1 #!/usr/bin/env python

     2 # -*- coding: utf-8 -*-

     3 

     4 # This file is part of Beremiz

     5 # Copyright (C) 2021: Edouard TISSERANT

     6 #

     7 # See COPYING file for copyrights details.

     8 

     9 # Based on Eelco Hoogendoorn stackoverflow answer about RingBuffer with numpy

    10 

    11 import numpy as np

    12 

    13 

    14 class RingBuffer(object):

    15     def __init__(self, width=None, size=65536, padding=None):

    16         self.size = size

    17         self.padding = size if padding is None else padding

    18         shape = (self.size+self.padding,)

    19         if width :

    20             shape += (width,)

    21         self.buffer = np.zeros(shape)

    22         self.counter = 0

    23         self.full = False

    24 

    25     def append(self, data):

    26         """this is an O(n) operation"""

    27         data = data[-self.padding:]

    28         n = len(data)

    29         if self.remaining < n: self.compact()

    30         self.buffer[self.counter+self.size:][:n] = data

    31         self.counter += n

    32 

    33     @property

    34     def count(self):

    35         return self.counter if not self.full else self.size

    36 

    37     @property

    38     def remaining(self):

    39         return self.padding-self.counter

    40 

    41     @property

    42     def view(self):

    43         """this is always an O(1) operation"""

    44         return self.buffer[self.counter:][:self.size]

    45 

    46     def compact(self):

    47         """

    48         note: only when this function is called, is an O(size) performance hit incurred,

    49         and this cost is amortized over the whole padding space

    50         """

    51         print 'compacting'

    52         self.buffer[:self.size] = self.view

    53         self.counter = 0

    54         self.full = True

    55