Contents of /alx-src/tags/kernel26-2.6.12-alx-r9/lib/div64.c
Parent Directory | Revision Log
Revision 630 -
(show annotations)
(download)
Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
File MIME type: text/plain
File size: 1313 byte(s)
Wed Mar 4 11:03:09 2009 UTC (15 years, 3 months ago) by niro
File MIME type: text/plain
File size: 1313 byte(s)
Tag kernel26-2.6.12-alx-r9
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 | |
26 | uint32_t __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 | |
59 | EXPORT_SYMBOL(__div64_32); |
60 | |
61 | #endif /* BITS_PER_LONG == 32 */ |