usr/src/lib/libm/common/m9x/fminf.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 (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  24  */
  25 /*
  26  * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  27  * Use is subject to license terms.
  28  */
  29
  30 #pragma weak fminf = __fminf
  31
  32 #include "libm.h"       /* for islessequal macro */
  33
  34 float
  35 __fminf(float x, float y) {
  36         /*
  37          * On SPARC v8plus/v9, this could be implemented as follows
  38          * (assuming %f0 = x, %f1 = y, return value left in %f0):
  39          *
  40          * fcmps        %fcc0,%f1,%f1
  41          * fmovsu       %fcc0,%f0,%f1
  42          * fcmps        %fcc0,%f0,%f1
  43          * fmovsug      %fcc0,%f1,%f0
  44          * st           %f0,[x]
  45          * st           %f1,[y]
  46          * ld           [x],%l0
  47          * ld           [y],%l1
  48          * or           %l0,%l1,%l2
  49          * sethi        %hi(0x80000000),%l3
  50          * and          %l3,%l2,%l2
  51          * or           %l0,%l2,%l0
  52          * st           %l0,[x]
  53          * ld           [x],%f0
  54          *
  55          * If VIS instructions are available, use this code instead:
  56          *
  57          * fcmps        %fcc0,%f1,%f1
  58          * fmovsu       %fcc0,%f0,%f1
  59          * fcmps        %fcc0,%f0,%f1
  60          * fmovsug      %fcc0,%f1,%f0
  61          * fors         %f0,%f1,%f2
  62          * fzeros       %f3
  63          * fnegs        %f3,%f3
  64          * fands        %f3,%f2,%f2
  65          * fors         %f0,%f2,%f0
  66          *
  67          * If VIS 3.0 instructions are available, use this:
  68          *
  69          * flcmps       %fcc0,%f0,%f1
  70          * fmovsge      %fcc0,%f1,%f0   ! move if %fcc0 is 0 or 2
  71          */
  72
  73         union {
  74                 unsigned i;
  75                 float f;
  76         } xx, yy;
  77         unsigned s;
  78
  79         /* if y is nan, replace it by x */
  80         if (y != y)
  81                 y = x;
  82
  83         /* if x is nan, replace it by y */
  84         if (x != x)
  85                 x = y;
  86
  87         /* At this point, x and y are either both numeric, or both NaN */
  88         if (!isnan(x) && !islessequal(x, y))
  89                 x = y;
  90
  91         /*
  92          * set the sign of the result if either x or y has its sign set
  93          */
  94         xx.f = x;
  95         yy.f = y;
  96         s = (xx.i | yy.i) & 0x80000000;
  97         xx.i |= s;
  98
  99         return (xx.f);
 100 }