public static EInteger ReduceTrailingZeros(
EInteger bigmant,
FastInteger exponentMutable,
int radix,
FastInteger digits,
FastInteger precision,
FastInteger idealExp) {
#if DEBUG
if (precision != null && digits == null) {
throw new ArgumentException("doesn't satisfy precision==null || digits!=null");
}
#endif
if (bigmant.IsZero) {
exponentMutable.SetInt(0);
return bigmant;
}
var bigradix = (EInteger)radix;
var bitToTest = 0;
var bitsToShift = new FastInteger(0);
while (!bigmant.IsZero) {
if (precision != null && digits.CompareTo(precision) == 0) {
break;
}
if (idealExp != null && exponentMutable.CompareTo(idealExp) == 0) {
break;
}
if (radix == 2) {
if (bitToTest < Int32.MaxValue) {
if (bigmant.GetSignedBit(bitToTest)) {
break;
}
++bitToTest;
bitsToShift.Increment();
} else {
if (!bigmant.IsEven) {
break;
}
bigmant >>= 1;
}
} else {
EInteger bigrem;
EInteger bigquo;
{
EInteger[] divrem = bigmant.DivRem(bigradix);
bigquo = divrem[0];
bigrem = divrem[1]; }
if (!bigrem.IsZero) {
break;
}
bigmant = bigquo;
}
exponentMutable.Increment();
if (digits != null) {
digits.Decrement();
}
}
if (radix == 2 && !bitsToShift.IsValueZero) {
while (bitsToShift.CompareToInt(1000000) > 0) {
bigmant >>= 1000000;
bitsToShift.SubtractInt(1000000);
}
int tmpshift = bitsToShift.AsInt32();
bigmant >>= tmpshift;
}
return bigmant;
}
public static EInteger ReduceTrailingZeros(
EInteger bigmant,
FastInteger exponentMutable,
int radix,
FastInteger digits,
FastInteger precision,
FastInteger idealExp)
{
#if DEBUG
if (precision != null && digits == null)
{
throw new ArgumentException("doesn't satisfy precision==null ||" +
"\u0020digits!=null");
}
if (!(bigmant.Sign >= 0))
{
throw new ArgumentException("doesn't satisfy bigmant.Sign >= 0");
}
#endif
if (bigmant.IsZero)
{
exponentMutable.SetInt(0);
return(bigmant);
}
if (radix == 2)
{
if (!bigmant.IsEven)
{
return(bigmant);
}
long lowbit = bigmant.GetLowBitAsInt64();
if (lowbit != Int64.MaxValue)
{
if (precision != null && digits.CompareTo(precision) >= 0)
{
// Limit by digits minus precision
EInteger tmp = digits.ToEInteger().Subtract(precision.ToEInteger());
if (tmp.CompareTo(EInteger.FromInt64(lowbit)) < 0)
{
lowbit = tmp.ToInt64Checked();
}
}
if (idealExp != null && exponentMutable.CompareTo(idealExp) <= 0)
{
// Limit by idealExp minus exponentMutable
EInteger tmp =
idealExp.ToEInteger().Subtract(exponentMutable.ToEInteger());
if (tmp.CompareTo(EInteger.FromInt64(lowbit)) < 0)
{
lowbit = tmp.ToInt64Checked();
}
}
bigmant = (lowbit <= Int32.MaxValue) ?
bigmant.ShiftRight((int)lowbit) :
bigmant.ShiftRight(EInteger.FromInt64(lowbit));
if (digits != null)
{
digits.SubtractInt64(lowbit);
}
if (exponentMutable != null)
{
exponentMutable.AddInt64(lowbit);
}
return(bigmant);
}
}
var bigradix = (EInteger)radix;
var bitsToShift = new FastInteger(0);
while (!bigmant.IsZero)
{
if (precision != null && digits.CompareTo(precision) == 0)
{
break;
}
if (idealExp != null && exponentMutable.CompareTo(idealExp) == 0)
{
break;
}
EInteger bigrem;
EInteger bigquo;
EInteger[] divrem = bigmant.DivRem(bigradix);
bigquo = divrem[0];
bigrem = divrem[1];
if (!bigrem.IsZero)
{
break;
}
bigmant = bigquo;
exponentMutable.Increment();
if (digits != null)
{
digits.Decrement();
}
}
return(bigmant);
}
private static FastInteger ByteArrayBitLength(byte[] bytes)
{
FastInteger fastKB = new FastInteger(bytes.Length).Multiply(8);
for (int i = bytes.Length - 1; i >= 0; i--) {
int b = (int)bytes[i];
if (b != 0) {
if ((b & 0x80) != 0) { break; }
if ((b & 0x40) != 0) { fastKB.Decrement(); break; }
if ((b & 0x20) != 0) { fastKB.SubtractInt(2); break; }
if ((b & 0x10) != 0) { fastKB.SubtractInt(3); break; }
if ((b & 0x08) != 0) { fastKB.SubtractInt(4); break; }
if ((b & 0x04) != 0) { fastKB.SubtractInt(5); break; }
if ((b & 0x02) != 0) { fastKB.SubtractInt(6); break; }
if ((b & 0x01) != 0) { fastKB.SubtractInt(7); break; }
}
fastKB.SubtractInt(8);
}
// Make sure bit length is 1 if value is 0
if (fastKB.Sign == 0) fastKB.Increment();
return fastKB;
}
