1/* Configuration for math routines.
2 Copyright (C) 2017-2024 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#ifndef _MATH_CONFIG_H
20#define _MATH_CONFIG_H
21
22#include <math.h>
23#include <math_private.h>
24#include <nan-high-order-bit.h>
25#include <stdint.h>
26
27#ifndef WANT_ROUNDING
28/* Correct special case results in non-nearest rounding modes. */
29# define WANT_ROUNDING 1
30#endif
31#ifndef WANT_ERRNO
32/* Set errno according to ISO C with (math_errhandling & MATH_ERRNO) != 0. */
33# define WANT_ERRNO 1
34#endif
35#ifndef WANT_ERRNO_UFLOW
36/* Set errno to ERANGE if result underflows to 0 (in all rounding modes). */
37# define WANT_ERRNO_UFLOW (WANT_ROUNDING && WANT_ERRNO)
38#endif
39
40#ifndef TOINT_INTRINSICS
41/* When set, the roundtoint and converttoint functions are provided with
42 the semantics documented below. */
43# define TOINT_INTRINSICS 0
44#endif
45
46#if TOINT_INTRINSICS
47/* Round x to nearest int in all rounding modes, ties have to be rounded
48 consistently with converttoint so the results match. If the result
49 would be outside of [-2^31, 2^31-1] then the semantics is unspecified. */
50static inline double_t
51roundtoint (double_t x);
52
53/* Convert x to nearest int in all rounding modes, ties have to be rounded
54 consistently with roundtoint. If the result is not representible in an
55 int32_t then the semantics is unspecified. */
56static inline int32_t
57converttoint (double_t x);
58#endif
59
60static inline uint32_t
61asuint (float f)
62{
63 union
64 {
65 float f;
66 uint32_t i;
67 } u = {f};
68 return u.i;
69}
70
71static inline float
72asfloat (uint32_t i)
73{
74 union
75 {
76 uint32_t i;
77 float f;
78 } u = {.i: i};
79 return u.f;
80}
81
82static inline uint64_t
83asuint64 (double f)
84{
85 union
86 {
87 double f;
88 uint64_t i;
89 } u = {f};
90 return u.i;
91}
92
93static inline double
94asdouble (uint64_t i)
95{
96 union
97 {
98 uint64_t i;
99 double f;
100 } u = {.i: i};
101 return u.f;
102}
103
104static inline int
105issignalingf_inline (float x)
106{
107 uint32_t ix = asuint (f: x);
108 if (HIGH_ORDER_BIT_IS_SET_FOR_SNAN)
109 return (ix & 0x7fc00000) == 0x7fc00000;
110 return 2 * (ix ^ 0x00400000) > 2 * 0x7fc00000UL;
111}
112
113#define BIT_WIDTH 32
114#define MANTISSA_WIDTH 23
115#define EXPONENT_WIDTH 8
116#define MANTISSA_MASK 0x007fffff
117#define EXPONENT_MASK 0x7f800000
118#define EXP_MANT_MASK 0x7fffffff
119#define QUIET_NAN_MASK 0x00400000
120#define SIGN_MASK 0x80000000
121
122static inline bool
123is_nan (uint32_t x)
124{
125 return (x & EXP_MANT_MASK) > EXPONENT_MASK;
126}
127
128static inline uint32_t
129get_mantissa (uint32_t x)
130{
131 return x & MANTISSA_MASK;
132}
133
134/* Convert integer number X, unbiased exponent EP, and sign S to double:
135
136 result = X * 2^(EP+1 - exponent_bias)
137
138 NB: zero is not supported. */
139static inline double
140make_float (uint32_t x, int ep, uint32_t s)
141{
142 int lz = __builtin_clz (x) - EXPONENT_WIDTH;
143 x <<= lz;
144 ep -= lz;
145
146 if (__glibc_unlikely (ep < 0 || x == 0))
147 {
148 x >>= -ep;
149 ep = 0;
150 }
151 return asfloat (i: s + x + (ep << MANTISSA_WIDTH));
152}
153
154attribute_hidden float __math_oflowf (uint32_t);
155attribute_hidden float __math_uflowf (uint32_t);
156attribute_hidden float __math_may_uflowf (uint32_t);
157attribute_hidden float __math_divzerof (uint32_t);
158attribute_hidden float __math_invalidf (float);
159attribute_hidden float __math_edomf (float x);
160
161/* Shared between expf, exp2f, exp10f, and powf. */
162#define EXP2F_TABLE_BITS 5
163#define EXP2F_POLY_ORDER 3
164extern const struct exp2f_data
165{
166 uint64_t tab[1 << EXP2F_TABLE_BITS];
167 double shift_scaled;
168 double poly[EXP2F_POLY_ORDER];
169 double shift;
170 double invln2_scaled;
171 double poly_scaled[EXP2F_POLY_ORDER];
172} __exp2f_data attribute_hidden;
173
174#define LOGF_TABLE_BITS 4
175#define LOGF_POLY_ORDER 4
176extern const struct logf_data
177{
178 struct
179 {
180 double invc, logc;
181 } tab[1 << LOGF_TABLE_BITS];
182 double ln2;
183 double poly[LOGF_POLY_ORDER - 1]; /* First order coefficient is 1. */
184} __logf_data attribute_hidden;
185
186#define LOG2F_TABLE_BITS 4
187#define LOG2F_POLY_ORDER 4
188extern const struct log2f_data
189{
190 struct
191 {
192 double invc, logc;
193 } tab[1 << LOG2F_TABLE_BITS];
194 double poly[LOG2F_POLY_ORDER];
195} __log2f_data attribute_hidden;
196
197#define POWF_LOG2_TABLE_BITS 4
198#define POWF_LOG2_POLY_ORDER 5
199#if TOINT_INTRINSICS
200# define POWF_SCALE_BITS EXP2F_TABLE_BITS
201#else
202# define POWF_SCALE_BITS 0
203#endif
204#define POWF_SCALE ((double) (1 << POWF_SCALE_BITS))
205extern const struct powf_log2_data
206{
207 struct
208 {
209 double invc, logc;
210 } tab[1 << POWF_LOG2_TABLE_BITS];
211 double poly[POWF_LOG2_POLY_ORDER];
212} __powf_log2_data attribute_hidden;
213
214#endif
215

source code of glibc/sysdeps/ieee754/flt-32/math_config.h