static void select(out GroupElementPreComp t, int pos, sbyte b)
{
GroupElementPreComp minust;
byte bnegative = negative(b);
byte babs = (byte)(b - (((-bnegative) & b) << 1));
ge_precomp_0(out t);
var table = LookupTables.Base[pos];
cmov(ref t, ref table[0], equal(babs, 1));
cmov(ref t, ref table[1], equal(babs, 2));
cmov(ref t, ref table[2], equal(babs, 3));
cmov(ref t, ref table[3], equal(babs, 4));
cmov(ref t, ref table[4], equal(babs, 5));
cmov(ref t, ref table[5], equal(babs, 6));
cmov(ref t, ref table[6], equal(babs, 7));
cmov(ref t, ref table[7], equal(babs, 8));
minust.yplusx = t.yminusx;
minust.yminusx = t.yplusx;
FieldOperations.fe_neg(out minust.xy2d, ref t.xy2d);
cmov(ref t, ref minust, bnegative);
}
/*
* r = p - q
*/
internal static void ge_msub(out GroupElementP1P1 r, ref GroupElementP3 p, ref GroupElementPreComp q)
{
FieldElement t0;
/* qhasm: enter ge_msub */
/* qhasm: fe X1 */
/* qhasm: fe Y1 */
/* qhasm: fe Z1 */
/* qhasm: fe T1 */
/* qhasm: fe ypx2 */
/* qhasm: fe ymx2 */
/* qhasm: fe xy2d2 */
/* qhasm: fe X3 */
/* qhasm: fe Y3 */
/* qhasm: fe Z3 */
/* qhasm: fe T3 */
/* qhasm: fe YpX1 */
/* qhasm: fe YmX1 */
/* qhasm: fe A */
/* qhasm: fe B */
/* qhasm: fe C */
/* qhasm: fe D */
/* qhasm: YpX1 = Y1+X1 */
/* asm 1: fe_add(>YpX1=fe#1,<Y1=fe#12,<X1=fe#11); */
/* asm 2: fe_add(>YpX1=r.X,<Y1=p.Y,<X1=p.X); */
FieldOperations.fe_add(out r.X, ref p.Y, ref p.X);
/* qhasm: YmX1 = Y1-X1 */
/* asm 1: fe_sub(>YmX1=fe#2,<Y1=fe#12,<X1=fe#11); */
/* asm 2: fe_sub(>YmX1=r.Y,<Y1=p.Y,<X1=p.X); */
FieldOperations.fe_sub(out r.Y, ref p.Y, ref p.X);
/* qhasm: A = YpX1*ymx2 */
/* asm 1: fe_mul(>A=fe#3,<YpX1=fe#1,<ymx2=fe#16); */
/* asm 2: fe_mul(>A=r.Z,<YpX1=r.X,<ymx2=q.yminusx); */
FieldOperations.fe_mul(out r.Z, ref r.X, ref q.yminusx);
/* qhasm: B = YmX1*ypx2 */
/* asm 1: fe_mul(>B=fe#2,<YmX1=fe#2,<ypx2=fe#15); */
/* asm 2: fe_mul(>B=r.Y,<YmX1=r.Y,<ypx2=q.yplusx); */
FieldOperations.fe_mul(out r.Y, ref r.Y, ref q.yplusx);
/* qhasm: C = xy2d2*T1 */
/* asm 1: fe_mul(>C=fe#4,<xy2d2=fe#17,<T1=fe#14); */
/* asm 2: fe_mul(>C=r.T,<xy2d2=q.xy2d,<T1=p.T); */
FieldOperations.fe_mul(out r.T, ref q.xy2d, ref p.T);
/* qhasm: D = 2*Z1 */
/* asm 1: fe_add(>D=fe#5,<Z1=fe#13,<Z1=fe#13); */
/* asm 2: fe_add(>D=t0,<Z1=p.Z,<Z1=p.Z); */
FieldOperations.fe_add(out t0, ref p.Z, ref p.Z);
/* qhasm: X3 = A-B */
/* asm 1: fe_sub(>X3=fe#1,<A=fe#3,<B=fe#2); */
/* asm 2: fe_sub(>X3=r.X,<A=r.Z,<B=r.Y); */
FieldOperations.fe_sub(out r.X, ref r.Z, ref r.Y);
/* qhasm: Y3 = A+B */
/* asm 1: fe_add(>Y3=fe#2,<A=fe#3,<B=fe#2); */
/* asm 2: fe_add(>Y3=r.Y,<A=r.Z,<B=r.Y); */
FieldOperations.fe_add(out r.Y, ref r.Z, ref r.Y);
/* qhasm: Z3 = D-C */
/* asm 1: fe_sub(>Z3=fe#3,<D=fe#5,<C=fe#4); */
/* asm 2: fe_sub(>Z3=r.Z,<D=t0,<C=r.T); */
FieldOperations.fe_sub(out r.Z, ref t0, ref r.T);
/* qhasm: T3 = D+C */
/* asm 1: fe_add(>T3=fe#4,<D=fe#5,<C=fe#4); */
/* asm 2: fe_add(>T3=r.T,<D=t0,<C=r.T); */
FieldOperations.fe_add(out r.T, ref t0, ref r.T);
/* qhasm: return */
}
internal static void ge_precomp_0(out GroupElementPreComp h)
{
FieldOperations.fe_1(out h.yplusx);
FieldOperations.fe_1(out h.yminusx);
FieldOperations.fe_0(out h.xy2d);
}
static void cmov(ref GroupElementPreComp t, ref GroupElementPreComp u, byte b)
{
FieldOperations.fe_cmov(ref t.yplusx, ref u.yplusx, b);
FieldOperations.fe_cmov(ref t.yminusx, ref u.yminusx, b);
FieldOperations.fe_cmov(ref t.xy2d, ref u.xy2d, b);
}
