# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1548594685 -3600
# Node ID 31053f0bb63b0acfe9179b7c1e1babc976836629
# Parent  9c9bd4fccad4e817b657077c5ff06a67d93c5aba
Experiment with a statically-allocated table of preallocated instances, also
marking the instances as "atomic".

diff -r 9c9bd4fccad4 -r 31053f0bb63b templates/native/float.c
--- a/templates/native/float.c	Sun Jan 27 01:08:28 2019 +0100
+++ b/templates/native/float.c	Sun Jan 27 14:11:25 2019 +0100
@@ -30,64 +30,50 @@
 
 /* A table of preallocated float instances. */
 
-struct float_table
-{
-    struct float_table *next;
-    char data[];
-};
+#define NUM_PREALLOCATED 1000
 
-static struct float_table *next_float = 0;
+__ref preallocated_floats[NUM_PREALLOCATED];
+
+static int floats_left = 0;
 
 /* Preallocate some float instances. */
 
-static void preallocate_floats(int num)
+static void preallocate_floats()
 {
-    struct float_table *latest;
     int i;
 
-    for (i = 0; i < num; i++)
+    for (i = 0; i < NUM_PREALLOCATED; i++)
     {
-        /* Allocate a table entry. */
+        /* Allocate a float for each table entry. */
 
-        latest = (struct float_table *)
-                 __ALLOCATE(1, sizeof(struct float_table *) +
-                               __INSTANCESIZE(__builtins___float_float));
+        preallocated_floats[i] = \
+            __ALLOCATEIM(1, __INSTANCESIZE(__builtins___float_float));
+    }
 
-        /* Reference the last entry from the new entry. */
-
-        latest->next = next_float;
-        next_float = latest;
-    }
+    floats_left = NUM_PREALLOCATED;
 }
 
 static __attr new_float(double n)
 {
-    struct float_table *this_float;
+    __ref obj;
     __attr attr;
 
-    if (!next_float)
-        preallocate_floats(1000);
-
-    /* Reference the next preallocated entry. */
+    if (!floats_left)
+        preallocate_floats();
 
-    this_float = next_float;
-
-    /* Initialise the embedded instance. */
+    floats_left--;
+    obj = preallocated_floats[floats_left];
 
-    __init((__ref) &this_float->data,
-           &__INSTANCETABLE(__builtins___float_float),
-           &__builtins___float_float);
+    /* Initialise the instance. */
+
+    __init(obj, &__INSTANCETABLE(__builtins___float_float),
+                &__builtins___float_float);
 
     /* Populate the float with the value. */
 
-    attr = __ATTRVALUE(&this_float->data);
+    attr = __ATTRVALUE(obj);
     __set_trailing_data(attr, __builtins___float_float, n);
 
-    /* Make the next entry available and detach it from this one. */
-
-    next_float = this_float->next;
-    this_float->next = 0;
-
     return attr;
 }