/// <summary>
/// Converts digits from internal representaion into given base.
/// </summary>
/// <param name="digits">Big integer digits.</param>
/// <param name="length">Big integer length.</param>
/// <param name="numberBase">Base to use for output.</param>
/// <param name="outputLength">Calculated output length (will be corrected inside).</param>
/// <returns>Conversion result (later will be transformed to string).</returns>
virtual public uint[] ToString(uint[] digits, uint length, uint numberBase, ref uint outputLength)
{
// Default implementation - always call pow2 converter if numberBase is pow of 2
return(numberBase == 1U << Bits.Msb(numberBase)
? _pow2StringConverter.ToString(digits, length, numberBase, ref outputLength)
: null);
}
/// <summary>
/// Converts digits from internal representaion into given base.
/// </summary>
/// <param name="digits">Big integer digits.</param>
/// <param name="length">Big integer length.</param>
/// <param name="numberBase">Base to use for output.</param>
/// <param name="outputLength">Calculated output length (will be corrected inside).</param>
/// <returns>Conversion result (later will be transformed to string).</returns>
override unsafe public uint[] ToString(uint[] digits, uint length, uint numberBase, ref uint outputLength)
{
uint[] outputArray = base.ToString(digits, length, numberBase, ref outputLength);
// Maybe base method already converted this number
if (outputArray != null)
{
return(outputArray);
}
// Check length - maybe use classic converter instead
if (length < Constants.FastConvertLengthLowerBound || length > Constants.FastConvertLengthUpperBound)
{
return(_classicStringConverter.ToString(digits, length, numberBase, ref outputLength));
}
int resultLengthLog2 = Bits.CeilLog2(outputLength);
uint resultLength = 1U << resultLengthLog2;
// Create and initially fill array for transofmed numbers storing
uint[] resultArray = ArrayPool <uint> .Instance.GetArray(resultLength);
Array.Copy(digits, resultArray, length);
// Create and initially fill array with lengths
uint[] resultArray2 = ArrayPool <uint> .Instance.GetArray(resultLength);
resultArray2[0] = length;
IMultiplier multiplier = MultiplyManager.GetCurrentMultiplier();
IDivider divider = DivideManager.GetCurrentDivider();
// Generate all needed pows of numberBase in stack
Stack baseIntStack = new Stack(resultLengthLog2);
IntX baseInt = null;
for (int i = 0; i < resultLengthLog2; ++i)
{
baseInt = baseInt == null ? numberBase : multiplier.Multiply(baseInt, baseInt);
baseIntStack.Push(baseInt);
}
// Create temporary buffer for second digits when doing div operation
uint[] tempBuffer = new uint[baseInt._length];
// We will use unsafe code here
fixed(uint *resultPtr1Const = resultArray, resultPtr2Const = resultArray2, tempBufferPtr = tempBuffer)
{
// Results pointers which will be modified (on swap)
uint *resultPtr1 = resultPtr1Const;
uint *resultPtr2 = resultPtr2Const;
// Temporary variables used on swapping
uint[] tempArray;
uint * tempPtr;
// Variables used in cycle
uint *ptr1, ptr2, ptr1end;
uint loLength;
// Outer cycle instead of recursion
for (uint innerStep = resultLength >> 1, outerStep = resultLength; innerStep > 0; innerStep >>= 1, outerStep >>= 1)
{
// Prepare pointers
ptr1 = resultPtr1;
ptr2 = resultPtr2;
ptr1end = resultPtr1 + resultLength;
// Get baseInt from stack and fix it too
baseInt = (IntX)baseIntStack.Pop();
fixed(uint *baseIntPtr = baseInt._digits)
{
// Cycle thru all digits and their lengths
for (; ptr1 < ptr1end; ptr1 += outerStep, ptr2 += outerStep)
{
// Divide ptr1 (with length in *ptr2) by baseIntPtr here.
// Results are stored in ptr2 & (ptr2 + innerStep), lengths - in *ptr1 and (*ptr1 + innerStep)
loLength = *ptr2;
*(ptr1 + innerStep) = divider.DivMod(
ptr1,
ptr2,
ref loLength,
baseIntPtr,
tempBufferPtr,
baseInt._length,
ptr2 + innerStep,
DivModResultFlags.Div | DivModResultFlags.Mod,
-2);
*ptr1 = loLength;
}
}
// After inner cycle resultArray will contain lengths and resultArray2 will contain actual values
// so we need to swap them here
tempArray = resultArray;
resultArray = resultArray2;
resultArray2 = tempArray;
tempPtr = resultPtr1;
resultPtr1 = resultPtr2;
resultPtr2 = tempPtr;
}
// Retrieve real output length
outputLength = DigitHelper.GetRealDigitsLength(resultArray2, outputLength);
// Create output array
outputArray = new uint[outputLength];
// Copy each digit but only if length is not null
fixed(uint *outputPtr = outputArray)
{
for (uint i = 0; i < outputLength; ++i)
{
if (resultPtr2[i] != 0)
{
outputPtr[i] = resultPtr1[i];
}
}
}
}
// Return temporary arrays to pool
ArrayPool <uint> .Instance.AddArray(resultArray);
ArrayPool <uint> .Instance.AddArray(resultArray2);
return(outputArray);
}