WebSVN – HelenOS-historic – Diff – /uspace/trunk/softint/generic/division.c


/*
 * Copyright (C) 2006 Josef Cejka
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
/** @addtogroup softint SoftInt
 * @brief   Software implementation of basic arithmetic operations.
 * @{
 */
/**
 * @file
 * SW implementation of 32 and 64 bit division and modulo.
 */
 
#include <division.h>
 
#define ABSVAL(x) ( (x) > 0 ? (x) : -(x))
#define SGN(x) ( (x) >= 0 ? 1 : 0 )
                     
static unsigned int divandmod32(unsigned int a, unsigned int b, unsigned int *remainder)
{
    unsigned int result;
    int steps = sizeof(unsigned int) * 8;
   
    *remainder = 0;
    result = 0;
   
    if (b == 0) {
        /* FIXME: division by zero */
        return 0;
    }
   
    if ( a < b) {
        *remainder = a;
        return 0;
    }
 
    for ( ; steps > 0; steps--) {
        /* shift one bit to remainder */
        *remainder = ( (*remainder) << 1) | (( a >> 31) & 0x1);
        result <<= 1;
       
        if (*remainder >= b) {
                *remainder -= b;
                result |= 0x1;
        }
        a <<= 1;
    }
 
    return result;
}
 
 
static unsigned long long divandmod64(unsigned long long a, unsigned long long b, unsigned long long *remainder)
{
    unsigned long long result;
    int steps = sizeof(unsigned long long) * 8;
   
    *remainder = 0;
    result = 0;
   
    if (b == 0) {
        /* FIXME: division by zero */
        return 0;
    }
   
    if ( a < b) {
        *remainder = a;
        return 0;
    }
 
    for ( ; steps > 0; steps--) {
        /* shift one bit to remainder */
        *remainder = ( (*remainder) << 1) | ((a >> 63) & 0x1);
        result <<= 1;
       
        if (*remainder >= b) {
                *remainder -= b;
                result |= 0x1;
        }
        a <<= 1;
    }
 
    return result;
}
 
/* 32bit integer division */
int __divsi3(int a, int b)
{
    unsigned int rem;
    int result;
   
    result = (int)divandmod32(ABSVAL(a), ABSVAL(b), &rem);
 
    if ( SGN(a) == SGN(b)) return result;
    return -result;
}
 
/* 64bit integer division */
long long __divdi3(long long a, long long b)
{
    unsigned long long rem;
    long long result;
   
    result = (long long)divandmod64(ABSVAL(a), ABSVAL(b), &rem);
 
    if ( SGN(a) == SGN(b)) return result;
    return -result;
}
 
/* 32bit unsigned integer division */
unsigned int __udivsi3(unsigned int a, unsigned int b)
{
    unsigned int rem;
    return divandmod32(a, b, &rem);
}
 
/* 64bit unsigned integer division */
unsigned long long __udivdi3(unsigned long long a, unsigned long long b)
{
    unsigned long long  rem;
    return divandmod64(a, b, &rem);
}
 
/* 32bit remainder of the signed division */
int __modsi3(int a, int b)
{
    unsigned int rem;
    divandmod32(a, b, &rem);
   
    /* if divident is negative, remainder must be too */
    if (!(SGN(a))) {
        return -((int)rem);
    }
   
    return (int)rem;
}
 
/* 64bit remainder of the signed division */
long long __moddi3(long long a,long  long b)
{
    unsigned long long rem;
    divandmod64(a, b, &rem);
   
    /* if divident is negative, remainder must be too */
    if (!(SGN(a))) {
        return -((long long)rem);
    }
   
    return (long long)rem;
}
 
/* 32bit remainder of the unsigned division */
unsigned int __umodsi3(unsigned int a, unsigned int b)
{
    unsigned int rem;
    divandmod32(a, b, &rem);
    return rem;
}
 
/* 64bit remainder of the unsigned division */
unsigned long long __umoddi3(unsigned long long a, unsigned long long b)
{
    unsigned long long rem;
    divandmod64(a, b, &rem);
    return rem;
}
 
unsigned long long __udivmoddi3(unsigned long long a, unsigned long long b, unsigned long long *c)
{
    return divandmod64(a, b, c);
}
 
/** @}
 */
 

Rev 991	Rev 1653
1	/*	1	/*
2	* Copyright (C) 2006 Josef Cejka	2	* Copyright (C) 2006 Josef Cejka
3	* All rights reserved.	3	* All rights reserved.
4	*	4	*
5	* Redistribution and use in source and binary forms, with or without	5	* Redistribution and use in source and binary forms, with or without
6	* modification, are permitted provided that the following conditions	6	* modification, are permitted provided that the following conditions
7	* are met:	7	* are met:
8	*	8	*
9	* - Redistributions of source code must retain the above copyright	9	* - Redistributions of source code must retain the above copyright
10	* notice, this list of conditions and the following disclaimer.	10	* notice, this list of conditions and the following disclaimer.
11	* - Redistributions in binary form must reproduce the above copyright	11	* - Redistributions in binary form must reproduce the above copyright
12	* notice, this list of conditions and the following disclaimer in the	12	* notice, this list of conditions and the following disclaimer in the
13	* documentation and/or other materials provided with the distribution.	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	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.	15	* derived from this software without specific prior written permission.
16	*	16	*
17	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR	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	18	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.	19	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,	20	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT	21	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,	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	23	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT	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	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.	26	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27	*/	27	*/
28		28
-		29	/** @addtogroup softint SoftInt
-		30	* @brief Software implementation of basic arithmetic operations.
-		31	* @{
-		32	*/
-		33	/**
-		34	* @file
-		35	* SW implementation of 32 and 64 bit division and modulo.
-		36	*/
-		37
29	#include <division.h>	38	#include <division.h>
30		39
31	#define ABSVAL(x) ( (x) > 0 ? (x) : -(x))	40	#define ABSVAL(x) ( (x) > 0 ? (x) : -(x))
32	#define SGN(x) ( (x) >= 0 ? 1 : 0 )	41	#define SGN(x) ( (x) >= 0 ? 1 : 0 )
33		42
34	static unsigned int divandmod32(unsigned int a, unsigned int b, unsigned int *remainder)	43	static unsigned int divandmod32(unsigned int a, unsigned int b, unsigned int *remainder)
35	{	44	{
36	unsigned int result;	45	unsigned int result;
37	int steps = sizeof(unsigned int) * 8;	46	int steps = sizeof(unsigned int) * 8;
38		47
39	*remainder = 0;	48	*remainder = 0;
40	result = 0;	49	result = 0;
41		50
42	if (b == 0) {	51	if (b == 0) {
43	/* FIXME: division by zero */	52	/* FIXME: division by zero */
44	return 0;	53	return 0;
45	}	54	}
46		55
47	if ( a < b) {	56	if ( a < b) {
48	*remainder = a;	57	*remainder = a;
49	return 0;	58	return 0;
50	}	59	}
51		60
52	for ( ; steps > 0; steps--) {	61	for ( ; steps > 0; steps--) {
53	/* shift one bit to remainder */	62	/* shift one bit to remainder */
54	remainder = ( (remainder) << 1) \| (( a >> 31) & 0x1);	63	remainder = ( (remainder) << 1) \| (( a >> 31) & 0x1);
55	result <<= 1;	64	result <<= 1;
56		65
57	if (*remainder >= b) {	66	if (*remainder >= b) {
58	*remainder -= b;	67	*remainder -= b;
59	result \|= 0x1;	68	result \|= 0x1;
60	}	69	}
61	a <<= 1;	70	a <<= 1;
62	}	71	}
63		72
64	return result;	73	return result;
65	}	74	}
66		75
67		76
68	static unsigned long long divandmod64(unsigned long long a, unsigned long long b, unsigned long long *remainder)	77	static unsigned long long divandmod64(unsigned long long a, unsigned long long b, unsigned long long *remainder)
69	{	78	{
70	unsigned long long result;	79	unsigned long long result;
71	int steps = sizeof(unsigned long long) * 8;	80	int steps = sizeof(unsigned long long) * 8;
72		81
73	*remainder = 0;	82	*remainder = 0;
74	result = 0;	83	result = 0;
75		84
76	if (b == 0) {	85	if (b == 0) {
77	/* FIXME: division by zero */	86	/* FIXME: division by zero */
78	return 0;	87	return 0;
79	}	88	}
80		89
81	if ( a < b) {	90	if ( a < b) {
82	*remainder = a;	91	*remainder = a;
83	return 0;	92	return 0;
84	}	93	}
85		94
86	for ( ; steps > 0; steps--) {	95	for ( ; steps > 0; steps--) {
87	/* shift one bit to remainder */	96	/* shift one bit to remainder */
88	remainder = ( (remainder) << 1) \| ((a >> 63) & 0x1);	97	remainder = ( (remainder) << 1) \| ((a >> 63) & 0x1);
89	result <<= 1;	98	result <<= 1;
90		99
91	if (*remainder >= b) {	100	if (*remainder >= b) {
92	*remainder -= b;	101	*remainder -= b;
93	result \|= 0x1;	102	result \|= 0x1;
94	}	103	}
95	a <<= 1;	104	a <<= 1;
96	}	105	}
97		106
98	return result;	107	return result;
99	}	108	}
100		109
101	/* 32bit integer division */	110	/* 32bit integer division */
102	int __divsi3(int a, int b)	111	int __divsi3(int a, int b)
103	{	112	{
104	unsigned int rem;	113	unsigned int rem;
105	int result;	114	int result;
106		115
107	result = (int)divandmod32(ABSVAL(a), ABSVAL(b), &rem);	116	result = (int)divandmod32(ABSVAL(a), ABSVAL(b), &rem);
108		117
109	if ( SGN(a) == SGN(b)) return result;	118	if ( SGN(a) == SGN(b)) return result;
110	return -result;	119	return -result;
111	}	120	}
112		121
113	/* 64bit integer division */	122	/* 64bit integer division */
114	long long __divdi3(long long a, long long b)	123	long long __divdi3(long long a, long long b)
115	{	124	{
116	unsigned long long rem;	125	unsigned long long rem;
117	long long result;	126	long long result;
118		127
119	result = (long long)divandmod64(ABSVAL(a), ABSVAL(b), &rem);	128	result = (long long)divandmod64(ABSVAL(a), ABSVAL(b), &rem);
120		129
121	if ( SGN(a) == SGN(b)) return result;	130	if ( SGN(a) == SGN(b)) return result;
122	return -result;	131	return -result;
123	}	132	}
124		133
125	/* 32bit unsigned integer division */	134	/* 32bit unsigned integer division */
126	unsigned int __udivsi3(unsigned int a, unsigned int b)	135	unsigned int __udivsi3(unsigned int a, unsigned int b)
127	{	136	{
128	unsigned int rem;	137	unsigned int rem;
129	return divandmod32(a, b, &rem);	138	return divandmod32(a, b, &rem);
130	}	139	}
131		140
132	/* 64bit unsigned integer division */	141	/* 64bit unsigned integer division */
133	unsigned long long __udivdi3(unsigned long long a, unsigned long long b)	142	unsigned long long __udivdi3(unsigned long long a, unsigned long long b)
134	{	143	{
135	unsigned long long rem;	144	unsigned long long rem;
136	return divandmod64(a, b, &rem);	145	return divandmod64(a, b, &rem);
137	}	146	}
138		147
139	/* 32bit remainder of the signed division */	148	/* 32bit remainder of the signed division */
140	int __modsi3(int a, int b)	149	int __modsi3(int a, int b)
141	{	150	{
142	unsigned int rem;	151	unsigned int rem;
143	divandmod32(a, b, &rem);	152	divandmod32(a, b, &rem);
144		153
145	/* if divident is negative, remainder must be too */	154	/* if divident is negative, remainder must be too */
146	if (!(SGN(a))) {	155	if (!(SGN(a))) {
147	return -((int)rem);	156	return -((int)rem);
148	}	157	}
149		158
150	return (int)rem;	159	return (int)rem;
151	}	160	}
152		161
153	/* 64bit remainder of the signed division */	162	/* 64bit remainder of the signed division */
154	long long __moddi3(long long a,long long b)	163	long long __moddi3(long long a,long long b)
155	{	164	{
156	unsigned long long rem;	165	unsigned long long rem;
157	divandmod64(a, b, &rem);	166	divandmod64(a, b, &rem);
158		167
159	/* if divident is negative, remainder must be too */	168	/* if divident is negative, remainder must be too */
160	if (!(SGN(a))) {	169	if (!(SGN(a))) {
161	return -((long long)rem);	170	return -((long long)rem);
162	}	171	}
163		172
164	return (long long)rem;	173	return (long long)rem;
165	}	174	}
166		175
167	/* 32bit remainder of the unsigned division */	176	/* 32bit remainder of the unsigned division */
168	unsigned int __umodsi3(unsigned int a, unsigned int b)	177	unsigned int __umodsi3(unsigned int a, unsigned int b)
169	{	178	{
170	unsigned int rem;	179	unsigned int rem;
171	divandmod32(a, b, &rem);	180	divandmod32(a, b, &rem);
172	return rem;	181	return rem;
173	}	182	}
174		183
175	/* 64bit remainder of the unsigned division */	184	/* 64bit remainder of the unsigned division */
176	unsigned long long __umoddi3(unsigned long long a, unsigned long long b)	185	unsigned long long __umoddi3(unsigned long long a, unsigned long long b)
177	{	186	{
178	unsigned long long rem;	187	unsigned long long rem;
179	divandmod64(a, b, &rem);	188	divandmod64(a, b, &rem);
180	return rem;	189	return rem;
181	}	190	}
182		191
183	unsigned long long __udivmoddi3(unsigned long long a, unsigned long long b, unsigned long long *c)	192	unsigned long long __udivmoddi3(unsigned long long a, unsigned long long b, unsigned long long *c)
184	{	193	{
185	return divandmod64(a, b, c);	194	return divandmod64(a, b, c);
186	}	195	}
187		196
-		197	/** @}
188		198	*/
189		199

Subversion Repositories HelenOS-historic

(root)/uspace/trunk/softint/generic/division.c – Rev 991 → 1653