src/main/common/utils.h

   1 /*
   2  * This file is part of Cleanflight and Betaflight.
   3  *
   4  * Cleanflight and Betaflight are free software. You can redistribute
   5  * this software and/or modify this software under the terms of the
   6  * GNU General Public License as published by the Free Software
   7  * Foundation, either version 3 of the License, or (at your option)
   8  * any later version.
   9  *
  10  * Cleanflight and Betaflight are distributed in the hope that they
  11  * will be useful, but WITHOUT ANY WARRANTY; without even the implied
  12  * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  13  * See the GNU General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this software.
  17  *
  18  * If not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #pragma once
  22
  23 #include <stddef.h>
  24 #include <stdint.h>
  25
  26 #define NOOP do {} while (0)
  27
  28 #define ARRAYLEN(x) (sizeof(x) / sizeof((x)[0]))
  29 #define ARRAYEND(x) (&(x)[ARRAYLEN(x)])
  30
  31 #define CONST_CAST(type, value) ((type)(value))
  32
  33 #define CONCAT_HELPER(x,y) x ## y
  34 #define CONCAT(x,y) CONCAT_HELPER(x, y)
  35 #define CONCAT2(_1,_2) CONCAT(_1, _2)
  36 #define CONCAT3(_1,_2,_3)  CONCAT(CONCAT(_1, _2), _3)
  37 #define CONCAT4(_1,_2,_3,_4)  CONCAT(CONCAT3(_1, _2, _3), _4)
  38
  39 #define STR_HELPER(x) #x
  40 #define STR(x) STR_HELPER(x)
  41
  42 #define EXPAND_I(x) x
  43 #define EXPAND(x) EXPAND_I(x)
  44
  45 // expand to t if bit is 1, f when bit is 0. Other bit values are not supported
  46 #define PP_IIF(bit, t, f) PP_IIF_I(bit, t, f)
  47 #define PP_IIF_I(bit, t, f) PP_IIF_ ## bit(t, f)
  48 #define PP_IIF_0(t, f) f
  49 #define PP_IIF_1(t, f) t
  50
  51 // Expand all arguments and call macro with them. When expansion of some argument contains ',', it will be passed as multiple arguments
  52 // #define TAKE3(_1,_2,_3) CONCAT3(_1,_2,_3)
  53 // #define MULTI2 A,B
  54 // PP_CALL(TAKE3, MULTI2, C) expands to ABC
  55 #define PP_CALL(macro, ...) macro(__VA_ARGS__)
  56
  57 #if !defined(UNUSED)
  58 #define UNUSED(x) (void)(x) // Variables and parameters that are not used
  59 #endif
  60
  61 #define DISCARD(x) (void)(x) // To explicitly ignore result of x (usually an I/O register access).
  62
  63 #define STATIC_ASSERT(condition, name) _Static_assert((condition), #name)
  64
  65
  66 #define BIT(x) (1 << (x))
  67
  68 /*
  69 http://resnet.uoregon.edu/~gurney_j/jmpc/bitwise.html
  70 */
  71 #define BITCOUNT(x) (((BX_(x)+(BX_(x)>>4)) & 0x0F0F0F0F) % 255)
  72 #define BX_(x) ((x) - (((x)>>1)&0x77777777) - (((x)>>2)&0x33333333) - (((x)>>3)&0x11111111))
  73
  74
  75 /*
  76  * https://groups.google.com/forum/?hl=en#!msg/comp.lang.c/attFnqwhvGk/sGBKXvIkY3AJ
  77  * Return (v ? floor(log2(v)) : 0) when 0 <= v < 1<<[8, 16, 32, 64].
  78  * Inefficient algorithm, intended for compile-time constants.
  79  */
  80 #define LOG2_8BIT(v)  (8 - 90/(((v)/4+14)|1) - 2/((v)/2+1))
  81 #define LOG2_16BIT(v) (8*((v)>255) + LOG2_8BIT((v) >>8*((v)>255)))
  82 #define LOG2_32BIT(v) (16*((v)>65535L) + LOG2_16BIT((v)*1L >>16*((v)>65535L)))
  83 #define LOG2_64BIT(v) \
  84     (32*((v)/2L>>31 > 0) \
  85      + LOG2_32BIT((v)*1L >>16*((v)/2L>>31 > 0) \
  86                          >>16*((v)/2L>>31 > 0)))
  87 #define LOG2(v) LOG2_64BIT(v)
  88
  89 #if 0
  90 // ISO C version, but no type checking
  91 #define container_of(ptr, type, member) \
  92                       ((type *) ((char *)(ptr) - offsetof(type, member)))
  93 #else
  94 // non ISO variant from linux kernel; checks ptr type, but triggers 'ISO C forbids braced-groups within expressions [-Wpedantic]'
  95 //  __extension__ is here to disable this warning
  96 #define container_of(ptr, type, member)  ( __extension__ ({     \
  97         const typeof( ((type *)0)->member ) *__mptr = (ptr);    \
  98         (type *)( (char *)__mptr - offsetof(type,member) );}))
  99
 100 static inline int16_t cmp16(uint16_t a, uint16_t b) { return (int16_t)(a-b); }
 101 static inline int32_t cmp32(uint32_t a, uint32_t b) { return (int32_t)(a-b); }
 102
 103 // using memcpy_fn will force memcpy function call, instead of inlining it. In most cases function call takes fewer instructions
 104 //  than inlined version (inlining is cheaper for very small moves < 8 bytes / 2 store instructions)
 105 #if defined(UNIT_TEST) || defined(SIMULATOR_BUILD)
 106 // Call memcpy when building unittest - this is easier that asm symbol name mangling (symbols start with _underscore on win32)
 107 #include <string.h>
 108 static inline void  memcpy_fn ( void * destination, const void * source, size_t num ) { memcpy(destination, source, num); }
 109 #else
 110 void * memcpy_fn ( void * destination, const void * source, size_t num ) asm("memcpy");
 111 #endif
 112
 113
 114 #endif
 115
 116 #if __GNUC__ > 6
 117 #define FALLTHROUGH __attribute__ ((fallthrough))
 118 #else
 119 #define FALLTHROUGH do {} while(0)
 120 #endif