mirror of
https://github.com/DrasLorus/CORDIC_Rotate_APFX.git
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25255802f1
- Use of `rom_cordic_rotate` namespace to isolate functions and
variables. Useful when CORDICS are included in super project.
- Add define barrier to exclude some code when used when Xilinx v2019.1,
especially C++11/14 code that are not fully supported by the (crazy)
old version of GCC in use (v4.6.3).
Need the definition of `XILINX_MAJOR` (can be done using `set
XILINX_MAJOR [expr {int( [version -short] )}]` in a Xilinx TCL script
and then adding it to the cflags using the `-cflags` switch with
`-DXILINX_MAJOR=${XILINX_MAJOR}` or by manually adding the major
version to the CFLAGS in gui.
- Add a template version of the helper function, to support v2019.1.
202 lines
No EOL
7.3 KiB
C++
202 lines
No EOL
7.3 KiB
C++
/*
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*
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* Copyright 2022 Camille "DrasLorus" Monière.
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*
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* This file is part of CORDIC_Rotate_APFX.
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*
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* This program is free software: you can redistribute it and/or modify it under the terms of the GNU
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* Lesser General Public License as published by the Free Software Foundation, either version 3 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
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* even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License along with this program.
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* If not, see <https://www.gnu.org/licenses/>.
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*
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*/
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#ifndef C_CORDIC_ROTATE_CONSTEXPR_HPP
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#define C_CORDIC_ROTATE_CONSTEXPR_HPP
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#include <climits>
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#include <cmath>
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#include <cstdint>
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#include <cstdlib>
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#include <complex>
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#include <ap_fixed.h>
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#include <ap_int.h>
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#include "RomGeneratorConst/RomGeneratorConst.hpp"
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namespace rcr = rom_cordic_rotate;
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template <unsigned TIn_W, unsigned TIn_I, unsigned Tnb_stages, unsigned Tq, unsigned divider = 2>
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class CCordicRotateConstexpr {
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static_assert(TIn_W > 0, "Inputs can't be on zero bits.");
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static_assert(Tnb_stages < 8, "7 stages of CORDIC is the maximum supported.");
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static_assert(Tnb_stages > 1, "2 stages of CORDIC is the minimum.");
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static_assert(rcr::is_pow_2<divider>(), "divider must be a power of 2.");
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public:
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// ``` GNU Octave
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// kn_values(X) = prod(1 ./ abs(1 + 1j * 2.^ (-(0:X))))
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// ```
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static constexpr double kn_values[7] = {
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0.70710678118655, 0.632455532033680, 0.613571991077900,
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0.608833912517750, 0.607648256256170, 0.607351770141300, 0.607277644093530};
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static constexpr const CRomGeneratorConst<TIn_W, Tnb_stages, Tq, divider> & rom_cordic {};
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static constexpr unsigned In_W = TIn_W;
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static constexpr unsigned In_I = TIn_I;
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static constexpr unsigned Out_W = In_W + 2;
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static constexpr unsigned Out_I = In_I + 2;
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static constexpr unsigned nb_stages = Tnb_stages;
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static constexpr unsigned kn_i = unsigned(kn_values[nb_stages - 1] * double(1U << 4)); // 4 bits are enough
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static constexpr unsigned in_scale_factor = unsigned(1U << (In_W - In_I));
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static constexpr unsigned out_scale_factor = unsigned(1U << (Out_W - Out_I));
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static constexpr double rotation = CRomGeneratorConst<TIn_W, Tnb_stages, Tq, divider>::rotation;
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static constexpr unsigned addr_length = CRomGeneratorConst<TIn_W, Tnb_stages, Tq, divider>::addr_length;
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static constexpr int64_t scale_cordic(int64_t in) {
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return in * kn_i / 16U;
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}
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static constexpr double scale_cordic(double in) {
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return in * kn_values[nb_stages - 1];
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}
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#if !defined(__SYNTHESIS__) && defined(SOFTWARE)
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static constexpr std::complex<int64_t> cordic(std::complex<int64_t> x_in,
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uint64_t counter) {
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int64_t A = x_in.real();
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int64_t B = x_in.imag();
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const uint8_t R = rom_cordic.rom[counter];
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uint8_t mask = 0x01;
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if ((R & mask) == mask) {
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A = -A;
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B = -B;
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}
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for (uint8_t u = 1; u < nb_stages + 1; u++) {
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mask = mask << 1;
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const int64_t Ri = (R & mask) == mask ? 1 : -1;
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const int64_t I = A + Ri * (B / int64_t(1U << (u - 1)));
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B = B - Ri * (A / int64_t(1U << (u - 1)));
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A = I;
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}
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return {(A), (B)};
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}
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static constexpr std::complex<double> cordic(std::complex<double> x_in,
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uint64_t counter) {
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const std::complex<int64_t> fx_x_in(int64_t(x_in.real() * double(in_scale_factor)),
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int64_t(x_in.imag() * double(in_scale_factor)));
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const std::complex<int64_t> fx_out = cordic(fx_x_in, counter);
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return {scale_cordic(double(fx_out.real())) / double(out_scale_factor), scale_cordic(double(fx_out.imag())) / double(out_scale_factor)};
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}
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#endif
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static ap_int<Out_W> scale_cordic(const ap_int<Out_W> & in) {
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const ap_int<Out_W + 4> tmp = in * ap_uint<4>(kn_i);
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return ap_int<Out_W>(tmp >> 4);
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}
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static void cordic(const ap_int<In_W> & re_in, const ap_int<In_W> & im_in,
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const ap_uint<addr_length> & counter,
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ap_int<Out_W> & re_out, ap_int<Out_W> & im_out) {
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const ap_uint<nb_stages + 1> R = rom_cordic.rom[counter];
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ap_int<Out_W> A = bool(R[0]) ? ap_int<In_W>(-re_in) : re_in;
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ap_int<Out_W> B = bool(R[0]) ? ap_int<In_W>(-im_in) : im_in;
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for (uint8_t u = 1; u < nb_stages + 1; u++) { // nb_stages stages
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const bool Ri = bool(R[u]);
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// Results in (X / 2^(u - 1)), meaning only the
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// Out_W - u LSBs are meaninfull in shifted_X
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// Can't use range access since 11111111 (-1) would become 00001111 (15).
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// Would be possible if the loop is manually unrolled, to predict bitsize,
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// thus directly put 1111 into 4 bits (so still -1).
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const ap_int<Out_W> shifted_A = A >> (u - 1); // A(Out_W - 1, u - 1);
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const ap_int<Out_W> shifted_B = B >> (u - 1); // B(Out_W - 1, u - 1);
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const ap_int<Out_W> arc_step_A
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= Ri
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? ap_int<Out_W>(-shifted_A)
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: shifted_A;
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const ap_int<Out_W> arc_step_B
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= Ri
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? shifted_B
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: ap_int<Out_W>(-shifted_B);
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const ap_int<Out_W + 1> I = A + arc_step_B;
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B = B + arc_step_A;
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A = I;
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}
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re_out = A;
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im_out = B;
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}
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constexpr CCordicRotateConstexpr() = default;
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};
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#if 0
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template <>
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inline void CCordicRotateConstexpr<16, 4, 6, 64>::cordic(
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const ap_int<16> & re_in, const ap_int<16> & im_in,
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const ap_uint<8> & counter,
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ap_int<Out_W> & re_out, ap_int<Out_W> & im_out) const {
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const ap_uint<6 + 1> R = (rom_cordic.rom[counter.to_uint()] >> (7 - 6));
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ap_int<Out_W> A = bool(R[6]) ? ap_int<16>(-re_in) : re_in;
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ap_int<Out_W> B = bool(R[6]) ? ap_int<16>(-im_in) : im_in;
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for (uint8_t u = 1; u < 6 + 1; u++) { // 6 stages
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const bool Ri = bool(R[6 - u]);
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// Results in (X / 2^(u - 1)), meaning only the
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// Out_W - u LSBs are meaninfull in shifted_X
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// Can't use range access since 11111111 (-1) would become 00001111 (15).
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// Would be possible if the loop is manually unrolled, to predict bitsize,
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// thus directly put 1111 into 4 bits (so still -1).
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const ap_int<Out_W> shifted_A = A >> (u - 1); // A(Out_W - 1, u - 1);
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const ap_int<Out_W> shifted_B = B >> (u - 1); // B(Out_W - 1, u - 1);
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const ap_int<Out_W> arc_step_A
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= Ri
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? ap_int<Out_W>(-shifted_A)
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: shifted_A;
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const ap_int<Out_W> arc_step_B
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= Ri
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? shifted_B
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: ap_int<Out_W>(-shifted_B);
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const auto I = A + arc_step_B;
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B = B + arc_step_A;
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A = I;
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}
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re_out = A;
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im_out = B;
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}
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#endif
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#endif // C_CORDIC_ROTATE_CONSTEXPR_HPP
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