mul: function()

in src/ecp.js [1119:1210]
79 lines of code
10 McCabe index (conditional complexity)

        mul: function(e) {
            var P, D, R0, R1, mt, t, Q, C, W, w,
                i, b, nb, s, ns;

            if (e.iszilch() || this.is_infinity()) {
                return new ECP();
            }

            P = new ECP();

            if (ECP.CURVETYPE == ECP.MONTGOMERY) { /* use ladder */
                D = new ECP();
                R0 = new ECP();
                R0.copy(this);
                R1 = new ECP();
                R1.copy(this);
                R1.dbl();
                D.copy(this);
                D.affine();
                nb = e.nbits();
                for (i = nb - 2; i >= 0; i--) {
                    b = e.bit(i);
                    P.copy(R1);
                    P.dadd(R0, D);

                    R0.cswap(R1, b);
                    R1.copy(P);
                    R0.dbl();
                    R0.cswap(R1, b);
                }
                P.copy(R0);
            } else {
                // fixed size windows
                mt = new ctx.BIG();
                t = new ctx.BIG();
                Q = new ECP();
                C = new ECP();
                W = [];
                w = [];

                // precompute table
                Q.copy(this);
                Q.dbl();
                W[0] = new ECP();
                W[0].copy(this);

                for (i = 1; i < 8; i++) {
                    W[i] = new ECP();
                    W[i].copy(W[i - 1]);
                    W[i].add(Q);
                }

                // make exponent odd - add 2P if even, P if odd
                t.copy(e);
                s = t.parity();
                t.inc(1);
                t.norm();
                ns = t.parity();
                mt.copy(t);
                mt.inc(1);
                mt.norm();
                t.cmove(mt, s);
                Q.cmove(this, ns);
                C.copy(Q);

                nb = 1 + Math.floor((t.nbits() + 3) / 4);

                // convert exponent to signed 4-bit window
                for (i = 0; i < nb; i++) {
                    w[i] = (t.lastbits(5) - 16);
                    t.dec(w[i]);
                    t.norm();
                    t.fshr(4);
                }
                w[nb] = t.lastbits(5);

                P.copy(W[Math.floor((w[nb] - 1) / 2)]);
                for (i = nb - 1; i >= 0; i--) {
                    Q.select(W, w[i]);
                    P.dbl();
                    P.dbl();
                    P.dbl();
                    P.dbl();
                    P.add(Q);
                }
                P.sub(C);
            }

            P.affine();

            return P;
        },