private static void ge_msub(ref ge_p1p1 r, ge_p3 p, ge_precomp q)
{
Span <int> t0 = stackalloc int[10];
ge_p1p1 result = new()
{
X = stackalloc int[10],
Y = stackalloc int[10],
Z = stackalloc int[10],
T = stackalloc int[10],
};
r.X.CopyTo(result.X);
r.Y.CopyTo(result.Y);
r.Z.CopyTo(result.Z);
r.T.CopyTo(result.T);
fe_add(ref result.X, p.Y, p.X);
fe_sub(ref result.Y, p.Y, p.X);
fe_mul(ref result.Z, result.X, q.yminusx);
fe_mul(ref result.Y, result.Y, q.yplusx);
fe_mul(ref result.T, q.xy2d, p.T);
fe_add(ref t0, p.Z, p.Z);
fe_sub(ref result.X, result.Z, result.Y);
fe_add(ref result.Y, result.Z, result.Y);
fe_sub(ref result.Z, t0, result.T);
fe_add(ref result.T, t0, result.T);
result.X.CopyTo(r.X);
result.Y.CopyTo(r.Y);
result.Z.CopyTo(r.Z);
result.T.CopyTo(r.T);
}
private static void select(ref ge_precomp t, int pos, sbyte b)
{
ge_precomp result = new()
{
yminusx = stackalloc int[10],
yplusx = stackalloc int[10],
xy2d = stackalloc int[10],
};
ge_precomp minust = new()
{
yminusx = stackalloc int[10],
yplusx = stackalloc int[10],
xy2d = stackalloc int[10],
};
ge_precomp p0 = new()
{
yminusx = stackalloc int[10],
yplusx = stackalloc int[10],
xy2d = stackalloc int[10],
};
byte bnegative = negative(b);
byte babs = (byte)(b - (((-bnegative) & b) << 1));
fe_1(ref result.yplusx);
fe_1(ref result.yminusx);
fe_0(ref result.xy2d);
fe_0(ref minust.yplusx);
fe_0(ref minust.yminusx);
fe_0(ref minust.xy2d);
GetPrecompBase(pos, 0, ref p0);
cmov(ref result, p0, equal((sbyte)babs, 1));
GetPrecompBase(pos, 1, ref p0);
cmov(ref result, p0, equal((sbyte)babs, 2));
GetPrecompBase(pos, 2, ref p0);
cmov(ref result, p0, equal((sbyte)babs, 3));
GetPrecompBase(pos, 3, ref p0);
cmov(ref result, p0, equal((sbyte)babs, 4));
GetPrecompBase(pos, 4, ref p0);
cmov(ref result, p0, equal((sbyte)babs, 5));
GetPrecompBase(pos, 5, ref p0);
cmov(ref result, p0, equal((sbyte)babs, 6));
GetPrecompBase(pos, 6, ref p0);
cmov(ref result, p0, equal((sbyte)babs, 7));
GetPrecompBase(pos, 7, ref p0);
cmov(ref result, p0, equal((sbyte)babs, 8));
fe_copy(ref minust.yminusx, result.yplusx);
fe_copy(ref minust.yplusx, result.yminusx);
fe_neg(ref minust.xy2d, result.xy2d);
cmov(ref result, minust, bnegative);
result.yplusx.CopyTo(t.yplusx);
result.yminusx.CopyTo(t.yminusx);
result.xy2d.CopyTo(t.xy2d);
}
private static void cmov(ref ge_precomp t, ge_precomp u, byte b)
{
Span <int> yplusx = stackalloc int[10];
Span <int> yminusx = stackalloc int[10];
Span <int> xy2d = stackalloc int[10];
t.yplusx.CopyTo(yplusx);
t.yminusx.CopyTo(yminusx);
t.xy2d.CopyTo(xy2d);
fe_cmov(ref yplusx, u.yplusx, b);
fe_cmov(ref yminusx, u.yminusx, b);
fe_cmov(ref xy2d, u.xy2d, b);
yplusx.CopyTo(t.yplusx);
yminusx.CopyTo(t.yminusx);
xy2d.CopyTo(t.xy2d);
}
