Root/include/asm-generic/div64.h

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
35extern 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

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