/// <summary>
/// Adds two big integers.
/// </summary>
/// <param name="int1">First big integer.</param>
/// <param name="int2">Second big integer.</param>
/// <returns>Resulting big integer.</returns>
/// <exception cref="ArgumentException"><paramref name="int1" /> or <paramref name="int2" /> is too big for add operation.</exception>
static public IntX Add(IntX int1, IntX int2)
{
// Process zero values in special way
if (int2._length == 0)
{
return(new IntX(int1));
}
if (int1._length == 0)
{
IntX x = new IntX(int2);
x._negative = int1._negative; // always get sign of the first big integer
return(x);
}
// Determine big int with lower length
IntX smallerInt;
IntX biggerInt;
DigitHelper.GetMinMaxLengthObjects(int1, int2, out smallerInt, out biggerInt);
// Check for add operation possibility
if (biggerInt._length == uint.MaxValue)
{
throw new ArgumentException(Strings.IntegerTooBig);
}
// Create new big int object of needed length
IntX newInt = new IntX(biggerInt._length + 1, int1._negative);
// Do actual addition
newInt._length = DigitOpHelper.Add(
biggerInt._digits,
biggerInt._length,
smallerInt._digits,
smallerInt._length,
newInt._digits);
// Normalization may be needed
newInt.TryNormalize();
return(newInt);
}
/// <summary>
/// Parses provided string representation of <see cref="IntX" /> object.
/// </summary>
/// <param name="value">Number as string.</param>
/// <param name="startIndex">Index inside string from which to start.</param>
/// <param name="endIndex">Index inside string on which to end.</param>
/// <param name="numberBase">Number base.</param>
/// <param name="charToDigits">Char->digit dictionary.</param>
/// <param name="digitsRes">Resulting digits.</param>
/// <returns>Parsed integer length.</returns>
override unsafe public uint Parse(string value, int startIndex, int endIndex, uint numberBase, IDictionary <char, uint> charToDigits, uint[] digitsRes)
{
uint newLength = base.Parse(value, startIndex, endIndex, numberBase, charToDigits, digitsRes);
// Maybe base method already parsed this number
if (newLength != 0)
{
return(newLength);
}
// Check length - maybe use classic parser instead
uint initialLength = (uint)digitsRes.LongLength;
if (initialLength < Constants.FastParseLengthLowerBound || initialLength > Constants.FastParseLengthUpperBound)
{
return(_classicParser.Parse(value, startIndex, endIndex, numberBase, charToDigits, digitsRes));
}
uint valueLength = (uint)(endIndex - startIndex + 1);
uint digitsLength = 1U << Bits.CeilLog2(valueLength);
// Prepare array for digits in other base
uint[] valueDigits = ArrayPool <uint> .Instance.GetArray(digitsLength);
// This second array will store integer lengths initially
uint[] valueDigits2 = ArrayPool <uint> .Instance.GetArray(digitsLength);
fixed(uint *valueDigitsStartPtr = valueDigits, valueDigitsStartPtr2 = valueDigits2)
{
// In the string first digit means last in digits array
uint *valueDigitsPtr = valueDigitsStartPtr + valueLength - 1;
uint *valueDigitsPtr2 = valueDigitsStartPtr2 + valueLength - 1;
// Reverse copy characters into digits
fixed(char *valueStartPtr = value)
{
char *valuePtr = valueStartPtr + startIndex;
char *valueEndPtr = valuePtr + valueLength;
for (; valuePtr < valueEndPtr; ++valuePtr, --valueDigitsPtr, --valueDigitsPtr2)
{
// Get digit itself - this call will throw an exception if char is invalid
*valueDigitsPtr = StrRepHelper.GetDigit(charToDigits, *valuePtr, numberBase);
// Set length of this digit (zero for zero)
*valueDigitsPtr2 = *valueDigitsPtr == 0U ? 0U : 1U;
}
}
// We have retrieved lengths array from pool - it needs to be cleared before using
DigitHelper.SetBlockDigits(valueDigitsStartPtr2 + valueLength, digitsLength - valueLength, 0);
// Now start from the digit arrays beginning
valueDigitsPtr = valueDigitsStartPtr;
valueDigitsPtr2 = valueDigitsStartPtr2;
// Current multiplier (classic or fast) will be used
IMultiplier multiplier = MultiplyManager.GetCurrentMultiplier();
// Here base in needed power will be stored
IntX baseInt = null;
// Temporary variables used on swapping
uint[] tempDigits;
uint * tempPtr;
// Variables used in cycle
uint *ptr1, ptr2, valueDigitsPtrEnd;
uint loLength, hiLength;
// Outer cycle instead of recursion
for (uint innerStep = 1, outerStep = 2; innerStep < digitsLength; innerStep <<= 1, outerStep <<= 1)
{
// Maybe baseInt must be multiplied by itself
baseInt = baseInt == null ? numberBase : baseInt * baseInt;
// Using unsafe here
fixed(uint *baseDigitsPtr = baseInt._digits)
{
// Start from arrays beginning
ptr1 = valueDigitsPtr;
ptr2 = valueDigitsPtr2;
// vauleDigits array end
valueDigitsPtrEnd = valueDigitsPtr + digitsLength;
// Cycle thru all digits and their lengths
for (; ptr1 < valueDigitsPtrEnd; ptr1 += outerStep, ptr2 += outerStep)
{
// Get lengths of "lower" and "higher" value parts
loLength = *ptr2;
hiLength = *(ptr2 + innerStep);
if (hiLength != 0)
{
// We always must clear an array before multiply
DigitHelper.SetBlockDigits(ptr2, outerStep, 0U);
// Multiply per baseInt
hiLength = multiplier.Multiply(
baseDigitsPtr,
baseInt._length,
ptr1 + innerStep,
hiLength,
ptr2);
}
// Sum results
if (hiLength != 0 || loLength != 0)
{
*ptr1 = DigitOpHelper.Add(
ptr2,
hiLength,
ptr1,
loLength,
ptr2);
}
else
{
*ptr1 = 0U;
}
}
}
// After inner cycle valueDigits will contain lengths and valueDigits2 will contain actual values
// so we need to swap them here
tempDigits = valueDigits;
valueDigits = valueDigits2;
valueDigits2 = tempDigits;
tempPtr = valueDigitsPtr;
valueDigitsPtr = valueDigitsPtr2;
valueDigitsPtr2 = tempPtr;
}
}
// Determine real length of converted number
uint realLength = valueDigits2[0];
// Copy to result
Array.Copy(valueDigits, digitsRes, realLength);
// Return arrays to pool
ArrayPool <uint> .Instance.AddArray(valueDigits);
ArrayPool <uint> .Instance.AddArray(valueDigits2);
return(realLength);
}