Annotation of sys/arch/sh/include/ieee.h, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: ieee.h,v 1.2 2006/11/10 20:29:36 otto 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_frac:23;
! 88: u_int sng_exp:8;
! 89: u_int sng_sign:1;
! 90: };
! 91:
! 92: struct ieee_double {
! 93: u_int dbl_fracl;
! 94: u_int dbl_frach:20;
! 95: u_int dbl_exp:11;
! 96: u_int dbl_sign:1;
! 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
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