Function mul [src]

Multiply two field elements

Prototype

pub fn mul(a: Fe, b: Fe) callconv(bloaty_inline) Fe

Parameters

a: Feb: Fe

Source

  pub fn mul(a: Fe, b: Fe) callconv(bloaty_inline) Fe {
    var ax: [5]u128 = undefined;
    var bx: [5]u128 = undefined;
    var a19: [5]u128 = undefined;
    var r: [5]u128 = undefined;
    comptime var i = 0;
    inline while (i < 5) : (i += 1) {
        ax[i] = @as(u128, @intCast(a.limbs[i]));
        bx[i] = @as(u128, @intCast(b.limbs[i]));
    }
    i = 1;
    inline while (i < 5) : (i += 1) {
        a19[i] = 19 * ax[i];
    }
    r[0] = ax[0] * bx[0] + a19[1] * bx[4] + a19[2] * bx[3] + a19[3] * bx[2] + a19[4] * bx[1];
    r[1] = ax[0] * bx[1] + ax[1] * bx[0] + a19[2] * bx[4] + a19[3] * bx[3] + a19[4] * bx[2];
    r[2] = ax[0] * bx[2] + ax[1] * bx[1] + ax[2] * bx[0] + a19[3] * bx[4] + a19[4] * bx[3];
    r[3] = ax[0] * bx[3] + ax[1] * bx[2] + ax[2] * bx[1] + ax[3] * bx[0] + a19[4] * bx[4];
    r[4] = ax[0] * bx[4] + ax[1] * bx[3] + ax[2] * bx[2] + ax[3] * bx[1] + ax[4] * bx[0];

    return _carry128(&r);
}  