android_kernel_motorola_sm6225/include/asm-x86/div64.h
Roman Zippel f8bd2258e2 remove div_long_long_rem
x86 is the only arch right now, which provides an optimized for
div_long_long_rem and it has the downside that one has to be very careful that
the divide doesn't overflow.

The API is a little akward, as the arguments for the unsigned divide are
signed.  The signed version also doesn't handle a negative divisor and
produces worse code on 64bit archs.

There is little incentive to keep this API alive, so this converts the few
users to the new API.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-01 08:03:58 -07:00

60 lines
1.4 KiB
C

#ifndef _ASM_X86_DIV64_H
#define _ASM_X86_DIV64_H
#ifdef CONFIG_X86_32
#include <linux/types.h>
/*
* do_div() is NOT a C function. It wants to return
* two values (the quotient and the remainder), but
* since that doesn't work very well in C, what it
* does is:
*
* - modifies the 64-bit dividend _in_place_
* - returns the 32-bit remainder
*
* This ends up being the most efficient "calling
* convention" on x86.
*/
#define do_div(n, base) \
({ \
unsigned long __upper, __low, __high, __mod, __base; \
__base = (base); \
asm("":"=a" (__low), "=d" (__high) : "A" (n)); \
__upper = __high; \
if (__high) { \
__upper = __high % (__base); \
__high = __high / (__base); \
} \
asm("divl %2":"=a" (__low), "=d" (__mod) \
: "rm" (__base), "0" (__low), "1" (__upper)); \
asm("":"=A" (n) : "a" (__low), "d" (__high)); \
__mod; \
})
static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
{
union {
u64 v64;
u32 v32[2];
} d = { dividend };
u32 upper;
upper = d.v32[1];
d.v32[1] = 0;
if (upper >= divisor) {
d.v32[1] = upper / divisor;
upper %= divisor;
}
asm ("divl %2" : "=a" (d.v32[0]), "=d" (*remainder) :
"rm" (divisor), "0" (d.v32[0]), "1" (upper));
return d.v64;
}
#define div_u64_rem div_u64_rem
#else
# include <asm-generic/div64.h>
#endif /* CONFIG_X86_32 */
#endif /* _ASM_X86_DIV64_H */