WebSVN – HelenOS – Blame – /trunk/kernel/genarch/src/softint/division.c

Rev	Author	Line No.	Line
810	cejka	1	/*
2071	jermar	2	* Copyright (c) 2006 Josef Cejka
810	cejka	3	* All rights reserved.
		4	*
		5	* Redistribution and use in source and binary forms, with or without
		6	* modification, are permitted provided that the following conditions
		7	* are met:
		8	*
		9	* - Redistributions of source code must retain the above copyright
		10	* notice, this list of conditions and the following disclaimer.
		11	* - Redistributions in binary form must reproduce the above copyright
		12	* notice, this list of conditions and the following disclaimer in the
		13	* documentation and/or other materials provided with the distribution.
		14	* - The name of the author may not be used to endorse or promote products
		15	* derived from this software without specific prior written permission.
		16	*
		17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
		18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
		19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
		20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
		21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
		22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
		23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
		24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
		25	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
		26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
		27	*/
		28
1888	jermar	29	/** @addtogroup genarch
1702	cejka	30	* @{
		31	*/
		32	/** @file
		33	*/
		34
811	jermar	35	#include <genarch/softint/division.h>
810	cejka	36
2505	jermar	37	#define ABSVAL(x) ((x) > 0 ? (x) : -(x))
		38	#define SGN(x) ((x) >= 0 ? 1 : 0)
810	cejka	39
2505	jermar	40	static unsigned int divandmod32(unsigned int a, unsigned int b,
		41	unsigned int *remainder)
810	cejka	42	{
		43	unsigned int result;
811	jermar	44	int steps = sizeof(unsigned int) * 8;
810	cejka	45
		46	*remainder = 0;
		47	result = 0;
		48
		49	if (b == 0) {
		50	/* FIXME: division by zero */
		51	return 0;
		52	}
		53
2505	jermar	54	if (a < b) {
810	cejka	55	*remainder = a;
		56	return 0;
		57	}
		58
2505	jermar	59	for (; steps > 0; steps--) {
810	cejka	60	/* shift one bit to remainder */
2505	jermar	61	remainder = ((remainder) << 1) \| (( a >> 31) & 0x1);
810	cejka	62	result <<= 1;
		63
		64	if (*remainder >= b) {
2505	jermar	65	*remainder -= b;
		66	result \|= 0x1;
810	cejka	67	}
811	jermar	68	a <<= 1;
810	cejka	69	}
		70
		71	return result;
		72	}
		73
		74
2505	jermar	75	static unsigned long long divandmod64(unsigned long long a,
		76	unsigned long long b, unsigned long long *remainder)
810	cejka	77	{
1196	cejka	78	unsigned long long result;
		79	int steps = sizeof(unsigned long long) * 8;
810	cejka	80
		81	*remainder = 0;
		82	result = 0;
		83
		84	if (b == 0) {
		85	/* FIXME: division by zero */
		86	return 0;
		87	}
		88
2505	jermar	89	if (a < b) {
810	cejka	90	*remainder = a;
		91	return 0;
		92	}
		93
2505	jermar	94	for (; steps > 0; steps--) {
810	cejka	95	/* shift one bit to remainder */
2505	jermar	96	remainder = ((remainder) << 1) \| ((a >> 63) & 0x1);
810	cejka	97	result <<= 1;
		98
		99	if (*remainder >= b) {
2505	jermar	100	*remainder -= b;
		101	result \|= 0x1;
810	cejka	102	}
811	jermar	103	a <<= 1;
810	cejka	104	}
		105
		106	return result;
		107	}
		108
		109	/* 32bit integer division */
		110	int __divsi3(int a, int b)
		111	{
		112	unsigned int rem;
		113	int result;
		114
2505	jermar	115	result = (int) divandmod32(ABSVAL(a), ABSVAL(b), &rem);
810	cejka	116
2505	jermar	117	if (SGN(a) == SGN(b))
		118	return result;
810	cejka	119	return -result;
		120	}
		121
		122	/* 64bit integer division */
1196	cejka	123	long long __divdi3(long long a, long long b)
810	cejka	124	{
1196	cejka	125	unsigned long long rem;
		126	long long result;
810	cejka	127
2505	jermar	128	result = (long long) divandmod64(ABSVAL(a), ABSVAL(b), &rem);
810	cejka	129
2505	jermar	130	if (SGN(a) == SGN(b))
		131	return result;
810	cejka	132	return -result;
		133	}
		134
		135	/* 32bit unsigned integer division */
		136	unsigned int __udivsi3(unsigned int a, unsigned int b)
		137	{
		138	unsigned int rem;
		139	return divandmod32(a, b, &rem);
		140	}
		141
		142	/* 64bit unsigned integer division */
1196	cejka	143	unsigned long long __udivdi3(unsigned long long a, unsigned long long b)
810	cejka	144	{
1196	cejka	145	unsigned long long rem;
810	cejka	146	return divandmod64(a, b, &rem);
		147	}
		148
		149	/* 32bit remainder of the signed division */
		150	int __modsi3(int a, int b)
		151	{
		152	unsigned int rem;
		153	divandmod32(a, b, &rem);
		154
811	jermar	155	/* if divident is negative, remainder must be too */
810	cejka	156	if (!(SGN(a))) {
2505	jermar	157	return -((int) rem);
810	cejka	158	}
		159
2505	jermar	160	return (int) rem;
810	cejka	161	}
		162
		163	/* 64bit remainder of the signed division */
1196	cejka	164	long long __moddi3(long long a,long long b)
810	cejka	165	{
1196	cejka	166	unsigned long long rem;
810	cejka	167	divandmod64(a, b, &rem);
		168
811	jermar	169	/* if divident is negative, remainder must be too */
810	cejka	170	if (!(SGN(a))) {
2505	jermar	171	return -((long long) rem);
810	cejka	172	}
		173
2505	jermar	174	return (long long) rem;
810	cejka	175	}
		176
		177	/* 32bit remainder of the unsigned division */
		178	unsigned int __umodsi3(unsigned int a, unsigned int b)
		179	{
		180	unsigned int rem;
		181	divandmod32(a, b, &rem);
		182	return rem;
		183	}
		184
		185	/* 64bit remainder of the unsigned division */
1196	cejka	186	unsigned long long __umoddi3(unsigned long long a, unsigned long long b)
810	cejka	187	{
1196	cejka	188	unsigned long long rem;
810	cejka	189	divandmod64(a, b, &rem);
		190	return rem;
		191	}
		192
2505	jermar	193	unsigned long long __udivmoddi3(unsigned long long a, unsigned long long b,
		194	unsigned long long *c)
810	cejka	195	{
		196	return divandmod64(a, b, c);
		197	}
		198
1888	jermar	199	/** @}
1702	cejka	200	*/

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