fpu_arith.h revision 91174 
1/*
2 * Copyright (c) 1992, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This software was developed by the Computer Systems Engineering group
6 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
7 * contributed to Berkeley.
8 *
9 * All advertising materials mentioning features or use of this software
10 * must display the following acknowledgement:
11 *	This product includes software developed by the University of
12 *	California, Lawrence Berkeley Laboratory.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 *    notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 *    notice, this list of conditions and the following disclaimer in the
21 *    documentation and/or other materials provided with the distribution.
22 * 3. All advertising materials mentioning features or use of this software
23 *    must display the following acknowledgement:
24 *	This product includes software developed by the University of
25 *	California, Berkeley and its contributors.
26 * 4. Neither the name of the University nor the names of its contributors
27 *    may be used to endorse or promote products derived from this software
28 *    without specific prior written permission.
29 *
30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
40 * SUCH DAMAGE.
41 *
42 *	from: @(#)fpu_arith.h	8.1 (Berkeley) 6/11/93
43 *	from: NetBSD: fpu_arith.h,v 1.3 2000/07/24 04:11:03 mycroft
44 *
45 * $FreeBSD: head/lib/libc/sparc64/fpu/fpu_arith.h 91174 2002-02-23 21:37:18Z tmm $
46 */
47
48/*
49 * Extended-precision arithmetic.
50 *
51 * We hold the notion of a `carry register', which may or may not be a
52 * machine carry bit or register.  On the SPARC, it is just the machine's
53 * carry bit.
54 *
55 * In the worst case, you can compute the carry from x+y as
56 *	(unsigned)(x + y) < (unsigned)x
57 * and from x+y+c as
58 *	((unsigned)(x + y + c) <= (unsigned)x && (y|c) != 0)
59 * for example.
60 */
61
62/* set up for extended-precision arithemtic */
63#define	FPU_DECL_CARRY
64
65/*
66 * We have three kinds of add:
67 *	add with carry:					  r = x + y + c
68 *	add (ignoring current carry) and set carry:	c'r = x + y + 0
69 *	add with carry and set carry:			c'r = x + y + c
70 * The macros use `C' for `use carry' and `S' for `set carry'.
71 * Note that the state of the carry is undefined after ADDC and SUBC,
72 * so if all you have for these is `add with carry and set carry',
73 * that is OK.
74 *
75 * The same goes for subtract, except that we compute x - y - c.
76 *
77 * Finally, we have a way to get the carry into a `regular' variable,
78 * or set it from a value.  SET_CARRY turns 0 into no-carry, nonzero
79 * into carry; GET_CARRY sets its argument to 0 or 1.
80 */
81#define	FPU_ADDC(r, x, y) \
82	__asm __volatile("addx %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
83#define	FPU_ADDS(r, x, y) \
84	__asm __volatile("addcc %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
85#define	FPU_ADDCS(r, x, y) \
86	__asm __volatile("addxcc %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
87#define	FPU_SUBC(r, x, y) \
88	__asm __volatile("subx %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
89#define	FPU_SUBS(r, x, y) \
90	__asm __volatile("subcc %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
91#define	FPU_SUBCS(r, x, y) \
92	__asm __volatile("subxcc %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
93
94#define	FPU_GET_CARRY(r) __asm __volatile("addx %%g0,%%g0,%0" : "=r"(r))
95#define	FPU_SET_CARRY(v) __asm __volatile("addcc %0,-1,%%g0" : : "r"(v))
96
97#define	FPU_SHL1_BY_ADD	/* shift left 1 faster by ADDC than (a<<1)|(b>>31) */
98