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

PiperOrigin-RevId: 561066311
Change-Id: I4d0e645e6c254dd906bfc42159e0e99149a7c6c8

doc/XMLreference.rst

@@ -450,7 +450,7 @@ compilation.
 
 :at:`nstack`: :at-val:`int, "-1"` |nbsp| |nbsp| |nbsp| (legacy)
    This is a deprecated legacy attribute. In versions prior to 2.3.0, it determined the maximum size of the
-   :ref:`stack <siStack>`. After version 2.3.0, if :at:`nstack` is specified, then the size of ``mjData.arena`` is
+   :ref:`stack <siStack>`. After version 2.3.0, if :at:`nstack` is specified, then the size of ``mjData.narena`` is
    ``nstack * sizeof(mjtNum)`` bytes, plus an additional space for the constraint solver. Specifying both :at:`nstack`
    and :at:`memory` leads to an error.
 

doc/changelog.rst

@@ -39,6 +39,8 @@ General
 #. Added the flag :ref:`invdiscrete<option-flag-invdiscrete>`, which enables discrete-time inverse dynamics for all
    :ref:`integrators<option-integrator>` other than ``RK4``. See the flag documentation for more details.
 #. Renamed the function ``mj_stackAlloc`` to ``mj_stackAllocNum``.
+#. Renamed the ``nstack`` field in ``mjModel`` and ``mjData`` to ``narena``. Changed ``narena``, ``pstack``, and
+   ``maxuse_stack`` to count number of bytes rather than number of ``mjtNum``s.
 
 Python bindings
 ^^^^^^^^^^^^^^^

doc/includes/references.h

@@ -124,8 +124,8 @@ struct mjSolverStat_ {       // per-iteration solver statistics
 typedef struct mjSolverStat_ mjSolverStat;
 struct mjData_ {
   // constant sizes
-  int     nstack;            // number of mjtNums that can fit in the arena+stack space
-  int     nbuffer;           // size of main buffer in bytes
+  size_t  narena;            // size of the arena in bytes (inclusive of the stack)
+  size_t  nbuffer;           // size of main buffer in bytes
   int     nplugin;           // number of plugin instances
 
   // stack pointer
@@ -135,7 +135,7 @@ struct mjData_ {
   size_t  parena;            // first available byte in arena
 
   // memory utilization stats
-  int     maxuse_stack;      // maximum stack allocation
+  size_t  maxuse_stack;      // maximum stack allocation
   size_t  maxuse_arena;      // maximum arena allocation
   int     maxuse_con;        // maximum number of contacts
   int     maxuse_efc;        // maximum number of scalar constraints
@@ -881,12 +881,12 @@ struct mjModel_ {
   int nemax;                      // number of potential equality-constraint rows
   int njmax;                      // number of available rows in constraint Jacobian
   int nconmax;                    // number of potential contacts in contact list
-  int nstack;                     // number of fields in mjData stack
   int nuserdata;                  // number of extra fields in mjData
   int nsensordata;                // number of fields in sensor data vector
   int npluginstate;               // number of fields in plugin state vector
 
-  int nbuffer;                    // number of bytes in buffer
+  size_t narena;                  // number of bytes in the mjData arena (inclusive of stack)
+  size_t nbuffer;                 // number of bytes in buffer
 
   // ------------------------------- options and statistics