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Annotation of sys/arch/mips64/include/ieee.h, Revision 1.1.1.1

1.1       nbrk        1: /*     $OpenBSD: ieee.h,v 1.2 2005/08/07 07:29:44 miod Exp $   */
                      2:
                      3: /*
                      4:  * Copyright (c) 1992, 1993
                      5:  *     The Regents of the University of California.  All rights reserved.
                      6:  *
                      7:  * This software was developed by the Computer Systems Engineering group
                      8:  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
                      9:  * contributed to Berkeley.
                     10:  *
                     11:  * All advertising materials mentioning features or use of this software
                     12:  * must display the following acknowledgement:
                     13:  *     This product includes software developed by the University of
                     14:  *     California, Lawrence Berkeley Laboratory.
                     15:  *
                     16:  * Redistribution and use in source and binary forms, with or without
                     17:  * modification, are permitted provided that the following conditions
                     18:  * are met:
                     19:  * 1. Redistributions of source code must retain the above copyright
                     20:  *    notice, this list of conditions and the following disclaimer.
                     21:  * 2. Redistributions in binary form must reproduce the above copyright
                     22:  *    notice, this list of conditions and the following disclaimer in the
                     23:  *    documentation and/or other materials provided with the distribution.
                     24:  * 3. Neither the name of the University nor the names of its contributors
                     25:  *    may be used to endorse or promote products derived from this software
                     26:  *    without specific prior written permission.
                     27:  *
                     28:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     29:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     30:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     31:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     32:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     33:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     34:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     35:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     36:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     37:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     38:  * SUCH DAMAGE.
                     39:  *
                     40:  *     @(#)ieee.h      8.1 (Berkeley) 6/11/93
                     41:  */
                     42:
                     43: /*
                     44:  * ieee.h defines the machine-dependent layout of the machine's IEEE
                     45:  * floating point.  It does *not* define (yet?) any of the rounding
                     46:  * mode bits, exceptions, and so forth.
                     47:  */
                     48:
                     49: /*
                     50:  * Define the number of bits in each fraction and exponent.
                     51:  *
                     52:  *                  k           k+1
                     53:  * Note that  1.0 x 2  == 0.1 x 2      and that denorms are represented
                     54:  *
                     55:  *                                       (-exp_bias+1)
                     56:  * as fractions that look like 0.fffff x 2             .  This means that
                     57:  *
                     58:  *                      -126
                     59:  * the number 0.10000 x 2    , for instance, is the same as the normalized
                     60:  *
                     61:  *             -127                       -128
                     62:  * float 1.0 x 2    .  Thus, to represent 2    , we need one leading zero
                     63:  *
                     64:  *                               -129
                     65:  * in the fraction; to represent 2    , we need two, and so on.  This
                     66:  *
                     67:  *                                                  (-exp_bias-fracbits+1)
                     68:  * implies that the smallest denormalized number is 2
                     69:  *
                     70:  * for whichever format we are talking about: for single precision, for
                     71:  *
                     72:  *                                             -126            -149
                     73:  * instance, we get .00000000000000000000001 x 2    , or 1.0 x 2    , and
                     74:  *
                     75:  * -149 == -127 - 23 + 1.
                     76:  */
                     77: #define        SNG_EXPBITS     8
                     78: #define        SNG_FRACBITS    23
                     79:
                     80: #define        DBL_EXPBITS     11
                     81: #define        DBL_FRACBITS    52
                     82:
                     83: #define        EXT_EXPBITS     15
                     84: #define        EXT_FRACBITS    112
                     85:
                     86: struct ieee_single {
                     87:        u_int   sng_sign:1;
                     88:        u_int   sng_exp:8;
                     89:        u_int   sng_frac:23;
                     90: };
                     91:
                     92: struct ieee_double {
                     93:        u_int   dbl_sign:1;
                     94:        u_int   dbl_exp:11;
                     95:        u_int   dbl_frach:20;
                     96:        u_int   dbl_fracl;
                     97: };
                     98:
                     99: struct ieee_ext {
                    100:        u_int   ext_sign:1;
                    101:        u_int   ext_exp:15;
                    102:        u_int   ext_frach:16;
                    103:        u_int   ext_frachm;
                    104:        u_int   ext_fraclm;
                    105:        u_int   ext_fracl;
                    106: };
                    107:
                    108: /*
                    109:  * Floats whose exponent is in [1..INFNAN) (of whatever type) are
                    110:  * `normal'.  Floats whose exponent is INFNAN are either Inf or NaN.
                    111:  * Floats whose exponent is zero are either zero (iff all fraction
                    112:  * bits are zero) or subnormal values.
                    113:  *
                    114:  * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
                    115:  * high fraction; if the bit is set, it is a `quiet NaN'.
                    116:  */
                    117: #define        SNG_EXP_INFNAN  255
                    118: #define        DBL_EXP_INFNAN  2047
                    119: #define        EXT_EXP_INFNAN  32767
                    120:
                    121: #if 0
                    122: #define        SNG_QUIETNAN    (1 << 22)
                    123: #define        DBL_QUIETNAN    (1 << 19)
                    124: #define        EXT_QUIETNAN    (1 << 15)
                    125: #endif
                    126:
                    127: /*
                    128:  * Exponent biases.
                    129:  */
                    130: #define        SNG_EXP_BIAS    127
                    131: #define        DBL_EXP_BIAS    1023
                    132: #define        EXT_EXP_BIAS    16383