1 /* 2 * Copyright (C) 2008 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #pragma once 30 31 /** 32 * @file sys/param.h 33 * @brief Various macros. 34 */ 35 36 #include <endian.h> 37 #include <limits.h> 38 #include <linux/param.h> 39 #include <sys/cdefs.h> 40 41 /** The unit of `st_blocks` in `struct stat`. */ 42 #define DEV_BSIZE 512 43 44 /** A historical name for PATH_MAX. */ 45 #define MAXPATHLEN PATH_MAX 46 47 #define MAXSYMLINKS 8 48 49 #ifndef howmany 50 #define howmany(x, y) (((x)+((y)-1))/(y)) 51 #endif 52 #define roundup(x, y) ((((x)+((y)-1))/(y))*(y)) 53 54 /** 55 * Returns true if the binary representation of the argument is all zeros 56 * or has exactly one bit set. Contrary to the macro name, this macro 57 * DOES NOT determine if the provided value is a power of 2. In particular, 58 * this function falsely returns true for powerof2(0) and some negative 59 * numbers. 60 */ 61 #define powerof2(x) \ 62 ({ \ 63 __typeof__(x) _x = (x); \ 64 __typeof__(x) _x2; \ 65 __builtin_add_overflow(_x, -1, &_x2) ? 1 : ((_x2 & _x) == 0); \ 66 }) 67 68 /** Returns the lesser of its two arguments. */ 69 #define MIN(a,b) (((a)<(b))?(a):(b)) 70 /** Returns the greater of its two arguments. */ 71 #define MAX(a,b) (((a)>(b))?(a):(b)) 72