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Use a unique_ptr for constructing the bsinc table coefficients

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This commit is contained in:
Chris Robinson
2020-04-07 08:30:37 -07:00
parent 2fcc3f3887
commit efed431237
1 changed files with 22 additions and 25 deletions
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common/bsinc_tables.cpp
+22 -25
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@@ -2,6 +2,7 @@
#include "bsinc_tables.h"
#include <algorithm>
#include <array>
#include <cassert>
#include <cmath>
#include <limits>
@@ -198,25 +199,19 @@ constexpr BSincHeader GenerateBSincHeader(int Rejection, int Order)
}
/* 11th and 23rd order filters (12 and 24-point respectively) with a 60dB drop
* at nyquist. Each filter will scale up the order when downsampling, to 23 and
* 47th order respectively.
* at nyquist. Each filter will scale up the order when downsampling, to 23rd
* and 47th order respectively.
*/
constexpr BSincHeader bsinc12_hdr{GenerateBSincHeader(60, 11)};
constexpr BSincHeader bsinc24_hdr{GenerateBSincHeader(60, 23)};
/* std::array is missing constexpr for several methods. */
template<typename T, size_t N>
struct Array {
T data[N];
};
/* FIXME: This should be constexpr, but the temporary filter table is apparently too big
* (~200K) for some systems. This requires using heap space, which is not
* allowed in a constexpr function.
/* FIXME: This should be constexpr, but the temporary filter arrays are too
* big. This requires using heap space, which is not allowed in a constexpr
* function (maybe in C++20).
*/
template<size_t total_size>
auto GenerateBSincCoeffs(const BSincHeader &hdr)
std::array<float,total_size> GenerateBSincCoeffs(const BSincHeader &hdr)
{
auto filter = std::make_unique<double[][BSincPhaseCount+1][BSincPointsMax]>(BSincScaleCount);
@@ -248,7 +243,7 @@ auto GenerateBSincCoeffs(const BSincHeader &hdr)
}
}
Array<float,total_size> ret{};
auto ret = std::make_unique<std::array<float,total_size>>();
size_t idx{0};
for(unsigned int si{0};si < BSincScaleCount-1;++si)
@@ -262,7 +257,7 @@ auto GenerateBSincCoeffs(const BSincHeader &hdr)
* scale deltas.
*/
for(int i{0};i < m;++i)
ret.data[idx++] = static_cast<float>(filter[si][pi][o+i]);
(*ret)[idx++] = static_cast<float>(filter[si][pi][o+i]);
/* Linear interpolation between phases is simplified by pre-
* calculating the delta (b - a) in: x = a + f (b - a)
@@ -270,7 +265,7 @@ auto GenerateBSincCoeffs(const BSincHeader &hdr)
for(int i{0};i < m;++i)
{
const double phDelta{filter[si][pi+1][o+i] - filter[si][pi][o+i]};
ret.data[idx++] = static_cast<float>(phDelta);
(*ret)[idx++] = static_cast<float>(phDelta);
}
/* Linear interpolation between scales is also simplified.
@@ -281,7 +276,7 @@ auto GenerateBSincCoeffs(const BSincHeader &hdr)
for(int i{0};i < m;++i)
{
const double scDelta{filter[si+1][pi][o+i] - filter[si][pi][o+i]};
ret.data[idx++] = static_cast<float>(scDelta);
(*ret)[idx++] = static_cast<float>(scDelta);
}
/* This last simplification is done to complete the bilinear
@@ -291,7 +286,7 @@ auto GenerateBSincCoeffs(const BSincHeader &hdr)
{
const double spDelta{(filter[si+1][pi+1][o+i] - filter[si+1][pi][o+i]) -
(filter[si][pi+1][o+i] - filter[si][pi][o+i])};
ret.data[idx++] = static_cast<float>(spDelta);
(*ret)[idx++] = static_cast<float>(spDelta);
}
}
}
@@ -304,24 +299,26 @@ auto GenerateBSincCoeffs(const BSincHeader &hdr)
for(int pi{0};pi < BSincPhaseCount;++pi)
{
for(int i{0};i < m;++i)
ret.data[idx++] = static_cast<float>(filter[si][pi][o+i]);
(*ret)[idx++] = static_cast<float>(filter[si][pi][o+i]);
for(int i{0};i < m;++i)
{
const double phDelta{filter[si][pi+1][o+i] - filter[si][pi][o+i]};
ret.data[idx++] = static_cast<float>(phDelta);
(*ret)[idx++] = static_cast<float>(phDelta);
}
for(int i{0};i < m;++i)
ret.data[idx++] = 0.0f;
(*ret)[idx++] = 0.0f;
for(int i{0};i < m;++i)
ret.data[idx++] = 0.0f;
(*ret)[idx++] = 0.0f;
}
}
assert(idx == total_size);
return ret;
return *ret;
}
/* FIXME: These can't be constexpr due to reaching the step limit. */
/* FIXME: These can't be constexpr due to the calls reaching the compiler's
* step limit.
*/
alignas(16) const auto bsinc12_table = GenerateBSincCoeffs<bsinc12_hdr.total_size>(bsinc12_hdr);
alignas(16) const auto bsinc24_table = GenerateBSincCoeffs<bsinc24_hdr.total_size>(bsinc24_hdr);
@@ -342,5 +339,5 @@ constexpr BSincTable GenerateBSincTable(const BSincHeader &hdr, const float *tab
} // namespace
const BSincTable bsinc12{GenerateBSincTable(bsinc12_hdr, bsinc12_table.data)};
const BSincTable bsinc24{GenerateBSincTable(bsinc24_hdr, bsinc24_table.data)};
const BSincTable bsinc12{GenerateBSincTable(bsinc12_hdr, &bsinc12_table.front())};
const BSincTable bsinc24{GenerateBSincTable(bsinc24_hdr, &bsinc24_table.front())};