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Do in-place initialization for the bsinc filters

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Requires less dynamic allocations and less troublesome return values of large
arrays. Also reduces repetition with specified parameters.
This commit is contained in:
Chris Robinson
2020-10-18 05:34:27 -07:00
parent 24c7ddbac2
commit 20cc3882b4
1 changed files with 93 additions and 90 deletions
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alc/bsinc_tables.cpp
+32 -29
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@@ -155,13 +155,17 @@ constexpr BSincHeader bsinc24_hdr{GenerateBSincHeader(60, 23)};
* big. This requires using heap space, which is not allowed in a constexpr
* function (maybe in C++20).
*/
template<size_t total_size>
std::array<float,total_size> GenerateBSincCoeffs(const BSincHeader &hdr)
{
auto filter = std::make_unique<double[][BSincPhaseCount+1][BSincPointsMax]>(BSincScaleCount);
template<const BSincHeader &hdr>
struct BSincFilterArray {
alignas(16) std::array<float, hdr.total_size> mTable;
/* Calculate the Kaiser-windowed Sinc filter coefficients for each scale
* and phase index.
BSincFilterArray()
{
using filter_type = double[][BSincPhaseCount+1][BSincPointsMax];
auto filter = std::make_unique<filter_type>(BSincScaleCount);
/* Calculate the Kaiser-windowed Sinc filter coefficients for each
* scale and phase index.
*/
for(unsigned int si{0};si < BSincScaleCount;++si)
{
@@ -172,8 +176,8 @@ std::array<float,total_size> GenerateBSincCoeffs(const BSincHeader &hdr)
const double scale{hdr.scaleBase + (hdr.scaleRange * si / (BSincScaleCount - 1))};
const double cutoff{scale - (hdr.scaleBase * std::max(0.5, scale) * 2.0)};
/* Do one extra phase index so that the phase delta has a proper target
* for its last index.
/* Do one extra phase index so that the phase delta has a proper
* target for its last index.
*/
for(int pi{0};pi <= BSincPhaseCount;++pi)
{
@@ -188,9 +192,7 @@ std::array<float,total_size> GenerateBSincCoeffs(const BSincHeader &hdr)
}
}
auto ret = std::make_unique<std::array<float,total_size>>();
size_t idx{0};
for(unsigned int si{0};si < BSincScaleCount-1;++si)
{
const int m{((hdr.a[si]*2) + 3) & ~3};
@@ -198,11 +200,11 @@ std::array<float,total_size> GenerateBSincCoeffs(const BSincHeader &hdr)
for(int pi{0};pi < BSincPhaseCount;++pi)
{
/* Write out the filter. Also calculate and write out the phase and
* scale deltas.
/* Write out the filter. Also calculate and write out the phase
* and scale deltas.
*/
for(int i{0};i < m;++i)
(*ret)[idx++] = static_cast<float>(filter[si][pi][o+i]);
mTable[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)
@@ -210,7 +212,7 @@ std::array<float,total_size> 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)[idx++] = static_cast<float>(phDelta);
mTable[idx++] = static_cast<float>(phDelta);
}
/* Linear interpolation between scales is also simplified.
@@ -221,7 +223,7 @@ std::array<float,total_size> 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)[idx++] = static_cast<float>(scDelta);
mTable[idx++] = static_cast<float>(scDelta);
}
/* This last simplification is done to complete the bilinear
@@ -231,12 +233,14 @@ std::array<float,total_size> 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)[idx++] = static_cast<float>(spDelta);
mTable[idx++] = static_cast<float>(spDelta);
}
}
}
{
/* The last scale index doesn't have any scale or scale-phase deltas. */
/* The last scale index doesn't have any scale or scale-phase
* deltas.
*/
const unsigned int si{BSincScaleCount - 1};
const int m{((hdr.a[si]*2) + 3) & ~3};
const int o{BSincPointsHalf - (m/2)};
@@ -244,28 +248,27 @@ std::array<float,total_size> GenerateBSincCoeffs(const BSincHeader &hdr)
for(int pi{0};pi < BSincPhaseCount;++pi)
{
for(int i{0};i < m;++i)
(*ret)[idx++] = static_cast<float>(filter[si][pi][o+i]);
mTable[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)[idx++] = static_cast<float>(phDelta);
mTable[idx++] = static_cast<float>(phDelta);
}
for(int i{0};i < m;++i)
(*ret)[idx++] = 0.0f;
mTable[idx++] = 0.0f;
for(int i{0};i < m;++i)
(*ret)[idx++] = 0.0f;
mTable[idx++] = 0.0f;
}
}
assert(idx == total_size);
return *ret;
}
assert(idx == hdr.total_size);
}
};
/* 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);
const BSincFilterArray<bsinc12_hdr> bsinc12_filter{};
const BSincFilterArray<bsinc24_hdr> bsinc24_filter{};
constexpr BSincTable GenerateBSincTable(const BSincHeader &hdr, const float *tab)
@@ -284,5 +287,5 @@ constexpr BSincTable GenerateBSincTable(const BSincHeader &hdr, const float *tab
} // namespace
const BSincTable bsinc12{GenerateBSincTable(bsinc12_hdr, &bsinc12_table.front())};
const BSincTable bsinc24{GenerateBSincTable(bsinc24_hdr, &bsinc24_table.front())};
const BSincTable bsinc12{GenerateBSincTable(bsinc12_hdr, &bsinc12_filter.mTable.front())};
const BSincTable bsinc24{GenerateBSincTable(bsinc24_hdr, &bsinc24_filter.mTable.front())};