ncd: ncd.c: save memory by not storing pointer to and size of preallocated process memory. Instead, to figure out if statement

memory was individually allocated or is part of preallocated memory, use negative mem_size for individually allocated.

ncd/ncd.c

@@ -89,8 +89,6 @@ struct process {
     BSmallTimer wait_timer;
     BSmallPending work_job;
     LinkedList1Node list_node; // node in processes
-    char *mem;
-    int mem_size;
     int state;
     int ap;
     int fp;
@@ -160,7 +158,6 @@ static void signal_handler (void *unused);
 static void start_terminate (int exit_code);
 static int process_new (NCDInterpProcess *iprocess, NCDModuleProcess *module_process);
 static void process_free (struct process *p, NCDModuleProcess **out_mp);
-static int process_mem_is_preallocated (struct process *p, char *mem);
 static void process_start_terminating (struct process *p);
 static int process_have_child (struct process *p);
 static void process_assert_pointers (struct process *p);
@@ -176,6 +173,8 @@ static int process_resolve_object_expr (struct process *p, int pos, const char *
 static int process_resolve_variable_expr (struct process *p, int pos, const char *names, size_t num_names, NCDValMem *mem, NCDValRef *out_value);
 static void statement_logfunc (struct statement *ps);
 static void statement_log (struct statement *ps, int level, const char *fmt, ...);
+static int statement_mem_is_allocated (struct statement *ps);
+static int statement_mem_size (struct statement *ps);
 static int statement_allocate_memory (struct statement *ps, int alloc_size);
 static void statement_instance_func_event (struct statement *ps, int event);
 static int statement_instance_func_getobj (struct statement *ps, const char *objname, NCDObject *out_object);
@@ -699,8 +698,6 @@ int process_new (NCDInterpProcess *iprocess, NCDModuleProcess *module_process)
     // set variables
     p->iprocess = iprocess;
     p->module_process = module_process;
-    p->mem = (char *)p + mem_off;
-    p->mem_size = mem_size;
     p->state = PSTATE_WORKING;
     p->ap = 0;
     p->fp = 0;
@@ -715,13 +712,14 @@ int process_new (NCDInterpProcess *iprocess, NCDModuleProcess *module_process)
     }
     
     // init statements
+    char *mem = (char *)p + mem_off;
     for (int i = 0; i < num_statements; i++) {
         struct statement *ps = &p->statements[i];
         ps->p = p;
         ps->i = i;
         ps->state = SSTATE_FORGOTTEN;
         ps->mem_size = NCDInterpProcess_StatementPreallocSize(iprocess, i);
-        ps->mem = (ps->mem_size == 0 ? NULL : p->mem + NCDInterpProcess_StatementPreallocOffset(iprocess, i));
+        ps->mem = (ps->mem_size == 0 ? NULL : mem + NCDInterpProcess_StatementPreallocOffset(iprocess, i));
     }
     
     // init timer
@@ -754,7 +752,7 @@ void process_free (struct process *p, NCDModuleProcess **out_mp)
     // free statement memory
     for (int i = 0; i < p->num_statements; i++) {
         struct statement *ps = &p->statements[i];
-        if (ps->mem && !process_mem_is_preallocated(p, ps->mem)) {
+        if (statement_mem_is_allocated(ps)) {
             free(ps->mem);
         }
     }
@@ -772,13 +770,6 @@ void process_free (struct process *p, NCDModuleProcess **out_mp)
     BFree(p);
 }
 
-int process_mem_is_preallocated (struct process *p, char *mem)
-{
-    ASSERT(mem)
-    
-    return (mem >= p->mem && mem < p->mem + p->mem_size);
-}
-
 void process_start_terminating (struct process *p)
 {
     ASSERT(p->state != PSTATE_TERMINATING)
@@ -1217,12 +1208,22 @@ void statement_log (struct statement *ps, int level, const char *fmt, ...)
     va_end(vl);
 }
 
+int statement_mem_is_allocated (struct statement *ps)
+{
+    return (ps->mem_size < 0);
+}
+
+int statement_mem_size (struct statement *ps)
+{
+    return (ps->mem_size >= 0 ? ps->mem_size : -ps->mem_size);
+}
+
 int statement_allocate_memory (struct statement *ps, int alloc_size)
 {
     ASSERT(alloc_size >= 0)
     
-    if (alloc_size > ps->mem_size) {
-        if (ps->mem && !process_mem_is_preallocated(ps->p, ps->mem)) {
+    if (alloc_size > statement_mem_size(ps)) {
+        if (statement_mem_is_allocated(ps)) {
             free(ps->mem);
         }
         
@@ -1232,7 +1233,7 @@ int statement_allocate_memory (struct statement *ps, int alloc_size)
             return 0;
         }
         
-        ps->mem_size = alloc_size;
+        ps->mem_size = -alloc_size;
     }
     
     return 1;