[people/ms/u-boot.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
 * or by defining a preprocessor macro in arch/include/asm/div64.h.
 */

#include <linux/compat.h>
#include <linux/kernel.h>
#include <linux/math64.h>

/* Not needed on 64bit architectures */
#if BITS_PER_LONG == 32

#ifndef __div64_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);
#endif

#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

/**
 * div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder
 * @dividend:	64bit dividend
 * @divisor:	64bit divisor
 * @remainder:  64bit remainder
 *
 * This implementation is a comparable to algorithm used by div64_u64.
 * But this operation, which includes math for calculating the remainder,
 * is kept distinct to avoid slowing down the div64_u64 operation on 32bit
 * systems.
 */
#ifndef div64_u64_rem
u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder)
{
	u32 high = divisor >> 32;
	u64 quot;

	if (high == 0) {
		u32 rem32;
		quot = div_u64_rem(dividend, divisor, &rem32);
		*remainder = rem32;
	} else {
		int n = 1 + fls(high);
		quot = div_u64(dividend >> n, divisor >> n);

		if (quot != 0)
			quot--;

		*remainder = dividend - quot * divisor;
		if (*remainder >= divisor) {
			quot++;
			*remainder -= divisor;
		}
	}

	return quot;
}
EXPORT_SYMBOL(div64_u64_rem);
#endif

/**
 * div64_u64 - unsigned 64bit divide with 64bit divisor
 * @dividend:	64bit dividend
 * @divisor:	64bit divisor
 *
 * This implementation is a modified version of the algorithm proposed
 * by the book 'Hacker's Delight'.  The original source and full proof
 * can be found here and is available for use without restriction.
 *
 * 'http://www.hackersdelight.org/hdcodetxt/divDouble.c.txt'
 */
#ifndef div64_u64
u64 div64_u64(u64 dividend, u64 divisor)
{
	u32 high = divisor >> 32;
	u64 quot;

	if (high == 0) {
		quot = div_u64(dividend, divisor);
	} else {
		int n = 1 + fls(high);
		quot = div_u64(dividend >> n, divisor >> n);

		if (quot != 0)
			quot--;
		if ((dividend - quot * divisor) >= divisor)
			quot++;
	}

	return quot;
}
EXPORT_SYMBOL(div64_u64);
#endif

/**
 * div64_s64 - signed 64bit divide with 64bit divisor
 * @dividend:	64bit dividend
 * @divisor:	64bit divisor
 */
#ifndef div64_s64
s64 div64_s64(s64 dividend, s64 divisor)
{
	s64 quot, t;

	quot = div64_u64(abs(dividend), abs(divisor));
	t = (dividend ^ divisor) >> 63;

	return (quot ^ t) - t;
}
EXPORT_SYMBOL(div64_s64);
#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
7b64fef3 WD	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
0342e335 PF	16	* assembly versions such as arch/ppc/lib/div64.S and arch/sh/lib/div64.S
0342e335 PF	17	* or by defining a preprocessor macro in arch/include/asm/div64.h.
7b64fef3 WD	18	*/
7b64fef3 WD	19
0342e335 PF	20	#include <linux/compat.h>
	21	#include <linux/kernel.h>
	22	#include <linux/math64.h>
7b64fef3	23
0342e335 PF	24	/* Not needed on 64bit architectures */
	25	#if BITS_PER_LONG == 32
	26
	27	#ifndef __div64_32
	28	uint32_t __attribute__((weak)) __div64_32(uint64_t *n, uint32_t base)
7b64fef3 WD	29	{
	30	uint64_t rem = *n;
	31	uint64_t b = base;
	32	uint64_t res, d = 1;
	33	uint32_t high = rem >> 32;
	34
	35	/* Reduce the thing a bit first */
	36	res = 0;
	37	if (high >= base) {
	38	high /= base;
	39	res = (uint64_t) high << 32;
	40	rem -= (uint64_t) (high*base) << 32;
	41	}
	42
	43	while ((int64_t)b > 0 && b < rem) {
	44	b = b+b;
	45	d = d+d;
	46	}
	47
	48	do {
	49	if (rem >= b) {
	50	rem -= b;
	51	res += d;
	52	}
	53	b >>= 1;
	54	d >>= 1;
	55	} while (d);
	56
	57	*n = res;
	58	return rem;
	59	}
0342e335 PF	60	EXPORT_SYMBOL(__div64_32);
	61	#endif
	62
	63	#ifndef div_s64_rem
	64	s64 div_s64_rem(s64 dividend, s32 divisor, s32 *remainder)
	65	{
	66	u64 quotient;
	67
	68	if (dividend < 0) {
	69	quotient = div_u64_rem(-dividend, abs(divisor), (u32 *)remainder);
	70	remainder = -remainder;
	71	if (divisor > 0)
	72	quotient = -quotient;
	73	} else {
	74	quotient = div_u64_rem(dividend, abs(divisor), (u32 *)remainder);
	75	if (divisor < 0)
	76	quotient = -quotient;
	77	}
	78	return quotient;
	79	}
	80	EXPORT_SYMBOL(div_s64_rem);
	81	#endif
	82
	83	/**
	84	* div64_u64_rem - unsigned 64bit divide with 64bit divisor and remainder
	85	* @dividend: 64bit dividend
	86	* @divisor: 64bit divisor
	87	* @remainder: 64bit remainder
	88	*
	89	* This implementation is a comparable to algorithm used by div64_u64.
	90	* But this operation, which includes math for calculating the remainder,
	91	* is kept distinct to avoid slowing down the div64_u64 operation on 32bit
	92	* systems.
	93	*/
	94	#ifndef div64_u64_rem
	95	u64 div64_u64_rem(u64 dividend, u64 divisor, u64 *remainder)
	96	{
	97	u32 high = divisor >> 32;
	98	u64 quot;
	99
	100	if (high == 0) {
	101	u32 rem32;
	102	quot = div_u64_rem(dividend, divisor, &rem32);
	103	*remainder = rem32;
	104	} else {
	105	int n = 1 + fls(high);
	106	quot = div_u64(dividend >> n, divisor >> n);
	107
	108	if (quot != 0)
	109	quot--;
	110
	111	remainder = dividend - quot divisor;
	112	if (*remainder >= divisor) {
	113	quot++;
	114	*remainder -= divisor;
	115	}
	116	}
	117
	118	return quot;
	119	}
	120	EXPORT_SYMBOL(div64_u64_rem);
	121	#endif
	122
	123	/**
124	* div64_u64 - unsigned 64bit divide with 64bit divisor
125	* @dividend: 64bit dividend
126	* @divisor: 64bit divisor
127	*
128	* This implementation is a modified version of the algorithm proposed
129	* by the book 'Hacker's Delight'. The original source and full proof
130	* can be found here and is available for use without restriction.
131	*
132	* 'http://www.hackersdelight.org/hdcodetxt/divDouble.c.txt'
133	*/
134	#ifndef div64_u64
135	u64 div64_u64(u64 dividend, u64 divisor)
136	{
137	u32 high = divisor >> 32;
138	u64 quot;
139
140	if (high == 0) {
141	quot = div_u64(dividend, divisor);
142	} else {
143	int n = 1 + fls(high);
144	quot = div_u64(dividend >> n, divisor >> n);
145
146	if (quot != 0)
147	quot--;
148	if ((dividend - quot * divisor) >= divisor)
149	quot++;
150	}
151
152	return quot;
153	}
154	EXPORT_SYMBOL(div64_u64);
155	#endif
156
157	/**
158	* div64_s64 - signed 64bit divide with 64bit divisor
159	* @dividend: 64bit dividend
160	* @divisor: 64bit divisor
161	*/
162	#ifndef div64_s64
163	s64 div64_s64(s64 dividend, s64 divisor)
164	{
165	s64 quot, t;
166
167	quot = div64_u64(abs(dividend), abs(divisor));
168	t = (dividend ^ divisor) >> 63;
169
170	return (quot ^ t) - t;
171	}
172	EXPORT_SYMBOL(div64_s64);
173	#endif
174
175	#endif /* BITS_PER_LONG == 32 */
176
177	/*
178	* Iterative div/mod for use when dividend is not expected to be much
179	* bigger than divisor.
180	*/
181	u32 iter_div_u64_rem(u64 dividend, u32 divisor, u64 *remainder)
182	{
183	return __iter_div_u64_rem(dividend, divisor, remainder);
184	}
185	EXPORT_SYMBOL(iter_div_u64_rem);