2 * Copyright (C) 2003 Bernardo Innocenti <bernie@develer.com>
4 * Based on former do_div() implementation from asm-parisc/div64.h:
5 * Copyright (C) 1999 Hewlett-Packard Co
6 * Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
9 * Generic C version of 64bit/32bit division and modulo, with
10 * 64bit result and 32bit remainder.
12 * The fast case for (n>>32 == 0) is handled inline by do_div().
14 * Code generated for this function might be very inefficient
15 * for some CPUs. __div64_32() can be overridden by linking arch-specific
16 * assembly versions such as arch/ppc/lib/div64.S and arch/sh/lib/div64.S.
19 #include <linux/module.h>
20 #include <linux/math64.h>
22 /* Not needed on 64bit architectures */
23 #if BITS_PER_LONG == 32
25 uint32_t __attribute__((weak
)) __div64_32(uint64_t *n
, uint32_t base
)
30 uint32_t high
= rem
>> 32;
32 /* Reduce the thing a bit first */
36 res
= (uint64_t) high
<< 32;
37 rem
-= (uint64_t) (high
*base
) << 32;
40 while ((int64_t)b
> 0 && b
< rem
) {
58 EXPORT_SYMBOL(__div64_32
);
61 s64
div_s64_rem(s64 dividend
, s32 divisor
, s32
*remainder
)
66 quotient
= div_u64_rem(-dividend
, abs(divisor
), (u32
*)remainder
);
67 *remainder
= -*remainder
;
71 quotient
= div_u64_rem(dividend
, abs(divisor
), (u32
*)remainder
);
77 EXPORT_SYMBOL(div_s64_rem
);
81 * div64_u64 - unsigned 64bit divide with 64bit divisor
82 * @dividend: 64bit dividend
83 * @divisor: 64bit divisor
85 * This implementation is a modified version of the algorithm proposed
86 * by the book 'Hacker's Delight'. The original source and full proof
87 * can be found here and is available for use without restriction.
89 * 'http://www.hackersdelight.org/HDcode/newCode/divDouble.c'
92 u64
div64_u64(u64 dividend
, u64 divisor
)
94 u32 high
= divisor
>> 32;
98 quot
= div_u64(dividend
, divisor
);
100 int n
= 1 + fls(high
);
101 quot
= div_u64(dividend
>> n
, divisor
>> n
);
105 if ((dividend
- quot
* divisor
) >= divisor
)
111 EXPORT_SYMBOL(div64_u64
);
115 * div64_s64 - signed 64bit divide with 64bit divisor
116 * @dividend: 64bit dividend
117 * @divisor: 64bit divisor
120 s64
div64_s64(s64 dividend
, s64 divisor
)
124 quot
= div64_u64(abs64(dividend
), abs64(divisor
));
125 t
= (dividend
^ divisor
) >> 63;
127 return (quot
^ t
) - t
;
129 EXPORT_SYMBOL(div64_s64
);
132 #endif /* BITS_PER_LONG == 32 */
135 * Iterative div/mod for use when dividend is not expected to be much
136 * bigger than divisor.
138 u32
iter_div_u64_rem(u64 dividend
, u32 divisor
, u64
*remainder
)
140 return __iter_div_u64_rem(dividend
, divisor
, remainder
);
142 EXPORT_SYMBOL(iter_div_u64_rem
);
This page took 0.033014 seconds and 6 git commands to generate.