src/main/common/utils.h

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