1 files changed, 63 insertions, 0 deletions
diff --git a/heap.c b/heap.c
new file mode 100644
index 0000000..0789abc
--- /dev/null
+++ b/heap.c
@@ -0,0 +1,63 @@
+#include<u.h>
+#include<libc.h>
+#include<mheap.h>
+
+static void *pool = nil;
+static void *ptop;
+static ulong psz = 0;
+static ulong csz = 0;
+
+static void *stack[128]; // Stack depth is 128 maximum
+static void **stop = stack;
+
+int hdebug = 0;
+
+void
+hinit(ulong sz)
+{
+	if(pool)
+		free(pool);
+	pool = malloc(sz);
+	if(pool == nil)
+		sysfatal("hinit: %r");
+	
+	psz = sz;
+	csz = 0;
+	ptop = pool;
+}
+
+void *
+halloc(ulong sz)
+{
+	void *ptr;
+	
+	/* Check bounds */
+	if(sz + csz > psz)
+		sysfatal("halloc: heap exhausted");
+	
+	ptr = ptop;
+	ptop = sz + (uchar*)ptop;
+	csz += sz;
+	
+	if(hdebug)
+		fprint(2, "halloc: %uld\n", csz);
+	
+	return ptr;
+}
+
+/* Stack management */
+
+ulong
+hpush(void)
+{
+	*stop = ptop;
+	return (ulong)*stop++;
+}
+
+ulong
+hpop(void)
+{
+	ptop = *--stop;
+	csz = ((uchar *)ptop - (uchar*)pool);
+	return (ulong)ptop;
+}