Added a skeleton function for updating an arbitrary block inside the computational domain instead of the whole mesh

include/astaroth.h

@@ -341,6 +341,12 @@ AcResult acIntegrate(const AcReal& dt);
 /** Performs a single RK3 step without computing boundary conditions. */
 AcResult acIntegrateStep(const int& isubstep, const AcReal& dt);
 
+/** Performs a single RK3 step without computing boundary conditions.
+    Operates on a three-dimensional cuboid, where start and end are the
+    opposite corners. */
+AcResult acIntegrateStepWithOffset(const int& isubstep, const AcReal& dt, const int3& start,
+                                   const int3& end);
+
 /** Applies boundary conditions on the GPU meshs and communicates the
  ghost zones among GPUs if necessary */
 AcResult acBoundcondStep(void);

src/core/astaroth.cu

@@ -269,6 +269,20 @@ acIntegrateStep(const int& isubstep, const AcReal& dt)
     return AC_SUCCESS;
 }
 
+AcResult
+acIntegrateStepWithOffset(const int& isubstep, const AcReal& dt, const int3& start, const int3& end)
+{
+    /*
+    // A skeleton function for computing integrations with arbitrary subblocks
+    // Uncommenting the following should work with a single GPU.
+    const int3 start = (int3){STENCIL_ORDER / 2, STENCIL_ORDER / 2, STENCIL_ORDER / 2};
+    const int3 end   = (int3){STENCIL_ORDER / 2 + subgrid.n.x, STENCIL_ORDER / 2 + subgrid.n.y,
+                            STENCIL_ORDER / 2 + subgrid.n.z};
+    rkStep(devices[0], STREAM_PRIMARY, isubstep, start, end, dt);
+    */
+    return AC_FAILURE;
+}
+
 AcResult
 acBoundcondStep(void)
 {