1 files changed, 125 insertions, 0 deletions
diff --git a/server/zalloc.c b/server/zalloc.c
new file mode 100644
index 0000000..783cde8
--- /dev/null
+++ b/server/zalloc.c
@@ -0,0 +1,125 @@
+/*
+ * Memory allocator for Zephyr server.
+ */
+
+#include <stdio.h>
+#include "zalloc.h"
+
+/*
+ * Pick some size here that will help keep down the number of calls to
+ * malloc, but doesn't waste too much space.  To avoid waste of space,
+ * we leave some overhead before the next power of two.
+ */
+const int alloc_size = 16368;
+
+/*
+ * What's the maximum number of words to expect to allocate through
+ * this mechanism?  (Larger requests will be fed to malloc.)
+ */
+const int max_size = 32;
+
+static void *free_space;
+static int free_space_size;
+static void *buckets[max_size];
+
+const unsigned int sz = sizeof (void *);
+inline unsigned int round (unsigned int size) {
+    size += sz - 1;
+    size -= (size % sz);
+    return size;
+}
+#define ROUND(size)	(size = round (size))
+inline int BUCKET (unsigned int size) {
+    ROUND (size);
+    return size / sz - 1;
+}
+
+extern "C" {
+    void * malloc (unsigned int);
+    void free (void *);
+    void abort ();
+    void bzero (void *, unsigned int);
+}
+
+static inline void memset (void *ptr, int size, int fill) {
+#ifdef ZALLOC_DEBUG
+    char *cptr = (char *) ptr;
+    while (size--)
+	cptr[size] = fill;
+#endif
+}
+
+void *zalloc (unsigned int size) {
+    ROUND (size);
+
+    int bucket = BUCKET (size);
+    if (bucket < 0 || bucket >= max_size)
+	return malloc (size);
+
+    void *ret;
+    void **ptr = &buckets[bucket];
+#ifdef ZALLOC_DEBUG
+    fprintf (stderr, "zalloc(%d); looking in bucket %d, found %08X\n",
+	     size, bucket, *ptr);
+#endif
+    if (*ptr) {
+	ret = *ptr;
+	*ptr = *(void**)ret;
+	memset (ret, size, 0xe5);
+	return ret;
+    }
+
+    if (free_space_size < size) {
+	if (free_space_size > 0) {
+	    ptr = &buckets[BUCKET (free_space_size)];
+	    *(void**)free_space = *ptr;
+	    *ptr = free_space;
+#ifdef ZALLOC_DEBUG
+	    fprintf (stderr, "tossing %08X into bucket %d\n",
+		     free_space, bucket);
+#endif
+	}
+
+	free_space_size = (4080 / sizeof (void *)) * sizeof (void *);
+	free_space = malloc (free_space_size);
+	if (!free_space)
+	    abort ();
+#ifdef ZALLOC_DEBUG
+	fprintf (stderr, "grabbing more free store at %08X\n", free_space);
+#endif
+    }
+
+    ret = free_space;
+    free_space = (char *) free_space + size;
+    free_space_size -= size;
+#ifdef ZALLOC_DEBUG
+    fprintf (stderr, "returning %08X\n", ret);
+#endif
+    memset (ret, size, 0xe5);
+    return ret;
+}
+
+void zfree (void *ptr, unsigned int size) {
+    ROUND (size);
+
+    int bucket = BUCKET (size);
+    if (bucket < 0 || bucket >= max_size) {
+	free (ptr);
+	return;
+    }
+
+    void **b = &buckets[bucket];
+    memset (ptr, size, 0xe5);
+    *(void **) ptr = *b;
+    *b = ptr;
+#ifdef ZALLOC_DEBUG
+    fprintf (stderr, "putting %08X into bucket %d\n",
+	     ptr, bucket);
+#if 0
+    fprintf (stderr, "bucket %d:");
+    for (ptr = buckets[bucket]; ptr; ptr=*(void**)ptr)
+	fprintf (stderr, " %X", ptr);
+    fprintf (stderr, "\n");
+#endif
+#endif
+}