 6, offDisks: 0, blocksize: int64(blockSizeV2), data: oneMiByte, offset: 1, algorithm: SHA256, shouldFail: false, shouldFailQuorum: false},                                 // 1
	{dataBlocks: 4, onDisks: 8, offDisks: 2, blocksize: int64(blockSizeV2), data: oneMiByte, offset: 2, algorithm: DefaultBitrotAlgorithm, shouldFail: false, shouldFailQuorum: false},                 // 2

		// for erasure coding information
		return true
	}
	dataBlocks := fi.Erasure.DataBlocks
	parityBlocks := fi.Erasure.ParityBlocks
	correctIndexes := (fi.Erasure.Index > 0 &&
		fi.Erasure.Index <= dataBlocks+parityBlocks &&
		len(fi.Erasure.Distribution) == (dataBlocks+parityBlocks))
	return ((dataBlocks >= parityBlocks) &&
		(dataBlocks > 0) && (parityBlocks >= 0) &&
		correctIndexes)
}

type ErasureInfo struct {
	// Algorithm is the string representation of erasure-coding-algorithm
	Algorithm string `json:"algorithm"`
	// DataBlocks is the number of data blocks for erasure-coding
	DataBlocks int `json:"data"`
	// ParityBlocks is the number of parity blocks for erasure-coding
	ParityBlocks int `json:"parity"`
	// BlockSize is the size of one erasure-coded block

type Erasure struct {
	encoder                  func() reedsolomon.Encoder
	dataBlocks, parityBlocks int
	blockSize                int64
}

// NewErasure creates a new ErasureStorage.
func NewErasure(ctx context.Context, dataBlocks, parityBlocks int, blockSize int64) (e Erasure, err error) {
	// Check the parameters for sanity now.
	if dataBlocks <= 0 || parityBlocks < 0 {
		return e, reedsolomon.ErrInvShardNum
	}

	} else {
		// Seed the buffers.
		for i := range bufs {
			bufs[i] = b[i*shardSize : (i+1)*shardSize]
		}
	}

	return &parallelReader{
		readers:       readers,
		orgReaders:    readers,
		dataBlocks:    e.dataBlocks,
		offset:        (offset / e.blockSize) * e.ShardSize(),
		shardSize:     e.ShardSize(),
		shardFileSize: e.ShardFileSize(totalLength),
		buf:           make([][]byte, len(readers)),
		readerToBuf:   r2b,

// newFileInfo - initializes new FileInfo, allocates a fresh erasure info.
func newFileInfo(object string, dataBlocks, parityBlocks int) (fi FileInfo) {
	fi.Erasure = ErasureInfo{
		Algorithm:    erasureAlgorithm,
		DataBlocks:   dataBlocks,
		ParityBlocks: parityBlocks,
		BlockSize:    blockSizeV2,
		Distribution: hashOrder(object, dataBlocks+parityBlocks),
	}
	return fi
}