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__div64_32(): make it overridable at compile time

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Some architectures may want to override the default implementation
at compile time to do things inline.  For example, ARM uses a
non-standard calling convention for better efficiency in this case.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
This commit is contained in:
Nicolas Pitre 2015-11-02 13:02:46 -05:00
parent f682b27c57
commit dce1eb93b1
2 changed files with 6 additions and 2 deletions
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2
include/asm-generic/div64.h
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@ -194,7 +194,9 @@ static inline uint64_t __arch_xprod_64(const uint64_t m, uint64_t n, bool bias)
}
#endif
#ifndef __div64_32
extern uint32_t __div64_32(uint64_t *dividend, uint32_t divisor);
#endif
/* The unnecessary pointer compare is there
* to check for type safety (n must be 64bit)

6
lib/div64.c
View file

@ -13,7 +13,8 @@
*
* 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.
* 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>
@ -23,6 +24,7 @@
/* 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;
@ -55,8 +57,8 @@ uint32_t __attribute__((weak)) __div64_32(uint64_t *n, uint32_t base)
*n = res;
return rem;
}
EXPORT_SYMBOL(__div64_32);
#endif
#ifndef div_s64_rem
s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)