f8bd2258e2
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>
61 lines
1.4 KiB
C
61 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 */
|