started a new database-backed runtime from scratch

src/runtime/c/db.h

@@ -0,0 +1,55 @@
+#ifndef DB_H
+#define DB_H
+
+class DB;
+
+extern thread_local PGF_INTERNAL_DECL unsigned char* current_base;
+extern thread_local PGF_INTERNAL_DECL DB* current_db;
+
+typedef size_t moffset;
+
+struct malloc_state;
+
+template<class A> class ref {
+    size_t offset;
+
+public:
+    ref<A>() { }
+    ref<A>(size_t o) { offset = o; }
+    inline A* operator->() const { return (A*) (current_base+offset); }
+    inline operator A*()   const { return (A*) (current_base+offset); }
+    inline bool operator ==(ref<A>& other) const { return offset==other->offset; }
+    inline operator size_t() { return offset; }
+};
+
+class PGF_INTERNAL_DECL DB {
+    int fd;
+    malloc_state* ms;
+
+public:
+    DB(const char* pathname);
+    ~DB();
+
+    template<class A> ref<A> malloc() {
+        return malloc(sizeof(A));
+    }
+
+    moffset malloc(size_t bytes);
+
+    template<class A> ref<A> get_root() {
+        return get_root_offset();
+    }
+    template<class A> void set_root(ref<A> root) {
+        set_root_offset(root);
+    }
+
+private:
+    void init_state(size_t size);
+
+    void free(moffset o);
+
+    moffset get_root_offset();
+    void set_root_offset(moffset root);
+};
+
+#endif