private BigDecimalMath() {}

  /**
   * 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},

  private BigDecimalMath() {}

  /**
   * 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},

import static com.google.common.math.MathPreconditions.checkRoundingUnnecessary;

import com.google.common.annotations.GwtIncompatible;
import java.math.RoundingMode;

/**
 * Helper type to implement rounding {@code X} to a representable {@code double} value according to
 * a {@link RoundingMode}.
 */
@GwtIncompatible
@ElementTypesAreNonnullByDefault
abstract class ToDoubleRounder<X extends Number & Comparable<X>> {
  /**

import static com.google.common.math.MathPreconditions.checkRoundingUnnecessary;

import com.google.common.annotations.GwtIncompatible;
import java.math.RoundingMode;

/**
 * Helper type to implement rounding {@code X} to a representable {@code double} value according to
 * a {@link RoundingMode}.
 */
@GwtIncompatible
@ElementTypesAreNonnullByDefault
abstract class ToDoubleRounder<X extends Number & Comparable<X>> {
  /**

find the definition of xxx.  If xxx is a type, cgo replaces C.xxx with
a Go translation.  C arithmetic types translate to precisely-sized Go
arithmetic types.  A C struct translates to a Go struct, field by
field; unrepresentable fields are replaced with opaque byte arrays.  A
C union translates into a struct containing the first union member and
perhaps additional padding.  C arrays become Go arrays.  C pointers