diff options
Diffstat (limited to 'common/bsinc_tables.cpp')
| -rw-r--r-- | common/bsinc_tables.cpp | 97 |
1 files changed, 49 insertions, 48 deletions
diff --git a/common/bsinc_tables.cpp b/common/bsinc_tables.cpp index f697e5f0..2fafb3a5 100644 --- a/common/bsinc_tables.cpp +++ b/common/bsinc_tables.cpp @@ -213,13 +213,10 @@ struct Array { template<size_t total_size> constexpr auto GenerateBSincCoeffs(const BSincHeader hdr) { - double filter[BSincScaleCount][BSincPhaseCount+1][BSincPointsMax]{}; - double phDeltas[BSincScaleCount][BSincPhaseCount ][BSincPointsMax]{}; - double scDeltas[BSincScaleCount][BSincPhaseCount ][BSincPointsMax]{}; - double spDeltas[BSincScaleCount][BSincPhaseCount ][BSincPointsMax]{}; + double filter[BSincScaleCount][BSincPhaseCount+1][BSincPointsMax]{}; /* Calculate the Kaiser-windowed Sinc filter coefficients for each scale - * and phase. + * and phase index. */ for(unsigned int si{0};si < BSincScaleCount;++si) { @@ -230,6 +227,9 @@ constexpr auto 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. + */ for(int pi{0};pi <= BSincPhaseCount;++pi) { const double phase{l + (pi/double{BSincPhaseCount})}; @@ -237,77 +237,78 @@ constexpr auto GenerateBSincCoeffs(const BSincHeader hdr) for(int i{0};i < m;++i) { const double x{i - phase}; - filter[si][pi][o + i] = Kaiser(hdr.beta, x/a, hdr.besseli_0_beta) * cutoff * + filter[si][pi][o+i] = Kaiser(hdr.beta, x/a, hdr.besseli_0_beta) * cutoff * Sinc(cutoff*x); } } } - /* Linear interpolation between phases is simplified by pre-calculating the - * delta (b - a) in: x = a + f (b - a) - */ - for(unsigned int si{0};si < BSincScaleCount;++si) + Array<float,total_size> ret{}; + size_t idx{0}; + + for(unsigned int si{0};si < BSincScaleCount-1;++si) { - const int m{hdr.a[si] * 2}; + const int m{((hdr.a[si]*2) + 3) & ~3}; const int o{BSincPointsHalf - (m/2)}; for(int pi{0};pi < BSincPhaseCount;++pi) { + /* Write out the filter. Also calculate and write out the phase and + * scale deltas. + */ for(int i{0};i < m;++i) - phDeltas[si][pi][o + i] = filter[si][pi + 1][o + i] - filter[si][pi][o + i]; - } - } + ret.data[idx++] = static_cast<float>(filter[si][pi][o+i]); - /* Linear interpolation between scales is also simplified. - * - * Given a difference in points between scales, the destination points will - * be 0, thus: x = a + f (-a) - */ - for(unsigned int si{0};si < (BSincScaleCount-1);++si) - { - const int m{hdr.a[si] * 2}; - const int o{BSincPointsHalf - (m/2)}; - - for(int pi{0};pi < BSincPhaseCount;++pi) - { + /* Linear interpolation between phases is simplified by pre- + * calculating the delta (b - a) in: x = a + f (b - a) + */ for(int i{0};i < m;++i) - scDeltas[si][pi][o + i] = filter[si + 1][pi][o + i] - filter[si][pi][o + i]; - } - } + { + const double phDelta{filter[si][pi+1][o+i] - filter[si][pi][o+i]}; + ret.data[idx++] = static_cast<float>(phDelta); + } - /* This last simplification is done to complete the bilinear equation for - * the combination of phase and scale. - */ - for(unsigned int si{0};si < (BSincScaleCount-1);++si) - { - const int m{hdr.a[si] * 2}; - const int o{BSincPointsHalf - (m/2)}; + /* Linear interpolation between scales is also simplified. + * + * Given a difference in points between scales, the destination + * points will be 0, thus: x = a + f (-a) + */ + 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); + } - for(int pi{0};pi < BSincPhaseCount;++pi) - { + /* This last simplification is done to complete the bilinear + * equation for the combination of phase and scale. + */ for(int i{0};i < m;++i) - spDeltas[si][pi][o + i] = phDeltas[si + 1][pi][o + i] - phDeltas[si][pi][o + i]; + { + 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); + } } } - - Array<float,total_size> ret{}; - size_t idx{0}; - - for(unsigned int si{0};si < BSincScaleCount;++si) { + /* 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)}; 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.data[idx++] = static_cast<float>(filter[si][pi][o+i]); for(int i{0};i < m;++i) - ret.data[idx++] = static_cast<float>(phDeltas[si][pi][o + i]); + { + const double phDelta{filter[si][pi+1][o+i] - filter[si][pi][o+i]}; + ret.data[idx++] = static_cast<float>(phDelta); + } for(int i{0};i < m;++i) - ret.data[idx++] = static_cast<float>(scDeltas[si][pi][o + i]); + ret.data[idx++] = 0.0f; for(int i{0};i < m;++i) - ret.data[idx++] = static_cast<float>(spDeltas[si][pi][o + i]); + ret.data[idx++] = 0.0f; } } assert(idx == total_size); |