Function mul32 [src]

Multiply a field element with a small (32-bit) integer

Prototype

pub inline fn mul32(a: Fe, comptime n: u32) Fe

Parameters

a: Fen: u32

Source

  pub inline fn mul32(a: Fe, comptime n: u32) Fe {
    const sn = @as(u128, @intCast(n));
    var fe: Fe = undefined;
    var x: u128 = 0;
    comptime var i = 0;
    inline while (i < 5) : (i += 1) {
        x = a.limbs[i] * sn + (x >> 51);
        fe.limbs[i] = @as(u64, @truncate(x)) & MASK51;
    }
    fe.limbs[0] += @as(u64, @intCast(x >> 51)) * 19;

    return fe;
}  