// using a given key. It provides the capability to encrypt
// or decrypt individual blocks. The mode implementations
// extend that capability to streams of blocks.
type Block interface {
	// BlockSize returns the cipher's block size.
	BlockSize() int

	// Encrypt encrypts the first block in src into dst.
	// Dst and src must overlap entirely or not at all.
	Encrypt(dst, src []byte)

	// Decrypt decrypts the first block in src into dst.

			unique = false
		}
	}()
	if !unique {
		panic("crypto/hmac: hash generation function does not produce unique values")
	}
	blocksize := hm.inner.BlockSize()
	hm.ipad = make([]byte, blocksize)
	hm.opad = make([]byte, blocksize)
	if len(key) > blocksize {
		// If key is too big, hash it.
		hm.outer.Write(key)
		key = hm.outer.Sum(nil)
	}
	copy(hm.ipad, key)
	copy(hm.opad, key)

			blockLength = e.blockSize - blockOffset
		case block == endBlock:
			blockOffset = 0
			blockLength = (offset + length) % e.blockSize
		default:
			blockOffset = 0
			blockLength = e.blockSize
		}
		if blockLength == 0 {
			break
		}

		var err error
		bufs, err = reader.Read(bufs)
		if len(bufs) > 0 {
			// Set only if there are be enough data for reconstruction.

// (and in that mode the real sha256 uses cgo).
package notsha256

import (
	"encoding/binary"
	"hash"
)

// The size of a checksum in bytes.
const Size = 32

// The blocksize in bytes.
const BlockSize = 64

const (
	chunk = 64
	init0 = 0x6A09E667
	init1 = 0xBB67AE85
	init2 = 0x3C6EF372
	init3 = 0xA54FF53A
	init4 = 0x510E527F
	init5 = 0x9B05688C
	init6 = 0x1F83D9AB
	init7 = 0x5BE0CD19

		values[2], values[3] = scaleHeapSample(r.InUseObjects(), r.InUseBytes(), rate)
		var blockSize int64
		if r.AllocObjects > 0 {
			blockSize = r.AllocBytes / r.AllocObjects
		}
		b.pbSample(values, locs, func() {
			if blockSize != 0 {
				b.pbLabel(tagSample_Label, "bytes", "", blockSize)
			}
		})
	}
	b.build()
	return nil
}

// scaleHeapSample adjusts the data from a heap Sample to

// column and first row.
var zigzag = [blockSize]int{
	0, 1, 5, 6, 14, 15, 27, 28,
	2, 4, 7, 13, 16, 26, 29, 42,
	3, 8, 12, 17, 25, 30, 41, 43,
	9, 11, 18, 24, 31, 40, 44, 53,
	10, 19, 23, 32, 39, 45, 52, 54,
	20, 22, 33, 38, 46, 51, 55, 60,
	21, 34, 37, 47, 50, 56, 59, 61,
	35, 36, 48, 49, 57, 58, 62, 63,
}

func TestZigUnzig(t *testing.T) {
	for i := 0; i < blockSize; i++ {
		if unzig[zigzag[i]] != i {

	fd := f.Fd()
	_, err := unix.FcntlInt(fd, unix.F_NOCACHE, 0)
	return err
}

// AlignedBlock - pass through to directio implementation.
func AlignedBlock(blockSize int) []byte {
	return directio.AlignedBlock(blockSize)

			Optional:    true,
		},
		config.HelpKV{
			Key:         BlockSize,
			Type:        "string",
			Description: "cache all objects below the specified block size" + defaultHelpPostfix(BlockSize),
			Optional:    true,
		},
	}

func (s *sum128) Size() int  { return 16 }
func (s *sum128a) Size() int { return 16 }

func (s *sum32) BlockSize() int   { return 1 }
func (s *sum32a) BlockSize() int  { return 1 }
func (s *sum64) BlockSize() int   { return 1 }
func (s *sum64a) BlockSize() int  { return 1 }
func (s *sum128) BlockSize() int  { return 1 }
func (s *sum128a) BlockSize() int { return 1 }

func (s *sum32) Sum(in []byte) []byte {
	v := uint32(*s)

	}
	flag &= ^(syscall.O_DIRECT)
	_, err = unix.FcntlInt(fd, unix.F_SETFL, flag)
	return err
}

// AlignedBlock - pass through to directio implementation.
func AlignedBlock(blockSize int) []byte {
	return directio.AlignedBlock(blockSize)