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betaflight/src/main/common/utils.h
2016-07-16 11:24:05 +02:00

74 lines
2.6 KiB
C

/*
* This file is part of Cleanflight.
*
* Cleanflight is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* Cleanflight is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with Cleanflight. If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once
#include <stddef.h>
#include <stdint.h>
#define ARRAYLEN(x) (sizeof(x) / sizeof((x)[0]))
#define CONCAT_HELPER(x,y) x ## y
#define CONCAT(x,y) CONCAT_HELPER(x, y)
#define STR_HELPER(x) #x
#define STR(x) STR_HELPER(x)
#define EXPAND_I(x) x
#define EXPAND(x) EXPAND_I(x)
#define UNUSED(x) (void)(x)
#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
#define BIT(x) (1 << (x))
/*
http://resnet.uoregon.edu/~gurney_j/jmpc/bitwise.html
*/
#define BITCOUNT(x) (((BX_(x)+(BX_(x)>>4)) & 0x0F0F0F0F) % 255)
#define BX_(x) ((x) - (((x)>>1)&0x77777777) - (((x)>>2)&0x33333333) - (((x)>>3)&0x11111111))
#define UNUSED(x) (void)(x)
/*
* https://groups.google.com/forum/?hl=en#!msg/comp.lang.c/attFnqwhvGk/sGBKXvIkY3AJ
* Return (v ? floor(log2(v)) : 0) when 0 <= v < 1<<[8, 16, 32, 64].
* Inefficient algorithm, intended for compile-time constants.
*/
#define LOG2_8BIT(v) (8 - 90/(((v)/4+14)|1) - 2/((v)/2+1))
#define LOG2_16BIT(v) (8*((v)>255) + LOG2_8BIT((v) >>8*((v)>255)))
#define LOG2_32BIT(v) (16*((v)>65535L) + LOG2_16BIT((v)*1L >>16*((v)>65535L)))
#define LOG2_64BIT(v) \
(32*((v)/2L>>31 > 0) \
+ LOG2_32BIT((v)*1L >>16*((v)/2L>>31 > 0) \
>>16*((v)/2L>>31 > 0)))
#if 0
// ISO C version, but no type checking
#define container_of(ptr, type, member) \
((type *) ((char *)(ptr) - offsetof(type, member)))
#else
// non ISO variant from linux kernel; checks ptr type, but triggers 'ISO C forbids braced-groups within expressions [-Wpedantic]'
// __extension__ is here to disable this warning
#define container_of(ptr, type, member) ( __extension__ ({ \
const typeof( ((type *)0)->member ) *__mptr = (ptr); \
(type *)( (char *)__mptr - offsetof(type,member) );}))
static inline int16_t cmp16(uint16_t a, uint16_t b) { return a-b; }
static inline int32_t cmp32(uint32_t a, uint32_t b) { return a-b; }
#endif