projects / mirror_ubuntu-artful-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| 1da177e4 LT |
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 */ |