1 /* Configuration for math routines.
2 Copyright (C) 2017-2023 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. */
50 static inline double_t
51 roundtoint (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. */
56 static inline int32_t
57 converttoint (double_t x);
58 #endif
59
60 static inline uint32_t
61 asuint (float f)
62 {
63 union
64 {
65 float f;
66 uint32_t i;
67 } u = {f};
68 return u.i;
69 }
70
71 static inline float
72 asfloat (uint32_t i)
73 {
74 union
75 {
76 uint32_t i;
77 float f;
78 } u = {i};
79 return u.f;
80 }
81
82 static inline uint64_t
83 asuint64 (double f)
84 {
85 union
86 {
87 double f;
88 uint64_t i;
89 } u = {f};
90 return u.i;
91 }
92
93 static inline double
94 asdouble (uint64_t i)
95 {
96 union
97 {
98 uint64_t i;
99 double f;
100 } u = {i};
101 return u.f;
102 }
103
104 static inline int
105 issignalingf_inline (float x)
106 {
107 uint32_t ix = asuint (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
122 static inline bool
123 is_nan (uint32_t x)
124 {
125 return (x & EXP_MANT_MASK) > EXPONENT_MASK;
126 }
127
128 static inline uint32_t
129 get_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. */
139 static inline double
140 make_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 (s + x + (ep << MANTISSA_WIDTH));
152 }
153
154 attribute_hidden float __math_oflowf (uint32_t);
155 attribute_hidden float __math_uflowf (uint32_t);
156 attribute_hidden float __math_may_uflowf (uint32_t);
157 attribute_hidden float __math_divzerof (uint32_t);
158 attribute_hidden float __math_invalidf (float);
159 attribute_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
164 extern 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
176 extern 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
188 extern 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))
205 extern 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