blob: 99726e325dafc263ddaf23bd7190e67420442df2 [file] [log] [blame]
Wolfgang Denk83c15852006-10-24 14:21:16 +02001/*
2 * Copyright (C) 2003 Bernardo Innocenti <bernie@develer.com>
3 *
4 * Based on former do_div() implementation from asm-parisc/div64.h:
5 * Copyright (C) 1999 Hewlett-Packard Co
6 * Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
7 *
8 *
9 * Generic C version of 64bit/32bit division and modulo, with
10 * 64bit result and 32bit remainder.
11 *
12 * The fast case for (n>>32 == 0) is handled inline by do_div().
13 *
14 * Code generated for this function might be very inefficient
15 * for some CPUs. __div64_32() can be overridden by linking arch-specific
16 * assembly versions such as arch/ppc/lib/div64.S and arch/sh/lib/div64.S.
17 */
18
19#include <linux/types.h>
20
21#include <asm/div64.h>
22
23uint32_t __div64_32(uint64_t *n, uint32_t base)
24{
25 uint64_t rem = *n;
26 uint64_t b = base;
27 uint64_t res, d = 1;
28 uint32_t high = rem >> 32;
29
30 /* Reduce the thing a bit first */
31 res = 0;
32 if (high >= base) {
33 high /= base;
34 res = (uint64_t) high << 32;
35 rem -= (uint64_t) (high*base) << 32;
36 }
37
38 while ((int64_t)b > 0 && b < rem) {
39 b = b+b;
40 d = d+d;
41 }
42
43 do {
44 if (rem >= b) {
45 rem -= b;
46 res += d;
47 }
48 b >>= 1;
49 d >>= 1;
50 } while (d);
51
52 *n = res;
53 return rem;
54}