diff options
Diffstat (limited to 'crypto/src/math/ec/Nat.cs')
| -rw-r--r-- | crypto/src/math/ec/Nat.cs | 1013 |
1 files changed, 1013 insertions, 0 deletions
diff --git a/crypto/src/math/ec/Nat.cs b/crypto/src/math/ec/Nat.cs new file mode 100644 index 000000000..17b632f26 --- /dev/null +++ b/crypto/src/math/ec/Nat.cs @@ -0,0 +1,1013 @@ +using System; +using System.Diagnostics; + +using Org.BouncyCastle.Crypto.Utilities; + +namespace Org.BouncyCastle.Math.EC +{ + internal abstract class Nat + { + private const ulong M = 0xFFFFFFFFUL; + + public static uint Add(int len, uint[] x, uint[] y, uint[] z) + { + ulong c = 0; + for (int i = 0; i < len; ++i) + { + c += (ulong)x[i] + y[i]; + z[i] = (uint)c; + c >>= 32; + } + return (uint)c; + } + + public static uint Add33At(int len, uint x, uint[] z, int zPos) + { + Debug.Assert(zPos <= (len - 2)); + ulong c = (ulong)z[zPos + 0] + x; + z[zPos + 0] = (uint)c; + c >>= 32; + c += (ulong)z[zPos + 1] + 1; + z[zPos + 1] = (uint)c; + c >>= 32; + return c == 0 ? 0 : IncAt(len, z, zPos + 2); + } + + public static uint Add33At(int len, uint x, uint[] z, int zOff, int zPos) + { + Debug.Assert(zPos <= (len - 2)); + ulong c = (ulong)z[zOff + zPos] + x; + z[zOff + zPos] = (uint)c; + c >>= 32; + c += (ulong)z[zOff + zPos + 1] + 1; + z[zOff + zPos + 1] = (uint)c; + c >>= 32; + return c == 0 ? 0 : IncAt(len, z, zOff, zPos + 2); + } + + public static uint Add33To(int len, uint x, uint[] z) + { + ulong c = (ulong)z[0] + x; + z[0] = (uint)c; + c >>= 32; + c += (ulong)z[1] + 1; + z[1] = (uint)c; + c >>= 32; + return c == 0 ? 0 : IncAt(len, z, 2); + } + + public static uint Add33To(int len, uint x, uint[] z, int zOff) + { + ulong c = (ulong)z[zOff + 0] + x; + z[zOff + 0] = (uint)c; + c >>= 32; + c += (ulong)z[zOff + 1] + 1; + z[zOff + 1] = (uint)c; + c >>= 32; + return c == 0 ? 0 : IncAt(len, z, zOff, 2); + } + + public static uint AddBothTo(int len, uint[] x, uint[] y, uint[] z) + { + ulong c = 0; + for (int i = 0; i < len; ++i) + { + c += (ulong)x[i] + y[i] + z[i]; + z[i] = (uint)c; + c >>= 32; + } + return (uint)c; + } + + public static uint AddBothTo(int len, uint[] x, int xOff, uint[] y, int yOff, uint[] z, int zOff) + { + ulong c = 0; + for (int i = 0; i < len; ++i) + { + c += (ulong)x[xOff + i] + y[yOff + i] + z[zOff + i]; + z[zOff + i] = (uint)c; + c >>= 32; + } + return (uint)c; + } + + public static uint AddDWordAt(int len, ulong x, uint[] z, int zPos) + { + Debug.Assert(zPos <= (len - 2)); + ulong c = (ulong)z[zPos + 0] + (x & M); + z[zPos + 0] = (uint)c; + c >>= 32; + c += (ulong)z[zPos + 1] + (x >> 32); + z[zPos + 1] = (uint)c; + c >>= 32; + return c == 0 ? 0 : IncAt(len, z, zPos + 2); + } + + public static uint AddDWordAt(int len, ulong x, uint[] z, int zOff, int zPos) + { + Debug.Assert(zPos <= (len - 2)); + ulong c = (ulong)z[zOff + zPos] + (x & M); + z[zOff + zPos] = (uint)c; + c >>= 32; + c += (ulong)z[zOff + zPos + 1] + (x >> 32); + z[zOff + zPos + 1] = (uint)c; + c >>= 32; + return c == 0 ? 0 : IncAt(len, z, zOff, zPos + 2); + } + + public static uint AddDWordTo(int len, ulong x, uint[] z) + { + ulong c = (ulong)z[0] + (x & M); + z[0] = (uint)c; + c >>= 32; + c += (ulong)z[1] + (x >> 32); + z[1] = (uint)c; + c >>= 32; + return c == 0 ? 0 : IncAt(len, z, 2); + } + + public static uint AddDWordTo(int len, ulong x, uint[] z, int zOff) + { + ulong c = (ulong)z[zOff + 0] + (x & M); + z[zOff + 0] = (uint)c; + c >>= 32; + c += (ulong)z[zOff + 1] + (x >> 32); + z[zOff + 1] = (uint)c; + c >>= 32; + return c == 0 ? 0 : IncAt(len, z, zOff, 2); + } + + public static uint AddTo(int len, uint[] x, uint[] z) + { + ulong c = 0; + for (int i = 0; i < len; ++i) + { + c += (ulong)x[i] + z[i]; + z[i] = (uint)c; + c >>= 32; + } + return (uint)c; + } + + public static uint AddTo(int len, uint[] x, int xOff, uint[] z, int zOff) + { + ulong c = 0; + for (int i = 0; i < len; ++i) + { + c += (ulong)x[xOff + i] + z[zOff + i]; + z[zOff + i] = (uint)c; + c >>= 32; + } + return (uint)c; + } + + public static uint AddWordAt(int len, uint x, uint[] z, int zPos) + { + Debug.Assert(zPos <= (len - 1)); + ulong c = (ulong)x + z[zPos]; + z[zPos] = (uint)c; + c >>= 32; + return c == 0 ? 0 : IncAt(len, z, zPos + 1); + } + + public static uint AddWordAt(int len, uint x, uint[] z, int zOff, int zPos) + { + Debug.Assert(zPos <= (len - 1)); + ulong c = (ulong)x + z[zOff + zPos]; + z[zOff + zPos] = (uint)c; + c >>= 32; + return c == 0 ? 0 : IncAt(len, z, zOff, zPos + 1); + } + + public static uint AddWordTo(int len, uint x, uint[] z) + { + ulong c = (ulong)x + z[0]; + z[0] = (uint)c; + c >>= 32; + return c == 0 ? 0 : IncAt(len, z, 1); + } + + public static uint AddWordTo(int len, uint x, uint[] z, int zOff) + { + ulong c = (ulong)x + z[zOff]; + z[zOff] = (uint)c; + c >>= 32; + return c == 0 ? 0 : IncAt(len, z, zOff, 1); + } + + public static void Copy(int len, uint[] x, uint[] z) + { + Array.Copy(x, 0, z, 0, len); + } + + public static uint[] Copy(int len, uint[] x) + { + uint[] z = new uint[len]; + Array.Copy(x, 0, z, 0, len); + return z; + } + + public static uint[] Create(int len) + { + return new uint[len]; + } + + public static int Dec(int len, uint[] z) + { + for (int i = 0; i < len; ++i) + { + if (--z[i] != uint.MaxValue) + { + return 0; + } + } + return -1; + } + + public static int Dec(int len, uint[] x, uint[] z) + { + int i = 0; + while (i < len) + { + uint c = x[i] - 1; + z[i] = c; + ++i; + if (c != uint.MaxValue) + { + while (i < len) + { + z[i] = x[i]; + ++i; + } + return 0; + } + } + return -1; + } + + public static int DecAt(int len, uint[] z, int zPos) + { + Debug.Assert(zPos <= len); + for (int i = zPos; i < len; ++i) + { + if (--z[i] != uint.MaxValue) + { + return 0; + } + } + return -1; + } + + public static int DecAt(int len, uint[] z, int zOff, int zPos) + { + Debug.Assert(zPos <= len); + for (int i = zPos; i < len; ++i) + { + if (--z[zOff + i] != uint.MaxValue) + { + return 0; + } + } + return -1; + } + + public static bool Eq(int len, uint[] x, uint[] y) + { + for (int i = len - 1; i >= 0; --i) + { + if (x[i] != y[i]) + { + return false; + } + } + return true; + } + + public static uint[] FromBigInteger(int bits, BigInteger x) + { + if (x.SignValue < 0 || x.BitLength > bits) + throw new ArgumentException(); + + int len = (bits + 31) >> 5; + uint[] z = Create(len); + int i = 0; + while (x.SignValue != 0) + { + z[i++] = (uint)x.IntValue; + x = x.ShiftRight(32); + } + return z; + } + + public static uint GetBit(uint[] x, int bit) + { + if (bit == 0) + { + return x[0] & 1; + } + int w = bit >> 5; + if (w < 0 || w >= x.Length) + { + return 0; + } + int b = bit & 31; + return (x[w] >> b) & 1; + } + + public static bool Gte(int len, uint[] x, uint[] y) + { + for (int i = len - 1; i >= 0; --i) + { + uint x_i = x[i], y_i = y[i]; + if (x_i < y_i) + return false; + if (x_i > y_i) + return true; + } + return true; + } + + public static uint Inc(int len, uint[] z) + { + for (int i = 0; i < len; ++i) + { + if (++z[i] != uint.MinValue) + { + return 0; + } + } + return 1; + } + + public static uint Inc(int len, uint[] x, uint[] z) + { + int i = 0; + while (i < len) + { + uint c = x[i] + 1; + z[i] = c; + ++i; + if (c != 0) + { + while (i < len) + { + z[i] = x[i]; + ++i; + } + return 0; + } + } + return 1; + } + + public static uint IncAt(int len, uint[] z, int zPos) + { + Debug.Assert(zPos <= len); + for (int i = zPos; i < len; ++i) + { + if (++z[i] != uint.MinValue) + { + return 0; + } + } + return 1; + } + + public static uint IncAt(int len, uint[] z, int zOff, int zPos) + { + Debug.Assert(zPos <= len); + for (int i = zPos; i < len; ++i) + { + if (++z[zOff + i] != uint.MinValue) + { + return 0; + } + } + return 1; + } + + public static bool IsOne(int len, uint[] x) + { + if (x[0] != 1) + { + return false; + } + for (int i = 1; i < len; ++i) + { + if (x[i] != 0) + { + return false; + } + } + return true; + } + + public static bool IsZero(int len, uint[] x) + { + if (x[0] != 0) + { + return false; + } + for (int i = 1; i < len; ++i) + { + if (x[i] != 0) + { + return false; + } + } + return true; + } + + public static void Mul(int len, uint[] x, uint[] y, uint[] zz) + { + zz[len] = (uint)MulWord(len, x[0], y, zz); + + for (int i = 1; i < len; ++i) + { + zz[i + len] = (uint)MulWordAddTo(len, x[i], y, 0, zz, i); + } + } + + public static void Mul(int len, uint[] x, int xOff, uint[] y, int yOff, uint[] zz, int zzOff) + { + zz[zzOff + len] = (uint)MulWord(len, x[xOff], y, yOff, zz, zzOff); + + for (int i = 1; i < len; ++i) + { + zz[zzOff + i + len] = (uint)MulWordAddTo(len, x[xOff + i], y, yOff, zz, zzOff + i); + } + } + + public static uint Mul31BothAdd(int len, uint a, uint[] x, uint b, uint[] y, uint[] z, int zOff) + { + ulong c = 0, aVal = (ulong)a, bVal = (ulong)b; + int i = 0; + do + { + c += aVal * x[i] + bVal * y[i] + z[zOff + i]; + z[zOff + i] = (uint)c; + c >>= 32; + } + while (++i < len); + return (uint)c; + } + + public static uint MulWord(int len, uint x, uint[] y, uint[] z) + { + ulong c = 0, xVal = (ulong)x; + int i = 0; + do + { + c += xVal * y[i]; + z[i] = (uint)c; + c >>= 32; + } + while (++i < len); + return (uint)c; + } + + public static uint MulWord(int len, uint x, uint[] y, int yOff, uint[] z, int zOff) + { + ulong c = 0, xVal = (ulong)x; + int i = 0; + do + { + c += xVal * y[yOff + i]; + z[zOff + i] = (uint)c; + c >>= 32; + } + while (++i < len); + return (uint)c; + } + + public static uint MulWordAddTo(int len, uint x, uint[] y, int yOff, uint[] z, int zOff) + { + ulong c = 0, xVal = (ulong)x; + int i = 0; + do + { + c += xVal * y[yOff + i] + z[zOff + i]; + z[zOff + i] = (uint)c; + c >>= 32; + } + while (++i < len); + return (uint)c; + } + + public static uint MulWordDwordAddAt(int len, uint x, ulong y, uint[] z, int zPos) + { + Debug.Assert(zPos <= (len - 3)); + ulong c = 0, xVal = (ulong)x; + c += xVal * (uint)y + z[zPos + 0]; + z[zPos + 0] = (uint)c; + c >>= 32; + c += xVal * (y >> 32) + z[zPos + 1]; + z[zPos + 1] = (uint)c; + c >>= 32; + c += (ulong)z[zPos + 2]; + z[zPos + 2] = (uint)c; + c >>= 32; + return c == 0 ? 0 : IncAt(len, z, zPos + 3); + } + + public static uint ShiftDownBit(int len, uint[] z, uint c) + { + int i = len; + while (--i >= 0) + { + uint next = z[i]; + z[i] = (next >> 1) | (c << 31); + c = next; + } + return c << 31; + } + + public static uint ShiftDownBit(int len, uint[] z, int zOff, uint c) + { + int i = len; + while (--i >= 0) + { + uint next = z[zOff + i]; + z[zOff + i] = (next >> 1) | (c << 31); + c = next; + } + return c << 31; + } + + public static uint ShiftDownBit(int len, uint[] x, uint c, uint[] z) + { + int i = len; + while (--i >= 0) + { + uint next = x[i]; + z[i] = (next >> 1) | (c << 31); + c = next; + } + return c << 31; + } + + public static uint ShiftDownBit(int len, uint[] x, int xOff, uint c, uint[] z, int zOff) + { + int i = len; + while (--i >= 0) + { + uint next = x[xOff + i]; + z[zOff + i] = (next >> 1) | (c << 31); + c = next; + } + return c << 31; + } + + public static uint ShiftDownBits(int len, uint[] z, int bits, uint c) + { + Debug.Assert(bits > 0 && bits < 32); + int i = len; + while (--i >= 0) + { + uint next = z[i]; + z[i] = (next >> bits) | (c << -bits); + c = next; + } + return c << -bits; + } + + public static uint ShiftDownBits(int len, uint[] z, int zOff, int bits, uint c) + { + Debug.Assert(bits > 0 && bits < 32); + int i = len; + while (--i >= 0) + { + uint next = z[zOff + i]; + z[zOff + i] = (next >> bits) | (c << -bits); + c = next; + } + return c << -bits; + } + + public static uint ShiftDownBits(int len, uint[] x, int bits, uint c, uint[] z) + { + Debug.Assert(bits > 0 && bits < 32); + int i = len; + while (--i >= 0) + { + uint next = x[i]; + z[i] = (next >> bits) | (c << -bits); + c = next; + } + return c << -bits; + } + + public static uint ShiftDownBits(int len, uint[] x, int xOff, int bits, uint c, uint[] z, int zOff) + { + Debug.Assert(bits > 0 && bits < 32); + int i = len; + while (--i >= 0) + { + uint next = x[xOff + i]; + z[zOff + i] = (next >> bits) | (c << -bits); + c = next; + } + return c << -bits; + } + + public static uint ShiftDownWord(int len, uint[] z, uint c) + { + int i = len; + while (--i >= 0) + { + uint next = z[i]; + z[i] = c; + c = next; + } + return c; + } + + public static uint ShiftUpBit(int len, uint[] z, uint c) + { + for (int i = 0; i < len; ++i) + { + uint next = z[i]; + z[i] = (next << 1) | (c >> 31); + c = next; + } + return c >> 31; + } + + public static uint ShiftUpBit(int len, uint[] z, int zOff, uint c) + { + for (int i = 0; i < len; ++i) + { + uint next = z[zOff + i]; + z[zOff + i] = (next << 1) | (c >> 31); + c = next; + } + return c >> 31; + } + + public static uint ShiftUpBit(int len, uint[] x, uint c, uint[] z) + { + for (int i = 0; i < len; ++i) + { + uint next = x[i]; + z[i] = (next << 1) | (c >> 31); + c = next; + } + return c >> 31; + } + + public static uint ShiftUpBit(int len, uint[] x, int xOff, uint c, uint[] z, int zOff) + { + for (int i = 0; i < len; ++i) + { + uint next = x[xOff + i]; + z[zOff + i] = (next << 1) | (c >> 31); + c = next; + } + return c >> 31; + } + + public static uint ShiftUpBits(int len, uint[] z, int bits, uint c) + { + Debug.Assert(bits > 0 && bits < 32); + for (int i = 0; i < len; ++i) + { + uint next = z[i]; + z[i] = (next << bits) | (c >> -bits); + c = next; + } + return c >> -bits; + } + + public static uint ShiftUpBits(int len, uint[] z, int zOff, int bits, uint c) + { + Debug.Assert(bits > 0 && bits < 32); + for (int i = 0; i < len; ++i) + { + uint next = z[zOff + i]; + z[zOff + i] = (next << bits) | (c >> -bits); + c = next; + } + return c >> -bits; + } + + public static uint ShiftUpBits(int len, uint[] x, int bits, uint c, uint[] z) + { + Debug.Assert(bits > 0 && bits < 32); + for (int i = 0; i < len; ++i) + { + uint next = x[i]; + z[i] = (next << bits) | (c >> -bits); + c = next; + } + return c >> -bits; + } + + public static uint ShiftUpBits(int len, uint[] x, int xOff, int bits, uint c, uint[] z, int zOff) + { + Debug.Assert(bits > 0 && bits < 32); + for (int i = 0; i < len; ++i) + { + uint next = x[xOff + i]; + z[zOff + i] = (next << bits) | (c >> -bits); + c = next; + } + return c >> -bits; + } + + public static void Square(int len, uint[] x, uint[] zz) + { + int extLen = len << 1; + uint c = 0; + int j = len, k = extLen; + do + { + ulong xVal = (ulong)x[--j]; + ulong p = xVal * xVal; + zz[--k] = (c << 31) | (uint)(p >> 33); + zz[--k] = (uint)(p >> 1); + c = (uint)p; + } + while (j > 0); + + for (int i = 1; i < len; ++i) + { + c = SquareWordAdd(x, i, zz); + AddWordAt(extLen, c, zz, i << 1); + } + + ShiftUpBit(extLen, zz, x[0] << 31); + } + + public static void Square(int len, uint[] x, int xOff, uint[] zz, int zzOff) + { + int extLen = len << 1; + uint c = 0; + int j = len, k = extLen; + do + { + ulong xVal = (ulong)x[xOff + --j]; + ulong p = xVal * xVal; + zz[zzOff + --k] = (c << 31) | (uint)(p >> 33); + zz[zzOff + --k] = (uint)(p >> 1); + c = (uint)p; + } + while (j > 0); + + for (int i = 1; i < len; ++i) + { + c = SquareWordAdd(x, xOff, i, zz, zzOff); + AddWordAt(extLen, c, zz, zzOff, i << 1); + } + + ShiftUpBit(extLen, zz, zzOff, x[xOff] << 31); + } + + public static uint SquareWordAdd(uint[] x, int xPos, uint[] z) + { + ulong c = 0, xVal = (ulong)x[xPos]; + int i = 0; + do + { + c += xVal * x[i] + z[xPos + i]; + z[xPos + i] = (uint)c; + c >>= 32; + } + while (++i < xPos); + return (uint)c; + } + + public static uint SquareWordAdd(uint[] x, int xOff, int xPos, uint[] z, int zOff) + { + ulong c = 0, xVal = (ulong)x[xOff + xPos]; + int i = 0; + do + { + c += xVal * (x[xOff + i] & M) + (z[xPos + zOff] & M); + z[xPos + zOff] = (uint)c; + c >>= 32; + ++zOff; + } + while (++i < xPos); + return (uint)c; + } + + public static int Sub(int len, uint[] x, uint[] y, uint[] z) + { + long c = 0; + for (int i = 0; i < len; ++i) + { + c += (long)x[i] - y[i]; + z[i] = (uint)c; + c >>= 32; + } + return (int)c; + } + + public static int Sub(int len, uint[] x, int xOff, uint[] y, int yOff, uint[] z, int zOff) + { + long c = 0; + for (int i = 0; i < len; ++i) + { + c += (long)x[xOff + i] - y[yOff + i]; + z[zOff + i] = (uint)c; + c >>= 32; + } + return (int)c; + } + public static int Sub33At(int len, uint x, uint[] z, int zPos) + { + Debug.Assert(zPos <= (len - 2)); + long c = (long)z[zPos + 0] - x; + z[zPos + 0] = (uint)c; + c >>= 32; + c += (long)z[zPos + 1] - 1; + z[zPos + 1] = (uint)c; + c >>= 32; + return c == 0 ? 0 : DecAt(len, z, zPos + 2); + } + + public static int Sub33At(int len, uint x, uint[] z, int zOff, int zPos) + { + Debug.Assert(zPos <= (len - 2)); + long c = (long)z[zOff + zPos] - x; + z[zOff + zPos] = (uint)c; + c >>= 32; + c += (long)z[zOff + zPos + 1] - 1; + z[zOff + zPos + 1] = (uint)c; + c >>= 32; + return c == 0 ? 0 : DecAt(len, z, zOff, zPos + 2); + } + + public static int Sub33From(int len, uint x, uint[] z) + { + long c = (long)z[0] - x; + z[0] = (uint)c; + c >>= 32; + c += (long)z[1] - 1; + z[1] = (uint)c; + c >>= 32; + return c == 0 ? 0 : DecAt(len, z, 2); + } + + public static int Sub33From(int len, uint x, uint[] z, int zOff) + { + long c = (long)z[zOff + 0] - x; + z[zOff + 0] = (uint)c; + c >>= 32; + c += (long)z[zOff + 1] - 1; + z[zOff + 1] = (uint)c; + c >>= 32; + return c == 0 ? 0 : DecAt(len, z, zOff, 2); + } + + public static int SubBothFrom(int len, uint[] x, uint[] y, uint[] z) + { + long c = 0; + for (int i = 0; i < len; ++i) + { + c += (long)z[i] - x[i] - y[i]; + z[i] = (uint)c; + c >>= 32; + } + return (int)c; + } + + public static int SubBothFrom(int len, uint[] x, int xOff, uint[] y, int yOff, uint[] z, int zOff) + { + long c = 0; + for (int i = 0; i < len; ++i) + { + c += (long)z[zOff + i] - x[xOff + i] - y[yOff + i]; + z[zOff + i] = (uint)c; + c >>= 32; + } + return (int)c; + } + + public static int SubDWordAt(int len, ulong x, uint[] z, int zPos) + { + Debug.Assert(zPos <= (len - 2)); + long c = (long)z[zPos + 0] - (long)(x & M); + z[zPos + 0] = (uint)c; + c >>= 32; + c += (long)z[zPos + 1] - (long)(x >> 32); + z[zPos + 1] = (uint)c; + c >>= 32; + return c == 0 ? 0 : DecAt(len, z, zPos + 2); + } + + public static int SubDWordAt(int len, ulong x, uint[] z, int zOff, int zPos) + { + Debug.Assert(zPos <= (len - 2)); + long c = (long)z[zOff + zPos] - (long)(x & M); + z[zOff + zPos] = (uint)c; + c >>= 32; + c += (long)z[zOff + zPos + 1] - (long)(x >> 32); + z[zOff + zPos + 1] = (uint)c; + c >>= 32; + return c == 0 ? 0 : DecAt(len, z, zOff, zPos + 2); + } + + public static int SubDWordFrom(int len, ulong x, uint[] z) + { + long c = (long)z[0] - (long)(x & M); + z[0] = (uint)c; + c >>= 32; + c += (long)z[1] - (long)(x >> 32); + z[1] = (uint)c; + c >>= 32; + return c == 0 ? 0 : DecAt(len, z, 2); + } + + public static int SubDWordFrom(int len, ulong x, uint[] z, int zOff) + { + long c = (long)z[zOff + 0] - (long)(x & M); + z[zOff + 0] = (uint)c; + c >>= 32; + c += (long)z[zOff + 1] - (long)(x >> 32); + z[zOff + 1] = (uint)c; + c >>= 32; + return c == 0 ? 0 : DecAt(len, z, zOff, 2); + } + + public static int SubFrom(int len, uint[] x, uint[] z) + { + long c = 0; + for (int i = 0; i < len; ++i) + { + c += (long)z[i] - x[i]; + z[i] = (uint)c; + c >>= 32; + } + return (int)c; + } + + public static int SubFrom(int len, uint[] x, int xOff, uint[] z, int zOff) + { + long c = 0; + for (int i = 0; i < len; ++i) + { + c += (long)z[zOff + i] - x[xOff + i]; + z[zOff + i] = (uint)c; + c >>= 32; + } + return (int)c; + } + + public static int SubWordAt(int len, uint x, uint[] z, int zPos) + { + Debug.Assert(zPos <= (len - 1)); + long c = (long)z[zPos] - x; + z[zPos] = (uint)c; + c >>= 32; + return c == 0 ? 0 : DecAt(len, z, zPos + 1); + } + + public static int SubWordAt(int len, uint x, uint[] z, int zOff, int zPos) + { + Debug.Assert(zPos <= (len - 1)); + long c = (long)z[zOff + zPos] - x; + z[zOff + zPos] = (uint)c; + c >>= 32; + return c == 0 ? 0 : DecAt(len, z, zOff, zPos + 1); + } + + public static int SubWordFrom(int len, uint x, uint[] z) + { + long c = (long)z[0] - x; + z[0] = (uint)c; + c >>= 32; + return c == 0 ? 0 : DecAt(len, z, 1); + } + + public static int SubWordFrom(int len, uint x, uint[] z, int zOff) + { + long c = (long)z[zOff + 0] - x; + z[zOff + 0] = (uint)c; + c >>= 32; + return c == 0 ? 0 : DecAt(len, z, zOff, 1); + } + + public static BigInteger ToBigInteger(int len, uint[] x) + { + byte[] bs = new byte[len << 2]; + for (int i = 0; i < len; ++i) + { + uint x_i = x[i]; + if (x_i != 0) + { + Pack.UInt32_To_BE(x_i, bs, (len - 1 - i) << 2); + } + } + return new BigInteger(1, bs); + } + + public static void Zero(int len, uint[] z) + { + for (int i = 0; i < len; ++i) + { + z[i] = 0; + } + } + } +} |