Rename nstack to narena, change it and pstack to count bytes.

PiperOrigin-RevId: 561066311
Change-Id: I4d0e645e6c254dd906bfc42159e0e99149a7c6c8

python/mujoco/bindings_test.py

@@ -946,7 +946,7 @@ Euler integrator, semi-implicit in velocity.
                      mujoco.mjtDisableBit.mjDSBL_CONTACT)
 
   def test_can_raise_error(self):
-    self.data.pstack = self.data.nstack
+    self.data.pstack = self.data.narena
     with self.assertRaisesRegex(mujoco.FatalError,
                                 r'\Amj_stackAllocByte: stack overflow'):
       mujoco.mj_forward(self.model, self.data)

python/mujoco/functions.cc

@@ -1341,7 +1341,7 @@ PYBIND11_MODULE(_functions, pymodule) {
 #ifdef ADDRESS_SANITIZER
         ASAN_POISON_MEMORY_REGION(
             static_cast<char*>(data->arena),
-            (data->nstack - data->pstack) * sizeof(mjtNum));
+            data->narena - data->pstack);
 #endif
           data->ncon = 0;
           data->nefc = 0;

python/mujoco/mjdata_meta.h

@@ -88,7 +88,7 @@ struct MjDataMetadata {
         is_dual(mj_isDual(m)) {
   }
 
-#define X(var) int var;
+#define X(var) decltype(raw::MjModel::var) var;
   MJMODEL_INTS
 #undef X
 #define X(type, var, n) std::shared_ptr<type[]> var;

python/mujoco/structs.cc

@@ -78,7 +78,7 @@ constexpr auto XArrayShapeImpl(const std::string_view dim1_str) {
 }
 
 inline std::size_t NConMax(const mjData* d) {
-  return d->nstack * sizeof(mjtNum) / sizeof(mjContact);
+  return d->narena / sizeof(mjContact);
 }
 }  // namespace
 
@@ -459,7 +459,7 @@ MjModelWrapper MjModelWrapper::Deserialize(std::istream& input) {
     throw py::value_error("Incompatible serialization version.");
   }
 
-  int model_size = ReadInt(input);
+  std::size_t model_size = ReadInt(input);
   CheckInput(input, "mjModel");
   if (model_size < 0) {
     throw py::value_error("Invalid serialized mjModel.");