| 1 | |
| 2 | * Copyright (C) 2003 Bernardo Innocenti <[email protected]>
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| 3 | *
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| 4 | * Based on former do_div() implementation from asm-parisc/div64.h:
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| 5 | * Copyright (C) 1999 Hewlett-Packard Co
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| 6 | * Copyright (C) 1999 David Mosberger-Tang <[email protected]>
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| 7 | *
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| 8 | *
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| 9 | * Generic C version of 64bit/32bit division and modulo, with
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| 10 | * 64bit result and 32bit remainder.
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| 11 | *
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| 12 | * The fast case for (n>>32 == 0) is handled inline by do_div().
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| 13 | *
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| 14 | * Code generated for this function might be very inefficient
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| 15 | * for some CPUs. __div64_32() can be overridden by linking arch-specific
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| 16 | * assembly versions such as arch/ppc/lib/div64.S and arch/sh/lib/div64.S.
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| 17 |
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| 18 |
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| 19 | #include <linux/types.h>
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| 20 | #include <linux/module.h>
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| 21 | #include <asm/div64.h>
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| 22 |
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| 23 |
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| 24 | #if BITS_PER_LONG == 32
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| 25 |
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| 26 | uint32_t __div64_32(uint64_t *n, uint32_t base)
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| 27 | {
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| 28 | uint64_t rem = *n;
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| 29 | uint64_t b = base;
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| 30 | uint64_t res, d = 1;
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| 31 | uint32_t high = rem >> 32;
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| 32 |
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| 33 |
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| 34 | res = 0;
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| 35 | if (high >= base) {
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| 36 | high /= base;
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| 37 | res = (uint64_t) high << 32;
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| 38 | rem -= (uint64_t) (high*base) << 32;
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| 39 | }
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| 40 |
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| 41 | while ((int64_t)b > 0 && b < rem) {
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| 42 | b = b+b;
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| 43 | d = d+d;
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| 44 | }
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| 45 |
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| 46 | do {
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| 47 | if (rem >= b) {
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| 48 | rem -= b;
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| 49 | res += d;
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| 50 | }
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| 51 | b >>= 1;
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| 52 | d >>= 1;
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| 53 | } while (d);
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| 54 |
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| 55 | *n = res;
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| 56 | return rem;
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| 57 | }
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| 58 |
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| 59 | EXPORT_SYMBOL(__div64_32);
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| 60 |
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| 61 | #endif
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