3927f2e8f9
Here is the current version of the 64 bit divide common code. Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
83 lines
1.7 KiB
C
83 lines
1.7 KiB
C
/*
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* Copyright (C) 2003 Bernardo Innocenti <bernie@develer.com>
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*
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* Based on former do_div() implementation from asm-parisc/div64.h:
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* Copyright (C) 1999 Hewlett-Packard Co
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* Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
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*
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*
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* Generic C version of 64bit/32bit division and modulo, with
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* 64bit result and 32bit remainder.
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*
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* The fast case for (n>>32 == 0) is handled inline by do_div().
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*
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* Code generated for this function might be very inefficient
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* for some CPUs. __div64_32() can be overridden by linking arch-specific
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* assembly versions such as arch/ppc/lib/div64.S and arch/sh/lib/div64.S.
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*/
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#include <linux/types.h>
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#include <linux/module.h>
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#include <asm/div64.h>
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/* Not needed on 64bit architectures */
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#if BITS_PER_LONG == 32
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uint32_t __div64_32(uint64_t *n, uint32_t base)
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{
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uint64_t rem = *n;
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uint64_t b = base;
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uint64_t res, d = 1;
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uint32_t high = rem >> 32;
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/* Reduce the thing a bit first */
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res = 0;
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if (high >= base) {
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high /= base;
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res = (uint64_t) high << 32;
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rem -= (uint64_t) (high*base) << 32;
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}
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while ((int64_t)b > 0 && b < rem) {
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b = b+b;
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d = d+d;
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}
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do {
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if (rem >= b) {
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rem -= b;
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res += d;
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}
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b >>= 1;
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d >>= 1;
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} while (d);
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*n = res;
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return rem;
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}
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EXPORT_SYMBOL(__div64_32);
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/* 64bit divisor, dividend and result. dynamic precision */
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uint64_t div64_64(uint64_t dividend, uint64_t divisor)
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{
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uint32_t d = divisor;
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if (divisor > 0xffffffffULL) {
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unsigned int shift = fls(divisor >> 32);
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d = divisor >> shift;
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dividend >>= shift;
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}
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/* avoid 64 bit division if possible */
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if (dividend >> 32)
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do_div(dividend, d);
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else
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dividend = (uint32_t) dividend / d;
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return dividend;
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}
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EXPORT_SYMBOL(div64_64);
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#endif /* BITS_PER_LONG == 32 */
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