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/* $OpenBSD: fpu_arith.h,v 1.3 2011/09/17 08:38:08 miod Exp $ */
/* $NetBSD: fpu_arith.h,v 1.2 1994/11/20 20:52:35 deraadt Exp $ */
/*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This software was developed by the Computer Systems Engineering group
* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
* contributed to Berkeley.
*
* All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Lawrence Berkeley Laboratory.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
*
* @(#)fpu_arith.h 8.1 (Berkeley) 6/11/93
*/
/*
* Extended-precision arithmetic.
*
* We hold the notion of a `carry register', which may or may not be a
* machine carry bit or register. On the SPARC, it is just the machine's
* carry bit.
*
* In the worst case, you can compute the carry from x+y as
* (unsigned)(x + y) < (unsigned)x
* and from x+y+c as
* ((unsigned)(x + y + c) <= (unsigned)x && (y|c) != 0)
* for example.
*/
/* set up for extended-precision arithmetic */
#define FPU_DECL_CARRY
/*
* We have three kinds of add:
* add with carry: r = x + y + c
* add (ignoring current carry) and set carry: c'r = x + y + 0
* add with carry and set carry: c'r = x + y + c
* The macros use `C' for `use carry' and `S' for `set carry'.
* Note that the state of the carry is undefined after ADDC and SUBC,
* so if all you have for these is `add with carry and set carry',
* that is OK.
*
* The same goes for subtract, except that we compute x - y - c.
*
* Finally, we have a way to get the carry into a `regular' variable,
* or set it from a value. SET_CARRY turns 0 into no-carry, nonzero
* into carry; GET_CARRY sets its argument to 0 or 1.
*/
#define FPU_ADDC(r, x, y) \
asm volatile("addx %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
#define FPU_ADDS(r, x, y) \
asm volatile("addcc %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
#define FPU_ADDCS(r, x, y) \
asm volatile("addxcc %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
#define FPU_SUBC(r, x, y) \
asm volatile("subx %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
#define FPU_SUBS(r, x, y) \
asm volatile("subcc %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
#define FPU_SUBCS(r, x, y) \
asm volatile("subxcc %1,%2,%0" : "=r"(r) : "r"(x), "r"(y))
#define FPU_GET_CARRY(r) asm volatile("addx %%g0,%%g0,%0" : "=r"(r))
#define FPU_SET_CARRY(v) asm volatile("addcc %0,-1,%%g0" : : "r"(v))
#define FPU_SHL1_BY_ADD /* shift left 1 faster by ADDC than (a<<1)|(b>>31) */
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