Line data    Source code

       1             : /* Copyright (C) 2020 Wildfire Games.
       2             :  *
       3             :  * Permission is hereby granted, free of charge, to any person obtaining
       4             :  * a copy of this software and associated documentation files (the
       5             :  * "Software"), to deal in the Software without restriction, including
       6             :  * without limitation the rights to use, copy, modify, merge, publish,
       7             :  * distribute, sublicense, and/or sell copies of the Software, and to
       8             :  * permit persons to whom the Software is furnished to do so, subject to
       9             :  * the following conditions:
      10             :  *
      11             :  * The above copyright notice and this permission notice shall be included
      12             :  * in all copies or substantial portions of the Software.
      13             :  *
      14             :  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
      15             :  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
      16             :  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
      17             :  * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
      18             :  * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
      19             :  * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
      20             :  * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
      21             :  */
      22             : 
      23             : /*
      24             :  * bit-twiddling.
      25             :  */
      26             : 
      27             : #include "precompiled.h"
      28             : #include "lib/bits.h"
      29             : 
      30             : #include <cstring>
      31             : 
      32          36 : static inline u32 get_float_bits(const float x)
      33             : {
      34             :     u32 ret;
      35          36 :     memcpy(&ret, &x, 4);
      36          36 :     return ret;
      37             : }
      38             : 
      39          36 : int floor_log2(const float x)
      40             : {
      41          36 :     const u32 i = get_float_bits(x);
      42          36 :     const u32 biased_exp = (i >> 23) & 0xFF;
      43          36 :     return (int)biased_exp - 127;
      44           3 : }