1 /* $NetBSD: ieee754.h,v 1.4 2003/10/27 02:30:26 simonb Exp $ */
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40 * @(#)ieee.h 8.1 (Berkeley) 6/11/93
47 * NOTICE: This is not a standalone file. To use it, #include it in
48 * your port's ieee.h header.
51 #include <machine/endian.h>
54 * <sys/ieee754.h> defines the layout of IEEE 754 floating point types.
55 * Only single-precision and double-precision types are defined here;
56 * extended types, if available, are defined in the machine-dependent
61 * Define the number of bits in each fraction and exponent.
64 * Note that 1.0 x 2 == 0.1 x 2 and that denorms are represented
67 * as fractions that look like 0.fffff x 2 . This means that
70 * the number 0.10000 x 2 , for instance, is the same as the normalized
73 * float 1.0 x 2 . Thus, to represent 2 , we need one leading zero
76 * in the fraction; to represent 2 , we need two, and so on. This
78 * (-exp_bias-fracbits+1)
79 * implies that the smallest denormalized number is 2
81 * for whichever format we are talking about: for single precision, for
84 * instance, we get .00000000000000000000001 x 2 , or 1.0 x 2 , and
86 * -149 == -127 - 23 + 1.
89 #define SNG_FRACBITS 23
91 #define DBL_EXPBITS 11
92 #define DBL_FRACBITS 52
95 #if _BYTE_ORDER == _BIG_ENDIAN
107 #if _BYTE_ORDER == _BIG_ENDIAN
121 * Floats whose exponent is in [1..INFNAN) (of whatever type) are
122 * `normal'. Floats whose exponent is INFNAN are either Inf or NaN.
123 * Floats whose exponent is zero are either zero (iff all fraction
124 * bits are zero) or subnormal values.
126 * A NaN is a `signalling NaN' if its QUIETNAN bit is clear in its
127 * high fraction; if the bit is set, it is a `quiet NaN'.
129 #define SNG_EXP_INFNAN 255
130 #define DBL_EXP_INFNAN 2047
133 #define SNG_QUIETNAN (1 << 22)
134 #define DBL_QUIETNAN (1 << 19)
140 #define SNG_EXP_BIAS 127
141 #define DBL_EXP_BIAS 1023
144 * Convenience data structures.
146 union ieee_single_u {
148 struct ieee_single sngu_sng;
151 union ieee_double_u {
153 struct ieee_double dblu_dbl;