Commit f7926850 authored by Frederic Weisbecker's avatar Frederic Weisbecker
Browse files

math64: New div64_u64_rem helper 



Provide an extended version of div64_u64() that
also returns the remainder of the division.

We are going to need this to refine the cputime
scaling code.

Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
parent 660cc00f

include/linux/math64.h

+18 −1
Original line number Diff line number Diff line
@@ -29,6 +29,15 @@ static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder) 
	return dividend / divisor;

}



/**

 * div64_u64_rem - unsigned 64bit divide with 64bit divisor

 */

static inline u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder)

{

	*remainder = dividend % divisor;

	return dividend / divisor;

}



/**

 * div64_u64 - unsigned 64bit divide with 64bit divisor

 */
@@ -61,8 +70,16 @@ static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder) 
extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);

#endif



#ifndef div64_u64_rem

extern u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder);

#endif



#ifndef div64_u64

extern u64 div64_u64(u64 dividend, u64 divisor);

static inline u64 div64_u64(u64 dividend, u64 divisor)

{

	u64 remainder;

	return div64_u64_rem(dividend, divisor, &remainder);

}

#endif



#ifndef div64_s64

lib/div64.c

+13 −6
Original line number Diff line number Diff line
@@ -79,9 +79,10 @@ EXPORT_SYMBOL(div_s64_rem); 
#endif



/**

 * div64_u64 - unsigned 64bit divide with 64bit divisor

 * div64_u64_rem - unsigned 64bit divide with 64bit divisor and 64bit remainder

 * @dividend:	64bit dividend

 * @divisor:	64bit divisor

 * @remainder:  64bit remainder

 *

 * This implementation is a modified version of the algorithm proposed

 * by the book 'Hacker's Delight'.  The original source and full proof
@@ -89,27 +90,33 @@ EXPORT_SYMBOL(div_s64_rem); 
 *

 * 'http://www.hackersdelight.org/HDcode/newCode/divDouble.c.txt'

 */

#ifndef div64_u64

u64 div64_u64(u64 dividend, u64 divisor)

#ifndef div64_u64_rem

u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder)

{

	u32 high = divisor >> 32;

	u64 quot;



	if (high == 0) {

		quot = div_u64(dividend, divisor);

		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--;

		if ((dividend - quot * divisor) >= divisor)



		*remainder = dividend - quot * divisor;

		if (*remainder >= divisor) {

			quot++;

			*remainder -= divisor;

		}

	}



	return quot;

}

EXPORT_SYMBOL(div64_u64);

EXPORT_SYMBOL(div64_u64_rem);

#endif



/**

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