ardupilot/libraries/AP_Buffer/AP_Buffer.cpp

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2013-05-29 20:53:15 -03:00
// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/// @file AP_Buffer.h
/// @brief fifo buffer template class
#include <AP_Buffer.h>
#include <stdint.h>
// Constructor
template <class T, uint8_t SIZE>
AP_Buffer<T,SIZE>::AP_Buffer() :
_num_items(0)
{
// clear the buffer
clear();
}
// clear - removes all points from the curve
template <class T, uint8_t SIZE>
void AP_Buffer<T,SIZE>::clear() {
// clear the curve
_num_items = 0;
_head = 0;
}
// add - adds an item to the buffer. returns TRUE if successfully added
template <class T, uint8_t SIZE>
void AP_Buffer<T,SIZE>::add( T item )
{
// determine position of new item
uint8_t tail = _head + _num_items;
if( tail >= SIZE ) {
tail -= SIZE;
}
// add item to buffer
_buff[tail] = item;
// increment number of items
if( _num_items < SIZE ) {
_num_items++;
}else{
// no room for new items so drop oldest item
_head++;
if( _head >= SIZE ) {
_head = 0;
}
}
}
// get - returns the next value in the buffer
template <class T, uint8_t SIZE>
T AP_Buffer<T,SIZE>::get()
{
T result;
// return zero if buffer is empty
if( _num_items == 0 ) {
return 0;
}
// get next value in buffer
result = _buff[_head];
// increment to next point
_head++;
if( _head >= SIZE )
_head = 0;
// reduce number of items
_num_items--;
// return item
return result;
}
// peek - check what the next value in the buffer is but don't pull it off
template <class T, uint8_t SIZE>
T AP_Buffer<T,SIZE>::peek(uint8_t position) const
{
uint8_t j = _head+position;
// return zero if position is out of range
if( position >= _num_items ) {
return 0;
}
// wrap around if necessary
if( j >= SIZE )
j -= SIZE;
// return desired value
return _buff[j];
}
template float AP_Buffer<float,5>::peek(uint8_t position) const;
template AP_Buffer<float, 5>::AP_Buffer();
template void AP_Buffer<float, 5>::clear();
template void AP_Buffer<float, 5>::add(float);
template float AP_Buffer<float,15>::peek(uint8_t position) const;
template AP_Buffer<float, 15>::AP_Buffer();
template void AP_Buffer<float, 15>::clear();
template void AP_Buffer<float, 15>::add(float);