},
}

func TestUnscaledQuant(t *testing.T) {
	bad := false
	for i := quantIndex(0); i < nQuantIndex; i++ {
		for zig := 0; zig < blockSize; zig++ {
			got := unscaledQuant[i][zig]
			want := unscaledQuantInNaturalOrder[i][unzig[zig]]
			if got != want {
				t.Errorf("i=%d, zig=%d: got %d, want %d", i, zig, got, want)
				bad = true
			}
		}
	}
	if bad {
		names := [nQuantIndex]string{"Luminance", "Chrominance"}

			}

			zig, err = d.refineNonZeroes(b, zig, zigEnd, int32(val0), delta)
			if err != nil {
				return err
			}
			if zig > zigEnd {
				return FormatError("too many coefficients")
			}
			if z != 0 {
				b[unzig[zig]] = z
			}
		}
	}
	if d.eobRun > 0 {
		d.eobRun--
		if _, err := d.refineNonZeroes(b, zig, zigEnd, -1, delta); err != nil {
			return err
		}

// natural (not zig-zag) order.
func (e *encoder) writeBlock(b *block, q quantIndex, prevDC int32) int32 {
	fdct(b)
	// Emit the DC delta.
	dc := div(b[0], 8*int32(e.quant[q][0]))
	e.emitHuffRLE(huffIndex(2*q+0), 0, dc-prevDC)
	// Emit the AC components.
	h, runLength := huffIndex(2*q+1), int32(0)
	for zig := 1; zig < blockSize; zig++ {
		ac := div(b[unzig[zig]], 8*int32(e.quant[q][zig]))
		if ac == 0 {

//   least significant bits
// - the most significant bit (msb) in each output byte indicates if there
//   is a continuation byte (msb = 1)
// - signed integers are mapped to unsigned integers using "zig-zag"
//   encoding: Positive values x are written as 2*x + 0, negative values
//   are written as 2*(^x) + 1; that is, negative numbers are complemented
//   and whether to complement is encoded in bit 0.
//
// Design note:

000002a0  a8 31 00 8a 30 81 87 02  42 01 21 7e c2 26 cb 5e  |.1..0...B.!~.&.^|
000002b0  f1 2a d2 9b 7f 3f b4 d4  28 5e 63 5a 20 aa 28 87  |.*...?..(^cZ .(.|
000002c0  bb dd 5c 6a 91 a2 2d 03  7a 69 67 8b ca 84 a6 1f  |..\j..-.zig.....|
000002d0  d3 58 40 eb 5c 54 95 96  05 d0 37 63 e4 a6 1b 51  |.X@.\T....7c...Q|
000002e0  9a d0 93 31 82 e6 8e a0  af 29 64 02 41 4c ff ac  |...1.....)d.AL..|

const (
	adobeTransformUnknown = 0
	adobeTransformYCbCr   = 1
	adobeTransformYCbCrK  = 2
)

// unzig maps from the zig-zag ordering to the natural ordering. For example,
// unzig[3] is the column and row of the fourth element in zig-zag order. The
// value is 16, which means first column (16%8 == 0) and third row (16/8 == 2).
var unzig = [blockSize]int{
	0, 1, 8, 16, 9, 2, 3, 10,

func (w *Encoder) rawUvarint(x uint64) {
	var buf [binary.MaxVarintLen64]byte
	n := binary.PutUvarint(buf[:], x)
	_, err := w.Data.Write(buf[:n])
	w.checkErr(err)
}

func (w *Encoder) rawVarint(x int64) {
	// Zig-zag encode.
	ux := uint64(x) << 1
	if x < 0 {
		ux = ^ux
	}

	w.rawUvarint(ux)
}

func (w *Encoder) rawReloc(r RelocKind, idx Index) int {
	e := RelocEnt{r, idx}
	if w.RelocMap != nil {

		// each time we observe a change in value we emit ", pc) (value".
		// When the scan is over, we emit the closing ", pc)".
		//
		// The table is delta-encoded. The value deltas are signed and
		// transmitted in zig-zag form, where a complement bit is placed in bit 0,
		// and the pc deltas are unsigned. Both kinds of deltas are sent
		// as variable-length little-endian base-128 integers,

 * </code></td>
 * </tr>
 * 
 * <tr>
 * <td width="20%"><code>
 *  smb://host/share/foo/bar/
 * </code></td>
 * <td width="20%"><code>
 *  /share2/zig/zag
 * </code></td>
 * <td><code>
 *  smb://host/share2/zig/zag
 * </code></td>
 * </tr>
 * 
 * <tr>
 * <td width="20%"><code>
 *  smb://host/share/foo/bar/
 * </code></td>
 * <td width="20%"><code>
 *  ../zip/

		s += 7
	}
	return x, overflow
}

var overflow = errors.New("pkgbits: readUvarint overflows a 64-bit integer")

func (r *Decoder) rawVarint() int64 {
	ux := r.rawUvarint()

	// Zig-zag decode.
	x := int64(ux >> 1)
	if ux&1 != 0 {
		x = ^x
	}
	return x
}

func (r *Decoder) rawReloc(k RelocKind, idx int) Index {
	e := r.Relocs[idx]
	assert(e.Kind == k)
	return e.Idx
}