Implemented some functionality for WM allocs

watermark_alloc.c

@@ -0,0 +1,44 @@
+/*
+ * Allocates space within a tree allocator for performing
+ * watermark allocations. 
+ */
+WatermarkAlloc *new_watermark_allocator(TreeAlloc *ta, int size) {
+	// TODO: Allocate space correctly when that is ironed out.
+	// This will just SIGSEGV 100% of the time for now.
+	WatermarkAlloc *wma = NULL; 
+	wma->type = RT_WATERMARK;
+	wma->parent = ta;
+	wma->left = wma->right = NULL; // TODO: How should these be set?
+	wma->size = size;
+	wma->num_allocs = 0;
+	wma->next_alloc = wma + sizeof(wma);
+	return wma;
+}
+
+/*
+ * Attempt to allocate space within a watermark region.
+ * Returns the null pointer if the allocation cannot fit.
+ */
+void *watermark_allocate(WatermarkAlloc *wma, int size) {
+	int space_left = wma + wma->size - wma->next_alloc;
+	if (space_left < size)
+		return NULL;
+
+	void *allocation = wma->next_alloc;
+	wma->next_alloc += size;
+	wma->num_allocs += 1;
+
+	return allocation;
+}
+
+/*
+ *	"Frees" space inside the watermark region. Since this
+ *	is watermark, however, this doesn't actually do anything
+ *	besides decrement the ref-count. It returns the new
+ *	ref-count so that the parent allocator can clean up the
+ *	space properly. 
+ */
+bool watermark_free(WatermarkAlloc *wma) {
+	wma->num_allocs -= 1;
+	return wma->num_allocs;
+}