Improves the code, such as adding missing "const"

This is a minor update to perform minor tidying of the code. The largest
change is the addition of missing "const" qualifiers in the C and CUDA
code.

Author: ar4

src/deepwave/acoustic.c

@@ -615,7 +615,7 @@ __declspec(dllexport)
       // Save snapshots
 #define SAVE_SNAPSHOT(name, grad_cond)                                     \
   if (grad_cond) {                                                         \
-    int64_t step_idx = t / step_ratio;                                     \
+    int64_t const step_idx = t / step_ratio;                               \
     storage_save_snapshot_cpu(                                             \
         name##_store_1_t, name##_store_2_t, fp_##name, storage_mode,       \
         storage_compression, step_idx, shot_bytes_uncomp, shot_bytes_comp, \
@@ -952,7 +952,7 @@ __declspec(dllexport)
                    : 0)) *                                                   \
           (int64_t)shot_bytes_comp;                                          \
   if ((grad_cond) && ((t % step_ratio) == 0)) {                              \
-    int64_t step_idx = t / step_ratio;                                       \
+    int64_t const step_idx = t / step_ratio;                                 \
     storage_load_snapshot_cpu(                                               \
         (void *)name##_store_1_t, name##_store_2_t, fp_##name, storage_mode, \
         storage_compression, step_idx, shot_bytes_uncomp, shot_bytes_comp,   \

src/deepwave/acoustic.cu

@@ -854,7 +854,7 @@ def forward(
                 receiver_amplitudes[i].resize_(nt, n_shots, n_per_shot)
                 receiver_amplitudes[i].fill_(0)
 
-        stream = 0
+        stream: Union[int, torch.Stream] = 0
         if is_cuda:
             aux = models[0].get_device()
             stream = torch.cuda.current_stream(aux)
@@ -1068,7 +1068,7 @@ def backward(ctx: Any, *args: torch.Tensor) -> Tuple[Optional[torch.Tensor], ...
 
         model_batched = [m.ndim == ndim + 1 and m.shape[0] > 1 for m in models[:2]]
 
-        stream = 0
+        stream: Union[int, torch.Stream] = 0
         if is_cuda:
             aux = models[0].get_device()
             stream = torch.cuda.current_stream(aux)

src/deepwave/acoustic.py

@@ -114,7 +114,7 @@ def get_scalar_born_forward_template(ndim: int) -> List[Any]:
     args += [c_void_p] * 4  # w_store_1a, w_store_1b, w_store_2, w_store_3
     args += [c_void_p]  # w_filenames
     args += [c_void_p] * 4  # wsc_store_1a, w_store_1b, wsc_store_2, wsc_store_3
-    args += [c_void_p]  #sc w_filenames
+    args += [c_void_p]  # sc w_filenames
     args += [c_void_p] * 2  # r, rsc
     args += [c_void_p] * (3 * ndim)  # a, b, dbdx
     args += [c_void_p] * 3  # sources_i, receivers_i, receiverssc_i

src/deepwave/backend_utils.py

@@ -99,7 +99,7 @@ def __init__(
 
     def get_ptrs(
         self,
-    ) -> Tuple[int, int, int, int, int, int, ctypes.Array[ctypes.c_char_p]]:
+    ) -> Tuple[int, int, int, int, ctypes.Array[ctypes.c_char_p]]:
         """Return pointers to the storage and filenames array."""
         return (
             self.store_1a.data_ptr(),

src/deepwave/common.py

@@ -341,13 +341,14 @@ static inline void add_pressure(
 
 static inline void record_pressure(
 #if DW_NDIM >= 3
-    DW_DTYPE const *__restrict sigmazz,
+    DW_DTYPE const *__restrict const sigmazz,
 #endif
 #if DW_NDIM >= 2
-    DW_DTYPE const *__restrict sigmayy,
+    DW_DTYPE const *__restrict const sigmayy,
 #endif
-    DW_DTYPE const *__restrict sigmaxx, int64_t const *__restrict locations,
-    DW_DTYPE *__restrict amplitudes, int64_t n) {
+    DW_DTYPE const *__restrict const sigmaxx,
+    int64_t const *__restrict const locations,
+    DW_DTYPE *__restrict const amplitudes, int64_t n) {
   int64_t i;
 #pragma omp simd
   for (i = 0; i < n; ++i) {
@@ -1231,7 +1232,7 @@ __declspec(dllexport)
 
 #define SAVE_SNAPSHOT(name, grad_cond)                                     \
   if (grad_cond) {                                                         \
-    int64_t step_idx = t / step_ratio;                                     \
+    int64_t const step_idx = t / step_ratio;                               \
     storage_save_snapshot_cpu(                                             \
         name##_store_1_t, name##_store_2_t, fp_##name, storage_mode,       \
         storage_compression, step_idx, shot_bytes_uncomp, shot_bytes_comp, \
@@ -1656,7 +1657,7 @@ __declspec(dllexport)
                    : 0)) *                                                   \
           (int64_t)shot_bytes_comp;                                          \
   if ((grad_cond) && ((t % step_ratio) == 0)) {                              \
-    int64_t step_idx = t / step_ratio;                                       \
+    int64_t const step_idx = t / step_ratio;                                 \
     storage_load_snapshot_cpu(                                               \
         (void *)name##_store_1_t, name##_store_2_t, fp_##name, storage_mode, \
         storage_compression, step_idx, shot_bytes_uncomp, shot_bytes_comp,   \