private void OptimizeInternal(int size, Trie <T>[] children)
{
var smallChildren = new Trie <T> [size];
Mask = int.MaxValue >> 31 - Bits.CeilLog2(size);
foreach (var trie in children)
{
var key = trie.Key[0] & Mask;
if (smallChildren[key] != null)
{
if (smallChildren[key] == trie)
{
break; // different casing, same val, nothing to do
}
// real collision, double the size and try again
OptimizeInternal(size * 2, children);
return;
}
trie.DebugKey = DebugKey + trie.Key;
smallChildren[key] = trie;
trie.Optimize();
}
Children = smallChildren;
}
public PageLocatorCurrent(LowLevelTransactionStub tx, int cacheSize = 8)
{
//Debug.Assert(tx != null);
//Debug.Assert(cacheSize > 0);
_tx = tx;
if (tx != null)
{
Debug.Fail("");
}
cacheSize = Bits.NextPowerOf2(cacheSize);
if (cacheSize > 1024)
{
cacheSize = 1024;
}
int shiftRight = Bits.CeilLog2(cacheSize);
_andMask = (int)(0xFFFFFFFF >> (sizeof(uint) * 8 - shiftRight));
_tx = tx;
_allocator.Allocate(cacheSize * sizeof(PageData), out _cacheMemory);
_cache = (PageData *)_cacheMemory.Ptr;
for (var i = 0; i < cacheSize; i++)
{
_cache[i].PageNumber = Invalid;
}
}
public void Renew(LowLevelTransaction tx, int cacheSize)
{
Debug.Assert(tx != null);
Debug.Assert(cacheSize > 0);
Debug.Assert(cacheSize <= 1024);
if (!Bits.IsPowerOfTwo(cacheSize))
{
cacheSize = Bits.NextPowerOf2(cacheSize);
}
int shiftRight = Bits.CeilLog2(cacheSize);
_andMask = (int)(0xFFFFFFFF >> (sizeof(uint) * 8 - shiftRight));
_tx = tx;
tx.Allocator.Allocate(cacheSize * sizeof(PageData), out _cacheMemory);
_cache = (PageData *)_cacheMemory.Ptr;
for (var i = 0; i < cacheSize; i++)
{
_cache[i].PageNumber = Invalid;
}
}
/// <summary>
/// Converts <see cref="IntX" /> digits into real representation (used in FHT).
/// </summary>
/// <param name="digitsPtr">Big integer digits.</param>
/// <param name="length"><paramref name="digitsPtr" /> length.</param>
/// <param name="newLength">Multiplication result length (must be pow of 2).</param>
/// <returns>Double array.</returns>
static public double[] ConvertDigitsToDouble(uint *digitsPtr, uint length, uint newLength)
{
// Maybe fix newLength (make it the nearest bigger pow of 2)
newLength = 1U << Bits.CeilLog2(newLength);
// For better FHT accuracy we will choose length smaller then dwords.
// So new length must be modified accordingly
newLength <<= DoubleDataLengthShift;
double[] data = ArrayPool <double> .Instance.GetArray(newLength);
// Run in unsafe context
fixed(double *slice = data)
{
// Amount of units pointed by digitsPtr
uint unitCount = length << DoubleDataLengthShift;
// Copy all words from digits into new double[]
byte *unitDigitsPtr = (byte *)digitsPtr;
for (uint i = 0; i < unitCount; ++i)
{
slice[i] = unitDigitsPtr[i];
}
// Clear remaining double values (this array is from pool and may be dirty)
DigitHelper.SetBlockDigits(slice + unitCount, newLength - unitCount, 0.0);
// FHT (as well as FFT) works more accurate with "balanced" data, so let's balance it
double carry = 0, dataDigit;
for (uint i = 0; i < unitCount || i < newLength && carry != 0; ++i)
{
dataDigit = slice[i] + carry;
if (dataDigit >= DoubleDataBaseDiv2)
{
dataDigit -= DoubleDataBase;
carry = 1.0;
}
else
{
carry = 0;
}
slice[i] = dataDigit;
}
if (carry > 0)
{
slice[0] -= carry;
}
}
return(data);
}
public void Bits_Ceil2Log()
{
Assert.Equal(0, Bits.CeilLog2(0));
Assert.Equal(0, Bits.CeilLog2(1));
Assert.Equal(1, Bits.CeilLog2(2));
Assert.Equal(2, Bits.CeilLog2(3));
Assert.Equal(2, Bits.CeilLog2(4));
Assert.Equal(16, Bits.CeilLog2(0x0000FF00));
Assert.Equal(31, Bits.CeilLog2(0x40B79DF0));
Assert.Equal(0, Bits.CeilLog2((uint)0));
Assert.Equal(0, Bits.CeilLog2((uint)1));
Assert.Equal(1, Bits.CeilLog2((uint)2));
Assert.Equal(2, Bits.CeilLog2((uint)3));
Assert.Equal(2, Bits.CeilLog2((uint)4));
Assert.Equal(16, Bits.CeilLog2((uint)0x0000FF00));
Assert.Equal(32, Bits.CeilLog2((uint)0xFFFF0000));
Assert.Equal(31, Bits.CeilLog2((uint)0x40B79DF0));
}
private static int CalculateCompressionAcceleration(int size)
{
return(Bits.CeilLog2(size));
}
/// <summary>
/// Generates integer opposite to the given one using approximation.
/// Uses algorithm from Khuth vol. 2 3rd Edition (4.3.3).
/// </summary>
/// <param name="digitsPtr">Initial big integer digits.</param>
/// <param name="length">Initial big integer length.</param>
/// <param name="maxLength">Precision length.</param>
/// <param name="bufferPtr">Buffer in which shifted big integer may be stored.</param>
/// <param name="newLength">Resulting big integer length.</param>
/// <param name="rightShift">How much resulting big integer is shifted to the left (or: must be shifted to the right).</param>
/// <returns>Resulting big integer digits.</returns>
static unsafe public uint[] GetIntegerOpposite(
uint *digitsPtr,
uint length,
uint maxLength,
uint *bufferPtr,
out uint newLength,
out ulong rightShift)
{
// Maybe initially shift original digits a bit to the left
// (it must have MSB on 2nd position in the highest digit)
int msb = Bits.Msb(digitsPtr[length - 1]);
rightShift = (ulong)(length - 1) * Constants.DigitBitCount + (ulong)msb + 1U;
if (msb != 2)
{
// Shift to the left (via actually right shift)
int leftShift = (2 - msb + Constants.DigitBitCount) % Constants.DigitBitCount;
length = DigitOpHelper.Shr(digitsPtr, length, bufferPtr + 1, Constants.DigitBitCount - leftShift, true) + 1U;
}
else
{
// Simply use the same digits without any shifting
bufferPtr = digitsPtr;
}
// Calculate possible result length
int lengthLog2 = Bits.CeilLog2(maxLength);
uint newLengthMax = 1U << (lengthLog2 + 1);
int lengthLog2Bits = lengthLog2 + Bits.Msb(Constants.DigitBitCount);
// Create result digits
uint[] resultDigits = ArrayPool <uint> .Instance.GetArray(newLengthMax); //new uint[newLengthMax];
uint resultLength;
// Create temporary digits for squared result (twice more size)
uint[] resultDigitsSqr = ArrayPool <uint> .Instance.GetArray(newLengthMax); //new uint[newLengthMax];
uint resultLengthSqr;
// Create temporary digits for squared result * buffer
uint[] resultDigitsSqrBuf = new uint[newLengthMax + length];
uint resultLengthSqrBuf;
// We will always use current multiplier
IMultiplier multiplier = MultiplyManager.GetCurrentMultiplier();
// Fix some digits
fixed(uint *resultPtrFixed = resultDigits, resultSqrPtrFixed = resultDigitsSqr, resultSqrBufPtr = resultDigitsSqrBuf)
{
uint *resultPtr = resultPtrFixed;
uint *resultSqrPtr = resultSqrPtrFixed;
// Cache two first digits
uint bufferDigitN1 = bufferPtr[length - 1];
uint bufferDigitN2 = bufferPtr[length - 2];
// Prepare result.
// Initially result = floor(32 / (4*v1 + 2*v2 + v3)) / 4
// (last division is not floored - here we emulate fixed point)
resultDigits[0] = 32 / bufferDigitN1;
resultLength = 1;
// Prepare variables
uint nextBufferTempStorage = 0;
int nextBufferTempShift;
uint nextBufferLength = 1U;
uint *nextBufferPtr = &nextBufferTempStorage;
ulong bitsAfterDotResult;
ulong bitsAfterDotResultSqr;
ulong bitsAfterDotNextBuffer;
ulong bitShift;
uint shiftOffset;
uint *tempPtr;
uint[] tempDigits;
// Iterate 'till result will be precise enough
for (int k = 0; k < lengthLog2Bits; ++k)
{
// Get result squared
resultLengthSqr = multiplier.Multiply(
resultPtr,
resultLength,
resultPtr,
resultLength,
resultSqrPtr);
// Calculate current result bits after dot
bitsAfterDotResult = (1UL << k) + 1UL;
bitsAfterDotResultSqr = bitsAfterDotResult << 1;
// Here we will get the next portion of data from bufferPtr
if (k < 4)
{
// For now buffer intermediate has length 1 and we will use this fact
nextBufferTempShift = 1 << (k + 1);
nextBufferTempStorage =
bufferDigitN1 << nextBufferTempShift |
bufferDigitN2 >> (Constants.DigitBitCount - nextBufferTempShift);
// Calculate amount of bits after dot (simple formula here)
bitsAfterDotNextBuffer = (ulong)nextBufferTempShift + 3UL;
}
else
{
// Determine length to get from bufferPtr
nextBufferLength = System.Math.Min((1U << (k - 4)) + 1U, length);
nextBufferPtr = bufferPtr + (length - nextBufferLength);
// Calculate amount of bits after dot (simple formula here)
bitsAfterDotNextBuffer = (ulong)(nextBufferLength - 1U) * Constants.DigitBitCount + 3UL;
}
// Multiply result ^ 2 and nextBuffer + calculate new amount of bits after dot
resultLengthSqrBuf = multiplier.Multiply(
resultSqrPtr,
resultLengthSqr,
nextBufferPtr,
nextBufferLength,
resultSqrBufPtr);
bitsAfterDotNextBuffer += bitsAfterDotResultSqr;
// Now calculate 2 * result - resultSqrBufPtr
--bitsAfterDotResult;
--bitsAfterDotResultSqr;
// Shift result on a needed amount of bits to the left
bitShift = bitsAfterDotResultSqr - bitsAfterDotResult;
shiftOffset = (uint)(bitShift / Constants.DigitBitCount);
resultLength =
shiftOffset + 1U +
DigitOpHelper.Shr(
resultPtr,
resultLength,
resultSqrPtr + shiftOffset + 1U,
Constants.DigitBitCount - (int)(bitShift % Constants.DigitBitCount),
true);
// Swap resultPtr and resultSqrPtr pointers
tempPtr = resultPtr;
resultPtr = resultSqrPtr;
resultSqrPtr = tempPtr;
tempDigits = resultDigits;
resultDigits = resultDigitsSqr;
resultDigitsSqr = tempDigits;
DigitHelper.SetBlockDigits(resultPtr, shiftOffset, 0U);
bitShift = bitsAfterDotNextBuffer - bitsAfterDotResultSqr;
shiftOffset = (uint)(bitShift / Constants.DigitBitCount);
if (shiftOffset < resultLengthSqrBuf)
{
// Shift resultSqrBufPtr on a needed amount of bits to the right
resultLengthSqrBuf = DigitOpHelper.Shr(
resultSqrBufPtr + shiftOffset,
resultLengthSqrBuf - shiftOffset,
resultSqrBufPtr,
(int)(bitShift % Constants.DigitBitCount),
false);
// Now perform actual subtraction
resultLength = DigitOpHelper.Sub(
resultPtr,
resultLength,
resultSqrBufPtr,
resultLengthSqrBuf,
resultPtr);
}
else
{
// Actually we can assume resultSqrBufPtr == 0 here and have nothing to do
}
}
}
// Return some arrays to pool
ArrayPool <uint> .Instance.AddArray(resultDigitsSqr);
rightShift += (1UL << lengthLog2Bits) + 1UL;
newLength = resultLength;
return(resultDigits);
}
private static int GetPoolIndexForReuse(int size)
{
return(Bits.CeilLog2(size) - 1); // x^0 = 1 therefore we start counting at 1 instead.
}
