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

Rev	Author	Line No.	Line
810	cejka	1	/*
		2	* Copyright (C) 2006 Josef 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
1702	cejka	29	/** @addtogroup genarch
		30	* @{
		31	*/
		32	/** @file
		33	*/
		34
811	jermar	35	#include <genarch/softint/division.h>
810	cejka	36
		37	#define ABSVAL(x) ( (x) > 0 ? (x) : -(x))
		38	#define SGN(x) ( (x) >= 0 ? 1 : 0 )
		39
		40	static unsigned int divandmod32(unsigned int a, unsigned int b, unsigned int *remainder)
		41	{
		42	unsigned int result;
811	jermar	43	int steps = sizeof(unsigned int) * 8;
810	cejka	44
		45	*remainder = 0;
		46	result = 0;
		47
		48	if (b == 0) {
		49	/* FIXME: division by zero */
		50	return 0;
		51	}
		52
		53	if ( a < b) {
		54	*remainder = a;
		55	return 0;
		56	}
		57
		58	for ( ; steps > 0; steps--) {
		59	/* shift one bit to remainder */
811	jermar	60	remainder = ( (remainder) << 1) \| (( a >> 31) & 0x1);
810	cejka	61	result <<= 1;
		62
		63	if (*remainder >= b) {
		64	*remainder -= b;
		65	result \|= 0x1;
		66	}
811	jermar	67	a <<= 1;
810	cejka	68	}
		69
		70	return result;
		71	}
		72
		73
1196	cejka	74	static unsigned long long divandmod64(unsigned long long a, unsigned long long b, unsigned long long *remainder)
810	cejka	75	{
1196	cejka	76	unsigned long long result;
		77	int steps = sizeof(unsigned long long) * 8;
810	cejka	78
		79	*remainder = 0;
		80	result = 0;
		81
		82	if (b == 0) {
		83	/* FIXME: division by zero */
		84	return 0;
		85	}
		86
		87	if ( a < b) {
		88	*remainder = a;
		89	return 0;
		90	}
		91
		92	for ( ; steps > 0; steps--) {
		93	/* shift one bit to remainder */
811	jermar	94	remainder = ( (remainder) << 1) \| ((a >> 63) & 0x1);
810	cejka	95	result <<= 1;
		96
		97	if (*remainder >= b) {
		98	*remainder -= b;
		99	result \|= 0x1;
		100	}
811	jermar	101	a <<= 1;
810	cejka	102	}
		103
		104	return result;
		105	}
		106
		107	/* 32bit integer division */
		108	int __divsi3(int a, int b)
		109	{
		110	unsigned int rem;
		111	int result;
		112
		113	result = (int)divandmod32(ABSVAL(a), ABSVAL(b), &rem);
		114
		115	if ( SGN(a) == SGN(b)) return result;
		116	return -result;
		117	}
		118
		119	/* 64bit integer division */
1196	cejka	120	long long __divdi3(long long a, long long b)
810	cejka	121	{
1196	cejka	122	unsigned long long rem;
		123	long long result;
810	cejka	124
1196	cejka	125	result = (long long)divandmod64(ABSVAL(a), ABSVAL(b), &rem);
810	cejka	126
		127	if ( SGN(a) == SGN(b)) return result;
		128	return -result;
		129	}
		130
		131	/* 32bit unsigned integer division */
		132	unsigned int __udivsi3(unsigned int a, unsigned int b)
		133	{
		134	unsigned int rem;
		135	return divandmod32(a, b, &rem);
		136	}
		137
		138	/* 64bit unsigned integer division */
1196	cejka	139	unsigned long long __udivdi3(unsigned long long a, unsigned long long b)
810	cejka	140	{
1196	cejka	141	unsigned long long rem;
810	cejka	142	return divandmod64(a, b, &rem);
		143	}
		144
		145	/* 32bit remainder of the signed division */
		146	int __modsi3(int a, int b)
		147	{
		148	unsigned int rem;
		149	divandmod32(a, b, &rem);
		150
811	jermar	151	/* if divident is negative, remainder must be too */
810	cejka	152	if (!(SGN(a))) {
		153	return -((int)rem);
		154	}
		155
		156	return (int)rem;
		157	}
		158
		159	/* 64bit remainder of the signed division */
1196	cejka	160	long long __moddi3(long long a,long long b)
810	cejka	161	{
1196	cejka	162	unsigned long long rem;
810	cejka	163	divandmod64(a, b, &rem);
		164
811	jermar	165	/* if divident is negative, remainder must be too */
810	cejka	166	if (!(SGN(a))) {
1196	cejka	167	return -((long long)rem);
810	cejka	168	}
		169
1196	cejka	170	return (long long)rem;
810	cejka	171	}
		172
		173	/* 32bit remainder of the unsigned division */
		174	unsigned int __umodsi3(unsigned int a, unsigned int b)
		175	{
		176	unsigned int rem;
		177	divandmod32(a, b, &rem);
		178	return rem;
		179	}
		180
		181	/* 64bit remainder of the unsigned division */
1196	cejka	182	unsigned long long __umoddi3(unsigned long long a, unsigned long long b)
810	cejka	183	{
1196	cejka	184	unsigned long long rem;
810	cejka	185	divandmod64(a, b, &rem);
		186	return rem;
		187	}
		188
1196	cejka	189	unsigned long long __udivmoddi3(unsigned long long a, unsigned long long b, unsigned long long *c)
810	cejka	190	{
		191	return divandmod64(a, b, c);
		192	}
		193
		194
1702	cejka	195
		196	/** @}
		197	*/
		198

Subversion Repositories HelenOS-historic

(root)/kernel/trunk/genarch/src/softint/division.c/ – Rev 1702