[linux-2.6-block.git] / lib / div64.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/module.h>
#include <linux/math64.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);

#ifndef div_s64_rem
s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
{
	u64 quotient;

	if (dividend < 0) {
		quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder);
		*remainder = -*remainder;
		if (divisor > 0)
			quotient = -quotient;
	} else {
		quotient = div_u64_rem(dividend, abs(divisor), (u32 *)remainder);
		if (divisor < 0)
			quotient = -quotient;
	}
	return quotient;
}
EXPORT_SYMBOL(div_s64_rem);
#endif

/* 64bit divisor, dividend and result. dynamic precision */
#ifndef div64_u64
u64 div64_u64(u64 dividend, u64 divisor)
{
	u32 high, d;

	high = divisor >> 32;
	if (high) {
		unsigned int shift = fls(high);

		d = divisor >> shift;
		dividend >>= shift;
	} else
		d = divisor;

	return div_u64(dividend, d);
}
EXPORT_SYMBOL(div64_u64);
#endif

#endif /* BITS_PER_LONG == 32 */

/*
 * Iterative div/mod for use when dividend is not expected to be much
 * bigger than divisor.
 */
u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
{
	return __iter_div_u64_rem(dividend, divisor, remainder);
}
EXPORT_SYMBOL(iter_div_u64_rem);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Copyright (C) 2003 Bernardo Innocenti <bernie@develer.com>
	3	*
	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>
	7	*
	8	*
	9	* Generic C version of 64bit/32bit division and modulo, with
	10	* 64bit result and 32bit remainder.
	11	*
	12	* The fast case for (n>>32 == 0) is handled inline by do_div().
	13	*
	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.
	17	*/
	18
1da177e4	19	#include <linux/module.h>
2418f4f2	20	#include <linux/math64.h>
1da177e4 LT	21
	22	/* Not needed on 64bit architectures */
	23	#if BITS_PER_LONG == 32
	24
cb8c181f	25	uint32_t __attribute__((weak)) __div64_32(uint64_t *n, uint32_t base)
1da177e4 LT	26	{
	27	uint64_t rem = *n;
	28	uint64_t b = base;
	29	uint64_t res, d = 1;
	30	uint32_t high = rem >> 32;
	31
	32	/* Reduce the thing a bit first */
	33	res = 0;
	34	if (high >= base) {
	35	high /= base;
	36	res = (uint64_t) high << 32;
	37	rem -= (uint64_t) (high*base) << 32;
	38	}
	39
	40	while ((int64_t)b > 0 && b < rem) {
	41	b = b+b;
	42	d = d+d;
	43	}
	44
	45	do {
	46	if (rem >= b) {
	47	rem -= b;
	48	res += d;
	49	}
	50	b >>= 1;
	51	d >>= 1;
	52	} while (d);
	53
	54	*n = res;
	55	return rem;
	56	}
	57
	58	EXPORT_SYMBOL(__div64_32);
	59
2418f4f2 RZ	60	#ifndef div_s64_rem
	61	s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
	62	{
	63	u64 quotient;
	64
	65	if (dividend < 0) {
	66	quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder);
	67	remainder = -remainder;
	68	if (divisor > 0)
	69	quotient = -quotient;
	70	} else {
	71	quotient = div_u64_rem(dividend, abs(divisor), (u32 *)remainder);
	72	if (divisor < 0)
	73	quotient = -quotient;
	74	}
	75	return quotient;
	76	}
	77	EXPORT_SYMBOL(div_s64_rem);
	78	#endif
	79
3927f2e8	80	/* 64bit divisor, dividend and result. dynamic precision */
6f6d6a1a RZ	81	#ifndef div64_u64
6f6d6a1a RZ	82	u64 div64_u64(u64 dividend, u64 divisor)
3927f2e8	83	{
6f6d6a1a	84	u32 high, d;
3927f2e8	85
22b9a0a3 SH	86	high = divisor >> 32;
	87	if (high) {
	88	unsigned int shift = fls(high);
3927f2e8 SH	89
	90	d = divisor >> shift;
	91	dividend >>= shift;
22b9a0a3 SH	92	} else
22b9a0a3 SH	93	d = divisor;
3927f2e8	94
6f6d6a1a	95	return div_u64(dividend, d);
3927f2e8	96	}
6f6d6a1a RZ	97	EXPORT_SYMBOL(div64_u64);
6f6d6a1a RZ	98	#endif
3927f2e8	99
1da177e4	100	#endif /* BITS_PER_LONG == 32 */
f595ec96 JF	101
	102	/*
	103	* Iterative div/mod for use when dividend is not expected to be much
	104	* bigger than divisor.
	105	*/
	106	u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
	107	{
d5e181f7	108	return __iter_div_u64_rem(dividend, divisor, remainder);
f595ec96 JF	109	}
f595ec96 JF	110	EXPORT_SYMBOL(iter_div_u64_rem);