src/cmd_helper.h

   1 /* $Id$ */
   2
   3 /*
   4  * This file is part of OpenTTD.
   5  * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
   6  * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   7  * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
   8  */
   9
  10 /** @file cmd_helper.h Helper functions to extract data from command parameters. */
  11
  12 #ifndef CMD_HELPER_H
  13 #define CMD_HELPER_H
  14
  15 #include "core/enum_type.hpp"
  16 #include "core/bitmath_func.hpp"
  17
  18 /**
  19  * Extracts a given type from a value.
  20  * @tparam T The type of data we're looking for.
  21  * @tparam S The offset in the data.
  22  * @tparam N The amount of bits to read.
  23  * @tparam U The type of data passed to us.
  24  * @param v The data to extract the value from.
  25  */
  26 template<typename T, uint S, uint N, typename U> static inline T Extract(U v)
  27 {
  28         /* Check if there are enough bits in v */
  29         assert_tcompile(N == EnumPropsT<T>::num_bits);
  30         assert_tcompile(S + N <= sizeof(U) * 8);
  31         assert_tcompile(EnumPropsT<T>::end <= (1 << N));
  32         U masked = GB(v, S, N);
  33         return IsInsideMM(masked, EnumPropsT<T>::begin, EnumPropsT<T>::end) ? (T)masked : EnumPropsT<T>::invalid;
  34 }
  35
  36 #endif /* CMD_HELPER_H */