117 lines
4.3 KiB
C
117 lines
4.3 KiB
C
#include "tool.h"
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/*
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* C 版 kodis
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*
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* Fortran signature:
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* subroutine kodis(ex,X,Y,Z,f,f_rhs,SoA,Symmetry,eps)
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*
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* 约定：
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* X: ex1, Y: ex2, Z: ex3
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* f, f_rhs: ex1*ex2*ex3 按 idx_ex 布局
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* SoA[3]
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* eps: double
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*/
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void kodis(const int ex[3],
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const double *X, const double *Y, const double *Z,
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const double *f, double *f_rhs,
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const double SoA[3],
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int Symmetry, double eps)
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{
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const double ONE = 1.0, SIX = 6.0, FIT = 15.0, TWT = 20.0;
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const double cof = 64.0; // 2^6
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const int NO_SYMM = 0, OCTANT = 2;
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const int ex1 = ex[0], ex2 = ex[1], ex3 = ex[2];
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// Fortran: dX = X(2)-X(1) -> C: X[1]-X[0]
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const double dX = X[1] - X[0];
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const double dY = Y[1] - Y[0];
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const double dZ = Z[1] - Z[0];
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(void)ONE; // ONE 在原 Fortran 里只是参数，这里不一定用得上
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// Fortran: imax=ex(1) 等是 1-based 上界
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const int imaxF = ex1;
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const int jmaxF = ex2;
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const int kmaxF = ex3;
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// Fortran: imin=jmin=kmin=1，某些对称情况变 -2
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int iminF = 1, jminF = 1, kminF = 1;
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if (Symmetry > NO_SYMM && fabs(Z[0]) < dZ) kminF = -2;
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if (Symmetry == OCTANT && fabs(X[0]) < dX) iminF = -2;
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if (Symmetry == OCTANT && fabs(Y[0]) < dY) jminF = -2;
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// 分配 fh：大小 (ex1+3)*(ex2+3)*(ex3+3)，对应 ord=3
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const size_t nx = (size_t)ex1 + 3;
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const size_t ny = (size_t)ex2 + 3;
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const size_t nz = (size_t)ex3 + 3;
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const size_t fh_size = nx * ny * nz;
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double *fh = (double*)malloc(fh_size * sizeof(double));
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if (!fh) return;
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// Fortran: call symmetry_bd(3,ex,f,fh,SoA)
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symmetry_bd(3, ex, f, fh, SoA);
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/*
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* Fortran loops:
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* do k=1,ex3
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* do j=1,ex2
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* do i=1,ex1
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*
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* C: k0=0..ex3-1, j0=0..ex2-1, i0=0..ex1-1
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* 并定义 Fortran index: iF=i0+1, ...
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*/
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// 收紧循环范围：只遍历满足 iF±3/jF±3/kF±3 条件的内部点
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// iF-3 >= iminF => iF >= iminF+3 => i0 >= iminF+2 (因为 iF=i0+1)
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// iF+3 <= imaxF => iF <= imaxF-3 => i0 <= imaxF-4
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const int i0_lo = (iminF + 2 > 0) ? iminF + 2 : 0;
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const int j0_lo = (jminF + 2 > 0) ? jminF + 2 : 0;
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const int k0_lo = (kminF + 2 > 0) ? kminF + 2 : 0;
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const int i0_hi = imaxF - 4; // inclusive
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const int j0_hi = jmaxF - 4;
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const int k0_hi = kmaxF - 4;
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if (i0_lo > i0_hi || j0_lo > j0_hi || k0_lo > k0_hi) {
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free(fh);
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return;
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}
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for (int k0 = k0_lo; k0 <= k0_hi; ++k0) {
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const int kF = k0 + 1;
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for (int j0 = j0_lo; j0 <= j0_hi; ++j0) {
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const int jF = j0 + 1;
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for (int i0 = i0_lo; i0 <= i0_hi; ++i0) {
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const int iF = i0 + 1;
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const size_t p = idx_ex(i0, j0, k0, ex);
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// 三个方向各一份同型的 7 点组合（实际上是对称的 6th-order dissipation/filter 核）
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const double Dx_term =
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( (fh[idx_fh_F(iF - 3, jF, kF, ex)] + fh[idx_fh_F(iF + 3, jF, kF, ex)]) -
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SIX * (fh[idx_fh_F(iF - 2, jF, kF, ex)] + fh[idx_fh_F(iF + 2, jF, kF, ex)]) +
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FIT * (fh[idx_fh_F(iF - 1, jF, kF, ex)] + fh[idx_fh_F(iF + 1, jF, kF, ex)]) -
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TWT * fh[idx_fh_F(iF , jF, kF, ex)] ) / dX;
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const double Dy_term =
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( (fh[idx_fh_F(iF, jF - 3, kF, ex)] + fh[idx_fh_F(iF, jF + 3, kF, ex)]) -
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SIX * (fh[idx_fh_F(iF, jF - 2, kF, ex)] + fh[idx_fh_F(iF, jF + 2, kF, ex)]) +
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FIT * (fh[idx_fh_F(iF, jF - 1, kF, ex)] + fh[idx_fh_F(iF, jF + 1, kF, ex)]) -
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TWT * fh[idx_fh_F(iF, jF , kF, ex)] ) / dY;
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const double Dz_term =
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( (fh[idx_fh_F(iF, jF, kF - 3, ex)] + fh[idx_fh_F(iF, jF, kF + 3, ex)]) -
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SIX * (fh[idx_fh_F(iF, jF, kF - 2, ex)] + fh[idx_fh_F(iF, jF, kF + 2, ex)]) +
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FIT * (fh[idx_fh_F(iF, jF, kF - 1, ex)] + fh[idx_fh_F(iF, jF, kF + 1, ex)]) -
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TWT * fh[idx_fh_F(iF, jF, kF , ex)] ) / dZ;
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// Fortran:
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// f_rhs(i,j,k) = f_rhs(i,j,k) + eps/cof*(Dx_term + Dy_term + Dz_term)
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f_rhs[p] += (eps / cof) * (Dx_term + Dy_term + Dz_term);
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}
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}
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}
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free(fh);
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} |