The C and C++ Include Header Files

/usr/include/linux/const.h


$ cat -n /usr/include/linux/const.h

     1	/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
     2	/* const.h: Macros for dealing with constants.  */
     3	
     4	#ifndef _LINUX_CONST_H
     5	#define _LINUX_CONST_H
     6	
     7	/* Some constant macros are used in both assembler and
     8	 * C code.  Therefore we cannot annotate them always with
     9	 * 'UL' and other type specifiers unilaterally.  We
    10	 * use the following macros to deal with this.
    11	 *
    12	 * Similarly, _AT() will cast an expression with a type in C, but
    13	 * leave it unchanged in asm.
    14	 */
    15	
    16	#ifdef __ASSEMBLY__
    17	#define _AC(X,Y)	X
    18	#define _AT(T,X)	X
    19	#else
    20	#define __AC(X,Y)	(X##Y)
    21	#define _AC(X,Y)	__AC(X,Y)
    22	#define _AT(T,X)	((T)(X))
    23	#endif
    24	
    25	#define _UL(x)		(_AC(x, UL))
    26	#define _ULL(x)		(_AC(x, ULL))
    27	
    28	#define _BITUL(x)	(_UL(1) << (x))
    29	#define _BITULL(x)	(_ULL(1) << (x))
    30	
    31	#define __ALIGN_KERNEL(x, a)		__ALIGN_KERNEL_MASK(x, (__typeof__(x))(a) - 1)
    32	#define __ALIGN_KERNEL_MASK(x, mask)	(((x) + (mask)) & ~(mask))
    33	
    34	#define __KERNEL_DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
    35	
    36	#endif /* _LINUX_CONST_H */