it("should concat Float32 arrays", () => {
   const a = new Float32Array([1, 2])
   const b = new Float32Array([3, 4])
   const r = typed_array.concat(a, b)
   expect(r).to.be.instanceof(Float32Array)
   expect(r).to.be.deep.equal(new Float32Array([1, 2, 3, 4]))
 })

export function stream_to_column(col: Arrayable, new_col: Arrayable, rollover?: number): Arrayable {
  if (isArray(col)) {
    const result = col.concat(new_col)

    if (rollover != null && result.length > rollover)
      return result.slice(-rollover)
    else
      return result
  } else if (isTypedArray(col)) {
    const total_len = col.length + new_col.length

    // handle rollover case for typed arrays
    if (rollover != null && total_len > rollover) {
      const start = total_len - rollover
      const end = col.length

      // resize col if it is shorter than the rollover length
      let result: TypedArray
      if (col.length < rollover) {
        result = new ((col as any).constructor)(rollover)
        result.set(col, 0)
      } else
        result = col

      // shift values in original col to accommodate new_col
      for (let i = start, endi = end; i < endi; i++) {
        result[i-start] = result[i]
      }

      // update end values in col with new_col
      for (let i = 0, endi = new_col.length; i < endi; i++) {
        result[i+(end-start)] = new_col[i]
      }

      return result
    } else {
      const tmp = new ((col as any).constructor)(new_col)
      return typed_array.concat(col, tmp)
    }
  } else
    throw new Error("unsupported array types")
}