rename lib

opencl_fdtd/kernels/update_h.cl

@@ -0,0 +1,125 @@
+/*
+ *  Update H-field, including any PMLs.
+ *   Also precalculate values for poynting vector if necessary.
+ *  
+ *  Template parameters:
+ *   common_header: Rendered contents of common.cl
+ *   pmls: [('x', 'n'), ('z', 'p'),...] list of pml axes and polarities
+ *   pml_thickness: Number of cells (integer)
+ *   do_poynting: Whether to precalculate poynting vector components (boolean)  
+ *
+ *  OpenCL args:
+ *   E, H, dt, [p{01}h{np}, Psi_{xyz}{np}_H], [oS]
+ */
+
+{{common_header}}
+
+////////////////////////////////////////////////////////////////////////////
+
+{% if pmls -%}
+const int pml_thickness = {{pml_thickness}};
+{%- endif %}
+
+/*
+ *  Precalculate derivatives
+ */
+ftype dExy = Ex[i + py] - Ex[i];
+ftype dExz = Ex[i + pz] - Ex[i];
+
+ftype dEyx = Ey[i + px] - Ey[i];
+ftype dEyz = Ey[i + pz] - Ey[i];
+
+ftype dEzx = Ez[i + px] - Ez[i];
+ftype dEzy = Ez[i + py] - Ez[i];
+
+{%- if do_poynting %}
+
+
+/*
+ *  Precalculate averaged E
+ */
+ftype aExy = Ex[i + py] + Ex[i];
+ftype aExz = Ex[i + pz] + Ex[i];
+
+ftype aEyx = Ey[i + px] + Ey[i];
+ftype aEyz = Ey[i + pz] + Ey[i];
+
+ftype aEzx = Ez[i + px] + Ez[i];
+ftype aEzy = Ez[i + py] + Ez[i];
+{%- endif %}
+
+
+/*
+ *  PML Update
+ */
+// PML contributions to H
+ftype pHxi = 0;
+ftype pHyi = 0;
+ftype pHzi = 0;
+
+{%- for r, p in pmls -%}
+    {%- set u, v = ['x', 'y', 'z'] | reject('equalto', r) -%}
+    {%- set psi = 'Psi_' ~ r ~ p ~ '_H' -%}
+    {%- if r != 'y' -%}
+        {%- set se, sh = '-', '+' -%}
+    {%- else -%}
+        {%- set se, sh = '+', '-' -%}
+    {%- endif -%}
+
+    {%- if p == 'n' %}
+
+if ( {{r}} < pml_thickness ) {
+    const size_t ir = {{r}};                          // index into pml parameters
+
+    {%- elif p == 'p' %}
+
+if ( s{{r}} > {{r}} && {{r}} >= s{{r}} - pml_thickness ) {
+    const size_t ir = (s{{r}} - 1) - {{r}};                     // index into pml parameters
+
+    {%- endif %}
+    const size_t ip = {{v}} + {{u}} * s{{v}} + ir * s{{v}} * s{{u}};  // linear index into Psi
+    {{psi ~ u}}[ip] = p0h{{p}}[ir] * {{psi ~ u}}[ip] + p1h{{p}}[ir] * dE{{v ~ r}};
+    {{psi ~ v}}[ip] = p0h{{p}}[ir] * {{psi ~ v}}[ip] + p1h{{p}}[ir] * dE{{u ~ r}};
+    pH{{u}}i {{sh}}= {{psi ~ u}}[ip];
+    pH{{v}}i {{se}}= {{psi ~ v}}[ip];
+}
+{%- endfor %}
+
+/*
+ *  Update H
+ */
+{% if do_poynting -%}
+// Save old H for averaging
+ftype Hx_old = Hx[i];
+ftype Hy_old = Hy[i];
+ftype Hz_old = Hz[i];
+{%- endif %}
+
+// H update equations
+Hx[i] -= dt * (dEzy - dEyz + pHxi);
+Hy[i] -= dt * (dExz - dEzx + pHyi);
+Hz[i] -= dt * (dEyx - dExy + pHzi);
+
+{% if do_poynting -%}
+// Average H across timesteps
+ftype aHxt = Hx[i] + Hx_old;
+ftype aHyt = Hy[i] + Hy_old;
+ftype aHzt = Hz[i] + Hz_old;
+
+/*
+ *  Calculate unscaled S components at H locations
+ */
+__global ftype *oSxy = oS + 0 * field_size;
+__global ftype *oSyz = oS + 1 * field_size;
+__global ftype *oSzx = oS + 2 * field_size;
+__global ftype *oSxz = oS + 3 * field_size;
+__global ftype *oSyx = oS + 4 * field_size;
+__global ftype *oSzy = oS + 5 * field_size;
+
+oSxy[i] = aEyx * aHzt;
+oSxz[i] = -aEzx * aHyt;
+oSyz[i] = aEzy * aHxt;
+oSyx[i] = -aExy * aHzt;
+oSzx[i] = aExz * aHyt;
+oSzy[i] = -aEyz * aHxt;
+{%- endif -%}