-void target_read_u32(struct target_s *target, u32 address, u32 *value);
-void target_read_u16(struct target_s *target, u32 address, u16 *value);
-void target_read_u8(struct target_s *target, u32 address, u8 *value);
-void target_write_u32(struct target_s *target, u32 address, u32 value);
-void target_write_u16(struct target_s *target, u32 address, u16 value);
-void target_write_u8(struct target_s *target, u32 address, u8 value);
+int target_read_u32(struct target_s *target, u32 address, u32 *value);
+int target_read_u16(struct target_s *target, u32 address, u16 *value);
+int target_read_u8(struct target_s *target, u32 address, u8 *value);
+int target_write_u32(struct target_s *target, u32 address, u32 value);
+int target_write_u16(struct target_s *target, u32 address, u16 value);
+int target_write_u8(struct target_s *target, u32 address, u8 value);