This operation is fused to save a // fieldReduceOnce after the subtraction. func fieldMulSub(a, b, c fieldElement) fieldElement { x := uint32(a) * uint32(b-c+q) return fieldReduce(x) } // fieldAddMul returns a * b + c * d. This operation is fused to save a // fieldReduceOnce and a fieldReduce. func fieldAddMul(a, b, c, d fieldElement) fieldElement { x := uint32(a) * uint32(b) x += uint32(c) * uint32(d) return fieldReduce(x) } // compress maps a field element uniformly to the range 0 to 2ᵈ-1, according...