From 53ed2f1de35f29b6177b4a2811b6ab2bf8bea72c Mon Sep 17 00:00:00 2001
From: Pauli Virtanen <pauli.t.virtanen@jyu.fi>
Date: Wed, 3 Aug 2022 16:39:59 +0300
Subject: [PATCH] array: use pointers, not offsets
---
src/array.hpp | 55 ++++++++++++++++++++-------------------------------
src/main.cpp | 4 ++--
2 files changed, 23 insertions(+), 36 deletions(-)
diff --git a/src/array.hpp b/src/array.hpp
index 575be9b..e223b14 100644
--- a/src/array.hpp
+++ b/src/array.hpp
@@ -90,19 +90,16 @@ namespace detail
class fixed_base
{
protected:
- size_t offset_;
-
- template <typename Storage>
- void data_bounds_check(Storage& data) const
+ void data_bounds_check(size_t size) const
{
#ifndef NO_BOUNDS_CHECK
- if (Shape::size > data.size())
+ if (Shape::size > size)
throw std::out_of_range("data array too small");
#endif
- }
+ }
public:
- fixed_base(size_t offset=0) : offset_(offset)
+ fixed_base()
{
static_assert(Shape::fixed, "array shape must be compile-time fixed");
}
@@ -112,7 +109,6 @@ namespace detail
constexpr std::array<size_t, Shape::ndim> shape() const { return Shape::shape(); }
constexpr std::array<size_t, Shape::ndim> strides() const { return Shape::strides(); }
- constexpr size_t offset() const { return offset_; }
constexpr size_t size() const { return Shape::size; }
};
@@ -124,10 +120,8 @@ namespace detail
protected:
std::array<size_t, Shape::ndim> shape_;
std::array<size_t, Shape::ndim> strides_;
- size_t offset_;
- template <typename Storage>
- void data_bounds_check(Storage& data) const
+ void data_bounds_check(size_t size) const
{
#ifndef NO_BOUNDS_CHECK
size_t total = 1;
@@ -137,15 +131,14 @@ namespace detail
if (shape_[i] != dim(i))
throw std::out_of_range("mismatch with fixed shape");
}
- total += offset_;
- if (total > data.size())
+ if (total > size)
throw std::out_of_range("data array too small");
#endif
}
public:
- dynamic_base(const std::array<size_t, Shape::ndim> shape, size_t offset)
- : shape_(shape), offset_(offset)
+ dynamic_base(const std::array<size_t, Shape::ndim> shape)
+ : shape_(shape)
{
static_assert(!Shape::fixed, "array shape must not be compile-time fixed");
@@ -181,7 +174,6 @@ namespace detail
const std::array<size_t, Shape::ndim>& shape() const { return shape_; }
const std::array<size_t, Shape::ndim>& strides() const { return strides_; }
- size_t offset() const { return offset_; }
size_t size() const
{
size_t size = 1;
@@ -194,13 +186,13 @@ namespace detail
/*! Simple data-by-reference strided array class a la Fortran
*/
-template <typename Scalar, typename Shape, typename Storage = std::vector<Scalar> >
+template <typename Scalar, typename Shape>
class Array : public std::conditional_t<Shape::fixed, detail::fixed_base<Shape>, detail::dynamic_base<Shape> >
{
private:
typedef std::conditional_t<Shape::fixed, detail::fixed_base<Shape>, detail::dynamic_base<Shape> > Base;
- Storage& data_;
+ Scalar *data_;
template <size_t axis>
static constexpr Eigen::Index eigen_shape()
@@ -210,16 +202,16 @@ private:
}
public:
- Array(Storage& data, const std::array<size_t, Shape::ndim> shape, const size_t offset=0)
- : Base(shape, offset), data_(data)
+ Array(Scalar *data, size_t size, const std::array<size_t, Shape::ndim> shape)
+ : Base(shape), data_(data)
{
- Base::data_bounds_check(data);
+ Base::data_bounds_check(size);
}
- Array(Storage& data, const size_t offset=0)
- : Base(offset), data_(data)
+ Array(Scalar *data, size_t size)
+ : Base(), data_(data)
{
- Base::data_bounds_check(data);
+ Base::data_bounds_check(size);
}
template <typename... Idx>
@@ -238,7 +230,7 @@ public:
return data_[index(idxs...)];
}
- Storage& data() { return data_; }
+ Scalar* data() { return data_; }
template <typename... Idx>
size_t index(Idx... idxs) const
@@ -247,7 +239,7 @@ public:
"number of indices must be smaller than the number of dimensions");
const std::array<size_t, Shape::ndim> m{idxs...};
- size_t idx = Base::offset();
+ size_t idx = 0;
for (size_t i = 0; i < sizeof...(idxs); ++i) {
idx += Base::stride(i) * m[i];
@@ -257,10 +249,6 @@ public:
#endif
}
-#ifndef NO_BOUNDS_CHECK
- if (idx >= data_.size())
- throw std::out_of_range("total index out of bounds");
-#endif
return idx;
}
@@ -275,7 +263,7 @@ public:
"number of indices must be small than the number of dimensions");
size_t offset = index(idxs...);
- return {data_, offset};
+ return {data_ + offset, Base::size() - offset};
}
/*! Extract partial matrix (compile-time dynamic size) */
@@ -292,7 +280,7 @@ public:
std::array<size_t, Shape::ndim - nidxs> shape;
for (size_t i = nidxs; i < Shape::ndim; ++i)
shape[i - nidxs] = Base::dim(i);
- return {data_, shape, offset};
+ return {data_ + offset, Base::size() - offset, shape};
}
typedef Eigen::Matrix<Scalar, eigen_shape<0>(), eigen_shape<1>(), Eigen::RowMajor> EigenMatrix;
@@ -301,8 +289,7 @@ public:
EigenMap matrix() const
{
static_assert(Shape::ndim == 2, "matrix must be two-dimensional");
- return {(Scalar *)data_.data() + Base::offset(),
- static_cast<Eigen::Index>(Base::dim(0)), static_cast<Eigen::Index>(Base::dim(1))};
+ return {data_, static_cast<Eigen::Index>(Base::dim(0)), static_cast<Eigen::Index>(Base::dim(1))};
}
operator EigenMap() const { return matrix(); }
diff --git a/src/main.cpp b/src/main.cpp
index 1a1444e..5ffac0b 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -17,7 +17,7 @@ void dump(Array<Scalar,Shape> Q)
}
}
- for (size_t i = 0; i < Q.data().size(); ++i) {
+ for (size_t i = 0; i < Q.size(); ++i) {
std::cout << Q.data()[i] << std::endl;
}
}
@@ -25,7 +25,7 @@ void dump(Array<Scalar,Shape> Q)
int main()
{
std::vector<double> v(7*2*2*2);
- Array<double,Shape<Dynamic,Dynamic,2,2> > Q0(v,{7,2,2,2});
+ Array<double,Shape<Dynamic,Dynamic,2,2> > Q0(v.data(), v.size(), {7,2,2,2});
auto Q = Q0.part(0u,1u);
S_2(Q);
--
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