f595ec964d
We have a few instances of the open-coded iterative div/mod loop, used when we don't expcet the dividend to be much bigger than the divisor. Unfortunately modern gcc's have the tendency to strength "reduce" this into a full mod operation, which isn't necessarily any faster, and even if it were, doesn't exist if gcc implements it in libgcc. The workaround is to put a dummy asm statement in the loop to prevent gcc from performing the transformation. This patch creates a single implementation of this loop, and uses it to replace the open-coded versions I know about. Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: john stultz <johnstul@us.ibm.com> Cc: Segher Boessenkool <segher@kernel.crashing.org> Cc: Christian Kujau <lists@nerdbynature.de> Cc: Robert Hancock <hancockr@shaw.ca> Signed-off-by: Ingo Molnar <mingo@elte.hu>
87 lines
1.8 KiB
C
87 lines
1.8 KiB
C
#ifndef _LINUX_MATH64_H
|
|
#define _LINUX_MATH64_H
|
|
|
|
#include <linux/types.h>
|
|
#include <asm/div64.h>
|
|
|
|
#if BITS_PER_LONG == 64
|
|
|
|
/**
|
|
* div_u64_rem - unsigned 64bit divide with 32bit divisor with remainder
|
|
*
|
|
* This is commonly provided by 32bit archs to provide an optimized 64bit
|
|
* divide.
|
|
*/
|
|
static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
|
|
{
|
|
*remainder = dividend % divisor;
|
|
return dividend / divisor;
|
|
}
|
|
|
|
/**
|
|
* div_s64_rem - signed 64bit divide with 32bit divisor with remainder
|
|
*/
|
|
static inline s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
|
|
{
|
|
*remainder = dividend % divisor;
|
|
return dividend / divisor;
|
|
}
|
|
|
|
/**
|
|
* div64_u64 - unsigned 64bit divide with 64bit divisor
|
|
*/
|
|
static inline u64 div64_u64(u64 dividend, u64 divisor)
|
|
{
|
|
return dividend / divisor;
|
|
}
|
|
|
|
#elif BITS_PER_LONG == 32
|
|
|
|
#ifndef div_u64_rem
|
|
static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
|
|
{
|
|
*remainder = do_div(dividend, divisor);
|
|
return dividend;
|
|
}
|
|
#endif
|
|
|
|
#ifndef div_s64_rem
|
|
extern s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder);
|
|
#endif
|
|
|
|
#ifndef div64_u64
|
|
extern u64 div64_u64(u64 dividend, u64 divisor);
|
|
#endif
|
|
|
|
#endif /* BITS_PER_LONG */
|
|
|
|
/**
|
|
* div_u64 - unsigned 64bit divide with 32bit divisor
|
|
*
|
|
* This is the most common 64bit divide and should be used if possible,
|
|
* as many 32bit archs can optimize this variant better than a full 64bit
|
|
* divide.
|
|
*/
|
|
#ifndef div_u64
|
|
static inline u64 div_u64(u64 dividend, u32 divisor)
|
|
{
|
|
u32 remainder;
|
|
return div_u64_rem(dividend, divisor, &remainder);
|
|
}
|
|
#endif
|
|
|
|
/**
|
|
* div_s64 - signed 64bit divide with 32bit divisor
|
|
*/
|
|
#ifndef div_s64
|
|
static inline s64 div_s64(s64 dividend, s32 divisor)
|
|
{
|
|
s32 remainder;
|
|
return div_s64_rem(dividend, divisor, &remainder);
|
|
}
|
|
#endif
|
|
|
|
u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder);
|
|
|
|
#endif /* _LINUX_MATH64_H */
|