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added sliding window accelerator

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Ahmet Inan 2020-10-06 20:10:11 +02:00
commit b643eade0d
3 changed files with 45 additions and 15 deletions
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6
README.md
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@ -102,7 +102,11 @@ The [simple moving average](https://en.wikipedia.org/wiki/Moving_average#Simple_
* SMA1 computes the sum of its internal history buffer at each new input from scratch is and therefore very slow.
* SMA2 updates its internal sum using only the new input and the oldest value in the history buffer. It is therefore the fastest of all and works perfect with integers but suffers from drift when used with floats on sequences having a high dynamic range.
* SMA3 is based on SMA2 but uses the [Kahan summation algorithm](https://en.wikipedia.org/wiki/Kahan_summation_algorithm) to reduce drift significantly.
* SMA4 uses a tree and only update nodes that depend on the new input value and is slower than SMA3 but it has no drift.
* SMA4 uses a tree and only updates nodes that depend on the new input value and is slower than SMA3 but it has no drift.
### [swa.hh](swa.hh)
The sliding window accelerator uses a tree and only updates nodes that depend on the new input value for the pairwise reduction.
### [bip_buffer.hh](bip_buffer.hh)

19
sma.hh
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@ -7,6 +7,7 @@ Copyright 2019 Ahmet Inan <inan@aicodix.de>
#pragma once
#include "kahan.hh"
#include "swa.hh"
namespace DSP {
@ -92,24 +93,14 @@ public:
template <typename TYPE, typename VALUE, int NUM, bool NORM = true>
class SMA4
{
TYPE tree[2 * NUM];
int leaf;
struct Add { TYPE operator () (TYPE a, TYPE b) { return a + b; } };
SWA<TYPE, Add, NUM> swa;
public:
SMA4() : leaf(NUM)
{
for (int i = 0; i < 2 * NUM; ++i)
tree[i] = 0;
}
TYPE operator () (TYPE input)
{
tree[leaf] = input;
for (int child = leaf, parent = leaf / 2; parent; child = parent, parent /= 2)
tree[parent] = tree[child] + tree[child^1];
if (++leaf >= 2 * NUM)
leaf = NUM;
if (NORM)
return tree[1] / VALUE(NUM);
return tree[1];
return swa(input) / VALUE(NUM);
return swa(input);
}
};

35
swa.hh Normal file
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@ -0,0 +1,35 @@
/*
Sliding window accelerator
Copyright 2020 Ahmet Inan <inan@aicodix.de>
*/
#pragma once
namespace DSP {
template <typename TYPE, typename OP, int NUM>
class SWA
{
TYPE tree[2 * NUM];
int leaf;
OP op;
public:
SWA() : leaf(NUM)
{
for (int i = 0; i < 2 * NUM; ++i)
tree[i] = 0;
}
TYPE operator () (TYPE input)
{
tree[leaf] = input;
for (int child = leaf, parent = leaf / 2; parent; child = parent, parent /= 2)
tree[parent] = op(tree[child], tree[child^1]);
if (++leaf >= 2 * NUM)
leaf = NUM;
return tree[1];
}
};
}