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RIOT/cpu/msp430_common/mspgcc-supplement.c 1.23 KB
a752c7ab   elopes   add first test an...
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  /*
   * Copyright (C) 2016 Eistec AB
   *
   * This file is subject to the terms and conditions of the GNU Lesser
   * General Public License v2.1. See the file LICENSE in the top level
   * directory for more details.
   */
  
  /**
   * @ingroup     cpu
   * @{
   *
   * @file
   * @brief       MSPGCC supplemental functions
   *
   * @author      Joakim Nohlgård <joakim.nohlgard@eistec.se
   *
   * @}
   */
  
  #ifdef __MSPGCC__
  
  /* internal GCC type for "half integer" (16 bit) */
  /* See also:
   * http://stackoverflow.com/questions/4559025/what-does-gcc-attribute-modexx-actually-do
   * http://www.delorie.com/gnu/docs/gcc/gccint_53.html
   */
  typedef unsigned int UHItype __attribute__ ((mode (HI)));
  
  /**
   * @brief Count leading zeros
   *
   * Naive implementation
   */
  int __clzhi2(UHItype x)
  {
      int i = 0;
      for (UHItype mask = (1 << 15); mask != 0; mask >>= 1) {
          if (x & mask) {
              return i;
          }
          ++i;
      }
      return i; /* returns 16 if x == 0 */
  }
  
  /**
   * @brief Count trailing zeros
   *
   * Naive implementation
   */
  int __ctzhi2(UHItype x)
  {
      int i = 0;
      for (UHItype mask = 1; mask != 0; mask <<= 1) {
          if (x & mask) {
              return i;
          }
          ++i;
      }
      return i; /* returns 16 if x == 0 */
  }
  #endif /* __MSPGCC__ */