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Add Java 9 BigInteger constructors (#9953)
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Emulate the `BigInteger(byte[] bytes, int offset, int length)` and
`BigInteger​(int signum, byte[] magnitude, int offset, int length)`
constructors that were added in java 9.

Fixes #9901
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@vegegoku
vegegoku authored Jun 3, 2024
1 parent f47c121 commit 6cf9146
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Showing 2 changed files with 666 additions and 25 deletions.
102 changes: 77 additions & 25 deletions user/super/com/google/gwt/emul/java/math/BigInteger.java
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Original file line number Diff line number Diff line change
Expand Up @@ -260,16 +260,42 @@ private static void setFromString(BigInteger bi, String val, int radix) {
* @throws NumberFormatException if the length of {@code val} is zero.
*/
public BigInteger(byte[] val) {
this(val, 0, val.length);
}

/**
* Constructs a new {@code BigInteger} from the given two's complement
* representation. The most significant byte is the entry at index 0. The most
* significant bit of this entry determines the sign of the new {@code
* BigInteger} instance. The given array must not be empty.
*
* @param val two's complement representation of the new {@code BigInteger}.
* @param offset the start offset of the binary representation.
* @param length the number of bytes to use.
* @throws NullPointerException if {@code val == null}.
* @throws NumberFormatException if the length of {@code val} is zero.
*/
public BigInteger(byte[] val, int offset, int length) {
if (val.length == 0) {
// math.12=Zero length BigInteger
throw new NumberFormatException("Zero length BigInteger"); //$NON-NLS-1$
}
if (val[0] < 0) {
if (length < 0 || offset < 0 || length > val.length - offset) {
throw new IndexOutOfBoundsException("Range check failed: offset=" + offset + ", length="
+ length + ", val.length=" + val.length);
}
if (length == 0) {
sign = 0;
numberLength = 1;
digits = new int[] {0};
return;
}
if (val[offset] < 0) {
sign = -1;
putBytesNegativeToIntegers(val);
putBytesNegativeToIntegers(val, offset, length);
} else {
sign = 1;
putBytesPositiveToIntegers(val);
putBytesPositiveToIntegers(val, offset, length);
}
cutOffLeadingZeroes();
}
Expand All @@ -289,27 +315,53 @@ public BigInteger(byte[] val) {
* sign is zero and the magnitude contains non-zero entries.
*/
public BigInteger(int signum, byte[] magnitude) {
this(signum, magnitude, 0, magnitude.length);
}

/**
* Constructs a new {@code BigInteger} instance with the given sign and the
* given magnitude. The sign is given as an integer (-1 for negative, 0 for
* zero, 1 for positive). The magnitude is specified as a byte array. The most
* significant byte is the entry at index 0.
*
* @param signum sign of the new {@code BigInteger} (-1 for negative, 0 for
* zero, 1 for positive).
* @param magnitude magnitude of the new {@code BigInteger} with the most
* significant byte first.
* @param offset the start offset of the binary representation.
* @param length the number of bytes to use.
* @throws NullPointerException if {@code magnitude == null}.
* @throws NumberFormatException if the sign is not one of -1, 0, 1 or if the
* sign is zero and the magnitude contains non-zero entries.
*/
public BigInteger(int signum, byte[] magnitude, int offset, int length) {
checkNotNull(magnitude);

if (length < 0 || offset < 0 || length > magnitude.length - offset) {
throw new IndexOutOfBoundsException("Range check failed: offset=" + offset + ", length="
+ length + ", val.length=" + magnitude.length);
}

if ((signum < -1) || (signum > 1)) {
// math.13=Invalid signum value
throw new NumberFormatException("Invalid signum value"); //$NON-NLS-1$
}
if (signum == 0) {
for (byte element : magnitude) {
for (int index = offset; index < offset + length; index++) {
byte element = magnitude[index];
if (element != 0) {
// math.14=signum-magnitude mismatch
throw new NumberFormatException("signum-magnitude mismatch"); //$NON-NLS-1$
}
}
}
if (magnitude.length == 0) {
if (length == 0) {
sign = 0;
numberLength = 1;
digits = new int[] {0};
} else {
sign = signum;
putBytesPositiveToIntegers(magnitude);
putBytesPositiveToIntegers(magnitude, offset, length);
cutOffLeadingZeroes();
}
}
Expand Down Expand Up @@ -1477,8 +1529,8 @@ void unCache() {
/**
* Puts a big-endian byte array into a little-endian applying two complement.
*/
private void putBytesNegativeToIntegers(byte[] byteValues) {
int bytesLen = byteValues.length;
private void putBytesNegativeToIntegers(byte[] byteValues, int offset, int length) {
int bytesLen = length;
int highBytes = bytesLen & 3;
numberLength = (bytesLen >> 2) + ((highBytes == 0) ? 0 : 1);
digits = new int[numberLength];
Expand All @@ -1487,19 +1539,19 @@ private void putBytesNegativeToIntegers(byte[] byteValues) {
digits[numberLength - 1] = -1;
// Put bytes to the int array starting from the end of the byte array
while (bytesLen > highBytes) {
digits[i] = (byteValues[--bytesLen] & 0xFF)
| (byteValues[--bytesLen] & 0xFF) << 8
| (byteValues[--bytesLen] & 0xFF) << 16
| (byteValues[--bytesLen] & 0xFF) << 24;
digits[i] = (byteValues[--bytesLen + offset] & 0xFF)
| (byteValues[--bytesLen + offset] & 0xFF) << 8
| (byteValues[--bytesLen + offset] & 0xFF) << 16
| (byteValues[--bytesLen + offset] & 0xFF) << 24;
if (digits[i] != 0) {
digits[i] = -digits[i];
firstNonzeroDigit = i;
i++;
while (bytesLen > highBytes) {
digits[i] = (byteValues[--bytesLen] & 0xFF)
| (byteValues[--bytesLen] & 0xFF) << 8
| (byteValues[--bytesLen] & 0xFF) << 16
| (byteValues[--bytesLen] & 0xFF) << 24;
digits[i] = (byteValues[--bytesLen + offset] & 0xFF)
| (byteValues[--bytesLen + offset] & 0xFF) << 8
| (byteValues[--bytesLen + offset] & 0xFF) << 16
| (byteValues[--bytesLen + offset] & 0xFF) << 24;
digits[i] = ~digits[i];
i++;
}
Expand All @@ -1510,12 +1562,12 @@ private void putBytesNegativeToIntegers(byte[] byteValues) {
if (highBytes != 0) {
// Put the first bytes in the highest element of the int array
if (firstNonzeroDigit != -2) {
for (int j = 0; j < bytesLen; j++) {
for (int j = offset; j < bytesLen + offset; j++) {
digits[i] = (digits[i] << 8) | (byteValues[j] & 0xFF);
}
digits[i] = ~digits[i];
} else {
for (int j = 0; j < bytesLen; j++) {
for (int j = offset; j < bytesLen + offset; j++) {
digits[i] = (digits[i] << 8) | (byteValues[j] & 0xFF);
}
digits[i] = -digits[i];
Expand All @@ -1526,21 +1578,21 @@ private void putBytesNegativeToIntegers(byte[] byteValues) {
/**
* Puts a big-endian byte array into a little-endian int array.
*/
private void putBytesPositiveToIntegers(byte[] byteValues) {
int bytesLen = byteValues.length;
private void putBytesPositiveToIntegers(byte[] byteValues, int offset, int length) {
int bytesLen = length;
int highBytes = bytesLen & 3;
numberLength = (bytesLen >> 2) + ((highBytes == 0) ? 0 : 1);
digits = new int[numberLength];
int i = 0;
// Put bytes to the int array starting from the end of the byte array
while (bytesLen > highBytes) {
digits[i++] = (byteValues[--bytesLen] & 0xFF)
| (byteValues[--bytesLen] & 0xFF) << 8
| (byteValues[--bytesLen] & 0xFF) << 16
| (byteValues[--bytesLen] & 0xFF) << 24;
digits[i++] = (byteValues[--bytesLen + offset] & 0xFF)
| (byteValues[--bytesLen + offset] & 0xFF) << 8
| (byteValues[--bytesLen + offset] & 0xFF) << 16
| (byteValues[--bytesLen + offset] & 0xFF) << 24;
}
// Put the first bytes in the highest element of the int array
for (int j = 0; j < bytesLen; j++) {
for (int j = offset; j < bytesLen + offset; j++) {
digits[i] = (digits[i] << 8) | (byteValues[j] & 0xFF);
}
}
Expand Down
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