// The mask for the sign bit.
  static const Bits kSignBitMask = static_cast<Bits>(1) << (kBitCount - 1);

  // The mask for the fraction bits.
  static const Bits kFractionBitMask =
    ~static_cast<Bits>(0) >> (kExponentBitCount + 1);

  // The mask for the exponent bits.
  static const Bits kExponentBitMask = ~(kSignBitMask | kFractionBitMask);

  // How many ULP's (Units in the Last Place) we want to tolerate when

   * interpreted as an unsigned 64-bit value. Specifically, the sign bit of {@code bits} is
   * interpreted as a normal bit, and all other bits are treated as usual.
   *
   * <p>If the argument is nonnegative, the returned result will be equal to {@code bits},
   * otherwise, the result will be equal to {@code 2^64 + bits}.
   *
   * <p>To represent decimal constants less than {@code 2^63}, consider {@link #valueOf(long)}

   * interpreted as an unsigned 64-bit value. Specifically, the sign bit of {@code bits} is
   * interpreted as a normal bit, and all other bits are treated as usual.
   *
   * <p>If the argument is nonnegative, the returned result will be equal to {@code bits},
   * otherwise, the result will be equal to {@code 2^64 + bits}.
   *
   * <p>To represent decimal constants less than {@code 2^63}, consider {@link #valueOf(long)}

package test

import (
	"math/bits"
	"testing"
)

func TestBitLen64(t *testing.T) {
	for i := 0; i <= 64; i++ {
		got := bits.Len64(1 << i)
		want := i + 1
		if want == 65 {
			want = 0
		}
		if got != want {
			t.Errorf("Len64(1<<%d) = %d, want %d", i, got, want)
		}
	}
}

func TestBitLen32(t *testing.T) {
	for i := 0; i <= 32; i++ {
		got := bits.Len32(1 << i)
		want := i + 1

package runtime

import (
	"internal/goarch"
	"internal/goos"
	"unsafe"
)

const (
	// addrBits is the number of bits needed to represent a virtual address.
	//
	// See heapAddrBits for a table of address space sizes on
	// various architectures. 48 bits is enough for all
	// architectures except s390x.
	//
	// On AMD64, virtual addresses are 48-bit (or 57-bit) numbers sign extended to 64.

		{8e-45, 0x00000006},
		{9e-45, 0x00000006},
		{1.0e-44, 0x00000007},
		{1.1e-44, 0x00000008},
		{1.2e-44, 0x00000009},
	} {
		got := math.Float32bits(t.value)
		want := t.bits
		if got != want {
			panic(fmt.Sprintf("bits(%g) = 0x%08x; want 0x%08x", t.value, got, want))
		}
	}

	if ps == zs {
		// Adding (pm1:pm2) + (zm1:zm2)
		pm2, c = bits.Add64(pm2, zm2, 0)
		pm1, _ = bits.Add64(pm1, zm1, c)
		pe -= int32(^pm1 >> 63)
		pm1, m = shrcompress(pm1, pm2, uint(64+pm1>>63))
	} else {
		// Subtracting (pm1:pm2) - (zm1:zm2)
		// TODO: should we special-case cancellation?
		pm2, c = bits.Sub64(pm2, zm2, 0)
		pm1, _ = bits.Sub64(pm1, zm1, c)
		nz := lz(pm1, pm2)
		pe -= nz

	// Only small positive powers of 10 are exact (5^28 has 66 bits).
	exact := q <= 27 && q >= 0

	di, dexp2, d0 := mult64bitPow10(mant, e2, q)
	if dexp2 >= 0 {
		panic("not enough significant bits after mult64bitPow10")
	}
	// As a special case, computation might still be exact, if exponent
	// was negative and if it amounts to computing an exact division.
	// In that case, we ignore all lower bits.

		*(*uint8)(f) &^= mask
	}
}

func (f bitset8) get2(shift uint8) uint8 {
	return uint8(f>>shift) & 3
}

// set2 sets two bits in f using the bottom two bits of b.
func (f *bitset8) set2(shift uint8, b uint8) {
	// Clear old bits.
	*(*uint8)(f) &^= 3 << shift
	// Set new bits.
	*(*uint8)(f) |= uint8(b&3) << shift
}

type bitset16 uint16

func (f *bitset16) set(mask uint16, b bool) {
	if b {

  TF_BFLOAT16 = 14,  // Float32 truncated to 16 bits.
  TF_QINT16 = 15,    // Quantized int16
  TF_QUINT16 = 16,   // Quantized uint16
  TF_UINT16 = 17,
  TF_COMPLEX128 = 18,  // Double-precision complex
  TF_HALF = 19,
  TF_RESOURCE = 20,
  TF_VARIANT = 21,
  TF_UINT32 = 22,
  TF_UINT64 = 23,
  TF_FLOAT8_E5M2 = 24,    // 5 exponent bits, 2 mantissa bits.
  TF_FLOAT8_E4M3FN = 25,  // 4 exponent bits, 3 mantissa bits, finite-only, with