// Set adds fd to the set fds.
func (fds *FdSet) Set(fd int) {
	fds.Bits[fd/NFDBITS] |= (1 << (uintptr(fd) % NFDBITS))
}

// Clear removes fd from the set fds.
func (fds *FdSet) Clear(fd int) {
	fds.Bits[fd/NFDBITS] &^= (1 << (uintptr(fd) % NFDBITS))
}

// IsSet returns whether fd is in the set fds.
func (fds *FdSet) IsSet(fd int) bool {
	return fds.Bits[fd/NFDBITS]&(1<<(uintptr(fd)%NFDBITS)) != 0
}

package zstd

import (
	"io"
	"math/bits"
)

// maxHuffmanBits is the largest possible Huffman table bits.
const maxHuffmanBits = 11

// readHuff reads Huffman table from data starting at off into table.
// Each entry in a Huffman table is a pair of bytes.
// The high byte is the encoded value. The low byte is the number
// of bits used to encode that value. We index into the table

	"hash"
)

// New224 creates a new SHA3-224 hash.
// Its generic security strength is 224 bits against preimage attacks,
// and 112 bits against collision attacks.
func New224() hash.Hash {
	return new224()
}

// New256 creates a new SHA3-256 hash.
// Its generic security strength is 256 bits against preimage attacks,
// and 128 bits against collision attacks.
func New256() hash.Hash {
	return new256()
}

	// Multiply mantissa by the digits and extract the upper two digits (hi, lo).
	z2hi, _ := bits.Mul64(z2, ix)
	z1hi, z1lo := bits.Mul64(z1, ix)
	z0lo := z0 * ix
	lo, c := bits.Add64(z1lo, z2hi, 0)
	hi, _ := bits.Add64(z0lo, z1hi, c)
	// The top 3 bits are j.
	j = hi >> 61
	// Extract the fraction and find its magnitude.
	hi = hi<<3 | lo>>61
	lz := uint(bits.LeadingZeros64(hi))
	e := uint64(bias - (lz + 1))

	if mask == 0 {
		return nil
	}

	// normalize the mask so that the set bits are left aligned
	o := bits.LeadingZeros64(^mask)
	mask = bits.RotateLeft64(mask, o)
	z := bits.LeadingZeros64(mask)
	mask = bits.RotateLeft64(mask, z)

	// check that the normalized mask is contiguous
	l := bits.LeadingZeros64(^mask)
	if l+bits.TrailingZeros64(mask) != 64 {
		return nil
	}

	Package("crypto/internal/bigmod")
	ConstraintExpr("!purego")

	addMulVVW(1024)
	addMulVVW(1536)
	addMulVVW(2048)

	Generate()
}

func addMulVVW(bits int) {
	if bits%64 != 0 {
		panic("bit size unsupported")
	}

	Implement("addMulVVW" + strconv.Itoa(bits))

	CMPB(Mem{Symbol: Symbol{Name: "·supportADX"}, Base: StaticBase}, Imm(1))
	JEQ(LabelRef("adx"))

	z := Mem{Base: Load(Param("z"), GP64())}

// digest returns the final hash value.
func (xh *xxhash64) digest() uint64 {
	var h64 uint64
	if xh.len < 32 {
		h64 = xh.v[2] + xxhPrime64c5
	} else {
		h64 = bits.RotateLeft64(xh.v[0], 1) +
			bits.RotateLeft64(xh.v[1], 7) +
			bits.RotateLeft64(xh.v[2], 12) +
			bits.RotateLeft64(xh.v[3], 18)
		h64 = xh.mergeRound(h64, xh.v[0])
		h64 = xh.mergeRound(h64, xh.v[1])
		h64 = xh.mergeRound(h64, xh.v[2])
		h64 = xh.mergeRound(h64, xh.v[3])

	}

	for _, c := range cvt {
		if bits(c.exact) != c.bits {
			bug()
			fmt.Printf("%s: inconsistent table: bits=%#x (%g) but exact=%g (%#x)\n", c.text, c.bits, fromBits(c.bits, c.exact), c.exact, bits(c.exact))
		}
		if c.approx != c.exact || bits(c.approx) != c.bits {
			bug()
			fmt.Printf("%s: have %g (%#x) want %g (%#x)\n", c.text, c.approx, bits(c.approx), c.exact, c.bits)
		}
	}
}

	a[2] = a[1] & bits.RotateLeft64(a[0], 13)
	// arm64: "ORR\tR[0-9]+@>51, R[0-9]+, R[0-9]+"
	a[5] = a[4] | bits.RotateLeft64(a[3], 13)
	// arm64: "EOR\tR[0-9]+@>51, R[0-9]+, R[0-9]+"
	a[8] = a[7] ^ bits.RotateLeft64(a[6], 13)
	// arm64: "MVN\tR[0-9]+@>51, R[0-9]+"
	a[10] = ^bits.RotateLeft64(a[9], 13)
	// arm64: "BIC\tR[0-9]+@>51, R[0-9]+, R[0-9]+"
	a[13] = a[12] &^ bits.RotateLeft64(a[11], 13)

// to another portably. Not all bits apply to all systems.
// The only required bit is [ModeDir] for directories.
type FileMode uint32

// The defined file mode bits are the most significant bits of the [FileMode].
// The nine least-significant bits are the standard Unix rwxrwxrwx permissions.
// The values of these bits should be considered part of the public API and
// may be used in wire protocols or disk representations: they must not be