Exemplo n.º 1
0
 protected BigInteger modReduce(BigInteger x) {
   if (r != null) {
     boolean negative = x.signum() < 0;
     if (negative) {
       x = x.abs();
     }
     int qLen = q.bitLength();
     boolean rIsOne = r.equals(ECConstants.ONE);
     while (x.bitLength() > (qLen + 1)) {
       BigInteger u = x.shiftRight(qLen);
       BigInteger v = x.subtract(u.shiftLeft(qLen));
       if (!rIsOne) {
         u = u.multiply(r);
       }
       x = u.add(v);
     }
     while (x.compareTo(q) >= 0) {
       x = x.subtract(q);
     }
     if (negative && x.signum() != 0) {
       x = q.subtract(x);
     }
   } else {
     x = x.mod(q);
   }
   return x;
 }
Exemplo n.º 2
0
  @Test
  public void testCheckFunctions() {
    assertFalse(ArbitraryInteger.ZERO.isNegativ());
    assertTrue(ArbitraryInteger.ZERO.isZero());
    assertFalse(ArbitraryInteger.ZERO.isPositiv());
    assertEquals(0, ArbitraryInteger.ZERO.signum());

    assertFalse(ArbitraryInteger.ONE.isNegativ());
    assertFalse(ArbitraryInteger.ONE.isZero());
    assertTrue(ArbitraryInteger.ONE.isPositiv());
    assertEquals(1, ArbitraryInteger.ONE.signum());

    assertTrue(ArbitraryInteger.MINUS_ONE.isNegativ());
    assertFalse(ArbitraryInteger.MINUS_ONE.isZero());
    assertFalse(ArbitraryInteger.MINUS_ONE.isPositiv());
    assertEquals(-1, ArbitraryInteger.MINUS_ONE.signum());

    for (int i = 0; i < this.iterations; i++) {
      BigInteger reference =
          BigInteger.valueOf(this.randomizer.nextLong() - Long.MAX_VALUE)
              .pow(this.randomizer.nextInt(20) + 10);
      ArbitraryInteger proband = ArbitraryInteger.valueOf(reference.toByteArray());
      assertEquals(reference.signum(), proband.signum());
      assertTrue(
          reference.signum() < 0 && proband.isNegativ()
              || reference.signum() > 0 && !proband.isNegativ());
      assertTrue(
          reference.signum() > 0 && proband.isPositiv()
              || reference.signum() < 0 && !proband.isPositiv());
      assertTrue(reference.bitLength() == proband.bitLength());
    }
  }
 /** @tests java.math.BigInteger#signum() */
 @TestTargetNew(
     level = TestLevel.COMPLETE,
     notes = "",
     method = "signum",
     args = {})
 public void test_signum() {
   assertTrue("Wrong positive signum", two.signum() == 1);
   assertTrue("Wrong zero signum", zero.signum() == 0);
   assertTrue("Wrong neg zero signum", zero.negate().signum() == 0);
   assertTrue("Wrong neg signum", two.negate().signum() == -1);
 }
Exemplo n.º 4
0
  /**
   * Constructs a new BigFraction from two BigDecimals.
   *
   * @throws ArithemeticException if denominator == 0.
   */
  private static BigFraction valueOfHelper(
      final BigDecimal numerator, final BigDecimal denominator) {
    // Note: Cannot use .equals(BigDecimal.ZERO), because "0.00" != "0.0".
    if (denominator.unscaledValue().equals(BigInteger.ZERO)) {
      throw new ArithmeticException("Divide by zero: fraction denominator is zero.");
    }

    // Format of BigDecimal: unscaled / 10^scale
    BigInteger tmpNumerator = numerator.unscaledValue();
    BigInteger tmpDenominator = denominator.unscaledValue();

    // (u1/10^s1) / (u2/10^s2) = u1 / (u2 * 10^(s1-s2)) = (u1 * 10^(s2-s1))
    // / u2
    if (numerator.scale() > denominator.scale()) {
      tmpDenominator =
          tmpDenominator.multiply(BigInteger.TEN.pow(numerator.scale() - denominator.scale()));
    } else if (numerator.scale() < denominator.scale()) {
      tmpNumerator =
          tmpNumerator.multiply(BigInteger.TEN.pow(denominator.scale() - numerator.scale()));
      // else: scales are equal, do nothing.
    }

    final BigInteger gcd = tmpNumerator.gcd(tmpDenominator);
    tmpNumerator = tmpNumerator.divide(gcd);
    tmpDenominator = tmpDenominator.divide(gcd);

    if (tmpDenominator.signum() < 0) {
      tmpNumerator = tmpNumerator.negate();
      tmpDenominator = tmpDenominator.negate();
    }

    return new BigFraction(tmpNumerator, tmpDenominator, Reduced.YES);
  }
Exemplo n.º 5
0
 public FpFieldElement(BigInteger q, BigInteger x) {
   if ((x == null) || (x.signum() < 0) || (x.compareTo(q) >= 0)) {
     throw new IllegalArgumentException("x value invalid in Fp field element");
   }
   this.q = q;
   this.x = x;
 }
Exemplo n.º 6
0
  public static void shift(int order) {
    int failCount1 = 0;
    int failCount2 = 0;
    int failCount3 = 0;

    for (int i = 0; i < 100; i++) {
      BigInteger x = fetchNumber(order);
      int n = Math.abs(rnd.nextInt() % 200);

      if (!x.shiftLeft(n).equals(x.multiply(BigInteger.valueOf(2L).pow(n)))) failCount1++;

      BigInteger y[] = x.divideAndRemainder(BigInteger.valueOf(2L).pow(n));
      BigInteger z = (x.signum() < 0 && y[1].signum() != 0 ? y[0].subtract(BigInteger.ONE) : y[0]);

      BigInteger b = x.shiftRight(n);

      if (!b.equals(z)) {
        System.err.println("Input is " + x.toString(2));
        System.err.println("shift is " + n);

        System.err.println("Divided " + z.toString(2));
        System.err.println("Shifted is " + b.toString(2));
        if (b.toString().equals(z.toString())) System.err.println("Houston, we have a problem.");
        failCount2++;
      }

      if (!x.shiftLeft(n).shiftRight(n).equals(x)) failCount3++;
    }
    report("baz shiftLeft", failCount1);
    report("baz shiftRight", failCount2);
    report("baz shiftLeft/Right", failCount3);
  }
Exemplo n.º 7
0
  public BDD varRange(BigInteger lo, BigInteger hi) {
    if (lo.signum() < 0 || hi.compareTo(size()) >= 0 || lo.compareTo(hi) > 0) {
      throw new BDDException("range <" + lo + ", " + hi + "> is invalid");
    }

    BDDFactory factory = getFactory();
    BDD result = factory.zero();
    int[] ivar = this.vars();
    while (lo.compareTo(hi) <= 0) {
      BDD v = factory.universe();
      for (int n = ivar.length - 1; ; n--) {
        if (lo.testBit(n)) {
          v.andWith(factory.ithVar(ivar[n]));
        } else {
          v.andWith(factory.nithVar(ivar[n]));
        }
        BigInteger mask = BigInteger.ONE.shiftLeft(n).subtract(BigInteger.ONE);
        if (!lo.testBit(n) && lo.or(mask).compareTo(hi) <= 0) {
          lo = lo.or(mask).add(BigInteger.ONE);
          break;
        }
      }
      result.orWith(v);
    }
    return result;
  }
Exemplo n.º 8
0
  /** *************************************************************************** */
  public Fraction(String strFrac) // constructor
        /** *************************************************************************** */
      {
    int tokens = 0;
    String strTokens[] = new String[2];

    StringTokenizer tokenizer = new StringTokenizer(strFrac, "/");

    try {
      while (tokenizer.hasMoreTokens()) {
        strTokens[tokens] = tokenizer.nextToken();
        tokens++;
      }
    } catch (ArrayIndexOutOfBoundsException e) {
      throw new NumberFormatException(strFrac + " is not a valid fraction.");
    }

    if (tokens == 1) {
      strTokens[1] = new String("1");
    }

    num = new BigInteger(strTokens[0]);
    denom = new BigInteger(strTokens[1]);

    if (denom.equals(BigInteger.ZERO))
      throw new ArithmeticException(
          "Denominator in fraction cannot be zero: " + num.toString() + "/" + denom.toString());

    if (denom.signum() == -1) {
      num = num.negate();
      denom = denom.negate();
    }
  }
Exemplo n.º 9
0
  /**
   * Private constructor, used when you can be certain that the fraction is already in lowest terms.
   * No check is done to reduce numerator/denominator. A check is still done to maintain a positive
   * denominator.
   *
   * @param isReduced Indicates whether or not the fraction is already known to be reduced to lowest
   *     terms.
   */
  private BigFraction(BigInteger numerator, BigInteger denominator, final Reduced reduced) {
    if (numerator == null) {
      throw new IllegalArgumentException("Numerator is null");
    }
    if (denominator == null) {
      throw new IllegalArgumentException("Denominator is null");
    }
    if (denominator.equals(BigInteger.ZERO)) {
      throw new ArithmeticException("Divide by zero: fraction denominator is zero.");
    }

    // only numerator should be negative.
    if (denominator.signum() < 0) {
      numerator = numerator.negate();
      denominator = denominator.negate();
    }

    if (reduced == Reduced.NO) {
      // create a reduced fraction
      final BigInteger gcd = numerator.gcd(denominator);
      numerator = numerator.divide(gcd);
      denominator = denominator.divide(gcd);
    }

    this.numerator = numerator;
    this.denominator = denominator;
  }
 /**
  * Add the specified value to this reference.
  *
  * @param val The value.
  * @return A reference with an index increased by <code>val</code>.
  */
 public Reference add(BigInteger val) {
   if (val.signum() == 0) {
     return this;
   } else {
     return new IndexReference(this, val);
   }
 }
  @TruffleBoundary
  @Specialization(guards = "isRubyBignum(value)")
  public byte[] format(int width, int precision, DynamicObject value) {
    final BigInteger bigInteger = Layouts.BIGNUM.getValue(value);
    final boolean isNegative = bigInteger.signum() == -1;
    final boolean negativeAndPadded = isNegative && (this.hasSpaceFlag || this.hasPlusFlag);

    final String formatted;
    if (negativeAndPadded) {
      formatted = bigInteger.abs().toString(2);
    } else if (!isNegative) {
      formatted = bigInteger.toString(2);
    } else {
      StringBuilder builder = new StringBuilder();
      final byte[] bytes = bigInteger.toByteArray();
      for (byte b : bytes) {
        builder.append(Integer.toBinaryString(b & 0xFF));
      }
      formatted = builder.toString();
    }
    return getFormattedString(
        formatted,
        width,
        precision,
        isNegative,
        this.hasSpaceFlag,
        this.hasPlusFlag,
        this.hasZeroFlag,
        this.useAlternativeFormat,
        this.hasMinusFlag,
        this.format);
  }
Exemplo n.º 12
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 public void objectiveFunctionToLP(ObjectiveFunction obj, StringBuffer buffer) {
   buffer.append("Minimize \n");
   buffer.append("obj: ");
   IVecInt variables = obj.getVars();
   IVec<BigInteger> coeffs = obj.getCoeffs();
   int n = variables.size();
   if (n > 0) {
     buffer.append(coeffs.get(0));
     buffer.append("x");
     buffer.append(variables.get(0));
     buffer.append(" ");
   }
   BigInteger coeff;
   for (int i = 1; i < n; i++) {
     coeff = coeffs.get(i);
     if (coeff.signum() > 0) {
       buffer.append("+ " + coeff);
     } else {
       buffer.append("- " + coeff.negate());
     }
     buffer.append("x");
     buffer.append(variables.get(i));
     buffer.append(" ");
   }
 }
Exemplo n.º 13
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 public void testIsPowerOfTwo() {
   for (BigInteger x : ALL_BIGINTEGER_CANDIDATES) {
     // Checks for a single bit set.
     boolean expected = x.signum() > 0 & x.and(x.subtract(ONE)).equals(ZERO);
     assertEquals(expected, BigIntegerMath.isPowerOfTwo(x));
   }
 }
 /**
  * Subtract the specified value from this reference.
  *
  * @param val The value.
  * @return A reference with an index decreased by <code>val</code>.
  */
 public Reference subtract(BigInteger val) {
   if (val.signum() == 0) {
     return this;
   } else {
     return new IndexReference(this, val.negate());
   }
 }
Exemplo n.º 15
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    /**
     * Constructor for PPB.
     *
     * @param m The exponent <code>m</code> of <code>F<sub>2<sup>m</sup></sub></code>.
     * @param k1 The integer <code>k1</code> where <code>x<sup>m</sup> +
     * x<sup>k3</sup> + x<sup>k2</sup> + x<sup>k1</sup> + 1</code> represents the reduction
     *     polynomial <code>f(z)</code>.
     * @param k2 The integer <code>k2</code> where <code>x<sup>m</sup> +
     * x<sup>k3</sup> + x<sup>k2</sup> + x<sup>k1</sup> + 1</code> represents the reduction
     *     polynomial <code>f(z)</code>.
     * @param k3 The integer <code>k3</code> where <code>x<sup>m</sup> +
     * x<sup>k3</sup> + x<sup>k2</sup> + x<sup>k1</sup> + 1</code> represents the reduction
     *     polynomial <code>f(z)</code>.
     * @param x The BigInteger representing the value of the field element.
     */
    public F2m(int m, int k1, int k2, int k3, BigInteger x) {
      // t = m / 32 rounded up to the next integer
      t = (m + 31) >> 5;
      this.x = new IntArray(x, t);

      if ((k2 == 0) && (k3 == 0)) {
        this.representation = TPB;
      } else {
        if (k2 >= k3) {
          throw new IllegalArgumentException("k2 must be smaller than k3");
        }
        if (k2 <= 0) {
          throw new IllegalArgumentException("k2 must be larger than 0");
        }
        this.representation = PPB;
      }

      if (x.signum() < 0) {
        throw new IllegalArgumentException("x value cannot be negative");
      }

      this.m = m;
      this.k1 = k1;
      this.k2 = k2;
      this.k3 = k3;
    }
Exemplo n.º 16
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 // c: rand_int
 private static IRubyObject randInt(
     ThreadContext context, RandomType random, RubyInteger vmax, boolean restrictive) {
   if (vmax instanceof RubyFixnum) {
     long max = RubyNumeric.fix2long(vmax);
     if (max == 0) {
       return context.nil;
     }
     if (max < 0) {
       if (restrictive) {
         return context.nil;
       }
       max = -max;
     }
     return randLimitedFixnum(context, random, max - 1);
   } else {
     BigInteger big = vmax.getBigIntegerValue();
     if (big.equals(BigInteger.ZERO)) {
       return context.nil;
     }
     if (big.signum() < 0) {
       if (restrictive) {
         return context.nil;
       }
       big = big.abs();
     }
     big = big.subtract(BigInteger.ONE);
     return randLimitedBignum(context, random, RubyBignum.newBignum(context.runtime, big));
   }
 }
Exemplo n.º 17
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  public SecT113FieldElement(BigInteger x) {
    if (x == null || x.signum() < 0 || x.bitLength() > 113) {
      throw new IllegalArgumentException("x value invalid for SecT113FieldElement");
    }

    this.x = SecT113Field.fromBigInteger(x);
  }
Exemplo n.º 18
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 public IConstr addExactly(IVecInt literals, IVec<BigInteger> coeffs, BigInteger weight)
     throws ContradictionException {
   StringBuffer out = getOut();
   assert literals.size() == coeffs.size();
   this.nbOfConstraints++;
   int n = literals.size();
   if (n > 0) {
     out.append(coeffs.get(0));
     out.append("x");
     out.append(literals.get(0));
     out.append(" ");
   }
   BigInteger coeff;
   for (int i = 1; i < n; i++) {
     coeff = coeffs.get(i);
     if (coeff.signum() > 0) {
       out.append("+ " + coeff);
     } else {
       out.append("- " + coeff.negate());
     }
     out.append("x");
     out.append(literals.get(i));
     out.append(" ");
   }
   out.append("= ");
   out.append(weight);
   out.append(" \n");
   return FAKE_CONSTR;
 }
Exemplo n.º 19
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 /**
  * MPI encoded numbers are produced by the OpenSSL BN_bn2mpi function. They consist of a 4 byte
  * big endian length field, followed by the stated number of bytes representing the number in big
  * endian format (with a sign bit).
  *
  * @param includeLength indicates whether the 4 byte length field should be included
  */
 public static byte[] encodeMPI(BigInteger value, boolean includeLength) {
   if (value.equals(BigInteger.ZERO)) {
     if (!includeLength) return new byte[] {};
     else return new byte[] {0x00, 0x00, 0x00, 0x00};
   }
   boolean isNegative = value.signum() < 0;
   if (isNegative) value = value.negate();
   byte[] array = value.toByteArray();
   int length = array.length;
   if ((array[0] & 0x80) == 0x80) length++;
   if (includeLength) {
     byte[] result = new byte[length + 4];
     System.arraycopy(array, 0, result, length - array.length + 3, array.length);
     uint32ToByteArrayBE(length, result, 0);
     if (isNegative) result[4] |= 0x80;
     return result;
   } else {
     byte[] result;
     if (length != array.length) {
       result = new byte[length];
       System.arraycopy(array, 0, result, 1, array.length);
     } else result = array;
     if (isNegative) result[0] |= 0x80;
     return result;
   }
 }
Exemplo n.º 20
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 protected BigInteger modSubtract(BigInteger x1, BigInteger x2) {
   BigInteger x3 = x1.subtract(x2);
   if (x3.signum() < 0) {
     x3 = x3.add(q);
   }
   return x3;
 }
Exemplo n.º 21
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  /** @tests java.math.BigInteger#shiftRight(int) */
  @TestTargetNew(
      level = TestLevel.COMPLETE,
      notes = "",
      method = "shiftRight",
      args = {int.class})
  public void test_shiftRightI() {
    assertTrue("1 >> 0", BigInteger.valueOf(1).shiftRight(0).equals(BigInteger.ONE));
    assertTrue("1 >> 1", BigInteger.valueOf(1).shiftRight(1).equals(BigInteger.ZERO));
    assertTrue("1 >> 63", BigInteger.valueOf(1).shiftRight(63).equals(BigInteger.ZERO));
    assertTrue("1 >> 64", BigInteger.valueOf(1).shiftRight(64).equals(BigInteger.ZERO));
    assertTrue("1 >> 65", BigInteger.valueOf(1).shiftRight(65).equals(BigInteger.ZERO));
    assertTrue("1 >> 1000", BigInteger.valueOf(1).shiftRight(1000).equals(BigInteger.ZERO));
    assertTrue("-1 >> 0", BigInteger.valueOf(-1).shiftRight(0).equals(minusOne));
    assertTrue("-1 >> 1", BigInteger.valueOf(-1).shiftRight(1).equals(minusOne));
    assertTrue("-1 >> 63", BigInteger.valueOf(-1).shiftRight(63).equals(minusOne));
    assertTrue("-1 >> 64", BigInteger.valueOf(-1).shiftRight(64).equals(minusOne));
    assertTrue("-1 >> 65", BigInteger.valueOf(-1).shiftRight(65).equals(minusOne));
    assertTrue("-1 >> 1000", BigInteger.valueOf(-1).shiftRight(1000).equals(minusOne));

    BigInteger a = BigInteger.ONE;
    BigInteger c = bi3;
    BigInteger E = bi3.negate();
    BigInteger e = E;
    for (int i = 0; i < 200; i++) {
      BigInteger b = BigInteger.ZERO.setBit(i);
      assertTrue("a==b", a.equals(b));
      a = a.shiftLeft(1);
      assertTrue("a non-neg", a.signum() >= 0);

      BigInteger d = bi3.shiftRight(i);
      assertTrue("c==d", c.equals(d));
      c = c.shiftRight(1);
      assertTrue(">>1 == /2", d.divide(two).equals(c));
      assertTrue("c non-neg", c.signum() >= 0);

      BigInteger f = E.shiftRight(i);
      assertTrue("e==f", e.equals(f));
      e = e.shiftRight(1);
      assertTrue(">>1 == /2", f.subtract(one).divide(two).equals(e));
      assertTrue("e negative", e.signum() == -1);

      assertTrue("b >> i", b.shiftRight(i).equals(one));
      assertTrue("b >> i+1", b.shiftRight(i + 1).equals(zero));
      assertTrue("b >> i-1", b.shiftRight(i - 1).equals(two));
    }
  }
Exemplo n.º 22
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 /**
  * Determine if this value can be represented as an unsigned long without truncation, that is if
  * the value is non-negative and its bit pattern completely fits in a long.
  *
  * @return true if this value is non-negative and fits in a long false otherwise.
  */
 public boolean isULong() {
   // Here we have the same problem as for isLong(), plus
   // the whole range 1<<63 .. (1<<64-1) is allowed.
   if (bigVal != null) {
     return bigVal.signum() >= 0 && bigVal.bitLength() <= 64;
   }
   return val >= 0;
 }
Exemplo n.º 23
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 /**
  * Private constructor, used when you can be certain that the fraction is already in lowest terms.
  * No check is done to reduce numerator/denominator. A check is still done to maintain a positive
  * denominator.
  *
  * @param throwaway unused variable, only here to signal to the compiler that this constructor
  *     should be used.
  */
 private BigFraction(BigInteger numerator, BigInteger denominator, boolean throwaway) {
   if (denominator.signum() < 0) {
     this.numerator = numerator.negate();
     this.denominator = denominator.negate();
   } else {
     this.numerator = numerator;
     this.denominator = denominator;
   }
 }
Exemplo n.º 24
0
    Fp(BigInteger q, BigInteger r, BigInteger x) {
      if (x == null || x.signum() < 0 || x.compareTo(q) >= 0) {
        throw new IllegalArgumentException("x value invalid in Fp field element");
      }

      this.q = q;
      this.r = r;
      this.x = x;
    }
  public static BigInteger toNanoCoins(final String value, final int shift) {
    final BigInteger nanoCoins =
        new BigDecimal(value).movePointRight(8 - shift).toBigIntegerExact();

    if (nanoCoins.signum() < 0) throw new IllegalArgumentException("negative amount: " + value);
    if (nanoCoins.compareTo(NetworkParameters.MAX_MONEY) > 0)
      throw new IllegalArgumentException("amount too large: " + value);

    return nanoCoins;
  }
Exemplo n.º 26
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 public static Long parseUnsignedLong(String number) {
   if (number == null) {
     return null;
   }
   BigInteger bigInt = new BigInteger(number.trim());
   if (bigInt.signum() < 0 || bigInt.compareTo(two64) != -1) {
     throw new IllegalArgumentException("overflow: " + number);
   }
   return zeroToNull(bigInt.longValue());
 }
 /** Compute the quadratic character of v, i.e. (v/p) for prime p. */
 public int legendre(BigInteger v) {
   // return v.modPow(p.shiftRight(1), p).add(_1).compareTo(p) == 0 ? -1 : 1; // v^((p-1)/2) mod p
   // = (v/p) for prime p
   int J = 1;
   BigInteger x = v, y = p;
   if (x.signum() < 0) {
     x = x.negate();
     if (y.testBit(0) && y.testBit(1)) { // y = 3 (mod 4)
       J = -J;
     }
   }
   while (y.compareTo(_1) > 0) {
     x = x.mod(y);
     if (x.compareTo(y.shiftRight(1)) > 0) {
       x = y.subtract(x);
       if (y.testBit(0) && y.testBit(1)) { // y = 3 (mod 4)
         J = -J;
       }
     }
     if (x.signum() == 0) {
       x = _1;
       y = _0;
       J = 0;
       break;
     }
     while (!x.testBit(0) && !x.testBit(1)) { // 4 divides x
       x = x.shiftRight(2);
     }
     if (!x.testBit(0)) { // 2 divides x
       x = x.shiftRight(1);
       if (y.testBit(0) && (y.testBit(1) == !y.testBit(2))) { // y = �3 (mod 8)
         J = -J;
       }
     }
     if (x.testBit(0) && x.testBit(1) && y.testBit(0) && y.testBit(1)) { // x = y = 3 (mod 4)
       J = -J;
     }
     BigInteger t = x;
     x = y;
     y = t; // switch x and y
   }
   return J;
 }
  public BigInteger getAmount() {
    BigInteger amount = BigInteger.ZERO;

    if (hasOutputs())
      for (final Output output : outputs)
        if (output.hasAmount()) amount = amount.add(output.amount);

    if (amount.signum() != 0) return amount;
    else return null;
  }
 /**
  * Compute a cube root of v (mod p) where p = 4 (mod 9).
  *
  * @return a cube root of v (mod p) if one exists, or null otherwise.
  * @exception IllegalArgumentException if the size p of the underlying finite field does not
  *     satisfy p = 4 (mod 9).
  */
 public BigInteger cbrt(BigInteger v) {
   if (p.mod(_9).intValue() != 4) {
     throw new IllegalArgumentException(
         "This implementation is optimized for, and only works with, prime fields GF(p) where p = 4 (mod 9)");
   }
   if (v.signum() == 0) {
     return _0;
   }
   BigInteger r = v.modPow(cbrtExponent, p); // r = v^{(2p + 1)/9}
   return r.multiply(r).multiply(r).subtract(v).mod(p).signum() == 0 ? r : null;
 }
Exemplo n.º 30
0
  public IntArray(BigInteger bigInt, int minIntLen) {
    if (bigInt.signum() == -1) {
      throw new IllegalArgumentException("Only positive Integers allowed");
    }
    if (bigInt.equals(ECConstants.ZERO)) {
      m_ints = new int[] {0};
      return;
    }

    byte[] barr = bigInt.toByteArray();
    int barrLen = barr.length;
    int barrStart = 0;
    if (barr[0] == 0) {
      // First byte is 0 to enforce highest (=sign) bit is zero.
      // In this case ignore barr[0].
      barrLen--;
      barrStart = 1;
    }
    int intLen = (barrLen + 3) / 4;
    if (intLen < minIntLen) {
      m_ints = new int[minIntLen];
    } else {
      m_ints = new int[intLen];
    }

    int iarrJ = intLen - 1;
    int rem = barrLen % 4 + barrStart;
    int temp = 0;
    int barrI = barrStart;
    if (barrStart < rem) {
      for (; barrI < rem; barrI++) {
        temp <<= 8;
        int barrBarrI = barr[barrI];
        if (barrBarrI < 0) {
          barrBarrI += 256;
        }
        temp |= barrBarrI;
      }
      m_ints[iarrJ--] = temp;
    }

    for (; iarrJ >= 0; iarrJ--) {
      temp = 0;
      for (int i = 0; i < 4; i++) {
        temp <<= 8;
        int barrBarrI = barr[barrI++];
        if (barrBarrI < 0) {
          barrBarrI += 256;
        }
        temp |= barrBarrI;
      }
      m_ints[iarrJ] = temp;
    }
  }