/* * 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. * * %sccs.include.redist.c% * * @(#)fpu_arith.h 8.1 (Berkeley) 06/11/93 * * from: $Header: fpu_arith.h,v 1.3 92/11/26 01:30:50 torek Exp $ */ /* * 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 arithemtic */ #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) */