// can only support up to 2^32 pushes before a reset. If every
	// span in the heap were stored in this set, and each span were
	// the minimum size (1 runtime page, 8 KiB), then roughly the
	// smallest heap which would be unrepresentable is 32 TiB in size.
	index atomicHeadTailIndex
}

const (
	spanSetBlockEntries = 512 // 4KB on 64-bit
	spanSetInitSpineCap = 256 // Enough for 1GB heap on 64-bit
)

type spanSetBlock struct {

		if err := dec.Decode(&s); err != nil {
			t.Fatal("decoder fail:", err)
		}
		if s != fmt.Sprintf("%d", i) {
			t.Fatalf("decode expected %d got %s", i, s)
		}
	}
}

// Should be able to have unrepresentable fields (chan, func, *chan etc.); we just ignore them.
type Bug2 struct {
	A   int
	C   chan int
	CP  *chan int
	F   func()
	FPP **func()
}

func TestChanFuncIgnored(t *testing.T) {

			want: []byte{0x18, 0xff},
		},
		{
			in:   FromInt32(math.MaxUint8 + 1), // min positive integer representable in three bytes
			want: []byte{0x19, 0x01, 0x00},
		},
		{
			in:   FromInt32(math.MaxUint16), // max positive integer representable in three bytes
			want: []byte{0x19, 0xff, 0xff},
		},
		{
			in:   FromInt32(math.MaxUint16 + 1), // min positive integer representable in five bytes

        .setExpectation(Math.pow(2, 53), values())
        .test();
  }

  public void testRoundToDouble_maxPreciselyRepresentablePlusOne() {
    double twoToThe53 = Math.pow(2, 53);
    // the representable doubles are 2^53 and 2^53 + 2.
    // 2^53+1 is halfway between, so HALF_UP will go up and HALF_DOWN will go down.
    new RoundToDoubleTester(BigDecimal.valueOf((1L << 53) + 1))

  }

  /**
   * Returns {@code x}, rounded to a {@code double} with the specified rounding mode. If {@code x}
   * is precisely representable as a {@code double}, its {@code double} value will be returned;
   * otherwise, the rounding will choose between the two nearest representable values with {@code
   * mode}.
   *
   * <p>For the case of {@link RoundingMode#HALF_DOWN}, {@code HALF_UP}, and {@code HALF_EVEN},

  }

  /**
   * Returns {@code x}, rounded to a {@code double} with the specified rounding mode. If {@code x}
   * is precisely representable as a {@code double}, its {@code double} value will be returned;
   * otherwise, the rounding will choose between the two nearest representable values with {@code
   * mode}.
   *
   * <p>For the case of {@link RoundingMode#HALF_DOWN}, {@code HALF_UP}, and {@code HALF_EVEN},

   * is precisely representable as a {@code double}, its {@code double} value will be returned;
   * otherwise, the rounding will choose between the two nearest representable values with {@code
   * mode}.
   *
   * <p>For the case of {@link RoundingMode#HALF_EVEN}, this implementation uses the IEEE 754
   * default rounding mode: if the two nearest representable values are equally near, the one with

		s    string
		l, r *stringVal
	}
	int64Val   int64                    // Int values representable as an int64
	intVal     struct{ val *big.Int }   // Int values not representable as an int64
	ratVal     struct{ val *big.Rat }   // Float values representable as a fraction
	floatVal   struct{ val *big.Float } // Float values not representable as a fraction
	complexVal struct{ re, im Value }
)

   * is precisely representable as a {@code double}, its {@code double} value will be returned;
   * otherwise, the rounding will choose between the two nearest representable values with {@code
   * mode}.
   *
   * <p>For the case of {@link RoundingMode#HALF_EVEN}, this implementation uses the IEEE 754
   * default rounding mode: if the two nearest representable values are equally near, the one with

        .test();
  }

  @J2ktIncompatible
  @GwtIncompatible
  public void testRoundToDouble_maxPreciselyRepresentablePlusOne() {
    double twoToThe53 = Math.pow(2, 53);
    // the representable doubles are 2^53 and 2^53 + 2.
    // 2^53+1 is halfway between, so HALF_UP will go up and HALF_DOWN will go down.
    new RoundToDoubleTester(BigInteger.valueOf((1L << 53) + 1))