shiftRightBy51(r3) c4 := shiftRightBy51(r4) rr0 := r0.lo&maskLow51Bits + mul19(c4) rr1 := r1.lo&maskLow51Bits + c0 rr2 := r2.lo&maskLow51Bits + c1 rr3 := r3.lo&maskLow51Bits + c2 rr4 := r4.lo&maskLow51Bits + c3 v.l0 = rr0&maskLow51Bits + mul19(rr4>>51) v.l1 = rr1&maskLow51Bits + rr0>>51 v.l2 = rr2&maskLow51Bits + rr1>>51 v.l3 = rr3&maskLow51Bits + rr2>>51 v.l4 = rr4&maskLow51Bits + rr3>>51 } // carryPropagate brings the limbs below 52 bits by applying the reduction // identity (a * 2²⁵⁵ + b = a * 19 + b) to the l4...

r0.lo&maskLow51Bits + c4*19 rr1 := r1.lo&maskLow51Bits + c0 rr2 := r2.lo&maskLow51Bits + c1 rr3 := r3.lo&maskLow51Bits + c2 rr4 := r4.lo&maskLow51Bits + c3 // Now all coefficients fit into 64-bit registers but are still too large to // be passed around as an Element. We therefore do one last carry chain, // where the carries will be small enough to fit in the wiggle room above 2⁵¹. *v = Element{rr0, rr1, rr2, rr3, rr4} v.carryPropagate() } func feSquareGeneric(v, a *Element) { l0 := a.l0 l1 := a.l1 l2...