var vectors = []struct {
		nbits uint // Number of bits to read
		value int  // Expected output value (0 for error)
		fail  bool // Expected operation failure?
	}{
		{nbits: 1, value: 1},
		{nbits: 1, value: 0},
		{nbits: 1, value: 1},
		{nbits: 5, value: 11},
		{nbits: 32, value: 0x12345678},
		{nbits: 15, value: 14495},
		{nbits: 3, value: 6},
		{nbits: 6, value: 13},
		{nbits: 1, fail: true},
	}

		{11, 2048 - 1024},
		{12, 4096 - 2048},
	}
	nCodes, nBits := 0, 0
	for _, e := range iterations {
		nCodes += e.n
		nBits += e.n * e.width
	}
	if nCodes != 3839 {
		t.Fatalf("nCodes: got %v, want %v", nCodes, 3839)
	}
	if nBits != 43255 {
		t.Fatalf("nBits: got %v, want %v", nBits, 43255)
	}

	// Construct our input of 43255 zero bits (which gets d.hi and d.width up

}

// writeLSB writes the code c for "Least Significant Bits first" data.
func (w *Writer) writeLSB(c uint32) error {
	w.bits |= c << w.nBits
	w.nBits += w.width
	for w.nBits >= 8 {
		if err := w.w.WriteByte(uint8(w.bits)); err != nil {
			return err
		}
		w.bits >>= 8
		w.nBits -= 8
	}
	return nil
}

// writeMSB writes the code c for "Most Significant Bits first" data.
func (w *Writer) writeMSB(c uint32) error {

}

// readLSB returns the next code for "Least Significant Bits first" data.
func (r *Reader) readLSB() (uint16, error) {
	for r.nBits < r.width {
		x, err := r.r.ReadByte()
		if err != nil {
			return 0, err
		}
		r.bits |= uint32(x) << r.nBits
		r.nBits += 8
	}
	code := uint16(r.bits & (1<<r.width - 1))
	r.bits >>= r.width
	r.nBits -= r.width
	return code, nil
}

	}
}

// generate all uint64 values x where x has at most n bits set in the low w
// and call f(x) for each.
func gen1(n, w int, f func(uint64)) {
	gen(0, 0, n, w-1, f)
}

func gen(val uint64, nbits, maxbits, pos int, f func(uint64)) {
	if pos < 0 {
		f(val)
		return
	}
	gen(val, nbits, maxbits, pos-1, f)
	if nbits < maxbits {
		gen(val|1<<uint(pos), nbits+1, maxbits, pos-1, f)
	}
}

		{10, 0xFFFF000000000001, 64, 63, 15, 0x400A3f10},
	}

	for i, v := range tests {
		result := encodePPC64RotateMask(v.rotate, int64(v.mask), v.nbits)
		if result != v.encoded {
			t.Errorf("encodePPC64RotateMask(%d,0x%x,%d) = 0x%x, expected 0x%x", v.rotate, v.mask, v.nbits, result, v.encoded)
		}
		rotate, mb, me, mask := DecodePPC64RotateMask(result)
		if rotate != v.rotate || mb != v.mb || me != v.me || mask != v.mask {

	cnt  uint32  // number of valid bits in the bits field
}

// makeBitReader makes a bit reader starting at off.
func (r *Reader) makeBitReader(data block, off int) bitReader {
	return bitReader{
		r:    r,
		data: data,
		off:  uint32(off),
	}
}

// moreBits is called to read more bits.
// This ensures that at least 16 bits are available.
func (br *bitReader) moreBits() error {
	for br.cnt < 16 {

func bitSetTest(x int) bool {
	// amd64:"ANDL\t[$]9, AX"
	// amd64:"CMPQ\tAX, [$]9"
	return x&9 == 9
}

// mask contiguous one bits
func cont1Mask64U(x uint64) uint64 {
	// s390x:"RISBGZ\t[$]16, [$]47, [$]0,"
	return x & 0x0000ffffffff0000
}

// mask contiguous zero bits
func cont0Mask64U(x uint64) uint64 {
	// s390x:"RISBGZ\t[$]48, [$]15, [$]0,"
	return x & 0xffff00000000ffff
}

	// cur is the bit buffer that has not been fed into n.
	// cbits is the number of low order bits in cur that are valid.
	// sbits is the number of bits of the symbol prefix being decoded.
	cur, cbits, sbits := uint(0), uint8(0), uint8(0)
	for _, b := range v {
		cur = cur<<8 | uint(b)
		cbits += 8
		sbits += 8
		for cbits >= 8 {
			idx := byte(cur >> (cbits - 8))
			n = n.children[idx]
			if n == nil {

Russ Cox <******@****.***> 1643915146 -0500