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Remove garbage DSP filter code.
This commit is contained in:
Jared Boone
parent
ccc3402869
commit
49215c3ae6
@ -385,76 +385,6 @@ buffer_s16_t DecimateBy2CIC4Real::execute(
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return { dst.p, src.count / 2, src.sampling_rate / 2 };
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}
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#if 0
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buffer_c16_t DecimateBy2HBF5Complex::execute(
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buffer_c16_t const src,
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buffer_c16_t const dst
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) {
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auto src_p = src.p;
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auto dst_p = dst.p;
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int32_t n = src.count;
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for(; n>0; n-=2) {
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/* TODO: Probably a lot of room to optimize... */
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z[0] = z[2];
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//z[1] = z[3];
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z[2] = z[4];
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//z[3] = z[5];
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z[4] = z[6];
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z[5] = z[7];
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z[6] = z[8];
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z[7] = z[9];
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z[8] = z[10];
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z[9] = *(src_p++);
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z[10] = *(src_p++);
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int32_t t_real { z[5].real * 256 };
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int32_t t_imag { z[5].imag * 256 };
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t_real += (z[ 0].real + z[10].real) * 3;
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t_imag += (z[ 0].imag + z[10].imag) * 3;
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t_real -= (z[ 2].real + z[ 8].real) * 25;
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t_imag -= (z[ 2].imag + z[ 8].imag) * 25;
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t_real += (z[ 4].real + z[ 6].real) * 150;
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t_imag += (z[ 4].imag + z[ 6].imag) * 150;
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*(dst_p++) = { t_real / 256, t_imag / 256 };
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}
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return { dst.p, src.count / 2, src.sampling_rate / 2 };
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}
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buffer_c16_t DecimateBy2HBF7Complex::execute(
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buffer_c16_t const src,
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buffer_c16_t const dst
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) {
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auto src_p = src.p;
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auto dst_p = dst.p;
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int32_t n = src.count;
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for(; n>0; n-=2) {
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/* TODO: Probably a lot of room to optimize... */
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z[0] = z[2];
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//z[1] = z[3];
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z[2] = z[4];
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//z[3] = z[5];
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z[4] = z[6];
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z[5] = z[7];
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z[6] = z[8];
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z[7] = z[9];
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z[8] = z[10];
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z[9] = *(src_p++);
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z[10] = *(src_p++);
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int32_t t_real { z[5].real * 512 };
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int32_t t_imag { z[5].imag * 512 };
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t_real += (z[ 0].real + z[10].real) * 7;
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t_imag += (z[ 0].imag + z[10].imag) * 7;
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t_real -= (z[ 2].real + z[ 8].real) * 53;
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t_imag -= (z[ 2].imag + z[ 8].imag) * 53;
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t_real += (z[ 4].real + z[ 6].real) * 302;
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t_imag += (z[ 4].imag + z[ 6].imag) * 302;
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*(dst_p++) = { t_real / 512, t_imag / 512 };
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}
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return { dst.p, src.count / 2, src.sampling_rate / 2 };
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}
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#endif
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} /* namespace decimate */
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} /* namespace dsp */
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@ -142,112 +142,7 @@ public:
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private:
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int16_t z[5];
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};
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#if 0
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class DecimateBy2HBF5Complex {
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public:
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buffer_c16_t execute(
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buffer_c16_t const src,
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buffer_c16_t const dst
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);
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private:
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complex16_t z[11];
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};
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class DecimateBy2HBF7Complex {
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public:
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buffer_c16_t execute(
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buffer_c16_t const src,
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buffer_c16_t const dst
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);
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private:
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complex16_t z[11];
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};
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#endif
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/* From http://www.dspguru.com/book/export/html/3
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Here are several basic techniques to fake circular buffers:
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Split the calculation: You can split any FIR calculation into its "pre-wrap"
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and "post-wrap" parts. By splitting the calculation into these two parts, you
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essentially can do the circular logic only once, rather than once per tap.
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(See fir_double_z in FirAlgs.c above.)
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Duplicate the delay line: For a FIR with N taps, use a delay line of size 2N.
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Copy each sample to its proper location, as well as at location-plus-N.
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Therefore, the FIR calculation's MAC loop can be done on a flat buffer of N
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points, starting anywhere within the first set of N points. The second set of
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N delayed samples provides the "wrap around" comparable to a true circular
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buffer. (See fir_double_z in FirAlgs.c above.)
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Duplicate the coefficients: This is similar to the above, except that the
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duplication occurs in terms of the coefficients, not the delay line.
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Compared to the previous method, this has a calculation advantage of not
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having to store each incoming sample twice, and it also has a memory
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advantage when the same coefficient set will be used on multiple delay lines.
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(See fir_double_h in FirAlgs.c above.)
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Use block processing: In block processing, you use a delay line which is a
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multiple of the number of taps. You therefore only have to move the data
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once per block to implement the delay-line mechanism. When the block size
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becomes "large", the overhead of a moving the delay line once per block
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becomes negligible.
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*/
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#if 0
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template<size_t N>
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class FIRAndDecimateBy2Complex {
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public:
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FIR64AndDecimateBy2Complex(
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const std::array<int16_t, N>& taps
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) : taps { taps }
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{
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}
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buffer_c16_t execute(
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buffer_c16_t const src,
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buffer_c16_t const dst
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) {
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/* int16_t input (sample count "n" must be multiple of 4)
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* -> int16_t output, decimated by 2.
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* taps are normalized to 1 << 16 == 1.0.
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*/
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return { dst.p, src.count / 2 };
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}
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private:
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std::array<complex16_t, N> z;
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const std::array<int16_t, N>& taps;
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complex<int16_t> process_one(const size_t start_offset) {
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const auto split = &z[start_offset];
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const auto end = &z[z.size()];
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auto tap = &taps[0];
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complex<int32_t> t { 0, 0 };
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auto p = split;
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while(p < end) {
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const auto t = *(tap++);
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const auto c = *(p++);
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t.real += c.real * t;
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t.imag += c.imag * t;
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}
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p = &z[0];
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while(p < split) {
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const auto t = *(tap++);
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const auto c = *(p++);
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t.real += c.real * t;
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t.imag += c.imag * t;
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}
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return { t.real / 65536, t.imag / 65536 };
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}
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};
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#endif
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} /* namespace decimate */
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} /* namespace dsp */
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