138 lines
2.6 KiB
C++
138 lines
2.6 KiB
C++
#pragma once
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#include <stdexcept>
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#include <stdlib.h>
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#include <cstdint>
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#include <vector>
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/*
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This file defines a simple "RollingBuffer" class, based on the
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implementation of SampleBuffer in ncmpcpp.
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*/
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template<class T>
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struct RollingBuffer {
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public:
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typedef typename std::vector<T>::iterator Iterator;
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RollingBuffer() : m_offset(0) { }
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void put(Iterator begin, Iterator end);
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size_t get(size_t elems, std::vector<T> &dest);
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void resize(size_t n);
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void clear();
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size_t size() const;
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const std::vector<T> &buffer() const;
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private:
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size_t m_offset;
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std::vector<T> m_buffer;
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};
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template <class T>
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void RollingBuffer<T>::put(
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RollingBuffer::Iterator begin,
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RollingBuffer::Iterator end
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) {
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// How many elements to put
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size_t elems = end - begin;
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if (elems > m_buffer.size()) {
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throw std::out_of_range("Size of the buffer is smaller than the amount of elements");
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}
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// How much space we have for new elements
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size_t free_elems = m_buffer.size() - m_offset;
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// If we don't have enough free space,
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// make more by moving the buffer forwards.
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if (elems > free_elems) {
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size_t to_remove = elems - free_elems;
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std::copy(
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m_buffer.begin() + to_remove,
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m_buffer.end() - free_elems,
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m_buffer.begin()
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);
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m_offset -= to_remove;
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}
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// Add new elements to buffer
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std::copy(begin, end, m_buffer.begin() + m_offset);
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m_offset += elems;
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}
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template <class T>
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size_t RollingBuffer<T>::get(
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size_t elems,
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std::vector<T> &dest
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) {
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// elems: how many samples to get
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// dest: where to put them
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// (m_offset == 0) => we have no data
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if (m_offset == 0) {
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return 0;
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}
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// If too many elements are requested,
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// give as much as we can.
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if (elems > m_offset) {
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elems = m_offset;
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}
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if (elems >= dest.size()) {
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// If dest is smaller than request size,
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// discard earlier elements to fit.
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size_t elems_lost = elems - dest.size();
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std::copy(m_buffer.begin() + elems_lost, m_buffer.begin() + elems, dest.begin());
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} else {
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// otherwise, copy samples to the destination buffer.
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std::copy(dest.begin() + elems, dest.end(), dest.begin());
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std::copy(m_buffer.begin(), m_buffer.begin() + elems, dest.end() - elems);
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}
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// Remove elements from the internal buffer.
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std::copy(m_buffer.begin() + elems, m_buffer.begin() + m_offset, m_buffer.begin());
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m_offset -= elems;
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return elems;
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}
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template <class T>
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void RollingBuffer<T>::resize(size_t n) {
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m_buffer.resize(n);
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clear();
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}
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template <class T>
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void RollingBuffer<T>::clear() {
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m_offset = 0;
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}
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template <class T>
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size_t RollingBuffer<T>::size() const {
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return m_offset;
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}
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template <class T>
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const std::vector<T> &RollingBuffer<T>::buffer() const {
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return m_buffer;
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}
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