1/*
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#include <linux/module.h>
21#include <asm/div64.h>
22
23/* Not needed on 64bit architectures */
24#if BITS_PER_LONG == 32
25
26uint32_t __attribute__((weak)) __div64_32(uint64_t *n, uint32_t base)
27{
28	uint64_t rem = *n;
29	uint64_t b = base;
30	uint64_t res, d = 1;
31	uint32_t high = rem >> 32;
32
33	/* Reduce the thing a bit first */
34	res = 0;
35	if (high >= base) {
36		high /= base;
37		res = (uint64_t) high << 32;
38		rem -= (uint64_t) (high*base) << 32;
39	}
40
41	while ((int64_t)b > 0 && b < rem) {
42		b = b+b;
43		d = d+d;
44	}
45
46	do {
47		if (rem >= b) {
48			rem -= b;
49			res += d;
50		}
51		b >>= 1;
52		d >>= 1;
53	} while (d);
54
55	*n = res;
56	return rem;
57}
58
59EXPORT_SYMBOL(__div64_32);
60
61/* 64bit divisor, dividend and result. dynamic precision */
62uint64_t div64_64(uint64_t dividend, uint64_t divisor)
63{
64	uint32_t high, d;
65
66	high = divisor >> 32;
67	if (high) {
68		unsigned int shift = fls(high);
69
70		d = divisor >> shift;
71		dividend >>= shift;
72	} else
73		d = divisor;
74
75	do_div(dividend, d);
76
77	return dividend;
78}
79EXPORT_SYMBOL(div64_64);
80
81#endif /* BITS_PER_LONG == 32 */
82