CTZ	X24, X25				// 931c1c60
	CTZW	X25, X26				// 1b9d1c60
	MAX	X26, X28, X29				// b36eae0b
	MAX	X26, X28				// 336eae0b
	MAXU	X28, X29, X30				// 33ffce0b
	MAXU	X28, X29				// b3fece0b
	MIN	X29, X30, X5				// b342df0b
	MIN	X29, X30				// 334fdf0b
	MINU	X30, X5, X6				// 33d3e20b
	MINU	X30, X5					// b3d2e20b
	ORN	X6, X7, X8				// 33e46340
	ORN	X6, X7					// b3e36340
	SEXTB	X16, X17				// 93184860

	MSGSCHEDULE1(index); \
	SHA512ROUND(index, a, b, c, d, e, f, g, h)

// func block(dig *digest, p []byte)
TEXT ·block(SB),0,$128-32
	MOV	p_base+8(FP), X29
	MOV	p_len+16(FP), X30
	SRL	$7, X30
	SLL	$7, X30

	ADD	X29, X30, X28
	BEQ	X28, X29, end

	MOV	·_K(SB), X18		// const table
	ADD	$8, X2, X19		// message schedule

	MOV	dig+0(FP), X20
	MOV	(0*8)(X20), X10		// a = H0

				{2, 1073741808},          // X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 g X28 X29 X30
				{0, 9223372037928517618}, // SP X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 g X28 X29 X30 SB
			},
			outputs: []outputInfo{
				{0, 1006632944}, // X5 X6 X7 X8 X9 X10 X11 X12 X13 X14 X15 X16 X17 X18 X19 X20 X21 X22 X23 X24 X25 X26 X28 X29 X30
			},
		},
	},

	var x21 [10<<20]byte
	var x22 [10<<20]byte
	var x23 [10<<20]byte
	var x24 [10<<20]byte
	var x25 [10<<20]byte
	var x26 [10<<20]byte
	var x27 [10<<20]byte
	var x28 [10<<20]byte
	var x29 [10<<20]byte
	var x30 [10<<20]byte
	var x31 [10<<20]byte
	var x32 [10<<20]byte
	var x33 [10<<20]byte
	var x34 [10<<20]byte
	var x35 [10<<20]byte
	var x36 [10<<20]byte
	var x37 [10<<20]byte
	var x38 [10<<20]byte
	var x39 [10<<20]byte

	exc uint32 // number of arm exception taken
}

type regs64 struct {
	x     [29]uint64 // registers x0 to x28
	fp    uint64     // frame register, x29
	lr    uint64     // link register, x30
	sp    uint64     // stack pointer, x31
	pc    uint64     // program counter
	cpsr  uint32     // current program status register
	__pad uint32
}

type neonstate64 struct {

    X13,
    X14,
    X15,
    X16,
    X17,
    X18,
    X19,
    X20,
    X21,
    X22,
    X23,
    X24,
    X25,
    X26,
    X27,
    X28,
    X29,
    X30,
    X31,
    X32,
    X33,
    X34,
    X35,
    X36,
    X37,
    X38,
    X39,
    X40,
    X41,
    X42,
    X43,
    X44,
    X45,
    X46,
    X47,

    X13,
    X14,
    X15,
    X16,
    X17,
    X18,
    X19,
    X20,
    X21,
    X22,
    X23,
    X24,
    X25,
    X26,
    X27,
    X28,
    X29,
    X30,
    X31,
    X32,
    X33,
    X34,
    X35,
    X36,
    X37,
    X38,
    X39,
    X40,
    X41,
    X42,
    X43,
    X44,
    X45,
    X46,
    X47,

const (
	headerStr = "GIF89a" +
		"\x02\x00\x01\x00" + // width=2, height=1
		"\x80\x00\x00" // headerFields=(a color table of 2 pixels), backgroundIndex, aspect
	paletteStr = "\x10\x20\x30\x40\x50\x60" // the color table, also known as a palette
	trailerStr = "\x3b"
)

// lzw.NewReader wants an io.ByteReader, this ensures we're compatible.
var _ io.ByteReader = (*blockReader)(nil)