1 #ifndef _ASM_GENERIC_DIV64_H
2 #define _ASM_GENERIC_DIV64_H
3 /*
4  * Copyright (C) 2003 Bernardo Innocenti <bernie@develer.com>
5  * Based on former asm-ppc/div64.h and asm-m68knommu/div64.h
6  *
7  * The semantics of do_div() are:
8  *
9  * uint32_t do_div(uint64_t *n, uint32_t base)
10  * {
11  * 	uint32_t remainder = *n % base;
12  * 	*n = *n / base;
13  * 	return remainder;
14  * }
15  *
16  * NOTE: macro parameter n is evaluated multiple times,
17  *       beware of side effects!
18  */
19 
20 #include <linux/types.h>
21 #include <linux/compiler.h>
22 
23 #if BITS_PER_LONG == 64
24 
25 # define do_div(n,base) ({					\
26 	uint32_t __base = (base);				\
27 	uint32_t __rem;						\
28 	__rem = ((uint64_t)(n)) % __base;			\
29 	(n) = ((uint64_t)(n)) / __base;				\
30 	__rem;							\
31  })
32 
33 #elif BITS_PER_LONG == 32
34 
35 extern uint32_t __div64_32(uint64_t *dividend, uint32_t divisor);
36 
37 /* The unnecessary pointer compare is there
38  * to check for type safety (n must be 64bit)
39  */
40 # define do_div(n,base) ({				\
41 	uint32_t __base = (base);			\
42 	uint32_t __rem;					\
43 	(void)(((typeof((n)) *)0) == ((uint64_t *)0));	\
44 	if (likely(((n) >> 32) == 0)) {			\
45 		__rem = (uint32_t)(n) % __base;		\
46 		(n) = (uint32_t)(n) / __base;		\
47 	} else 						\
48 		__rem = __div64_32(&(n), __base);	\
49 	__rem;						\
50  })
51 
52 #else /* BITS_PER_LONG == ?? */
53 
54 # error do_div() does not yet support the C64
55 
56 #endif /* BITS_PER_LONG */
57 
58 #endif /* _ASM_GENERIC_DIV64_H */
59