| // BigInteger.java -- an arbitrary-precision integer |
| |
| /* Copyright (C) 1999, 2000, 2001 Free Software Foundation |
| |
| This file is part of libgcj. |
| |
| This software is copyrighted work licensed under the terms of the |
| Libgcj License. Please consult the file "LIBGCJ_LICENSE" for |
| details. */ |
| |
| package java.math; |
| import gnu.gcj.math.*; |
| import java.util.Random; |
| import java.io.ObjectInputStream; |
| import java.io.ObjectOutputStream; |
| import java.io.IOException; |
| |
| /** |
| * @author Warren Levy <warrenl@cygnus.com> |
| * @date December 20, 1999. |
| */ |
| |
| /** |
| * Written using on-line Java Platform 1.2 API Specification, as well |
| * as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998) and |
| * "Applied Cryptography, Second Edition" by Bruce Schneier (Wiley, 1996). |
| |
| * |
| * Based primarily on IntNum.java BitOps.java by Per Bothner <per@bothner.com> |
| * (found in Kawa 1.6.62). |
| * |
| * Status: Believed complete and correct. |
| */ |
| |
| public class BigInteger extends Number implements Comparable |
| { |
| /** All integers are stored in 2's-complement form. |
| * If words == null, the ival is the value of this BigInteger. |
| * Otherwise, the first ival elements of words make the value |
| * of this BigInteger, stored in little-endian order, 2's-complement form. */ |
| transient private int ival; |
| transient private int[] words; |
| |
| // Serialization fields. |
| private int bitCount = -1; |
| private int bitLength = -1; |
| private int firstNonzeroByteNum = -2; |
| private int lowestSetBit = -2; |
| private byte[] magnitude; |
| private int signum; |
| private static final long serialVersionUID = -8287574255936472291L; |
| |
| |
| /** We pre-allocate integers in the range minFixNum..maxFixNum. */ |
| private static final int minFixNum = -100; |
| private static final int maxFixNum = 1024; |
| private static final int numFixNum = maxFixNum-minFixNum+1; |
| private static final BigInteger[] smallFixNums = new BigInteger[numFixNum]; |
| |
| static { |
| for (int i = numFixNum; --i >= 0; ) |
| smallFixNums[i] = new BigInteger(i + minFixNum); |
| } |
| |
| // JDK1.2 |
| public static final BigInteger ZERO = smallFixNums[-minFixNum]; |
| |
| // JDK1.2 |
| public static final BigInteger ONE = smallFixNums[1 - minFixNum]; |
| |
| /* Rounding modes: */ |
| private static final int FLOOR = 1; |
| private static final int CEILING = 2; |
| private static final int TRUNCATE = 3; |
| private static final int ROUND = 4; |
| |
| /** When checking the probability of primes, it is most efficient to |
| * first check the factoring of small primes, so we'll use this array. |
| */ |
| private static final int[] primes = |
| { 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, |
| 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, |
| 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, |
| 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251 }; |
| |
| private BigInteger() |
| { |
| } |
| |
| /* Create a new (non-shared) BigInteger, and initialize to an int. */ |
| private BigInteger(int value) |
| { |
| ival = value; |
| } |
| |
| public BigInteger(String val, int radix) |
| { |
| BigInteger result = valueOf(val, radix); |
| this.ival = result.ival; |
| this.words = result.words; |
| } |
| |
| public BigInteger(String val) |
| { |
| this(val, 10); |
| } |
| |
| /* Create a new (non-shared) BigInteger, and initialize from a byte array. */ |
| public BigInteger(byte[] val) |
| { |
| if (val == null || val.length < 1) |
| throw new NumberFormatException(); |
| |
| words = byteArrayToIntArray(val, val[0] < 0 ? -1 : 0); |
| BigInteger result = make(words, words.length); |
| this.ival = result.ival; |
| this.words = result.words; |
| } |
| |
| public BigInteger(int signum, byte[] magnitude) |
| { |
| if (magnitude == null || signum > 1 || signum < -1) |
| throw new NumberFormatException(); |
| |
| if (signum == 0) |
| { |
| int i; |
| for (i = magnitude.length - 1; i >= 0 && magnitude[i] == 0; --i) |
| ; |
| if (i >= 0) |
| throw new NumberFormatException(); |
| return; |
| } |
| |
| // Magnitude is always positive, so don't ever pass a sign of -1. |
| words = byteArrayToIntArray(magnitude, 0); |
| BigInteger result = make(words, words.length); |
| this.ival = result.ival; |
| this.words = result.words; |
| |
| if (signum < 0) |
| setNegative(); |
| } |
| |
| public BigInteger(int numBits, Random rnd) |
| { |
| if (numBits < 0) |
| throw new IllegalArgumentException(); |
| |
| // Result is always positive so tack on an extra zero word, it will be |
| // canonicalized out later if necessary. |
| int nwords = numBits / 32 + 2; |
| words = new int[nwords]; |
| words[--nwords] = 0; |
| words[--nwords] = rnd.nextInt() >>> (numBits % 32); |
| while (--nwords >= 0) |
| words[nwords] = rnd.nextInt(); |
| |
| BigInteger result = make(words, words.length); |
| this.ival = result.ival; |
| this.words = result.words; |
| } |
| |
| public BigInteger(int bitLength, int certainty, Random rnd) |
| { |
| this(bitLength, rnd); |
| |
| // Keep going until we find a probable prime. |
| while (true) |
| { |
| if (isProbablePrime(certainty)) |
| return; |
| |
| BigInteger next = new BigInteger(bitLength, rnd); |
| this.ival = next.ival; |
| this.words = next.words; |
| } |
| } |
| |
| /** Return a (possibly-shared) BigInteger with a given long value. */ |
| private static BigInteger make(long value) |
| { |
| if (value >= minFixNum && value <= maxFixNum) |
| return smallFixNums[(int)value - minFixNum]; |
| int i = (int) value; |
| if ((long)i == value) |
| return new BigInteger(i); |
| BigInteger result = alloc(2); |
| result.ival = 2; |
| result.words[0] = i; |
| result.words[1] = (int) (value >> 32); |
| return result; |
| } |
| |
| // FIXME: Could simply rename 'make' method above as valueOf while |
| // changing all instances of 'make'. Don't do this until this class |
| // is done as the Kawa class this is based on has 'make' methods |
| // with other parameters; wait to see if they are used in BigInteger. |
| public static BigInteger valueOf(long val) |
| { |
| return make(val); |
| } |
| |
| /** Make a canonicalized BigInteger from an array of words. |
| * The array may be reused (without copying). */ |
| private static BigInteger make(int[] words, int len) |
| { |
| if (words == null) |
| return make(len); |
| len = BigInteger.wordsNeeded(words, len); |
| if (len <= 1) |
| return len == 0 ? ZERO : make(words[0]); |
| BigInteger num = new BigInteger(); |
| num.words = words; |
| num.ival = len; |
| return num; |
| } |
| |
| /** Convert a big-endian byte array to a little-endian array of words. */ |
| private static int[] byteArrayToIntArray(byte[] bytes, int sign) |
| { |
| // Determine number of words needed. |
| int[] words = new int[(bytes.length + 3) / 4 + 1]; |
| int nwords = words.length; |
| |
| // For simplicity, tack on an extra word of sign at the front, |
| // it will be canonicalized out later. */ |
| words[--nwords] = sign; |
| |
| // Create a int out of modulo 4 high order bytes. |
| int bptr = 0; |
| int word = sign; |
| for (int i = bytes.length % 4; i > 0; --i, bptr++) |
| word = (word << 8) | (((int) bytes[bptr]) & 0xff); |
| words[--nwords] = word; |
| |
| // Elements remaining in byte[] are a multiple of 4. |
| while (nwords > 0) |
| words[--nwords] = bytes[bptr++] << 24 | |
| (((int) bytes[bptr++]) & 0xff) << 16 | |
| (((int) bytes[bptr++]) & 0xff) << 8 | |
| (((int) bytes[bptr++]) & 0xff); |
| return words; |
| } |
| |
| /** Allocate a new non-shared BigInteger. |
| * @param nwords number of words to allocate |
| */ |
| private static BigInteger alloc(int nwords) |
| { |
| if (nwords <= 1) |
| return new BigInteger(); |
| BigInteger result = new BigInteger(); |
| result.words = new int[nwords]; |
| return result; |
| } |
| |
| /** Change words.length to nwords. |
| * We allow words.length to be upto nwords+2 without reallocating. |
| */ |
| private void realloc(int nwords) |
| { |
| if (nwords == 0) |
| { |
| if (words != null) |
| { |
| if (ival > 0) |
| ival = words[0]; |
| words = null; |
| } |
| } |
| else if (words == null |
| || words.length < nwords |
| || words.length > nwords + 2) |
| { |
| int[] new_words = new int [nwords]; |
| if (words == null) |
| { |
| new_words[0] = ival; |
| ival = 1; |
| } |
| else |
| { |
| if (nwords < ival) |
| ival = nwords; |
| System.arraycopy(words, 0, new_words, 0, ival); |
| } |
| words = new_words; |
| } |
| } |
| |
| private final boolean isNegative() |
| { |
| return (words == null ? ival : words[ival - 1]) < 0; |
| } |
| |
| public int signum() |
| { |
| int top = words == null ? ival : words[ival-1]; |
| if (top == 0 && words == null) |
| return 0; |
| return top < 0 ? -1 : 1; |
| } |
| |
| private static int compareTo(BigInteger x, BigInteger y) |
| { |
| if (x.words == null && y.words == null) |
| return x.ival < y.ival ? -1 : x.ival > y.ival ? 1 : 0; |
| boolean x_negative = x.isNegative(); |
| boolean y_negative = y.isNegative(); |
| if (x_negative != y_negative) |
| return x_negative ? -1 : 1; |
| int x_len = x.words == null ? 1 : x.ival; |
| int y_len = y.words == null ? 1 : y.ival; |
| if (x_len != y_len) |
| return (x_len > y_len) != x_negative ? 1 : -1; |
| return MPN.cmp(x.words, y.words, x_len); |
| } |
| |
| // JDK1.2 |
| public int compareTo(Object obj) |
| { |
| if (obj instanceof BigInteger) |
| return compareTo(this, (BigInteger) obj); |
| throw new ClassCastException(); |
| } |
| |
| public int compareTo(BigInteger val) |
| { |
| return compareTo(this, val); |
| } |
| |
| public BigInteger min(BigInteger val) |
| { |
| return compareTo(this, val) < 0 ? this : val; |
| } |
| |
| public BigInteger max(BigInteger val) |
| { |
| return compareTo(this, val) > 0 ? this : val; |
| } |
| |
| private final boolean isOdd() |
| { |
| int low = words == null ? ival : words[0]; |
| return (low & 1) != 0; |
| } |
| |
| private final boolean isZero() |
| { |
| return words == null && ival == 0; |
| } |
| |
| private final boolean isOne() |
| { |
| return words == null && ival == 1; |
| } |
| |
| private final boolean isMinusOne() |
| { |
| return words == null && ival == -1; |
| } |
| |
| /** Calculate how many words are significant in words[0:len-1]. |
| * Returns the least value x such that x>0 && words[0:x-1]==words[0:len-1], |
| * when words is viewed as a 2's complement integer. |
| */ |
| private static int wordsNeeded(int[] words, int len) |
| { |
| int i = len; |
| if (i > 0) |
| { |
| int word = words[--i]; |
| if (word == -1) |
| { |
| while (i > 0 && (word = words[i - 1]) < 0) |
| { |
| i--; |
| if (word != -1) break; |
| } |
| } |
| else |
| { |
| while (word == 0 && i > 0 && (word = words[i - 1]) >= 0) i--; |
| } |
| } |
| return i + 1; |
| } |
| |
| private BigInteger canonicalize() |
| { |
| if (words != null |
| && (ival = BigInteger.wordsNeeded(words, ival)) <= 1) |
| { |
| if (ival == 1) |
| ival = words[0]; |
| words = null; |
| } |
| if (words == null && ival >= minFixNum && ival <= maxFixNum) |
| return smallFixNums[(int) ival - minFixNum]; |
| return this; |
| } |
| |
| /** Add two ints, yielding a BigInteger. */ |
| private static final BigInteger add(int x, int y) |
| { |
| return BigInteger.make((long) x + (long) y); |
| } |
| |
| /** Add a BigInteger and an int, yielding a new BigInteger. */ |
| private static BigInteger add(BigInteger x, int y) |
| { |
| if (x.words == null) |
| return BigInteger.add(x.ival, y); |
| BigInteger result = new BigInteger(0); |
| result.setAdd(x, y); |
| return result.canonicalize(); |
| } |
| |
| /** Set this to the sum of x and y. |
| * OK if x==this. */ |
| private void setAdd(BigInteger x, int y) |
| { |
| if (x.words == null) |
| { |
| set((long) x.ival + (long) y); |
| return; |
| } |
| int len = x.ival; |
| realloc(len + 1); |
| long carry = y; |
| for (int i = 0; i < len; i++) |
| { |
| carry += ((long) x.words[i] & 0xffffffffL); |
| words[i] = (int) carry; |
| carry >>= 32; |
| } |
| if (x.words[len - 1] < 0) |
| carry--; |
| words[len] = (int) carry; |
| ival = wordsNeeded(words, len + 1); |
| } |
| |
| /** Destructively add an int to this. */ |
| private final void setAdd(int y) |
| { |
| setAdd(this, y); |
| } |
| |
| /** Destructively set the value of this to a long. */ |
| private final void set(long y) |
| { |
| int i = (int) y; |
| if ((long) i == y) |
| { |
| ival = i; |
| words = null; |
| } |
| else |
| { |
| realloc(2); |
| words[0] = i; |
| words[1] = (int) (y >> 32); |
| ival = 2; |
| } |
| } |
| |
| /** Destructively set the value of this to the given words. |
| * The words array is reused, not copied. */ |
| private final void set(int[] words, int length) |
| { |
| this.ival = length; |
| this.words = words; |
| } |
| |
| /** Destructively set the value of this to that of y. */ |
| private final void set(BigInteger y) |
| { |
| if (y.words == null) |
| set(y.ival); |
| else if (this != y) |
| { |
| realloc(y.ival); |
| System.arraycopy(y.words, 0, words, 0, y.ival); |
| ival = y.ival; |
| } |
| } |
| |
| /** Add two BigIntegers, yielding their sum as another BigInteger. */ |
| private static BigInteger add(BigInteger x, BigInteger y, int k) |
| { |
| if (x.words == null && y.words == null) |
| return BigInteger.make((long) k * (long) y.ival + (long) x.ival); |
| if (k != 1) |
| { |
| if (k == -1) |
| y = BigInteger.neg(y); |
| else |
| y = BigInteger.times(y, BigInteger.make(k)); |
| } |
| if (x.words == null) |
| return BigInteger.add(y, x.ival); |
| if (y.words == null) |
| return BigInteger.add(x, y.ival); |
| // Both are big |
| int len; |
| if (y.ival > x.ival) |
| { // Swap so x is longer then y. |
| BigInteger tmp = x; x = y; y = tmp; |
| } |
| BigInteger result = alloc(x.ival + 1); |
| int i = y.ival; |
| long carry = MPN.add_n(result.words, x.words, y.words, i); |
| long y_ext = y.words[i - 1] < 0 ? 0xffffffffL : 0; |
| for (; i < x.ival; i++) |
| { |
| carry += ((long) x.words[i] & 0xffffffffL) + y_ext;; |
| result.words[i] = (int) carry; |
| carry >>>= 32; |
| } |
| if (x.words[i - 1] < 0) |
| y_ext--; |
| result.words[i] = (int) (carry + y_ext); |
| result.ival = i+1; |
| return result.canonicalize(); |
| } |
| |
| public BigInteger add(BigInteger val) |
| { |
| return add(this, val, 1); |
| } |
| |
| public BigInteger subtract(BigInteger val) |
| { |
| return add(this, val, -1); |
| } |
| |
| private static final BigInteger times(BigInteger x, int y) |
| { |
| if (y == 0) |
| return ZERO; |
| if (y == 1) |
| return x; |
| int[] xwords = x.words; |
| int xlen = x.ival; |
| if (xwords == null) |
| return BigInteger.make((long) xlen * (long) y); |
| boolean negative; |
| BigInteger result = BigInteger.alloc(xlen + 1); |
| if (xwords[xlen - 1] < 0) |
| { |
| negative = true; |
| negate(result.words, xwords, xlen); |
| xwords = result.words; |
| } |
| else |
| negative = false; |
| if (y < 0) |
| { |
| negative = !negative; |
| y = -y; |
| } |
| result.words[xlen] = MPN.mul_1(result.words, xwords, xlen, y); |
| result.ival = xlen + 1; |
| if (negative) |
| result.setNegative(); |
| return result.canonicalize(); |
| } |
| |
| private static final BigInteger times(BigInteger x, BigInteger y) |
| { |
| if (y.words == null) |
| return times(x, y.ival); |
| if (x.words == null) |
| return times(y, x.ival); |
| boolean negative = false; |
| int[] xwords; |
| int[] ywords; |
| int xlen = x.ival; |
| int ylen = y.ival; |
| if (x.isNegative()) |
| { |
| negative = true; |
| xwords = new int[xlen]; |
| negate(xwords, x.words, xlen); |
| } |
| else |
| { |
| negative = false; |
| xwords = x.words; |
| } |
| if (y.isNegative()) |
| { |
| negative = !negative; |
| ywords = new int[ylen]; |
| negate(ywords, y.words, ylen); |
| } |
| else |
| ywords = y.words; |
| // Swap if x is shorter then y. |
| if (xlen < ylen) |
| { |
| int[] twords = xwords; xwords = ywords; ywords = twords; |
| int tlen = xlen; xlen = ylen; ylen = tlen; |
| } |
| BigInteger result = BigInteger.alloc(xlen+ylen); |
| MPN.mul(result.words, xwords, xlen, ywords, ylen); |
| result.ival = xlen+ylen; |
| if (negative) |
| result.setNegative(); |
| return result.canonicalize(); |
| } |
| |
| public BigInteger multiply(BigInteger y) |
| { |
| return times(this, y); |
| } |
| |
| private static void divide(long x, long y, |
| BigInteger quotient, BigInteger remainder, |
| int rounding_mode) |
| { |
| boolean xNegative, yNegative; |
| if (x < 0) |
| { |
| xNegative = true; |
| if (x == Long.MIN_VALUE) |
| { |
| divide(BigInteger.make(x), BigInteger.make(y), |
| quotient, remainder, rounding_mode); |
| return; |
| } |
| x = -x; |
| } |
| else |
| xNegative = false; |
| |
| if (y < 0) |
| { |
| yNegative = true; |
| if (y == Long.MIN_VALUE) |
| { |
| if (rounding_mode == TRUNCATE) |
| { // x != Long.Min_VALUE implies abs(x) < abs(y) |
| if (quotient != null) |
| quotient.set(0); |
| if (remainder != null) |
| remainder.set(x); |
| } |
| else |
| divide(BigInteger.make(x), BigInteger.make(y), |
| quotient, remainder, rounding_mode); |
| return; |
| } |
| y = -y; |
| } |
| else |
| yNegative = false; |
| |
| long q = x / y; |
| long r = x % y; |
| boolean qNegative = xNegative ^ yNegative; |
| |
| boolean add_one = false; |
| if (r != 0) |
| { |
| switch (rounding_mode) |
| { |
| case TRUNCATE: |
| break; |
| case CEILING: |
| case FLOOR: |
| if (qNegative == (rounding_mode == FLOOR)) |
| add_one = true; |
| break; |
| case ROUND: |
| add_one = r > ((y - (q & 1)) >> 1); |
| break; |
| } |
| } |
| if (quotient != null) |
| { |
| if (add_one) |
| q++; |
| if (qNegative) |
| q = -q; |
| quotient.set(q); |
| } |
| if (remainder != null) |
| { |
| // The remainder is by definition: X-Q*Y |
| if (add_one) |
| { |
| // Subtract the remainder from Y. |
| r = y - r; |
| // In this case, abs(Q*Y) > abs(X). |
| // So sign(remainder) = -sign(X). |
| xNegative = ! xNegative; |
| } |
| else |
| { |
| // If !add_one, then: abs(Q*Y) <= abs(X). |
| // So sign(remainder) = sign(X). |
| } |
| if (xNegative) |
| r = -r; |
| remainder.set(r); |
| } |
| } |
| |
| /** Divide two integers, yielding quotient and remainder. |
| * @param x the numerator in the division |
| * @param y the denominator in the division |
| * @param quotient is set to the quotient of the result (iff quotient!=null) |
| * @param remainder is set to the remainder of the result |
| * (iff remainder!=null) |
| * @param rounding_mode one of FLOOR, CEILING, TRUNCATE, or ROUND. |
| */ |
| private static void divide(BigInteger x, BigInteger y, |
| BigInteger quotient, BigInteger remainder, |
| int rounding_mode) |
| { |
| if ((x.words == null || x.ival <= 2) |
| && (y.words == null || y.ival <= 2)) |
| { |
| long x_l = x.longValue(); |
| long y_l = y.longValue(); |
| if (x_l != Long.MIN_VALUE && y_l != Long.MIN_VALUE) |
| { |
| divide(x_l, y_l, quotient, remainder, rounding_mode); |
| return; |
| } |
| } |
| |
| boolean xNegative = x.isNegative(); |
| boolean yNegative = y.isNegative(); |
| boolean qNegative = xNegative ^ yNegative; |
| |
| int ylen = y.words == null ? 1 : y.ival; |
| int[] ywords = new int[ylen]; |
| y.getAbsolute(ywords); |
| while (ylen > 1 && ywords[ylen - 1] == 0) ylen--; |
| |
| int xlen = x.words == null ? 1 : x.ival; |
| int[] xwords = new int[xlen+2]; |
| x.getAbsolute(xwords); |
| while (xlen > 1 && xwords[xlen-1] == 0) xlen--; |
| |
| int qlen, rlen; |
| |
| int cmpval = MPN.cmp(xwords, xlen, ywords, ylen); |
| if (cmpval < 0) // abs(x) < abs(y) |
| { // quotient = 0; remainder = num. |
| int[] rwords = xwords; xwords = ywords; ywords = rwords; |
| rlen = xlen; qlen = 1; xwords[0] = 0; |
| } |
| else if (cmpval == 0) // abs(x) == abs(y) |
| { |
| xwords[0] = 1; qlen = 1; // quotient = 1 |
| ywords[0] = 0; rlen = 1; // remainder = 0; |
| } |
| else if (ylen == 1) |
| { |
| qlen = xlen; |
| // Need to leave room for a word of leading zeros if dividing by 1 |
| // and the dividend has the high bit set. It might be safe to |
| // increment qlen in all cases, but it certainly is only necessary |
| // in the following case. |
| if (ywords[0] == 1 && xwords[xlen-1] < 0) |
| qlen++; |
| rlen = 1; |
| ywords[0] = MPN.divmod_1(xwords, xwords, xlen, ywords[0]); |
| } |
| else // abs(x) > abs(y) |
| { |
| // Normalize the denominator, i.e. make its most significant bit set by |
| // shifting it normalization_steps bits to the left. Also shift the |
| // numerator the same number of steps (to keep the quotient the same!). |
| |
| int nshift = MPN.count_leading_zeros(ywords[ylen - 1]); |
| if (nshift != 0) |
| { |
| // Shift up the denominator setting the most significant bit of |
| // the most significant word. |
| MPN.lshift(ywords, 0, ywords, ylen, nshift); |
| |
| // Shift up the numerator, possibly introducing a new most |
| // significant word. |
| int x_high = MPN.lshift(xwords, 0, xwords, xlen, nshift); |
| xwords[xlen++] = x_high; |
| } |
| |
| if (xlen == ylen) |
| xwords[xlen++] = 0; |
| MPN.divide(xwords, xlen, ywords, ylen); |
| rlen = ylen; |
| MPN.rshift0 (ywords, xwords, 0, rlen, nshift); |
| |
| qlen = xlen + 1 - ylen; |
| if (quotient != null) |
| { |
| for (int i = 0; i < qlen; i++) |
| xwords[i] = xwords[i+ylen]; |
| } |
| } |
| |
| if (ywords[rlen-1] < 0) |
| { |
| ywords[rlen] = 0; |
| rlen++; |
| } |
| |
| // Now the quotient is in xwords, and the remainder is in ywords. |
| |
| boolean add_one = false; |
| if (rlen > 1 || ywords[0] != 0) |
| { // Non-zero remainder i.e. in-exact quotient. |
| switch (rounding_mode) |
| { |
| case TRUNCATE: |
| break; |
| case CEILING: |
| case FLOOR: |
| if (qNegative == (rounding_mode == FLOOR)) |
| add_one = true; |
| break; |
| case ROUND: |
| // int cmp = compareTo(remainder<<1, abs(y)); |
| BigInteger tmp = remainder == null ? new BigInteger() : remainder; |
| tmp.set(ywords, rlen); |
| tmp = shift(tmp, 1); |
| if (yNegative) |
| tmp.setNegative(); |
| int cmp = compareTo(tmp, y); |
| // Now cmp == compareTo(sign(y)*(remainder<<1), y) |
| if (yNegative) |
| cmp = -cmp; |
| add_one = (cmp == 1) || (cmp == 0 && (xwords[0]&1) != 0); |
| } |
| } |
| if (quotient != null) |
| { |
| quotient.set(xwords, qlen); |
| if (qNegative) |
| { |
| if (add_one) // -(quotient + 1) == ~(quotient) |
| quotient.setInvert(); |
| else |
| quotient.setNegative(); |
| } |
| else if (add_one) |
| quotient.setAdd(1); |
| } |
| if (remainder != null) |
| { |
| // The remainder is by definition: X-Q*Y |
| remainder.set(ywords, rlen); |
| if (add_one) |
| { |
| // Subtract the remainder from Y: |
| // abs(R) = abs(Y) - abs(orig_rem) = -(abs(orig_rem) - abs(Y)). |
| BigInteger tmp; |
| if (y.words == null) |
| { |
| tmp = remainder; |
| tmp.set(yNegative ? ywords[0] + y.ival : ywords[0] - y.ival); |
| } |
| else |
| tmp = BigInteger.add(remainder, y, yNegative ? 1 : -1); |
| // Now tmp <= 0. |
| // In this case, abs(Q) = 1 + floor(abs(X)/abs(Y)). |
| // Hence, abs(Q*Y) > abs(X). |
| // So sign(remainder) = -sign(X). |
| if (xNegative) |
| remainder.setNegative(tmp); |
| else |
| remainder.set(tmp); |
| } |
| else |
| { |
| // If !add_one, then: abs(Q*Y) <= abs(X). |
| // So sign(remainder) = sign(X). |
| if (xNegative) |
| remainder.setNegative(); |
| } |
| } |
| } |
| |
| public BigInteger divide(BigInteger val) |
| { |
| if (val.isZero()) |
| throw new ArithmeticException("divisor is zero"); |
| |
| BigInteger quot = new BigInteger(); |
| divide(this, val, quot, null, TRUNCATE); |
| return quot.canonicalize(); |
| } |
| |
| public BigInteger remainder(BigInteger val) |
| { |
| if (val.isZero()) |
| throw new ArithmeticException("divisor is zero"); |
| |
| BigInteger rem = new BigInteger(); |
| divide(this, val, null, rem, TRUNCATE); |
| return rem.canonicalize(); |
| } |
| |
| public BigInteger[] divideAndRemainder(BigInteger val) |
| { |
| if (val.isZero()) |
| throw new ArithmeticException("divisor is zero"); |
| |
| BigInteger[] result = new BigInteger[2]; |
| result[0] = new BigInteger(); |
| result[1] = new BigInteger(); |
| divide(this, val, result[0], result[1], TRUNCATE); |
| result[0].canonicalize(); |
| result[1].canonicalize(); |
| return result; |
| } |
| |
| public BigInteger mod(BigInteger m) |
| { |
| if (m.isNegative() || m.isZero()) |
| throw new ArithmeticException("non-positive modulus"); |
| |
| BigInteger rem = new BigInteger(); |
| divide(this, m, null, rem, FLOOR); |
| return rem.canonicalize(); |
| } |
| |
| /** Calculate power for BigInteger exponents. |
| * @param y exponent assumed to be non-negative. */ |
| private BigInteger pow(BigInteger y) |
| { |
| if (isOne()) |
| return this; |
| if (isMinusOne()) |
| return y.isOdd () ? this : ONE; |
| if (y.words == null && y.ival >= 0) |
| return pow(y.ival); |
| |
| // Assume exponent is non-negative. |
| if (isZero()) |
| return this; |
| |
| // Implemented by repeated squaring and multiplication. |
| BigInteger pow2 = this; |
| BigInteger r = null; |
| for (;;) // for (i = 0; ; i++) |
| { |
| // pow2 == x**(2**i) |
| // prod = x**(sum(j=0..i-1, (y>>j)&1)) |
| if (y.isOdd()) |
| r = r == null ? pow2 : times(r, pow2); // r *= pow2 |
| y = BigInteger.shift(y, -1); |
| if (y.isZero()) |
| break; |
| // pow2 *= pow2; |
| pow2 = times(pow2, pow2); |
| } |
| return r == null ? ONE : r; |
| } |
| |
| /** Calculate the integral power of a BigInteger. |
| * @param exponent the exponent (must be non-negative) |
| */ |
| public BigInteger pow(int exponent) |
| { |
| if (exponent <= 0) |
| { |
| if (exponent == 0) |
| return ONE; |
| else |
| throw new ArithmeticException("negative exponent"); |
| } |
| if (isZero()) |
| return this; |
| int plen = words == null ? 1 : ival; // Length of pow2. |
| int blen = ((bitLength() * exponent) >> 5) + 2 * plen; |
| boolean negative = isNegative() && (exponent & 1) != 0; |
| int[] pow2 = new int [blen]; |
| int[] rwords = new int [blen]; |
| int[] work = new int [blen]; |
| getAbsolute(pow2); // pow2 = abs(this); |
| int rlen = 1; |
| rwords[0] = 1; // rwords = 1; |
| for (;;) // for (i = 0; ; i++) |
| { |
| // pow2 == this**(2**i) |
| // prod = this**(sum(j=0..i-1, (exponent>>j)&1)) |
| if ((exponent & 1) != 0) |
| { // r *= pow2 |
| MPN.mul(work, pow2, plen, rwords, rlen); |
| int[] temp = work; work = rwords; rwords = temp; |
| rlen += plen; |
| while (rwords[rlen - 1] == 0) rlen--; |
| } |
| exponent >>= 1; |
| if (exponent == 0) |
| break; |
| // pow2 *= pow2; |
| MPN.mul(work, pow2, plen, pow2, plen); |
| int[] temp = work; work = pow2; pow2 = temp; // swap to avoid a copy |
| plen *= 2; |
| while (pow2[plen - 1] == 0) plen--; |
| } |
| if (rwords[rlen - 1] < 0) |
| rlen++; |
| if (negative) |
| negate(rwords, rwords, rlen); |
| return BigInteger.make(rwords, rlen); |
| } |
| |
| private static final int[] euclidInv(int a, int b, int prevDiv) |
| { |
| // Storage for return values, plus one slot for a temp int (see below). |
| int[] xy; |
| |
| if (b == 0) |
| throw new ArithmeticException("not invertible"); |
| else if (b == 1) |
| { |
| // Success: values are indeed invertible! |
| // Bottom of the recursion reached; start unwinding. |
| xy = new int[3]; |
| xy[0] = -prevDiv; |
| xy[1] = 1; |
| return xy; |
| } |
| |
| xy = euclidInv(b, a % b, a / b); // Recursion happens here. |
| |
| // xy[2] is just temp storage for intermediate results in the following |
| // calculation. This saves us a bit of space over having an int |
| // allocated at every level of this recursive method. |
| xy[2] = xy[0]; |
| xy[0] = xy[2] * -prevDiv + xy[1]; |
| xy[1] = xy[2]; |
| return xy; |
| } |
| |
| private static final BigInteger[] |
| euclidInv(BigInteger a, BigInteger b, BigInteger prevDiv) |
| { |
| // FIXME: This method could be more efficient memory-wise and should be |
| // modified as such since it is recursive. |
| |
| // Storage for return values, plus one slot for a temp int (see below). |
| BigInteger[] xy; |
| |
| if (b.isZero()) |
| throw new ArithmeticException("not invertible"); |
| else if (b.isOne()) |
| { |
| // Success: values are indeed invertible! |
| // Bottom of the recursion reached; start unwinding. |
| xy = new BigInteger[3]; |
| xy[0] = neg(prevDiv); |
| xy[1] = ONE; |
| return xy; |
| } |
| |
| // Recursion happens in the following conditional! |
| |
| // If a just contains an int, then use integer math for the rest. |
| if (a.words == null) |
| { |
| int[] xyInt = euclidInv(b.ival, a.ival % b.ival, a.ival / b.ival); |
| xy = new BigInteger[3]; |
| xy[0] = new BigInteger(xyInt[0]); |
| xy[1] = new BigInteger(xyInt[1]); |
| } |
| else |
| { |
| BigInteger rem = new BigInteger(); |
| BigInteger quot = new BigInteger(); |
| divide(a, b, quot, rem, FLOOR); |
| xy = euclidInv(b, rem, quot); |
| } |
| |
| // xy[2] is just temp storage for intermediate results in the following |
| // calculation. This saves us a bit of space over having a BigInteger |
| // allocated at every level of this recursive method. |
| xy[2] = xy[0]; |
| xy[0] = add(xy[1], times(xy[2], prevDiv), -1); |
| xy[1] = xy[2]; |
| return xy; |
| } |
| |
| public BigInteger modInverse(BigInteger y) |
| { |
| if (y.isNegative() || y.isZero()) |
| throw new ArithmeticException("non-positive modulo"); |
| |
| // Degenerate cases. |
| if (y.isOne()) |
| return ZERO; |
| else if (isOne()) |
| return ONE; |
| |
| // Use Euclid's algorithm as in gcd() but do this recursively |
| // rather than in a loop so we can use the intermediate results as we |
| // unwind from the recursion. |
| // Used http://www.math.nmsu.edu/~crypto/EuclideanAlgo.html as reference. |
| BigInteger result = new BigInteger(); |
| int xval = ival; |
| int yval = y.ival; |
| boolean swapped = false; |
| |
| if (y.words == null) |
| { |
| // The result is guaranteed to be less than the modulus, y (which is |
| // an int), so simplify this by working with the int result of this |
| // modulo y. Also, if this is negative, make it positive via modulo |
| // math. Note that BigInteger.mod() must be used even if this is |
| // already an int as the % operator would provide a negative result if |
| // this is negative, BigInteger.mod() never returns negative values. |
| if (words != null || isNegative()) |
| xval = mod(y).ival; |
| |
| // Swap values so x > y. |
| if (yval > xval) |
| { |
| int tmp = xval; xval = yval; yval = tmp; |
| swapped = true; |
| } |
| // Normally, the result is in the 2nd element of the array, but |
| // if originally x < y, then x and y were swapped and the result |
| // is in the 1st element of the array. |
| result.ival = |
| euclidInv(yval, xval % yval, xval / yval)[swapped ? 0 : 1]; |
| |
| // Result can't be negative, so make it positive by adding the |
| // original modulus, y.ival (not the possibly "swapped" yval). |
| if (result.ival < 0) |
| result.ival += y.ival; |
| } |
| else |
| { |
| BigInteger x = this; |
| |
| // As above, force this to be a positive value via modulo math. |
| if (isNegative()) |
| x = mod(y); |
| |
| // Swap values so x > y. |
| if (x.compareTo(y) < 0) |
| { |
| BigInteger tmp = x; x = y; y = tmp; |
| swapped = true; |
| } |
| // As above (for ints), result will be in the 2nd element unless |
| // the original x and y were swapped. |
| BigInteger rem = new BigInteger(); |
| BigInteger quot = new BigInteger(); |
| divide(x, y, quot, rem, FLOOR); |
| result = euclidInv(y, rem, quot)[swapped ? 0 : 1]; |
| |
| // Result can't be negative, so make it positive by adding the |
| // original modulus, y (which is now x if they were swapped). |
| if (result.isNegative()) |
| result = add(result, swapped ? x : y, 1); |
| } |
| |
| return result; |
| } |
| |
| public BigInteger modPow(BigInteger exponent, BigInteger m) |
| { |
| if (m.isNegative() || m.isZero()) |
| throw new ArithmeticException("non-positive modulo"); |
| |
| if (exponent.isNegative()) |
| return modInverse(m); |
| if (exponent.isOne()) |
| return mod(m); |
| |
| // To do this naively by first raising this to the power of exponent |
| // and then performing modulo m would be extremely expensive, especially |
| // for very large numbers. The solution is found in Number Theory |
| // where a combination of partial powers and modulos can be done easily. |
| // |
| // We'll use the algorithm for Additive Chaining which can be found on |
| // p. 244 of "Applied Cryptography, Second Edition" by Bruce Schneier. |
| BigInteger s, t, u; |
| int i; |
| |
| s = ONE; |
| t = this; |
| u = exponent; |
| |
| while (!u.isZero()) |
| { |
| if (u.and(ONE).isOne()) |
| s = times(s, t).mod(m); |
| u = u.shiftRight(1); |
| t = times(t, t).mod(m); |
| } |
| |
| return s; |
| } |
| |
| /** Calculate Greatest Common Divisor for non-negative ints. */ |
| private static final int gcd(int a, int b) |
| { |
| // Euclid's algorithm, copied from libg++. |
| if (b > a) |
| { |
| int tmp = a; a = b; b = tmp; |
| } |
| for(;;) |
| { |
| if (b == 0) |
| return a; |
| else if (b == 1) |
| return b; |
| else |
| { |
| int tmp = b; |
| b = a % b; |
| a = tmp; |
| } |
| } |
| } |
| |
| public BigInteger gcd(BigInteger y) |
| { |
| int xval = ival; |
| int yval = y.ival; |
| if (words == null) |
| { |
| if (xval == 0) |
| return BigInteger.abs(y); |
| if (y.words == null |
| && xval != Integer.MIN_VALUE && yval != Integer.MIN_VALUE) |
| { |
| if (xval < 0) |
| xval = -xval; |
| if (yval < 0) |
| yval = -yval; |
| return BigInteger.make(BigInteger.gcd(xval, yval)); |
| } |
| xval = 1; |
| } |
| if (y.words == null) |
| { |
| if (yval == 0) |
| return BigInteger.abs(this); |
| yval = 1; |
| } |
| int len = (xval > yval ? xval : yval) + 1; |
| int[] xwords = new int[len]; |
| int[] ywords = new int[len]; |
| getAbsolute(xwords); |
| y.getAbsolute(ywords); |
| len = MPN.gcd(xwords, ywords, len); |
| BigInteger result = new BigInteger(0); |
| result.ival = len; |
| result.words = xwords; |
| return result.canonicalize(); |
| } |
| |
| public boolean isProbablePrime(int certainty) |
| { |
| /** We'll use the Rabin-Miller algorithm for doing a probabilistic |
| * primality test. It is fast, easy and has faster decreasing odds of a |
| * composite passing than with other tests. This means that this |
| * method will actually have a probability much greater than the |
| * 1 - .5^certainty specified in the JCL (p. 117), but I don't think |
| * anyone will complain about better performance with greater certainty. |
| * |
| * The Rabin-Miller algorithm can be found on pp. 259-261 of "Applied |
| * Cryptography, Second Edition" by Bruce Schneier. |
| */ |
| |
| // First rule out small prime factors and assure the number is odd. |
| for (int i = 0; i < primes.length; i++) |
| { |
| if (words == null && ival == primes[i]) |
| return true; |
| if (remainder(make(primes[i])).isZero()) |
| return false; |
| } |
| |
| // Now perform the Rabin-Miller test. |
| // NB: I know that this can be simplified programatically, but |
| // I have tried to keep it as close as possible to the algorithm |
| // as written in the Schneier book for reference purposes. |
| |
| // Set b to the number of times 2 evenly divides (this - 1). |
| // I.e. 2^b is the largest power of 2 that divides (this - 1). |
| BigInteger pMinus1 = add(this, -1); |
| int b = pMinus1.getLowestSetBit(); |
| |
| // Set m such that this = 1 + 2^b * m. |
| BigInteger m = pMinus1.divide(make(2L << b - 1)); |
| |
| Random rand = new Random(); |
| while (certainty-- > 0) |
| { |
| // Pick a random number greater than 1 and less than this. |
| // The algorithm says to pick a small number to make the calculations |
| // go faster, but it doesn't say how small; we'll use 2 to 1024. |
| int a = rand.nextInt(); |
| a = (a < 0 ? -a : a) % 1023 + 2; |
| |
| BigInteger z = make(a).modPow(m, this); |
| if (z.isOne() || z.equals(pMinus1)) |
| continue; // Passes the test; may be prime. |
| |
| int i; |
| for (i = 0; i < b; ) |
| { |
| if (z.isOne()) |
| return false; |
| i++; |
| if (z.equals(pMinus1)) |
| break; // Passes the test; may be prime. |
| |
| z = z.modPow(make(2), this); |
| } |
| |
| if (i == b && !z.equals(pMinus1)) |
| return false; |
| } |
| return true; |
| } |
| |
| private void setInvert() |
| { |
| if (words == null) |
| ival = ~ival; |
| else |
| { |
| for (int i = ival; --i >= 0; ) |
| words[i] = ~words[i]; |
| } |
| } |
| |
| private void setShiftLeft(BigInteger x, int count) |
| { |
| int[] xwords; |
| int xlen; |
| if (x.words == null) |
| { |
| if (count < 32) |
| { |
| set((long) x.ival << count); |
| return; |
| } |
| xwords = new int[1]; |
| xwords[0] = x.ival; |
| xlen = 1; |
| } |
| else |
| { |
| xwords = x.words; |
| xlen = x.ival; |
| } |
| int word_count = count >> 5; |
| count &= 31; |
| int new_len = xlen + word_count; |
| if (count == 0) |
| { |
| realloc(new_len); |
| for (int i = xlen; --i >= 0; ) |
| words[i+word_count] = xwords[i]; |
| } |
| else |
| { |
| new_len++; |
| realloc(new_len); |
| int shift_out = MPN.lshift(words, word_count, xwords, xlen, count); |
| count = 32 - count; |
| words[new_len-1] = (shift_out << count) >> count; // sign-extend. |
| } |
| ival = new_len; |
| for (int i = word_count; --i >= 0; ) |
| words[i] = 0; |
| } |
| |
| private void setShiftRight(BigInteger x, int count) |
| { |
| if (x.words == null) |
| set(count < 32 ? x.ival >> count : x.ival < 0 ? -1 : 0); |
| else if (count == 0) |
| set(x); |
| else |
| { |
| boolean neg = x.isNegative(); |
| int word_count = count >> 5; |
| count &= 31; |
| int d_len = x.ival - word_count; |
| if (d_len <= 0) |
| set(neg ? -1 : 0); |
| else |
| { |
| if (words == null || words.length < d_len) |
| realloc(d_len); |
| MPN.rshift0 (words, x.words, word_count, d_len, count); |
| ival = d_len; |
| if (neg) |
| words[d_len-1] |= -1 << (32 - count); |
| } |
| } |
| } |
| |
| private void setShift(BigInteger x, int count) |
| { |
| if (count > 0) |
| setShiftLeft(x, count); |
| else |
| setShiftRight(x, -count); |
| } |
| |
| private static BigInteger shift(BigInteger x, int count) |
| { |
| if (x.words == null) |
| { |
| if (count <= 0) |
| return make(count > -32 ? x.ival >> (-count) : x.ival < 0 ? -1 : 0); |
| if (count < 32) |
| return make((long) x.ival << count); |
| } |
| if (count == 0) |
| return x; |
| BigInteger result = new BigInteger(0); |
| result.setShift(x, count); |
| return result.canonicalize(); |
| } |
| |
| public BigInteger shiftLeft(int n) |
| { |
| return shift(this, n); |
| } |
| |
| public BigInteger shiftRight(int n) |
| { |
| return shift(this, -n); |
| } |
| |
| private void format(int radix, StringBuffer buffer) |
| { |
| if (words == null) |
| buffer.append(Integer.toString(ival, radix)); |
| else if (ival <= 2) |
| buffer.append(Long.toString(longValue(), radix)); |
| else |
| { |
| boolean neg = isNegative(); |
| int[] work; |
| if (neg || radix != 16) |
| { |
| work = new int[ival]; |
| getAbsolute(work); |
| } |
| else |
| work = words; |
| int len = ival; |
| |
| int buf_size = len * (MPN.chars_per_word(radix) + 1); |
| if (radix == 16) |
| { |
| if (neg) |
| buffer.append('-'); |
| int buf_start = buffer.length(); |
| for (int i = len; --i >= 0; ) |
| { |
| int word = work[i]; |
| for (int j = 8; --j >= 0; ) |
| { |
| int hex_digit = (word >> (4 * j)) & 0xF; |
| // Suppress leading zeros: |
| if (hex_digit > 0 || buffer.length() > buf_start) |
| buffer.append(Character.forDigit(hex_digit, 16)); |
| } |
| } |
| } |
| else |
| { |
| int i = buffer.length(); |
| for (;;) |
| { |
| int digit = MPN.divmod_1(work, work, len, radix); |
| buffer.append(Character.forDigit(digit, radix)); |
| while (len > 0 && work[len-1] == 0) len--; |
| if (len == 0) |
| break; |
| } |
| if (neg) |
| buffer.append('-'); |
| /* Reverse buffer. */ |
| int j = buffer.length() - 1; |
| while (i < j) |
| { |
| char tmp = buffer.charAt(i); |
| buffer.setCharAt(i, buffer.charAt(j)); |
| buffer.setCharAt(j, tmp); |
| i++; j--; |
| } |
| } |
| } |
| } |
| |
| public String toString() |
| { |
| return toString(10); |
| } |
| |
| public String toString(int radix) |
| { |
| if (words == null) |
| return Integer.toString(ival, radix); |
| else if (ival <= 2) |
| return Long.toString(longValue(), radix); |
| int buf_size = ival * (MPN.chars_per_word(radix) + 1); |
| StringBuffer buffer = new StringBuffer(buf_size); |
| format(radix, buffer); |
| return buffer.toString(); |
| } |
| |
| public int intValue() |
| { |
| if (words == null) |
| return ival; |
| return words[0]; |
| } |
| |
| public long longValue() |
| { |
| if (words == null) |
| return ival; |
| if (ival == 1) |
| return words[0]; |
| return ((long)words[1] << 32) + ((long)words[0] & 0xffffffffL); |
| } |
| |
| public int hashCode() |
| { |
| // FIXME: May not match hashcode of JDK. |
| return words == null ? ival : (words[0] + words[ival - 1]); |
| } |
| |
| /* Assumes x and y are both canonicalized. */ |
| private static boolean equals(BigInteger x, BigInteger y) |
| { |
| if (x.words == null && y.words == null) |
| return x.ival == y.ival; |
| if (x.words == null || y.words == null || x.ival != y.ival) |
| return false; |
| for (int i = x.ival; --i >= 0; ) |
| { |
| if (x.words[i] != y.words[i]) |
| return false; |
| } |
| return true; |
| } |
| |
| /* Assumes this and obj are both canonicalized. */ |
| public boolean equals(Object obj) |
| { |
| if (obj == null || ! (obj instanceof BigInteger)) |
| return false; |
| return BigInteger.equals(this, (BigInteger) obj); |
| } |
| |
| private static BigInteger valueOf(String s, int radix) |
| throws NumberFormatException |
| { |
| int len = s.length(); |
| // Testing (len < MPN.chars_per_word(radix)) would be more accurate, |
| // but slightly more expensive, for little practical gain. |
| if (len <= 15 && radix <= 16) |
| return BigInteger.make(Long.parseLong(s, radix)); |
| |
| int byte_len = 0; |
| byte[] bytes = new byte[len]; |
| boolean negative = false; |
| for (int i = 0; i < len; i++) |
| { |
| char ch = s.charAt(i); |
| if (ch == '-') |
| negative = true; |
| else if (ch == '_' || (byte_len == 0 && (ch == ' ' || ch == '\t'))) |
| continue; |
| else |
| { |
| int digit = Character.digit(ch, radix); |
| if (digit < 0) |
| break; |
| bytes[byte_len++] = (byte) digit; |
| } |
| } |
| return valueOf(bytes, byte_len, negative, radix); |
| } |
| |
| private static BigInteger valueOf(byte[] digits, int byte_len, |
| boolean negative, int radix) |
| { |
| int chars_per_word = MPN.chars_per_word(radix); |
| int[] words = new int[byte_len / chars_per_word + 1]; |
| int size = MPN.set_str(words, digits, byte_len, radix); |
| if (size == 0) |
| return ZERO; |
| if (words[size-1] < 0) |
| words[size++] = 0; |
| if (negative) |
| negate(words, words, size); |
| return make(words, size); |
| } |
| |
| public double doubleValue() |
| { |
| if (words == null) |
| return (double) ival; |
| if (ival <= 2) |
| return (double) longValue(); |
| if (isNegative()) |
| return BigInteger.neg(this).roundToDouble(0, true, false); |
| else |
| return roundToDouble(0, false, false); |
| } |
| |
| public float floatValue() |
| { |
| return (float) doubleValue(); |
| } |
| |
| /** Return true if any of the lowest n bits are one. |
| * (false if n is negative). */ |
| private boolean checkBits(int n) |
| { |
| if (n <= 0) |
| return false; |
| if (words == null) |
| return n > 31 || ((ival & ((1 << n) - 1)) != 0); |
| int i; |
| for (i = 0; i < (n >> 5) ; i++) |
| if (words[i] != 0) |
| return true; |
| return (n & 31) != 0 && (words[i] & ((1 << (n & 31)) - 1)) != 0; |
| } |
| |
| /** Convert a semi-processed BigInteger to double. |
| * Number must be non-negative. Multiplies by a power of two, applies sign, |
| * and converts to double, with the usual java rounding. |
| * @param exp power of two, positive or negative, by which to multiply |
| * @param neg true if negative |
| * @param remainder true if the BigInteger is the result of a truncating |
| * division that had non-zero remainder. To ensure proper rounding in |
| * this case, the BigInteger must have at least 54 bits. */ |
| private double roundToDouble(int exp, boolean neg, boolean remainder) |
| { |
| // Compute length. |
| int il = bitLength(); |
| |
| // Exponent when normalized to have decimal point directly after |
| // leading one. This is stored excess 1023 in the exponent bit field. |
| exp += il - 1; |
| |
| // Gross underflow. If exp == -1075, we let the rounding |
| // computation determine whether it is minval or 0 (which are just |
| // 0x0000 0000 0000 0001 and 0x0000 0000 0000 0000 as bit |
| // patterns). |
| if (exp < -1075) |
| return neg ? -0.0 : 0.0; |
| |
| // gross overflow |
| if (exp > 1023) |
| return neg ? Double.NEGATIVE_INFINITY : Double.POSITIVE_INFINITY; |
| |
| // number of bits in mantissa, including the leading one. |
| // 53 unless it's denormalized |
| int ml = (exp >= -1022 ? 53 : 53 + exp + 1022); |
| |
| // Get top ml + 1 bits. The extra one is for rounding. |
| long m; |
| int excess_bits = il - (ml + 1); |
| if (excess_bits > 0) |
| m = ((words == null) ? ival >> excess_bits |
| : MPN.rshift_long(words, ival, excess_bits)); |
| else |
| m = longValue() << (- excess_bits); |
| |
| // Special rounding for maxval. If the number exceeds maxval by |
| // any amount, even if it's less than half a step, it overflows. |
| if (exp == 1023 && ((m >> 1) == (1L << 53) - 1)) |
| { |
| if (remainder || checkBits(il - ml)) |
| return neg ? Double.NEGATIVE_INFINITY : Double.POSITIVE_INFINITY; |
| else |
| return neg ? - Double.MAX_VALUE : Double.MAX_VALUE; |
| } |
| |
| // Normal round-to-even rule: round up if the bit dropped is a one, and |
| // the bit above it or any of the bits below it is a one. |
| if ((m & 1) == 1 |
| && ((m & 2) == 2 || remainder || checkBits(excess_bits))) |
| { |
| m += 2; |
| // Check if we overflowed the mantissa |
| if ((m & (1L << 54)) != 0) |
| { |
| exp++; |
| // renormalize |
| m >>= 1; |
| } |
| // Check if a denormalized mantissa was just rounded up to a |
| // normalized one. |
| else if (ml == 52 && (m & (1L << 53)) != 0) |
| exp++; |
| } |
| |
| // Discard the rounding bit |
| m >>= 1; |
| |
| long bits_sign = neg ? (1L << 63) : 0; |
| exp += 1023; |
| long bits_exp = (exp <= 0) ? 0 : ((long)exp) << 52; |
| long bits_mant = m & ~(1L << 52); |
| return Double.longBitsToDouble(bits_sign | bits_exp | bits_mant); |
| } |
| |
| /** Copy the abolute value of this into an array of words. |
| * Assumes words.length >= (this.words == null ? 1 : this.ival). |
| * Result is zero-extended, but need not be a valid 2's complement number. |
| */ |
| |
| private void getAbsolute(int[] words) |
| { |
| int len; |
| if (this.words == null) |
| { |
| len = 1; |
| words[0] = this.ival; |
| } |
| else |
| { |
| len = this.ival; |
| for (int i = len; --i >= 0; ) |
| words[i] = this.words[i]; |
| } |
| if (words[len - 1] < 0) |
| negate(words, words, len); |
| for (int i = words.length; --i > len; ) |
| words[i] = 0; |
| } |
| |
| /** Set dest[0:len-1] to the negation of src[0:len-1]. |
| * Return true if overflow (i.e. if src is -2**(32*len-1)). |
| * Ok for src==dest. */ |
| private static boolean negate(int[] dest, int[] src, int len) |
| { |
| long carry = 1; |
| boolean negative = src[len-1] < 0; |
| for (int i = 0; i < len; i++) |
| { |
| carry += ((long) (~src[i]) & 0xffffffffL); |
| dest[i] = (int) carry; |
| carry >>= 32; |
| } |
| return (negative && dest[len-1] < 0); |
| } |
| |
| /** Destructively set this to the negative of x. |
| * It is OK if x==this.*/ |
| private void setNegative(BigInteger x) |
| { |
| int len = x.ival; |
| if (x.words == null) |
| { |
| if (len == Integer.MIN_VALUE) |
| set(- (long) len); |
| else |
| set(-len); |
| return; |
| } |
| realloc(len + 1); |
| if (BigInteger.negate(words, x.words, len)) |
| words[len++] = 0; |
| ival = len; |
| } |
| |
| /** Destructively negate this. */ |
| private final void setNegative() |
| { |
| setNegative(this); |
| } |
| |
| private static BigInteger abs(BigInteger x) |
| { |
| return x.isNegative() ? neg(x) : x; |
| } |
| |
| public BigInteger abs() |
| { |
| return abs(this); |
| } |
| |
| private static BigInteger neg(BigInteger x) |
| { |
| if (x.words == null && x.ival != Integer.MIN_VALUE) |
| return make(- x.ival); |
| BigInteger result = new BigInteger(0); |
| result.setNegative(x); |
| return result.canonicalize(); |
| } |
| |
| public BigInteger negate() |
| { |
| return BigInteger.neg(this); |
| } |
| |
| /** Calculates ceiling(log2(this < 0 ? -this : this+1)) |
| * See Common Lisp: the Language, 2nd ed, p. 361. |
| */ |
| public int bitLength() |
| { |
| if (words == null) |
| return MPN.intLength(ival); |
| else |
| return MPN.intLength(words, ival); |
| } |
| |
| public byte[] toByteArray() |
| { |
| // Determine number of bytes needed. The method bitlength returns |
| // the size without the sign bit, so add one bit for that and then |
| // add 7 more to emulate the ceil function using integer math. |
| byte[] bytes = new byte[(bitLength() + 1 + 7) / 8]; |
| int nbytes = bytes.length; |
| |
| int wptr = 0; |
| int word; |
| |
| // Deal with words array until one word or less is left to process. |
| // If BigInteger is an int, then it is in ival and nbytes will be <= 4. |
| while (nbytes > 4) |
| { |
| word = words[wptr++]; |
| for (int i = 4; i > 0; --i, word >>= 8) |
| bytes[--nbytes] = (byte) word; |
| } |
| |
| // Deal with the last few bytes. If BigInteger is an int, use ival. |
| word = (words == null) ? ival : words[wptr]; |
| for ( ; nbytes > 0; word >>= 8) |
| bytes[--nbytes] = (byte) word; |
| |
| return bytes; |
| } |
| |
| /** Return the boolean opcode (for bitOp) for swapped operands. |
| * I.e. bitOp(swappedOp(op), x, y) == bitOp(op, y, x). |
| */ |
| private static int swappedOp(int op) |
| { |
| return |
| "\000\001\004\005\002\003\006\007\010\011\014\015\012\013\016\017" |
| .charAt(op); |
| } |
| |
| /** Do one the the 16 possible bit-wise operations of two BigIntegers. */ |
| private static BigInteger bitOp(int op, BigInteger x, BigInteger y) |
| { |
| switch (op) |
| { |
| case 0: return ZERO; |
| case 1: return x.and(y); |
| case 3: return x; |
| case 5: return y; |
| case 15: return make(-1); |
| } |
| BigInteger result = new BigInteger(); |
| setBitOp(result, op, x, y); |
| return result.canonicalize(); |
| } |
| |
| /** Do one the the 16 possible bit-wise operations of two BigIntegers. */ |
| private static void setBitOp(BigInteger result, int op, |
| BigInteger x, BigInteger y) |
| { |
| if (y.words == null) ; |
| else if (x.words == null || x.ival < y.ival) |
| { |
| BigInteger temp = x; x = y; y = temp; |
| op = swappedOp(op); |
| } |
| int xi; |
| int yi; |
| int xlen, ylen; |
| if (y.words == null) |
| { |
| yi = y.ival; |
| ylen = 1; |
| } |
| else |
| { |
| yi = y.words[0]; |
| ylen = y.ival; |
| } |
| if (x.words == null) |
| { |
| xi = x.ival; |
| xlen = 1; |
| } |
| else |
| { |
| xi = x.words[0]; |
| xlen = x.ival; |
| } |
| if (xlen > 1) |
| result.realloc(xlen); |
| int[] w = result.words; |
| int i = 0; |
| // Code for how to handle the remainder of x. |
| // 0: Truncate to length of y. |
| // 1: Copy rest of x. |
| // 2: Invert rest of x. |
| int finish = 0; |
| int ni; |
| switch (op) |
| { |
| case 0: // clr |
| ni = 0; |
| break; |
| case 1: // and |
| for (;;) |
| { |
| ni = xi & yi; |
| if (i+1 >= ylen) break; |
| w[i++] = ni; xi = x.words[i]; yi = y.words[i]; |
| } |
| if (yi < 0) finish = 1; |
| break; |
| case 2: // andc2 |
| for (;;) |
| { |
| ni = xi & ~yi; |
| if (i+1 >= ylen) break; |
| w[i++] = ni; xi = x.words[i]; yi = y.words[i]; |
| } |
| if (yi >= 0) finish = 1; |
| break; |
| case 3: // copy x |
| ni = xi; |
| finish = 1; // Copy rest |
| break; |
| case 4: // andc1 |
| for (;;) |
| { |
| ni = ~xi & yi; |
| if (i+1 >= ylen) break; |
| w[i++] = ni; xi = x.words[i]; yi = y.words[i]; |
| } |
| if (yi < 0) finish = 2; |
| break; |
| case 5: // copy y |
| for (;;) |
| { |
| ni = yi; |
| if (i+1 >= ylen) break; |
| w[i++] = ni; xi = x.words[i]; yi = y.words[i]; |
| } |
| break; |
| case 6: // xor |
| for (;;) |
| { |
| ni = xi ^ yi; |
| if (i+1 >= ylen) break; |
| w[i++] = ni; xi = x.words[i]; yi = y.words[i]; |
| } |
| finish = yi < 0 ? 2 : 1; |
| break; |
| case 7: // ior |
| for (;;) |
| { |
| ni = xi | yi; |
| if (i+1 >= ylen) break; |
| w[i++] = ni; xi = x.words[i]; yi = y.words[i]; |
| } |
| if (yi >= 0) finish = 1; |
| break; |
| case 8: // nor |
| for (;;) |
| { |
| ni = ~(xi | yi); |
| if (i+1 >= ylen) break; |
| w[i++] = ni; xi = x.words[i]; yi = y.words[i]; |
| } |
| if (yi >= 0) finish = 2; |
| break; |
| case 9: // eqv [exclusive nor] |
| for (;;) |
| { |
| ni = ~(xi ^ yi); |
| if (i+1 >= ylen) break; |
| w[i++] = ni; xi = x.words[i]; yi = y.words[i]; |
| } |
| finish = yi >= 0 ? 2 : 1; |
| break; |
| case 10: // c2 |
| for (;;) |
| { |
| ni = ~yi; |
| if (i+1 >= ylen) break; |
| w[i++] = ni; xi = x.words[i]; yi = y.words[i]; |
| } |
| break; |
| case 11: // orc2 |
| for (;;) |
| { |
| ni = xi | ~yi; |
| if (i+1 >= ylen) break; |
| w[i++] = ni; xi = x.words[i]; yi = y.words[i]; |
| } |
| if (yi < 0) finish = 1; |
| break; |
| case 12: // c1 |
| ni = ~xi; |
| finish = 2; |
| break; |
| case 13: // orc1 |
| for (;;) |
| { |
| ni = ~xi | yi; |
| if (i+1 >= ylen) break; |
| w[i++] = ni; xi = x.words[i]; yi = y.words[i]; |
| } |
| if (yi >= 0) finish = 2; |
| break; |
| case 14: // nand |
| for (;;) |
| { |
| ni = ~(xi & yi); |
| if (i+1 >= ylen) break; |
| w[i++] = ni; xi = x.words[i]; yi = y.words[i]; |
| } |
| if (yi < 0) finish = 2; |
| break; |
| default: |
| case 15: // set |
| ni = -1; |
| break; |
| } |
| // Here i==ylen-1; w[0]..w[i-1] have the correct result; |
| // and ni contains the correct result for w[i+1]. |
| if (i+1 == xlen) |
| finish = 0; |
| switch (finish) |
| { |
| case 0: |
| if (i == 0 && w == null) |
| { |
| result.ival = ni; |
| return; |
| } |
| w[i++] = ni; |
| break; |
| case 1: w[i] = ni; while (++i < xlen) w[i] = x.words[i]; break; |
| case 2: w[i] = ni; while (++i < xlen) w[i] = ~x.words[i]; break; |
| } |
| result.ival = i; |
| } |
| |
| /** Return the logical (bit-wise) "and" of a BigInteger and an int. */ |
| private static BigInteger and(BigInteger x, int y) |
| { |
| if (x.words == null) |
| return BigInteger.make(x.ival & y); |
| if (y >= 0) |
| return BigInteger.make(x.words[0] & y); |
| int len = x.ival; |
| int[] words = new int[len]; |
| words[0] = x.words[0] & y; |
| while (--len > 0) |
| words[len] = x.words[len]; |
| return BigInteger.make(words, x.ival); |
| } |
| |
| /** Return the logical (bit-wise) "and" of two BigIntegers. */ |
| public BigInteger and(BigInteger y) |
| { |
| if (y.words == null) |
| return and(this, y.ival); |
| else if (words == null) |
| return and(y, ival); |
| |
| BigInteger x = this; |
| if (ival < y.ival) |
| { |
| BigInteger temp = this; x = y; y = temp; |
| } |
| int i; |
| int len = y.isNegative() ? x.ival : y.ival; |
| int[] words = new int[len]; |
| for (i = 0; i < y.ival; i++) |
| words[i] = x.words[i] & y.words[i]; |
| for ( ; i < len; i++) |
| words[i] = x.words[i]; |
| return BigInteger.make(words, len); |
| } |
| |
| /** Return the logical (bit-wise) "(inclusive) or" of two BigIntegers. */ |
| public BigInteger or(BigInteger y) |
| { |
| return bitOp(7, this, y); |
| } |
| |
| /** Return the logical (bit-wise) "exclusive or" of two BigIntegers. */ |
| public BigInteger xor(BigInteger y) |
| { |
| return bitOp(6, this, y); |
| } |
| |
| /** Return the logical (bit-wise) negation of a BigInteger. */ |
| public BigInteger not() |
| { |
| return bitOp(12, this, ZERO); |
| } |
| |
| public BigInteger andNot(BigInteger val) |
| { |
| return and(val.not()); |
| } |
| |
| public BigInteger clearBit(int n) |
| { |
| if (n < 0) |
| throw new ArithmeticException(); |
| |
| return and(ONE.shiftLeft(n).not()); |
| } |
| |
| public BigInteger setBit(int n) |
| { |
| if (n < 0) |
| throw new ArithmeticException(); |
| |
| return or(ONE.shiftLeft(n)); |
| } |
| |
| public boolean testBit(int n) |
| { |
| if (n < 0) |
| throw new ArithmeticException(); |
| |
| return !and(ONE.shiftLeft(n)).isZero(); |
| } |
| |
| public BigInteger flipBit(int n) |
| { |
| if (n < 0) |
| throw new ArithmeticException(); |
| |
| return xor(ONE.shiftLeft(n)); |
| } |
| |
| public int getLowestSetBit() |
| { |
| if (isZero()) |
| return -1; |
| |
| if (words == null) |
| return MPN.findLowestBit(ival); |
| else |
| return MPN.findLowestBit(words); |
| } |
| |
| // bit4count[I] is number of '1' bits in I. |
| private static final byte[] bit4_count = { 0, 1, 1, 2, 1, 2, 2, 3, |
| 1, 2, 2, 3, 2, 3, 3, 4}; |
| |
| private static int bitCount(int i) |
| { |
| int count = 0; |
| while (i != 0) |
| { |
| count += bit4_count[i & 15]; |
| i >>>= 4; |
| } |
| return count; |
| } |
| |
| private static int bitCount(int[] x, int len) |
| { |
| int count = 0; |
| while (--len >= 0) |
| count += bitCount(x[len]); |
| return count; |
| } |
| |
| /** Count one bits in a BigInteger. |
| * If argument is negative, count zero bits instead. */ |
| public int bitCount() |
| { |
| int i, x_len; |
| int[] x_words = words; |
| if (x_words == null) |
| { |
| x_len = 1; |
| i = bitCount(ival); |
| } |
| else |
| { |
| x_len = ival; |
| i = bitCount(x_words, x_len); |
| } |
| return isNegative() ? x_len * 32 - i : i; |
| } |
| |
| private void readObject(ObjectInputStream s) |
| throws IOException, ClassNotFoundException |
| { |
| s.defaultReadObject(); |
| words = byteArrayToIntArray(magnitude, signum < 0 ? -1 : 0); |
| BigInteger result = make(words, words.length); |
| this.ival = result.ival; |
| this.words = result.words; |
| } |
| |
| private void writeObject(ObjectOutputStream s) |
| throws IOException, ClassNotFoundException |
| { |
| signum = signum(); |
| magnitude = toByteArray(); |
| s.defaultWriteObject(); |
| } |
| } |