shifts.fj

// ---------- Logical Shifts


ns bit {
    // Complexity: n(2@-1)
    //   x[:n] >>= 1
    def shr n, x {
        .shr n, 1, x
    }

    // Complexity: n(2@-1)
    //   x[:n] >>= times
    // times is a constant.
    def shr n, times, x {
        rep(n-times, i) .mov x+i*dw, x+(i+times)*dw
        .zero times, x+(n-times)*dw
    }

    // Complexity: n(2@-1)
    //   x[:n] >>= times (arithmetic shift right)
    // times is a constant.
    def shra n, times, x {
        rep(n-times, i) .mov x+i*dw, x+(i+times)*dw
        rep(times-1, i) .mov x+(n-1-(i+1))*dw, x+(n-1)*dw
    }


    // Complexity: n(2@-1)
    //   x[:n] <<= 1
    def shl n, x {
        .shl n, 1, x
    }

    // Complexity: n(2@-1)
    //   x[:n] <<= times
    // times is a constant.
    def shl n, times, x {
        rep(n-times, i) .mov x+(n-1-i)*dw, x+(n-1-i-times)*dw
        .zero times, x
    }


    // Complexity: n(2@-1)
    //   rotate x[:n] right by 1-bit
    def ror n, x @ temp_bit {
        .mov temp_bit, x
        rep(n-1, i) .mov x+i*dw, x+(i+1)*dw
        .mov x+(n-1)*dw, temp_bit
        stl.skip
      temp_bit:
        .bit
    }


    // Complexity: n(2@-1)
    //   rotate x[:n] left by 1-bit
    def rol n, x @ temp_bit {
        .mov temp_bit, x+(n-1)*dw
        rep(n-1, i) .mov x+(n-1-i)*dw, x+(n-1-i-1)*dw
        .mov x, temp_bit
        stl.skip
      temp_bit:
        .bit
    }
}