private static void LehmerGcd(ref BigIntegerBuilder reg1, ref BigIntegerBuilder reg2)
{
int num2;
uint num11;
int sign = 1;
Label_0002:
num2 = reg1._iuLast + 1;
int b = reg2._iuLast + 1;
if (num2 < b)
{
#if !(dotNET10 || dotNET11 || dotNETCF10)
NumericsHelpers.Swap <BigIntegerBuilder>(ref reg1, ref reg2);
NumericsHelpers.Swap <int>(ref num2, ref b);
#else
NumericsHelpers.Swap(ref reg1, ref reg2);
NumericsHelpers.Swap(ref num2, ref b);
#endif
}
if (b == 1)
{
if (num2 == 1)
{
reg1._uSmall = NumericsHelpers.GCD(reg1._uSmall, reg2._uSmall);
return;
}
if (reg2._uSmall != 0)
{
reg1.Set(NumericsHelpers.GCD(Mod(ref reg1, reg2._uSmall), reg2._uSmall));
}
return;
}
if (num2 == 2)
{
reg1.Set(NumericsHelpers.GCD(reg1.GetHigh2(2), reg2.GetHigh2(2)));
return;
}
if (b <= (num2 - 2))
{
reg1.Mod(ref reg2);
goto Label_0002;
}
ulong a = reg1.GetHigh2(num2);
ulong num5 = reg2.GetHigh2(num2);
int num6 = NumericsHelpers.CbitHighZero((ulong)(a | num5));
if (num6 > 0)
{
a = (a << num6) | (reg1._rgu[num2 - 3] >> (0x20 - num6));
num5 = (num5 << num6) | (reg2._rgu[num2 - 3] >> (0x20 - num6));
}
if (a < num5)
{
#if !(dotNET10 || dotNET11 || dotNETCF10)
NumericsHelpers.Swap <ulong>(ref a, ref num5);
NumericsHelpers.Swap <BigIntegerBuilder>(ref reg1, ref reg2);
#else
NumericsHelpers.Swap(ref a, ref num5);
NumericsHelpers.Swap(ref reg1, ref reg2);
#endif
}
if ((a == ulong.MaxValue) || (num5 == ulong.MaxValue))
{
a = a >> 1;
num5 = num5 >> 1;
}
if (a == num5)
{
reg1.Sub(ref sign, ref reg2);
goto Label_0002;
}
if (NumericsHelpers.GetHi(num5) == 0)
{
reg1.Mod(ref reg2);
goto Label_0002;
}
uint num7 = 1;
uint num8 = 0;
uint num9 = 0;
uint num10 = 1;
Label_0159:
num11 = 1;
ulong num12 = a - num5;
while ((num12 >= num5) && (num11 < 0x20))
{
num12 -= num5;
num11++;
}
if (num12 >= num5)
{
ulong num13 = a / num5;
if (num13 > 0xffffffffL)
{
goto Label_029E;
}
num11 = (uint)num13;
num12 = a - (num11 * num5);
}
ulong num14 = (ulong)num7 + (ulong)num11 * (ulong)num9;
ulong num15 = (ulong)num8 + (ulong)num11 * (ulong)num10;
if (((num14 <= 0x7fffffffL) && (num15 <= 0x7fffffffL)) && ((num12 >= num15) && ((num12 + num14) <= (num5 - num9))))
{
num7 = (uint)num14;
num8 = (uint)num15;
a = num12;
if (a > num8)
{
num11 = 1;
num12 = num5 - a;
while ((num12 >= a) && (num11 < 0x20))
{
num12 -= a;
num11++;
}
if (num12 >= a)
{
ulong num16 = num5 / a;
if (num16 > 0xffffffffL)
{
goto Label_029E;
}
num11 = (uint)num16;
num12 = num5 - (num11 * a);
}
num14 = (ulong)num10 + (ulong)num11 * (ulong)num8;
num15 = (ulong)num9 + (ulong)num11 * (ulong)num7;
if (((num14 <= 0x7fffffffL) && (num15 <= 0x7fffffffL)) && ((num12 >= num15) && ((num12 + num14) <= (a - num8))))
{
num10 = (uint)num14;
num9 = (uint)num15;
num5 = num12;
if (num5 > num9)
{
goto Label_0159;
}
}
}
}
Label_029E:
if (num8 == 0)
{
if ((a / ((ulong)2L)) >= num5)
{
reg1.Mod(ref reg2);
}
else
{
reg1.Sub(ref sign, ref reg2);
}
}
else
{
reg1.SetSizeKeep(b, 0);
reg2.SetSizeKeep(b, 0);
int num17 = 0;
int num18 = 0;
for (int i = 0; i < b; i++)
{
uint num20 = reg1._rgu[i];
uint num21 = reg2._rgu[i];
long num22 = (long)num20 * (long)num7 - (long)num21 * (long)num8 + (long)num17;
long num23 = (long)num21 * (long)num10 - (long)num20 * (long)num9 + (long)num18;
num17 = (int)(num22 >> 0x20);
num18 = (int)(num23 >> 0x20);
reg1._rgu[i] = (uint)num22;
reg2._rgu[i] = (uint)num23;
}
reg1.Trim();
reg2.Trim();
}
goto Label_0002;
}
// This leaves the GCD in reg1 and trash in reg2.
// This uses Lehmer's method, with test due to Jebelean / Belnkiy and Vidunas.
// See Knuth, vol 2, page 345; Jebelean (1993) "Improving the Multiprecision Euclidean Algorithm";
// and Belenkiy & Vidunas (1998) "A Greatest Common Divisor Algorithm".
private static void LehmerGcd(ref BigIntegerBuilder reg1, ref BigIntegerBuilder reg2)
{
// This value has no real significance. Occ----ionally we want to subtract
// the two registers and keep the absolute value of the difference. To do
// so we need to pass a ref sign to Sub.
int signTmp = +1;
for (; ;)
{
int cuMax = reg1._iuLast + 1;
int cuMin = reg2._iuLast + 1;
if (cuMax < cuMin)
{
NumericsHelpers.Swap(ref reg1, ref reg2);
NumericsHelpers.Swap(ref cuMax, ref cuMin);
}
if (cuMin == 1)
{
if (cuMax == 1)
{
reg1._uSmall = NumericsHelpers.GCD(reg1._uSmall, reg2._uSmall);
}
else if (reg2._uSmall != 0)
{
reg1.Set(NumericsHelpers.GCD(Mod(ref reg1, reg2._uSmall), reg2._uSmall));
}
return;
}
if (cuMax == 2)
{
reg1.Set(NumericsHelpers.GCD(reg1.GetHigh2(2), reg2.GetHigh2(2)));
return;
}
if (cuMin <= cuMax - 2)
{
// reg1 is much larger than reg2, so just mod.
reg1.Mod(ref reg2);
continue;
}
ulong uu1 = reg1.GetHigh2(cuMax);
ulong uu2 = reg2.GetHigh2(cuMax);
int cbit = NumericsHelpers.CbitHighZero(uu1 | uu2);
if (cbit > 0)
{
uu1 = (uu1 << cbit) | (reg1._rgu[cuMax - 3] >> (kcbitUint - cbit));
// Note that [cuMax - 3] is correct, NOT [cuMin - 3].
uu2 = (uu2 << cbit) | (reg2._rgu[cuMax - 3] >> (kcbitUint - cbit));
}
if (uu1 < uu2)
{
NumericsHelpers.Swap(ref uu1, ref uu2);
NumericsHelpers.Swap(ref reg1, ref reg2);
}
// Make sure we don't overflow.
if (uu1 == ulong.MaxValue || uu2 == ulong.MaxValue)
{
uu1 >>= 1;
uu2 >>= 1;
}
if (uu1 == uu2)
{
// The high bits are the same, so we don't know which
// is larger. No matter, just subtract one from the other
// and keep the absolute value of the result.
reg1.Sub(ref signTmp, ref reg2);
continue;
}
if (NumericsHelpers.GetHi(uu2) == 0)
{
// reg1 is much larger than reg2, so just mod.
reg1.Mod(ref reg2);
continue;
}
// These are the coefficients to apply to reg1 and reg2 to get
// the new values, using: a * reg1 - b * reg2 and -c * reg1 + d * reg2.
uint a = 1, b = 0;
uint c = 0, d = 1;
for (; ;)
{
uint uQuo = 1;
ulong uuNew = uu1 - uu2;
while (uuNew >= uu2 && uQuo < 32)
{
uuNew -= uu2;
uQuo++;
}
if (uuNew >= uu2)
{
ulong uuQuo = uu1 / uu2;
if (uuQuo > uint.MaxValue)
{
break;
}
uQuo = (uint)uuQuo;
uuNew = uu1 - uQuo * uu2;
}
ulong uuAdNew = a + (ulong)uQuo * c;
ulong uuBcNew = b + (ulong)uQuo * d;
if (uuAdNew > int.MaxValue || uuBcNew > int.MaxValue)
{
break;
}
// Jebelean / Belenkiy-Vidunas conditions
if (uuNew < uuBcNew || uuNew + uuAdNew > uu2 - c)
{
break;
}
a = (uint)uuAdNew;
b = (uint)uuBcNew;
uu1 = uuNew;
if (uu1 <= b)
{
break;
}
uQuo = 1;
uuNew = uu2 - uu1;
while (uuNew >= uu1 && uQuo < 32)
{
uuNew -= uu1;
uQuo++;
}
if (uuNew >= uu1)
{
ulong uuQuo = uu2 / uu1;
if (uuQuo > uint.MaxValue)
{
break;
}
uQuo = (uint)uuQuo;
uuNew = uu2 - uQuo * uu1;
}
uuAdNew = d + (ulong)uQuo * b;
uuBcNew = c + (ulong)uQuo * a;
if (uuAdNew > int.MaxValue || uuBcNew > int.MaxValue)
{
break;
}
// Jebelean / Belenkiy-Vidunas conditions
if (uuNew < uuBcNew || uuNew + uuAdNew > uu1 - b)
{
break;
}
d = (uint)uuAdNew;
c = (uint)uuBcNew;
uu2 = uuNew;
if (uu2 <= c)
{
break;
}
}
if (b == 0)
{
if (uu1 / 2 >= uu2)
{
reg1.Mod(ref reg2);
}
else
{
reg1.Sub(ref signTmp, ref reg2);
}
}
else
{
// Replace reg1 with a * reg1 - b * reg2.
// Replace reg2 with -c * reg1 + d * reg2.
// Do everything mod cuMin uint's.
reg1.SetSizeKeep(cuMin, 0);
reg2.SetSizeKeep(cuMin, 0);
int nCarry1 = 0;
int nCarry2 = 0;
for (int iu = 0; iu < cuMin; iu++)
{
uint u1 = reg1._rgu[iu];
uint u2 = reg2._rgu[iu];
long nn1 = (long)u1 * a - (long)u2 * b + nCarry1;
long nn2 = (long)u2 * d - (long)u1 * c + nCarry2;
nCarry1 = (int)(nn1 >> kcbitUint);
nCarry2 = (int)(nn2 >> kcbitUint);
reg1._rgu[iu] = (uint)nn1;
reg2._rgu[iu] = (uint)nn2;
}
reg1.Trim();
reg2.Trim();
}
}
}
