1 files changed, 45 insertions, 0 deletions
diff --git a/tangle/LLBM/kernel/collect_moments.h b/tangle/LLBM/kernel/collect_moments.h
new file mode 100644
index 0000000..b2ef09b
--- /dev/null
+++ b/tangle/LLBM/kernel/collect_moments.h
@@ -0,0 +1,45 @@
+#pragma once
+#include <LLBM/call_tag.h>
+
+struct CollectMomentsF {
+
+using call_tag = tag::call_by_cell_id;
+
+template <typename T, typename S>
+__device__ static void apply(descriptor::D2Q9, S f_curr[9], std::size_t gid, T* cell_rho, T* cell_u) {
+  T m0 = f_curr[1] + f_curr[2];
+  T m1 = f_curr[3] + f_curr[6];
+  T m2 = m0 + m1 + f_curr[0] + f_curr[4] + f_curr[5] + f_curr[7] + f_curr[8];
+  T m3 = f_curr[0] - f_curr[8];
+  T m4 = T{1} / (m2);
+  T rho = m2;
+  T u_0 = -m4*(m0 + m3 - f_curr[6] - f_curr[7]);
+  T u_1 = -m4*(m1 + m3 - f_curr[2] - f_curr[5]);
+
+  cell_rho[gid] = rho;
+  cell_u[2*gid+0] = u_0;
+  cell_u[2*gid+1] = u_1;
+}
+
+template <typename T, typename S>
+__device__ static void apply(descriptor::D3Q19, S f_curr[19], std::size_t gid, T* cell_rho, T* cell_u) {
+  T m0 = f_curr[10] + f_curr[13] + f_curr[17];
+  T m1 = f_curr[14] + f_curr[5] + f_curr[6];
+  T m2 = f_curr[1] + f_curr[2] + f_curr[4];
+  T m3 = m0 + m1 + m2 + f_curr[0] + f_curr[11] + f_curr[12] + f_curr[15] + f_curr[16] + f_curr[18] + f_curr[3] + f_curr[7] + f_curr[8] + f_curr[9];
+  T m4 = -f_curr[11] + f_curr[7];
+  T m5 = -f_curr[15] + f_curr[3];
+  T m6 = T{1} / (m3);
+  T m7 = f_curr[0] - f_curr[18];
+  T rho = m3;
+  T u_0 = m6*(m0 + m4 + m5 - f_curr[1] - f_curr[5] - f_curr[8]);
+  T u_1 = m6*(m1 + m4 + m7 - f_curr[12] - f_curr[13] - f_curr[4]);
+  T u_2 = m6*(m2 + m5 + m7 - f_curr[14] - f_curr[16] - f_curr[17]);
+
+  cell_rho[gid] = rho;
+  cell_u[3*gid+0] = u_0;
+  cell_u[3*gid+1] = u_1;
+  cell_u[3*gid+2] = u_2;
+}
+
+};