+/**
+ * Get the index of a position.
+ * @param pos The position.
+ * @return The index of the position.
+ */
+#define arch_pos_get_index(pos) ((pos) < 0 ? -(pos) - 1 : (pos))
+
+typedef struct _arch_irn_ops_t {
+
+ /**
+ * Get the register requirements for a given operand.
+ * @param irn The node.
+ * @param pos The operand's position.
+ * @return The register requirements for the selected operand,
+ * or NULL, if the operand is no register.
+ */
+ const arch_register_req_t *(*get_irn_reg_req)(const ir_node *irn, int pos);
+
+ /**
+ * Get the number of operands of a node.
+ * @param irn The node.
+ * @param in_out Denotes wither input (a number >= 0) or
+ * output (a number < 0).
+ * @return The number of operands for either in, or output.
+ */
+ int (*get_n_operands)(const ir_node *irn, int in_out);
+
+ /**
+ * Set the register for an output operand.
+ * @param irn The node.
+ * @param pos The position of the output operand.
+ * @param reg The register allocated to that operand.
+ * @note If the operand is not a register operand,
+ * the call is ignored.
+ */
+ void (*set_irn_reg)(ir_node *irn, int idx, const arch_register_t *reg);
+
+ /**
+ * Get the register allocated for an output operand.
+ * @param irn The node.
+ * @param pos The index of the output operand.
+ * @return The register allocated at that operand. NULL, if
+ * the operand was no register operand or
+ * @c arch_register_invalid, if no register has yet been
+ * allocated for this node.
+ */
+ const arch_register_t *(*get_irn_reg)(const ir_node *irn, int idx);
+
+ /**
+ * Classify the node.
+ * @param irn The node.
+ * @return A classification.
+ */
+ arch_irn_class_t (*classify)(const ir_node *irn);
+
+} arch_irn_ops_t;