[mirror_ubuntu-bionic-kernel.git] / lib / reciprocal_div.c

// SPDX-License-Identifier: GPL-2.0
#include <linux/kernel.h>
#include <asm/div64.h>
#include <linux/reciprocal_div.h>
#include <linux/export.h>

/*
 * For a description of the algorithm please have a look at
 * include/linux/reciprocal_div.h
 */

struct reciprocal_value reciprocal_value(u32 d)
{
	struct reciprocal_value R;
	u64 m;
	int l;

	l = fls(d - 1);
	m = ((1ULL << 32) * ((1ULL << l) - d));
	do_div(m, d);
	++m;
	R.m = (u32)m;
	R.sh1 = min(l, 1);
	R.sh2 = max(l - 1, 0);

	return R;
}
EXPORT_SYMBOL(reciprocal_value);
Commit	Line	Data
b2441318	1	// SPDX-License-Identifier: GPL-2.0
809fa972	2	#include <linux/kernel.h>
6a2d7a95 ED	3	#include <asm/div64.h>
6a2d7a95 ED	4	#include <linux/reciprocal_div.h>
8af2a218	5	#include <linux/export.h>
6a2d7a95	6
809fa972 HFS	7	/*
	8	* For a description of the algorithm please have a look at
	9	* include/linux/reciprocal_div.h
	10	*/
	11
	12	struct reciprocal_value reciprocal_value(u32 d)
6a2d7a95	13	{
809fa972 HFS	14	struct reciprocal_value R;
	15	u64 m;
	16	int l;
	17
	18	l = fls(d - 1);
	19	m = ((1ULL << 32) * ((1ULL << l) - d));
	20	do_div(m, d);
	21	++m;
	22	R.m = (u32)m;
	23	R.sh1 = min(l, 1);
	24	R.sh2 = max(l - 1, 0);
	25
	26	return R;
6a2d7a95	27	}
8af2a218	28	EXPORT_SYMBOL(reciprocal_value);