N, _ := NewModulusFromBig(n)
	A := NewNat().setBig(a).ExpandFor(N)
	B := NewNat().setBig(b).ExpandFor(N)

	if A.Mul(B, N).IsZero() != 1 {
		t.Error("a * b mod (a * b) != 0")
	}

	i := new(big.Int).ModInverse(a, b)
	N, _ = NewModulusFromBig(b)
	A = NewNat().setBig(a).ExpandFor(N)
	I := NewNat().setBig(i).ExpandFor(N)
	one := NewNat().setBig(big.NewInt(1)).ExpandFor(N)

	if A.Mul(I, N).Equal(one) != 1 {

func (x *Nat) set(y *Nat) *Nat {
	x.reset(len(y.limbs))
	copy(x.limbs, y.limbs)
	return x
}

// setBig assigns x = n, optionally resizing n to the appropriate size.
//
// The announced length of x is set based on the actual bit size of the input,
// ignoring leading zeroes.
func (x *Nat) setBig(n *big.Int) *Nat {
	limbs := n.Bits()
	x.reset(len(limbs))
	for i := range limbs {
		x.limbs[i] = uint(limbs[i])

func mdestroy(mp *m) {
}

func sigtramp()

type sigactiont struct {
	sa_sigaction uintptr
	sa_mask      uint32
	sa_flags     int32
}

//go:nosplit
//go:nowritebarrierrec
func setsig(i uint32, fn uintptr) {
	var sa sigactiont
	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
	sa.sa_mask = uint32(sigset_all)

var algPriority = [ASPECIAL + 1]int8{ASPECIAL: 1, ANOEQ: 2, ANOALG: 3, AMEM: -1}

// setAlg sets the algorithm type of t to a, if it is of higher
// priority to the current algorithm type.
func (t *Type) setAlg(a AlgKind) {
	if t.alg == AUNK {
		base.Fatalf("setAlg(%v,%s) starting with unknown priority", t, a)
	}
	if algPriority[a] > algPriority[t.alg] {
		t.alg = a

	case TFLOAT32:
		w = 4
		t.floatRegs = 1
		t.setAlg(AFLOAT32)

	case TFLOAT64:
		w = 8
		t.align = uint8(RegSize)
		t.floatRegs = 1
		t.setAlg(AFLOAT64)

	case TCOMPLEX64:
		w = 8
		t.align = 4
		t.floatRegs = 2
		t.setAlg(ACPLX64)

	case TCOMPLEX128:
		w = 16
		t.align = uint8(RegSize)
		t.floatRegs = 2
		t.setAlg(ACPLX128)

	case TPTR:
		w = int64(PtrSize)

	var uc ucontextt
	getcontext(unsafe.Pointer(&uc))

	// _UC_SIGMASK does not seem to work here.
	// It would be nice if _UC_SIGMASK and _UC_STACK
	// worked so that we could do all the work setting
	// the sigmask and the stack here, instead of setting
	// the mask here and the stack in netbsdMstart.
	// For now do the blocking manually.
	uc.uc_flags = _UC_SIGMASK | _UC_CPU
	uc.uc_link = nil
	uc.uc_sigmask = sigset_all

		// it may hit stack split that is not expected here.
		if gp != nil {
			setg(nil)
		}
		badsignal(uintptr(sig), c)
		// Restore g
		if gp != nil {
			setg(gp)
		}
		return
	}

	setg(gp.m.gsignal)

	// If some non-Go code called sigaltstack, adjust.
	var gsignalStack gsignalStack

        assertTrue(ZERO.setBit(result).compareTo(x) <= 0);
        assertTrue(ZERO.setBit(result + 1).compareTo(x) > 0);
      }
    }
  }

  public void testLog2Ceiling() {
    for (BigInteger x : POSITIVE_BIGINTEGER_CANDIDATES) {
      for (RoundingMode mode : asList(CEILING, UP)) {
        int result = BigIntegerMath.log2(x, mode);
        assertTrue(ZERO.setBit(result).compareTo(x) >= 0);

}

/* SIGNAL */

const (
	_NSIG = 256
)

// sigtramp is a function descriptor to _sigtramp defined in assembly
var sigtramp funcDescriptor

//go:nosplit
//go:nowritebarrierrec
func setsig(i uint32, fn uintptr) {
	var sa sigactiont
	sa.sa_flags = _SA_SIGINFO | _SA_ONSTACK | _SA_RESTART
	sa.sa_mask = sigset_all

			min = b
		}
	}

	// create bit pattern
	x := NewInt(0)
	for _, b := range bits {
		badj := b - min
		// propagate carry if necessary
		for x.Bit(badj) != 0 {
			x.SetBit(x, badj, 0)
			badj++
		}
		x.SetBit(x, badj, 1)
	}

	// create corresponding float
	z := new(Float).SetInt(x) // normalized
	if e := int64(z.exp) + int64(min); MinExp <= e && e <= MaxExp {
		z.exp = int32(e)
	} else {