// include it at the beginning of the ciphertext.
	if len(ciphertext) < aes.BlockSize {
		panic("ciphertext too short")
	}
	iv := ciphertext[:aes.BlockSize]
	ciphertext = ciphertext[aes.BlockSize:]

	// CBC mode always works in whole blocks.
	if len(ciphertext)%aes.BlockSize != 0 {
		panic("ciphertext is not a multiple of the block size")
	}

	mode := cipher.NewCBCDecrypter(block, iv)

	{dataBlocks: 6, onDisks: 12, offDisks: 0, blocksize: int64(oneMiByte), data: oneMiByte, offset: oneMiByte, length: 0, algorithm: BLAKE2b512, shouldFail: false, shouldFailQuorum: false},
	// 4

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

			t.Errorf("Size: got %v, want %v", s, tt.size)
		}
		if b := h.BlockSize(); b != tt.blocksize {
			t.Errorf("BlockSize: got %v, want %v", b, tt.blocksize)
		}
		for j := 0; j < 4; j++ {
			n, err := h.Write(tt.in)
			if n != len(tt.in) || err != nil {
				t.Errorf("test %d.%d: Write(%d) = %d, %v", i, j, len(tt.in), n, err)
				continue
			}

			// Repetitive Sum() calls should return the same value

		numBlocks := (len(src) + blockSize - 1) / blockSize
		buf := s.buf[bufSize-numBlocks*blockSize:]
		copy(buf, src)
		s.xorKeyStreamBlocksGeneric(buf, buf)
		s.len = len(buf) - copy(dst, buf)
		return
	}

	// If we have a partial (multi-)block, pad it for xorKeyStreamBlocks, and
	// keep the leftover keystream for the next XORKeyStream invocation.
	if len(src) > 0 {
		s.buf = [bufSize]byte{}
		copy(s.buf[:], src)

					testReadFrom{fileOps{
						int64(1e10 - blockSize),
						strings.Repeat("\x00", blockSize-100) + strings.Repeat("0123456789", 10),
						int64(1e10 - blockSize),
						strings.Repeat("\x00", blockSize-100) + strings.Repeat("0123456789", 10),
						int64(1e10 - blockSize),
						strings.Repeat("\x00", blockSize-100) + strings.Repeat("0123456789", 10),
						int64(1e10 - blockSize),

	}
}

func stable_func(data lessSwap, n int) {
	blockSize := 20 // must be > 0
	a, b := 0, blockSize
	for b <= n {
		insertionSort_func(data, a, b)
		a = b
		b += blockSize
	}
	insertionSort_func(data, a, n)

	for blockSize < n {
		a, b = 0, 2*blockSize
		for b <= n {
			symMerge_func(data, a, a+blockSize, b)
			a = b
			b += 2 * blockSize
		}
		if m := a + blockSize; m < n {

)

// blockPadding computes the number of bytes needed to pad offset up to the
// nearest block edge where 0 <= n < blockSize.
func blockPadding(offset int64) (n int64) {
	return -offset & (blockSize - 1)
}

var zeroBlock block

type block [blockSize]byte

// Convert block to any number of formats.
func (b *block) toV7() *headerV7       { return (*headerV7)(b) }

func stableOrdered[E cmp.Ordered](data []E, n int) {
	blockSize := 20 // must be > 0
	a, b := 0, blockSize
	for b <= n {
		insertionSortOrdered(data, a, b)
		a = b
		b += blockSize
	}
	insertionSortOrdered(data, a, n)

	for blockSize < n {
		a, b = 0, 2*blockSize
		for b <= n {
			symMergeOrdered(data, a, a+blockSize, b)
			a = b
			b += 2 * blockSize
		}
		if m := a + blockSize; m < n {

}

func stable(data Interface, n int) {
	blockSize := 20 // must be > 0
	a, b := 0, blockSize
	for b <= n {
		insertionSort(data, a, b)
		a = b
		b += blockSize
	}
	insertionSort(data, a, n)

	for blockSize < n {
		a, b = 0, 2*blockSize
		for b <= n {
			symMerge(data, a, a+blockSize, b)
			a = b
			b += 2 * blockSize
		}
		if m := a + blockSize; m < n {
			symMerge(data, a, m, n)
		}