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
811	jermar	29	#include <genarch/softint/division.h>
810	cejka	30
		31	#define ABSVAL(x) ( (x) > 0 ? (x) : -(x))
		32	#define SGN(x) ( (x) >= 0 ? 1 : 0 )
		33
		34	static unsigned int divandmod32(unsigned int a, unsigned int b, unsigned int *remainder)
		35	{
		36	unsigned int result;
811	jermar	37	int steps = sizeof(unsigned int) * 8;
810	cejka	38
		39	*remainder = 0;
		40	result = 0;
		41
		42	if (b == 0) {
		43	/* FIXME: division by zero */
		44	return 0;
		45	}
		46
		47	if ( a < b) {
		48	*remainder = a;
		49	return 0;
		50	}
		51
		52	for ( ; steps > 0; steps--) {
		53	/* shift one bit to remainder */
811	jermar	54	remainder = ( (remainder) << 1) \| (( a >> 31) & 0x1);
810	cejka	55	result <<= 1;
		56
		57	if (*remainder >= b) {
		58	*remainder -= b;
		59	result \|= 0x1;
		60	}
811	jermar	61	a <<= 1;
810	cejka	62	}
		63
		64	return result;
		65	}
		66
		67
		68	static unsigned long divandmod64(unsigned long a, unsigned long b, unsigned long *remainder)
		69	{
		70	unsigned long result;
811	jermar	71	int steps = sizeof(unsigned long) * 8;
810	cejka	72
		73	*remainder = 0;
		74	result = 0;
		75
		76	if (b == 0) {
		77	/* FIXME: division by zero */
		78	return 0;
		79	}
		80
		81	if ( a < b) {
		82	*remainder = a;
		83	return 0;
		84	}
		85
		86	for ( ; steps > 0; steps--) {
		87	/* shift one bit to remainder */
811	jermar	88	remainder = ( (remainder) << 1) \| ((a >> 63) & 0x1);
810	cejka	89	result <<= 1;
		90
		91	if (*remainder >= b) {
		92	*remainder -= b;
		93	result \|= 0x1;
		94	}
811	jermar	95	a <<= 1;
810	cejka	96	}
		97
		98	return result;
		99	}
		100
		101	/* 32bit integer division */
		102	int __divsi3(int a, int b)
		103	{
		104	unsigned int rem;
		105	int result;
		106
		107	result = (int)divandmod32(ABSVAL(a), ABSVAL(b), &rem);
		108
		109	if ( SGN(a) == SGN(b)) return result;
		110	return -result;
		111	}
		112
		113	/* 64bit integer division */
		114	long __divdi3(long a, long b)
		115	{
		116	unsigned long rem;
		117	long result;
		118
		119	result = (long)divandmod64(ABSVAL(a), ABSVAL(b), &rem);
		120
		121	if ( SGN(a) == SGN(b)) return result;
		122	return -result;
		123	}
		124
		125	/* 32bit unsigned integer division */
		126	unsigned int __udivsi3(unsigned int a, unsigned int b)
		127	{
		128	unsigned int rem;
		129	return divandmod32(a, b, &rem);
		130	}
		131
		132	/* 64bit unsigned integer division */
		133	unsigned long __udivdi3(unsigned long a, unsigned long b)
		134	{
		135	unsigned long rem;
		136	return divandmod64(a, b, &rem);
		137	}
		138
		139	/* 32bit remainder of the signed division */
		140	int __modsi3(int a, int b)
		141	{
		142	unsigned int rem;
		143	divandmod32(a, b, &rem);
		144
811	jermar	145	/* if divident is negative, remainder must be too */
810	cejka	146	if (!(SGN(a))) {
		147	return -((int)rem);
		148	}
		149
		150	return (int)rem;
		151	}
		152
		153	/* 64bit remainder of the signed division */
		154	long __moddi3(long a, long b)
		155	{
		156	unsigned long rem;
		157	divandmod64(a, b, &rem);
		158
811	jermar	159	/* if divident is negative, remainder must be too */
810	cejka	160	if (!(SGN(a))) {
		161	return -((long)rem);
		162	}
		163
		164	return (long)rem;
		165	}
		166
		167	/* 32bit remainder of the unsigned division */
		168	unsigned int __umodsi3(unsigned int a, unsigned int b)
		169	{
		170	unsigned int rem;
		171	divandmod32(a, b, &rem);
		172	return rem;
		173	}
		174
		175	/* 64bit remainder of the unsigned division */
		176	unsigned long __umoddi3(unsigned long a, unsigned long b)
		177	{
		178	unsigned long rem;
		179	divandmod64(a, b, &rem);
		180	return rem;
		181	}
		182
		183	unsigned long __udivmoddi3(unsigned long a, unsigned long b, unsigned long *c)
		184	{
		185	return divandmod64(a, b, c);
		186	}
		187
		188

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(root)/kernel/trunk/genarch/src/softint/division.c – Rev 811