Class: WSK::Model::CachedBufferReader

Inherits:
Object
  • Object
show all
Defined in:
lib/WSK/Model/CachedBufferReader.rb

Overview

Class to be inherited to define the following virtual methods:

  • read_buffer(iIdxStart, iIdxEnd) -> Buffer

  • extract_sub_buffer(iBuffer, iIdxStart, iIdxEnd) -> Buffer

  • get_nbr_samples_per_buffer -> Integer (number of samples in 1 buffer)

  • get_nbr_samples -> Integer (total number of samples)

Direct Known Subclasses

RawReader, WaveReader

Instance Method Summary collapse

Constructor Details

#initialize ⇒ CachedBufferReader

Constructor



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# File 'lib/WSK/Model/CachedBufferReader.rb', line 18

def initialize
  @NbrSamples = get_nbr_samples
  @NbrSamplesPerBuffer = get_nbr_samples_per_buffer
  # The position of the first sample of the buffer
  # Integer
  @IdxStartBufferSample = nil
  # The position of the last sample of the buffer
  # Integer
  @IdxEndBufferSample = nil
  # The buffer itself
  @Buffer = nil
end

Instance Method Details

#each_buffer(iIdxStartSample = 0, iIdxEndSample = @NbrSamples-1, iOptions = {}) ⇒ Object

Iterate through the buffers.

Parameters

  • iIdxStartSample (Integer): Index of the first sample to begin with [optional = 0]

  • iIdxEndSample (Integer): Index of the last sample to end with [optional = @NbrSamples-1]

  • iOptions (map<Symbol,Object>): Additional options [optional = {}]:

    • :nbr_samples_prefetch (Integer): Specify a number of samples to effectively read if the data needs to be accessed. This number will always be minored by the number of samples to read and majored by the number of samples per buffer. [optional = 0]

  • CodeBlock: The code called for each iteration:

    • iBuffer (String): The buffer

    • iNbrSamples (Integer): The number of samples in this buffer



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# File 'lib/WSK/Model/CachedBufferReader.rb', line 41

def each_buffer(iIdxStartSample = 0, iIdxEndSample = @NbrSamples-1, iOptions = {})
  lNbrSamplesPrefetch = iOptions[:nbr_samples_prefetch]
  if (lNbrSamplesPrefetch == nil)
    lNbrSamplesPrefetch = 0
  end
  lIdxFirstSample = iIdxStartSample
  while (lIdxFirstSample <= iIdxEndSample)
    lIdxLastSample = lIdxFirstSample+@NbrSamplesPerBuffer
    if (lIdxLastSample > iIdxEndSample)
      lIdxLastSample = iIdxEndSample
    end
    # Compute the last sample to prefetch
    lIdxLastSamplePrefetch = lIdxFirstSample + lNbrSamplesPrefetch
    if (lIdxLastSamplePrefetch < lIdxLastSample)
      lIdxLastSamplePrefetch = lIdxLastSample
    elsif (lIdxLastSamplePrefetch > lIdxFirstSample+@NbrSamplesPerBuffer)
      lIdxLastSamplePrefetch = lIdxFirstSample+@NbrSamplesPerBuffer
    end
    prepare_buffer(lIdxFirstSample, lIdxLastSample, lIdxFirstSample, lIdxLastSamplePrefetch)
    # Check if we need to return a sub-copy of the buffer
    lBuffer = []
    if ((lIdxFirstSample == @IdxStartBufferSample) and
        (lIdxLastSample == @IdxEndBufferSample))
      lBuffer = @Buffer
    else
      lBuffer = extract_sub_buffer(@Buffer, lIdxFirstSample - @IdxStartBufferSample, lIdxLastSample - @IdxStartBufferSample)
    end
    # Call client code
    yield(lBuffer, lIdxLastSample - lIdxFirstSample + 1)
    lIdxFirstSample = lIdxLastSample+1
  end
end

#each_reverse_buffer(iIdxStartSample = 0, iIdxEndSample = @NbrSamples-1, iOptions = {}) ⇒ Object

Iterate through the buffers in reverse order.

Parameters

  • iIdxStartSample (Integer): Index of the first sample to begin with [optional = 0]

  • iIdxEndSample (Integer): Index of the last sample to end with [optional = @NbrSamples-1]

  • iOptions (map<Symbol,Object>): Additional options [optional = {}]:

    • :nbr_samples_prefetch (Integer): Specify a number of samples to effectively read if the data needs to be accessed. This number will always be minored by the number of samples to read and majored by the number of samples per buffer. [optional = 0]

  • CodeBlock: The code called for each iteration:

    • iBuffer (String): The buffer

    • iNbrSamples (Integer): The number of samples in this buffer



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# File 'lib/WSK/Model/CachedBufferReader.rb', line 84

def each_reverse_buffer(iIdxStartSample = 0, iIdxEndSample = @NbrSamples-1, iOptions = {})
  lNbrSamplesPrefetch = iOptions[:nbr_samples_prefetch]
  if (lNbrSamplesPrefetch == nil)
    lNbrSamplesPrefetch = 0
  end
  lIdxLastSample = iIdxEndSample
  while (lIdxLastSample >= iIdxStartSample)
    lIdxFirstSample = lIdxLastSample-@NbrSamplesPerBuffer
    if (lIdxFirstSample < iIdxStartSample)
      lIdxFirstSample = iIdxStartSample
    end
    # Compute the first sample to prefetch
    lIdxFirstSamplePrefetch = lIdxLastSample - lNbrSamplesPrefetch
    if (lIdxFirstSamplePrefetch > lIdxFirstSample)
      lIdxFirstSamplePrefetch = lIdxFirstSample
    elsif (lIdxFirstSamplePrefetch < lIdxLastSample-@NbrSamplesPerBuffer)
      lIdxFirstSamplePrefetch = lIdxLastSample-@NbrSamplesPerBuffer
    end
    prepare_buffer(lIdxFirstSample, lIdxLastSample, lIdxFirstSamplePrefetch, lIdxLastSample)
    # Check if we need to return a sub-copy of the buffer
    lBuffer = []
    if ((lIdxFirstSample == @IdxStartBufferSample) and
        (lIdxLastSample == @IdxEndBufferSample))
      lBuffer = @Buffer
    else
      lBuffer = extract_sub_buffer(@Buffer, lIdxFirstSample - @IdxStartBufferSample, lIdxLastSample - @IdxStartBufferSample)
    end
    # Call client code
    yield(lBuffer, lIdxLastSample - lIdxFirstSample + 1)
    lIdxLastSample = lIdxFirstSample-1
  end
end

#get_current_buffer ⇒ Object

Get the current buffer

Return

  • Object: The current buffer

  • Integer: The first sample of the buffer

  • Integer: The last sample of the buffer



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# File 'lib/WSK/Model/CachedBufferReader.rb', line 143

def get_current_buffer
  return @Buffer, @IdxStartBufferSample, @IdxEndBufferSample
end

#prepare_buffer(iIdxStartSample, iIdxEndSample, iIdxStartSamplePrefetch = iIdxStartSample, iIdxEndSamplePrefetch = iIdxEndSample) ⇒ Object

Ensure that a given samples range is loaded in the buffer. Use the caching mechanism if needed. The buffer might contain more samples than desired.

Parameters

  • iIdxStartSample (Integer): Index of the first sample to begin with [optional = 0]

  • iIdxEndSample (Integer): Index of the last sample to end with [optional = @NbrSamples-1]

  • iIdxStartSamplePrefetch (Integer): Specify the first sample to effectively read if the data needs to be accessed. [optional = iIdxStartSample]

  • iIdxEndSamplePrefetch (Integer): Specify the last sample to effectively read if the data needs to be accessed. [optional = iIdxEndSample]



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# File 'lib/WSK/Model/CachedBufferReader.rb', line 126

def prepare_buffer(iIdxStartSample, iIdxEndSample, iIdxStartSamplePrefetch = iIdxStartSample, iIdxEndSamplePrefetch = iIdxEndSample)
  if ((@Buffer == nil) or
      (iIdxStartSample < @IdxStartBufferSample) or
      (iIdxEndSample > @IdxEndBufferSample))
    # Read all from the data
    @Buffer = read_buffer(iIdxStartSamplePrefetch, iIdxEndSamplePrefetch)
    @IdxStartBufferSample = iIdxStartSamplePrefetch
    @IdxEndBufferSample = iIdxEndSamplePrefetch
  end
end