File	Doc	Category	Size	Date	Package
Division.java	API Doc	Android 1.5 API	8510	Wed May 06 22:41:04 BST 2009	java.math

Division

• java.lang.Object

Fields Summary

Constructors Summary

Methods Summary
static java.math.BigInteger[]	divideAndRemainderByInteger(java.math.BigInteger val, int divisor, int divisorSign) Computes the quotient and the remainder after a division by an {@code int} number. return an array of the form {@code [quotient, remainder]}. // BEGIN android-added val.establishOldRepresentation("Division.divideAndRemainderByInteger"); // END android-added // res[0] is a quotient and res[1] is a remainder: int[] valDigits = val.digits; int valLen = val.numberLength; int valSign = val.sign; if (valLen == 1) { long a = (valDigits[0] & 0xffffffffL); long b = (divisor & 0xffffffffL); long quo = a / b; long rem = a % b; if (valSign != divisorSign) { quo = -quo; } if (valSign < 0) { rem = -rem; } return new BigInteger[] { BigInteger.valueOf(quo), BigInteger.valueOf(rem) }; } int quotientLength = valLen; int quotientSign = ((valSign == divisorSign) ? 1 : -1); int quotientDigits[] = new int[quotientLength]; int remainderDigits[]; remainderDigits = new int[] { Division.divideArrayByInt( quotientDigits, valDigits, valLen, divisor) }; BigInteger result0 = new BigInteger(quotientSign, quotientLength, quotientDigits); BigInteger result1 = new BigInteger(valSign, 1, remainderDigits); result0.cutOffLeadingZeroes(); result1.cutOffLeadingZeroes(); return new BigInteger[] { result0, result1 };
static int	divideArrayByInt(int[] dest, int[] src, int srcLength, int divisor) Divides an array by an integer value. Implements the Knuth's division algorithm. See D. Knuth, The Art of Computer Programming, vol. 2. param dest the quotient param src the dividend param srcLength the length of the dividend param divisor the divisor return remainder long rem = 0; long bLong = divisor & 0xffffffffL; for (int i = srcLength - 1; i >= 0; i--) { long temp = (rem << 32) | (src[i] & 0xffffffffL); long quot; if (temp >= 0) { quot = (temp / bLong); rem = (temp % bLong); } else { /* * make the dividend positive shifting it right by 1 bit then * get the quotient an remainder and correct them properly */ long aPos = temp >>> 1; long bPos = divisor >>> 1; quot = aPos / bPos; rem = aPos % bPos; // double the remainder and add 1 if a is odd rem = (rem << 1) + (temp & 1); if ((divisor & 1) != 0) { // the divisor is odd if (quot <= rem) { rem -= quot; } else { if (quot - rem <= bLong) { rem += bLong - quot; quot -= 1; } else { rem += (bLong << 1) - quot; quot -= 2; } } } } dest[i] = (int) (quot & 0xffffffffL); } return (int) rem;
static long	divideLongByInt(long a, int b) Divides an unsigned long a by an unsigned int b. It is supposed that the most significant bit of b is set to 1, i.e. b < 0 param a the dividend param b the divisor return the long value containing the unsigned integer remainder in the left half and the unsigned integer quotient in the right half long quot; long rem; long bLong = b & 0xffffffffL; if (a >= 0) { quot = (a / bLong); rem = (a % bLong); } else { /* * Make the dividend positive shifting it right by 1 bit then get * the quotient an remainder and correct them properly */ long aPos = a >>> 1; long bPos = b >>> 1; quot = aPos / bPos; rem = aPos % bPos; // double the remainder and add 1 if a is odd rem = (rem << 1) + (a & 1); if ((b & 1) != 0) { // the divisor is odd if (quot <= rem) { rem -= quot; } else { if (quot - rem <= bLong) { rem += bLong - quot; quot -= 1; } else { rem += (bLong << 1) - quot; quot -= 2; } } } } return (rem << 32) | (quot & 0xffffffffL);
static int	remainder(java.math.BigInteger dividend, int divisor) Divides a BigInteger by a signed int and returns the remainder. param dividend the BigInteger to be divided. Must be non-negative. param divisor a signed int return divide % divisor // BEGIN android-added dividend.establishOldRepresentation("Division.remainder"); // END android-added return remainderArrayByInt(dividend.digits, dividend.numberLength, divisor);
static int	remainderArrayByInt(int[] src, int srcLength, int divisor) Divides an array by an integer value. Implements the Knuth's division algorithm. See D. Knuth, The Art of Computer Programming, vol. 2. param src the dividend param srcLength the length of the dividend param divisor the divisor return remainder long result = 0; for (int i = srcLength - 1; i >= 0; i--) { long temp = (result << 32) + (src[i] & 0xffffffffL); long res = divideLongByInt(temp, divisor); result = (int) (res >> 32); } return (int) result;