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Release 4.12 lib/div64.c

Directory: lib
/*
 * Copyright (C) 2003 Bernardo Innocenti <bernie@develer.com>
 *
 * Based on former do_div() implementation from asm-parisc/div64.h:
 *      Copyright (C) 1999 Hewlett-Packard Co
 *      Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
 *
 *
 * Generic C version of 64bit/32bit division and modulo, with
 * 64bit result and 32bit remainder.
 *
 * The fast case for (n>>32 == 0) is handled inline by do_div(). 
 *
 * Code generated for this function might be very inefficient
 * for some CPUs. __div64_32() can be overridden by linking arch-specific
 * assembly versions such as arch/ppc/lib/div64.S and arch/sh/lib/div64.S
 * or by defining a preprocessor macro in arch/include/asm/div64.h.
 */

#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/math64.h>

/* Not needed on 64bit architectures */
#if BITS_PER_LONG == 32

#ifndef __div64_32

uint32_t __attribute__((weak)) __div64_32(uint64_t *n, uint32_t base)
{
	uint64_t rem = *n;
	uint64_t b = base;
	uint64_t res, d = 1;
	uint32_t high = rem >> 32;

	/* Reduce the thing a bit first */
	res = 0;
	if (high >= base) {
		high /= base;
		res = (uint64_t) high << 32;
		rem -= (uint64_t) (high*base) << 32;
	}

	while ((int64_t)b > 0 && b < rem) {
		b = b+b;
		d = d+d;
	}

	do {
		if (rem >= b) {
			rem -= b;
			res += d;
		}
		b >>= 1;
		d >>= 1;
	} while (d);

	*n = res;
	return rem;
}

EXPORT_SYMBOL(__div64_32);
#endif

#ifndef div_s64_rem

s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder) { u64 quotient; if (dividend < 0) { quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder); *remainder = -*remainder; if (divisor > 0) quotient = -quotient; } else { quotient = div_u64_rem(dividend, abs(divisor), (u32 *)remainder); if (divisor < 0) quotient = -quotient; } return quotient; }

Contributors

PersonTokensPropCommitsCommitProp
Roman Zippel98100.00%1100.00%
Total98100.00%1100.00%

EXPORT_SYMBOL(div_s64_rem); #endif /** * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder * @dividend: 64bit dividend * @divisor: 64bit divisor * @remainder: 64bit remainder * * This implementation is a comparable to algorithm used by div64_u64. * But this operation, which includes math for calculating the remainder, * is kept distinct to avoid slowing down the div64_u64 operation on 32bit * systems. */ #ifndef div64_u64_rem
u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder) { u32 high = divisor >> 32; u64 quot; if (high == 0) { u32 rem32; quot = div_u64_rem(dividend, divisor, &rem32); *remainder = rem32; } else { int n = 1 + fls(high); quot = div_u64(dividend >> n, divisor >> n); if (quot != 0) quot--; *remainder = dividend - quot * divisor; if (*remainder >= divisor) { quot++; *remainder -= divisor; } } return quot; }

Contributors

PersonTokensPropCommitsCommitProp
Mike Snitzer117100.00%1100.00%
Total117100.00%1100.00%

EXPORT_SYMBOL(div64_u64_rem); #endif /** * div64_u64 - unsigned 64bit divide with 64bit divisor * @dividend: 64bit dividend * @divisor: 64bit divisor * * This implementation is a modified version of the algorithm proposed * by the book 'Hacker's Delight'. The original source and full proof * can be found here and is available for use without restriction. * * 'http://www.hackersdelight.org/hdcodetxt/divDouble.c.txt' */ #ifndef div64_u64
u64 div64_u64(u64 dividend, u64 divisor) { u32 high = divisor >> 32; u64 quot; if (high == 0) { quot = div_u64(dividend, divisor); } else { int n = 1 + fls(high); quot = div_u64(dividend >> n, divisor >> n); if (quot != 0) quot--; if ((dividend - quot * divisor) >= divisor) quot++; } return quot; }

Contributors

PersonTokensPropCommitsCommitProp
Brian Behlendorf5156.04%120.00%
Stephen Hemminger2931.87%240.00%
Stanislaw Gruszka66.59%120.00%
Roman Zippel55.49%120.00%
Total91100.00%5100.00%

EXPORT_SYMBOL(div64_u64); #endif /** * div64_s64 - signed 64bit divide with 64bit divisor * @dividend: 64bit dividend * @divisor: 64bit divisor */ #ifndef div64_s64
s64 div64_s64(s64 dividend, s64 divisor) { s64 quot, t; quot = div64_u64(abs(dividend), abs(divisor)); t = (dividend ^ divisor) >> 63; return (quot ^ t) - t; }

Contributors

PersonTokensPropCommitsCommitProp
Brian Behlendorf4386.00%133.33%
Stephen Hemminger510.00%133.33%
Andrew Morton24.00%133.33%
Total50100.00%3100.00%

EXPORT_SYMBOL(div64_s64); #endif #endif /* BITS_PER_LONG == 32 */ /* * Iterative div/mod for use when dividend is not expected to be much * bigger than divisor. */
u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder) { return __iter_div_u64_rem(dividend, divisor, remainder); }

Contributors

PersonTokensPropCommitsCommitProp
Jeremy Fitzhardinge25100.00%2100.00%
Total25100.00%2100.00%

EXPORT_SYMBOL(iter_div_u64_rem);

Overall Contributors

PersonTokensPropCommitsCommitProp
Mike Snitzer12821.05%15.88%
Roman Zippel11819.41%211.76%
Brian Behlendorf10417.11%15.88%
Randolph Chung9715.95%15.88%
Bernardo Innocenti609.87%211.76%
Stephen Hemminger396.41%211.76%
Jeremy Fitzhardinge315.10%211.76%
David S. Miller101.64%15.88%
Stanislaw Gruszka81.32%15.88%
Nico Pitre60.99%15.88%
Paul Gortmaker40.66%15.88%
Andrew Morton20.33%15.88%
Heinrich Schuchardt10.16%15.88%
Total608100.00%17100.00%
Directory: lib
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