/* $OpenBSD: fpu_compare.c,v 1.1 2003/07/21 18:41:30 jason 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. 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, Berkeley and its contributors. * 4. 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_compare.c 8.1 (Berkeley) 6/11/93 * $NetBSD: fpu_compare.c,v 1.3 2001/08/26 05:46:31 eeh Exp $ */ #include #if 0 __FBSDID("$FreeBSD: src/lib/libc/sparc64/fpu/fpu_compare.c,v 1.4 2002/03/22 21:52:58 obrien Exp $"); #endif /* * CMP and CMPE instructions. * * These rely on the fact that our internal wide format is achieved by * adding zero bits to the end of narrower mantissas. */ #include #include #include #include "fpu_arith.h" #include "fpu_emu.h" #include "fpu_extern.h" static u_long fcc_nmask[] = { ~FSR_FCC, ~FSR_FCC1, ~FSR_FCC2, ~FSR_FCC3 }; /* XXX: we don't use the FSR_FCCx macros here; it's much easier this way. */ static int fcc_shift[] = { FSR_FCC_SHIFT, FSR_FCC1_SHIFT, FSR_FCC2_SHIFT, FSR_FCC3_SHIFT }; /* * Perform a compare instruction (with or without unordered exception). * This updates the fcc field in the fsr. * * If either operand is NaN, the result is unordered. For cmpe, this * causes an NV exception. Everything else is ordered: * |Inf| > |numbers| > |0|. * We already arranged for fp_class(Inf) > fp_class(numbers) > fp_class(0), * so we get this directly. Note, however, that two zeros compare equal * regardless of sign, while everything else depends on sign. * * Incidentally, two Infs of the same sign compare equal (per the 80387 * manual---it would be nice if the SPARC documentation were more * complete). */ void __fpu_compare(struct fpemu *fe, int cmpe, int fcc) { struct fpn *a, *b; int cc; FPU_DECL_CARRY a = &fe->fe_f1; b = &fe->fe_f2; if (ISNAN(a) || ISNAN(b)) { /* * In any case, we already got an exception for signalling * NaNs; here we may replace that one with an identical * exception, but so what?. */ if (cmpe) fe->fe_cx = FSR_NV; cc = FSR_CC_UO; goto done; } /* * Must handle both-zero early to avoid sign goofs. Otherwise, * at most one is 0, and if the signs differ we are done. */ if (ISZERO(a) && ISZERO(b)) { cc = FSR_CC_EQ; goto done; } if (a->fp_sign) { /* a < 0 (or -0) */ if (!b->fp_sign) { /* b >= 0 (or if a = -0, b > 0) */ cc = FSR_CC_LT; goto done; } } else { /* a > 0 (or +0) */ if (b->fp_sign) { /* b <= -0 (or if a = +0, b < 0) */ cc = FSR_CC_GT; goto done; } } /* * Now the signs are the same (but may both be negative). All * we have left are these cases: * * |a| < |b| [classes or values differ] * |a| > |b| [classes or values differ] * |a| == |b| [classes and values identical] * * We define `diff' here to expand these as: * * |a| < |b|, a,b >= 0: a < b => FSR_CC_LT * |a| < |b|, a,b < 0: a > b => FSR_CC_GT * |a| > |b|, a,b >= 0: a > b => FSR_CC_GT * |a| > |b|, a,b < 0: a < b => FSR_CC_LT */ #define opposite_cc(cc) ((cc) == FSR_CC_LT ? FSR_CC_GT : FSR_CC_LT) #define diff(magnitude) (a->fp_sign ? opposite_cc(magnitude) : (magnitude)) if (a->fp_class < b->fp_class) { /* |a| < |b| */ cc = diff(FSR_CC_LT); goto done; } if (a->fp_class > b->fp_class) { /* |a| > |b| */ cc = diff(FSR_CC_GT); goto done; } /* now none can be 0: only Inf and numbers remain */ if (ISINF(a)) { /* |Inf| = |Inf| */ cc = FSR_CC_EQ; goto done; } /* * Only numbers remain. To compare two numbers in magnitude, we * simply subtract them. */ a = __fpu_sub(fe); if (a->fp_class == FPC_ZERO) cc = FSR_CC_EQ; else cc = diff(FSR_CC_GT); done: fe->fe_fsr = (fe->fe_fsr & fcc_nmask[fcc]) | ((u_long)cc << fcc_shift[fcc]); }