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 * %sccs.include.redist.c% 15 * 16 * @(#)fpu_arith.h 8.1 (Berkeley) 06/11/93 17 * 18 * from: $Header: fpu_arith.h,v 1.3 92/11/26 01:30:50 torek Exp $ 19 */ 20 21 /* 22 * Extended-precision arithmetic. 23 * 24 * We hold the notion of a `carry register', which may or may not be a 25 * machine carry bit or register. On the SPARC, it is just the machine's 26 * carry bit. 27 * 28 * In the worst case, you can compute the carry from x+y as 29 * (unsigned)(x + y) < (unsigned)x 30 * and from x+y+c as 31 * ((unsigned)(x + y + c) <= (unsigned)x && (y|c) != 0) 32 * for example. 33 */ 34 35 /* set up for extended-precision arithemtic */ 36 #define FPU_DECL_CARRY 37 38 /* 39 * We have three kinds of add: 40 * add with carry: r = x + y + c 41 * add (ignoring current carry) and set carry: c'r = x + y + 0 42 * add with carry and set carry: c'r = x + y + c 43 * The macros use `C' for `use carry' and `S' for `set carry'. 44 * Note that the state of the carry is undefined after ADDC and SUBC, 45 * so if all you have for these is `add with carry and set carry', 46 * that is OK. 47 * 48 * The same goes for subtract, except that we compute x - y - c. 49 * 50 * Finally, we have a way to get the carry into a `regular' variable, 51 * or set it from a value. SET_CARRY turns 0 into no-carry, nonzero 52 * into carry; GET_CARRY sets its argument to 0 or 1. 53 */ 54 #define FPU_ADDC(r, x, y) \ 55 asm volatile("addx %1,%2,%0" : "=r"(r) : "r"(x), "r"(y)) 56 #define FPU_ADDS(r, x, y) \ 57 asm volatile("addcc %1,%2,%0" : "=r"(r) : "r"(x), "r"(y)) 58 #define FPU_ADDCS(r, x, y) \ 59 asm volatile("addxcc %1,%2,%0" : "=r"(r) : "r"(x), "r"(y)) 60 #define FPU_SUBC(r, x, y) \ 61 asm volatile("subx %1,%2,%0" : "=r"(r) : "r"(x), "r"(y)) 62 #define FPU_SUBS(r, x, y) \ 63 asm volatile("subcc %1,%2,%0" : "=r"(r) : "r"(x), "r"(y)) 64 #define FPU_SUBCS(r, x, y) \ 65 asm volatile("subxcc %1,%2,%0" : "=r"(r) : "r"(x), "r"(y)) 66 67 #define FPU_GET_CARRY(r) asm volatile("addx %%g0,%%g0,%0" : "=r"(r)) 68 #define FPU_SET_CARRY(v) asm volatile("addcc %0,-1,%%g0" : : "r"(v)) 69 70 #define FPU_SHL1_BY_ADD /* shift left 1 faster by ADDC than (a<<1)|(b>>31) */ 71