usr/src/lib/libc/sparc/fp/_Q_sub.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 #include "quad.h"
  30
  31 #ifdef __sparcv9
  32
  33 /*
  34  * _Qp_sub(pz, ox, oy) sets *pz = *ox - *oy.
  35  */
  36 void
  37 _Qp_sub(union longdouble *pz, const union longdouble *ox,
  38         const union longdouble *oy)
  39
  40 #else
  41
  42 /*
  43  * _Q_sub(ox, oy) returns *ox - *oy.
  44  */
  45 union longdouble
  46 _Q_sub(const union longdouble *ox, const union longdouble *oy)
  47
  48 #endif  /* __sparcv9 */
  49
  50 {
  51         union longdouble        z;
  52         const union longdouble  *x, *y;
  53         unsigned int            xm, ym, tm, fsr;
  54         int                     flip;
  55
  56         /* sort so |x| >= |y| */
  57         xm = ox->l.msw & 0x7fffffff;
  58         ym = oy->l.msw & 0x7fffffff;
  59         if (ym > xm || ym == xm && (oy->l.frac2 > ox->l.frac2 ||
  60             oy->l.frac2 == ox->l.frac2 && (oy->l.frac3 > ox->l.frac3 ||
  61             oy->l.frac3 == ox->l.frac3 && oy->l.frac4 > ox->l.frac4))) {
  62                 y = ox;
  63                 x = oy;
  64                 tm = xm;
  65                 xm = ym;
  66                 ym = tm;
  67                 flip = 0x80000000;
  68         } else {
  69                 x = ox;
  70                 y = oy;
  71                 flip = 0;
  72         }
  73
  74         /* get the fsr */
  75         __quad_getfsrp(&fsr);
  76
  77         /* handle nan and inf cases */
  78         if (xm >= 0x7fff0000) {
  79                 /* x is nan or inf */
  80                 if (ym >= 0x7fff0000) {
  81                         /* y is nan or inf */
  82                         if ((ym & 0xffff) | y->l.frac2 | y->l.frac3 |
  83                             y->l.frac4) {
  84                                 /* y is nan; x must be nan too */
  85                                 /* the following logic implements V9 app. B */
  86                                 if (!(ym & 0x8000)) {
  87                                         /* y is snan, signal invalid */
  88                                         if (fsr & FSR_NVM) {
  89                                                 __quad_fsubq(ox, oy, &Z);
  90                                         } else {
  91                                                 Z = (xm & 0x8000)? *y : *oy;
  92                                                 Z.l.msw |= 0x8000;
  93                                                 fsr = (fsr & ~FSR_CEXC) |
  94                                                     FSR_NVA | FSR_NVC;
  95                                                 __quad_setfsrp(&fsr);
  96                                         }
  97                                         QUAD_RETURN(Z);
  98                                 }
  99                                 /* x and y are both qnan */
 100                                 Z = *oy;
 101                                 QUAD_RETURN(Z);
 102                         }
 103                         if (!((xm & 0xffff) | x->l.frac2 | x->l.frac3 |
 104                             x->l.frac4)) {
 105                                 /* x and y are both inf */
 106                                 if (!((x->l.msw ^ y->l.msw) & 0x80000000)) {
 107                                         /* inf - inf, signal invalid */
 108                                         if (fsr & FSR_NVM) {
 109                                                 __quad_fsubq(ox, oy, &Z);
 110                                         } else {
 111                                                 Z.l.msw = 0x7fffffff;
 112                                                 Z.l.frac2 = Z.l.frac3 =
 113                                                     Z.l.frac4 = 0xffffffff;
 114                                                 fsr = (fsr & ~FSR_CEXC) |
 115                                                     FSR_NVA | FSR_NVC;
 116                                                 __quad_setfsrp(&fsr);
 117                                         }
 118                                         QUAD_RETURN(Z);
 119                                 }
 120                                 /* inf + inf, return inf */
 121                                 Z = *x;
 122                                 Z.l.msw ^= flip;
 123                                 QUAD_RETURN(Z);
 124                         }
 125                 }
 126                 if ((xm & 0xffff) | x->l.frac2 | x->l.frac3 | x->l.frac4) {
 127                         /* x is nan */
 128                         if (!(xm & 0x8000)) {
 129                                 /* snan, signal invalid */
 130                                 if (fsr & FSR_NVM) {
 131                                         __quad_fsubq(ox, oy, &Z);
 132                                 } else {
 133                                         Z = *x;
 134                                         Z.l.msw |= 0x8000;
 135                                         fsr = (fsr & ~FSR_CEXC) | FSR_NVA |
 136                                             FSR_NVC;
 137                                         __quad_setfsrp(&fsr);
 138                                 }
 139                                 QUAD_RETURN(Z);
 140                         }
 141                         Z = *x;
 142                         QUAD_RETURN(Z);
 143                 }
 144                 /* x is inf */
 145                 Z = *x;
 146                 Z.l.msw ^= flip;
 147                 QUAD_RETURN(Z);
 148         }
 149
 150         /* now x and y are finite and |x| >= |y| */
 151         fsr &= ~FSR_CEXC;
 152         z.l.msw = (x->l.msw & 0x80000000) ^ flip;
 153         if ((x->l.msw ^ y->l.msw) & 0x80000000)
 154                 __quad_mag_add(x, y, &z, &fsr);
 155         else
 156                 __quad_mag_sub(x, y, &z, &fsr);
 157         if ((fsr & FSR_CEXC) & (fsr >> 23)) {
 158                 __quad_setfsrp(&fsr);
 159                 __quad_fsubq(ox, oy, &Z);
 160         } else {
 161                 Z = z;
 162                 fsr |= (fsr & 0x1f) << 5;
 163                 __quad_setfsrp(&fsr);
 164         }
 165         QUAD_RETURN(Z);
 166 }