}
	origPtr := uint(br.ReadBits(24))

	// If not every byte value is used in the block (i.e., it's text) then
	// the symbol set is reduced. The symbols used are stored as a
	// two-level, 16x16 bitmap.
	symbolRangeUsedBitmap := br.ReadBits(16)
	symbolPresent := make([]bool, 256)
	numSymbols := 0
	for symRange := uint(0); symRange < 16; symRange++ {
		if symbolRangeUsedBitmap&(1<<(15-symRange)) != 0 {

			}
			yi := m.YOffset(sx, sy)
			ci := m.COffset(sx, sy)
			yBlock[8*j+i] = int32(m.Y[yi])
			cbBlock[8*j+i] = int32(m.Cb[ci])
			crBlock[8*j+i] = int32(m.Cr[ci])
		}
	}
}

// scale scales the 16x16 region represented by the 4 src blocks to the 8x8
// dst block.
func scale(dst *block, src *[4]block) {
	for i := 0; i < 4; i++ {
		dstOff := (i&2)<<4 | (i&1)<<2
		for y := 0; y < 4; y++ {
			for x := 0; x < 4; x++ {

00000060  d1 56 18 67 59 a5 e1 ed  99 0f ca e5 6b 5f e3 d9  |.V.gY.......k_..|
00000070  e3 fd e6 a2 50 93 bf 87  85 60 e7 7f 0b a0 96 c4  |....P....`......|
00000080  29 55 63 de fe 6b 75 99  b2 a6 75 92 61 d0 96 19  |)Uc..ku...u.a...|
00000090  f5 60 8f ec e9 d3 98 4a  b9 6b 98 26 c1 3e 27 7e  |.`.....J.k.&.>'~|
000000a0  17 03 03 00 17 5a aa bb  35 67 ec 83 da 8e 85 bd  |.....Z..5g......|

    X180,
    X181,
    X182,
    X183,
    X184,
    X185,
    X186,
    X187,
    X188,
    X189,
    X190,
    X191,
    X192,
    X193,
    X194,
    X195,
    X196,
    X197,
    X198,
    X199,
    X200,
    X201,
    X202,
    X203,
    X204,
    X205,
    X206,
    X207,
    X208,
    X209,
    X210,
    X211,
    X212,

	0x18c: 0x4a52, 0x18d: 0x0012, 0x18e: 0x0012, 0x18f: 0x0012, 0x190: 0x0012, 0x191: 0x0012,
	0x192: 0x4152, 0x193: 0x0012, 0x194: 0x0010, 0x195: 0x0012, 0x196: 0x0012, 0x197: 0x0012,
	0x198: 0x0012, 0x199: 0x0012, 0x19a: 0x0012, 0x19b: 0x0012, 0x19c: 0x0012, 0x19d: 0x118a,
	0x19e: 0x120a, 0x19f: 0x0012, 0x1a0: 0x0012, 0x1a1: 0x0012, 0x1a2: 0x0012, 0x1a3: 0x0012,

	0x18c: 0x4a52, 0x18d: 0x0012, 0x18e: 0x0012, 0x18f: 0x0012, 0x190: 0x0012, 0x191: 0x0012,
	0x192: 0x4152, 0x193: 0x0012, 0x194: 0x0010, 0x195: 0x0012, 0x196: 0x0012, 0x197: 0x0012,
	0x198: 0x0012, 0x199: 0x0012, 0x19a: 0x0012, 0x19b: 0x0012, 0x19c: 0x0012, 0x19d: 0x120a,
	0x19e: 0x128a, 0x19f: 0x0012, 0x1a0: 0x0012, 0x1a1: 0x0012, 0x1a2: 0x0012, 0x1a3: 0x0012,

	0x186: 0x000a, 0x187: 0x000a, 0x188: 0x000a, 0x189: 0x000a, 0x18a: 0x000a, 0x18b: 0x000a,
	0x18c: 0x000a, 0x18d: 0x000a, 0x18e: 0x000a, 0x18f: 0x000a,
	0x192: 0x000a, 0x193: 0x000a, 0x194: 0x000a, 0x195: 0x000a, 0x196: 0x000a, 0x197: 0x000a,
	0x198: 0x000a, 0x199: 0x000a, 0x19a: 0x000a, 0x19b: 0x000a, 0x19c: 0x000a, 0x19d: 0x000a,
	0x19e: 0x000a, 0x19f: 0x000a,
	0x1a5: 0x000a, 0x1a6: 0x000a, 0x1a7: 0x000a, 0x1a8: 0x000a, 0x1a9: 0x000a,

	0x186: 0x000a, 0x187: 0x000a, 0x188: 0x000a, 0x189: 0x000a, 0x18a: 0x000a, 0x18b: 0x000a,
	0x18c: 0x000a, 0x18d: 0x000a, 0x18e: 0x000a, 0x18f: 0x000a,
	0x192: 0x000a, 0x193: 0x000a, 0x194: 0x000a, 0x195: 0x000a, 0x196: 0x000a, 0x197: 0x000a,
	0x198: 0x000a, 0x199: 0x000a, 0x19a: 0x000a, 0x19b: 0x000a, 0x19c: 0x000a, 0x19d: 0x000a,
	0x19e: 0x000a, 0x19f: 0x000a,
	0x1a5: 0x000a, 0x1a6: 0x000a, 0x1a7: 0x000a, 0x1a8: 0x000a, 0x1a9: 0x000a,

	0x186: 0x000a, 0x187: 0x000a, 0x188: 0x000a, 0x189: 0x000a, 0x18a: 0x000a, 0x18b: 0x000a,
	0x18c: 0x000a, 0x18d: 0x000a, 0x18e: 0x000a, 0x18f: 0x000a,
	0x192: 0x000a, 0x193: 0x000a, 0x194: 0x000a, 0x195: 0x000a, 0x196: 0x000a, 0x197: 0x000a,
	0x198: 0x000a, 0x199: 0x000a, 0x19a: 0x000a, 0x19b: 0x000a, 0x19c: 0x000a, 0x19d: 0x000a,
	0x19e: 0x000a, 0x19f: 0x000a,
	0x1a5: 0x000a, 0x1a6: 0x000a, 0x1a7: 0x000a, 0x1a8: 0x000a, 0x1a9: 0x000a,

	0x186: 0x000a, 0x187: 0x000a, 0x188: 0x000a, 0x189: 0x000a, 0x18a: 0x000a, 0x18b: 0x000a,
	0x18c: 0x000a, 0x18d: 0x000a, 0x18e: 0x000a, 0x18f: 0x000a,
	0x192: 0x000a, 0x193: 0x000a, 0x194: 0x000a, 0x195: 0x000a, 0x196: 0x000a, 0x197: 0x000a,
	0x198: 0x000a, 0x199: 0x000a, 0x19a: 0x000a, 0x19b: 0x000a, 0x19c: 0x000a, 0x19d: 0x000a,
	0x19e: 0x000a, 0x19f: 0x000a,
	0x1a5: 0x000a, 0x1a6: 0x000a, 0x1a7: 0x000a, 0x1a8: 0x000a, 0x1a9: 0x000a,