Added missing functions to fix backwards compatibility with the version interfaced with Pencil Code

src/core/astaroth.cu

@@ -19,6 +19,8 @@
 // #include "astaroth_defines.h"
 #include "astaroth.h"
 
+#include "math_utils.h" // int3 + int3
+
 #define AC_GEN_STR(X) #X
 const char* intparam_names[]   = {AC_FOR_BUILTIN_INT_PARAM_TYPES(AC_GEN_STR) //
                                 AC_FOR_USER_INT_PARAM_TYPES(AC_GEN_STR)};
@@ -33,10 +35,13 @@ const char* vtxbuf_names[]     = {AC_FOR_VTXBUF_HANDLES(AC_GEN_STR)};
 
 static const int num_nodes = 1;
 static Node nodes[num_nodes];
+static int3 grid_n;
 
 AcResult
 acInit(const AcMeshInfo mesh_info)
 {
+    grid_n = (int3){mesh_info.int_params[AC_nx], mesh_info.int_params[AC_ny],
+                    mesh_info.int_params[AC_nz]};
     return acNodeCreate(0, mesh_info, &nodes[0]);
 }
 
@@ -46,6 +51,12 @@ acQuit(void)
     return acNodeDestroy(nodes[0]);
 }
 
+AcResult
+acSynchronize(void)
+{
+    return acNodeSynchronizeStream(nodes[0], STREAM_ALL);
+}
+
 AcResult
 acSynchronizeStream(const Stream stream)
 {
@@ -80,6 +91,20 @@ acIntegrate(const AcReal dt)
     return acNodeIntegrate(nodes[0], dt);
 }
 
+AcResult
+acIntegrateStep(const int& isubstep, const AcReal dt)
+{
+    const int3 start = (int3){NGHOST, NGHOST, NGHOST};
+    const int3 end   = start + grid_n;
+    return acNodeIntegrateSubstep(nodes[0], STREAM_DEFAULT, isubstep, start, end, dt);
+}
+
+AcResult
+acIntegrateStepWithOffset(const int isubstep, const AcReal dt, const int3 start, const int3 end)
+{
+    return acNodeIntegrateSubstep(nodes[0], STREAM_DEFAULT, isubstep, start, end, dt);
+}
+
 AcResult
 acBoundcondStep(void)
 {