libjaylink/util.c

   1 /*
   2  * This file is part of the libjaylink project.
   3  *
   4  * Copyright (C) 2014-2015 Marc Schink <jaylink-dev@marcschink.de>
   5  *
   6  * This program is free software: you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation, either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <stdbool.h>
  21
  22 #include "libjaylink.h"
  23
  24 /**
  25  * @file
  26  *
  27  * Utility functions.
  28  */
  29
  30 /**
  31  * Check for a capability.
  32  *
  33  * The capabilities are expected to be stored in a bit array consisting of one
  34  * or more bytes where each individual bit represents a capability. The first
  35  * bit of this array is the least significant bit of the first byte and the
  36  * following bits are sequentially numbered in order of increasing bit
  37  * significance and byte index. A set bit indicates a supported capability.
  38  *
  39  * @param[in] caps Buffer with capabilities.
  40  * @param[in] cap Bit position of the capability to check for.
  41  *
  42  * @retval true Capability is supported.
  43  * @retval false Capability is not supported or invalid argument.
  44  *
  45  * @since 0.1.0
  46  */
  47 JAYLINK_API bool jaylink_has_cap(const uint8_t *caps, uint32_t cap)
  48 {
  49         if (!caps)
  50                 return false;
  51
  52         if (caps[cap / 8] & (1 << (cap % 8)))
  53                 return true;
  54
  55         return false;
  56 }