82 lines
1.6 KiB
C
82 lines
1.6 KiB
C
/*
|
|
* Copyright (C) 2003 Bernardo Innocenti <bernie@develer.com>
|
|
*
|
|
* Based on former do_div() implementation from asm-parisc/div64.h:
|
|
* Copyright (C) 1999 Hewlett-Packard Co
|
|
* Copyright (C) 1999 David Mosberger-Tang <davidm@hpl.hp.com>
|
|
*
|
|
*
|
|
* Generic C version of 64bit/32bit division and modulo, with
|
|
* 64bit result and 32bit remainder.
|
|
*
|
|
* The fast case for (n>>32 == 0) is handled inline by do_div().
|
|
*
|
|
* 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.
|
|
*/
|
|
|
|
#include <linux/types.h>
|
|
#include <linux/module.h>
|
|
#include <asm/div64.h>
|
|
|
|
/* Not needed on 64bit architectures */
|
|
#if BITS_PER_LONG == 32
|
|
|
|
uint32_t __attribute__((weak)) __div64_32(uint64_t *n, uint32_t base)
|
|
{
|
|
uint64_t rem = *n;
|
|
uint64_t b = base;
|
|
uint64_t res, d = 1;
|
|
uint32_t high = rem >> 32;
|
|
|
|
/* Reduce the thing a bit first */
|
|
res = 0;
|
|
if (high >= base) {
|
|
high /= base;
|
|
res = (uint64_t) high << 32;
|
|
rem -= (uint64_t) (high*base) << 32;
|
|
}
|
|
|
|
while ((int64_t)b > 0 && b < rem) {
|
|
b = b+b;
|
|
d = d+d;
|
|
}
|
|
|
|
do {
|
|
if (rem >= b) {
|
|
rem -= b;
|
|
res += d;
|
|
}
|
|
b >>= 1;
|
|
d >>= 1;
|
|
} while (d);
|
|
|
|
*n = res;
|
|
return rem;
|
|
}
|
|
|
|
EXPORT_SYMBOL(__div64_32);
|
|
|
|
/* 64bit divisor, dividend and result. dynamic precision */
|
|
uint64_t div64_64(uint64_t dividend, uint64_t divisor)
|
|
{
|
|
uint32_t high, d;
|
|
|
|
high = divisor >> 32;
|
|
if (high) {
|
|
unsigned int shift = fls(high);
|
|
|
|
d = divisor >> shift;
|
|
dividend >>= shift;
|
|
} else
|
|
d = divisor;
|
|
|
|
do_div(dividend, d);
|
|
|
|
return dividend;
|
|
}
|
|
EXPORT_SYMBOL(div64_64);
|
|
|
|
#endif /* BITS_PER_LONG == 32 */
|