1 /*
2  * Common Float Helpers
3  *
4  * This contains a series of useful utility routines and a set of
5  * floating point constants useful for exercising the edge cases in
6  * floating point tests.
7  *
8  * Copyright (c) 2019, 2024 Linaro
9  *
10  * SPDX-License-Identifier: GPL-2.0-or-later
11  */
12 
13 /* we want additional float type definitions */
14 #define __STDC_WANT_IEC_60559_BFP_EXT__
15 #define __STDC_WANT_IEC_60559_TYPES_EXT__
16 
17 #define _GNU_SOURCE
18 #include <stdio.h>
19 #include <stdlib.h>
20 #include <inttypes.h>
21 #include <math.h>
22 #include <float.h>
23 #include <fenv.h>
24 
25 #include "../float_helpers.h"
26 
27 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
28 
29 /*
30  * Half Precision Numbers
31  *
32  * Not yet well standardised so we return a plain uint16_t for now.
33  */
34 
35 /* no handy defines for these numbers */
36 static uint16_t f16_numbers[] = {
37     0xffff, /* -NaN / AHP -Max */
38     0xfcff, /* -NaN / AHP */
39     0xfc01, /* -NaN / AHP */
40     0xfc00, /* -Inf */
41     0xfbff, /* -Max */
42     0xc000, /* -2 */
43     0xbc00, /* -1 */
44     0x8001, /* -MIN subnormal */
45     0x8000, /* -0 */
46     0x0000, /* +0 */
47     0x0001, /* MIN subnormal */
48     0x3c00, /* 1 */
49     0x7bff, /* Max */
50     0x7c00, /* Inf */
51     0x7c01, /* NaN / AHP */
52     0x7cff, /* NaN / AHP */
53     0x7fff, /* NaN / AHP +Max*/
54 };
55 
56 static const int num_f16 = ARRAY_SIZE(f16_numbers);
57 
58 int get_num_f16(void)
59 {
60     return num_f16;
61 }
62 
63 uint16_t get_f16(int i)
64 {
65     return f16_numbers[i % num_f16];
66 }
67 
68 /* only display as hex */
69 char *fmt_16(uint16_t num)
70 {
71     char *fmt;
72     asprintf(&fmt, "f16(%#04x)", num);
73     return fmt;
74 }
75 
76 /*
77  * Single Precision Numbers
78  */
79 
80 #ifndef SNANF
81 /* Signaling NaN macros, if supported.  */
82 #  define SNANF (__builtin_nansf (""))
83 #  define SNAN (__builtin_nans (""))
84 #  define SNANL (__builtin_nansl (""))
85 #endif
86 
87 static float f32_numbers[] = {
88     -SNANF,
89     -NAN,
90     -INFINITY,
91     -FLT_MAX,
92     -0x1.1874b2p+103,
93     -0x1.c0bab6p+99,
94     -0x1.31f75p-40,
95     -0x1.505444p-66,
96     -FLT_MIN,
97     0.0,
98     FLT_MIN,
99     0x1p-25,
100     0x1.ffffe6p-25, /* min positive FP16 subnormal */
101     0x1.ff801ap-15, /* max subnormal FP16 */
102     0x1.00000cp-14, /* min positive normal FP16 */
103     1.0,
104     0x1.004p+0, /* smallest float after 1.0 FP16 */
105     2.0,
106     M_E, M_PI,
107     0x1.ffbep+15,
108     0x1.ffcp+15, /* max FP16 */
109     0x1.ffc2p+15,
110     0x1.ffbfp+16,
111     0x1.ffcp+16, /* max AFP */
112     0x1.ffc1p+16,
113     0x1.c0bab6p+99,
114     FLT_MAX,
115     INFINITY,
116     NAN,
117     SNANF
118 };
119 
120 static const int num_f32 = ARRAY_SIZE(f32_numbers);
121 
122 int get_num_f32(void)
123 {
124     return num_f32;
125 }
126 
127 float get_f32(int i)
128 {
129     return f32_numbers[i % num_f32];
130 }
131 
132 char *fmt_f32(float num)
133 {
134     uint32_t single_as_hex = *(uint32_t *) &num;
135     char *fmt;
136     asprintf(&fmt, "f32(%02.20a:%#010x)", num, single_as_hex);
137     return fmt;
138 }
139 
140 
141 /* This allows us to initialise some doubles as pure hex */
142 typedef union {
143     double d;
144     uint64_t h;
145 } test_doubles;
146 
147 static test_doubles f64_numbers[] = {
148     {SNAN},
149     {-NAN},
150     {-INFINITY},
151     {-DBL_MAX},
152     {-FLT_MAX-1.0},
153     {-FLT_MAX},
154     {-1.111E+31},
155     {-1.111E+30}, /* half prec */
156     {-2.0}, {-1.0},
157     {-DBL_MIN},
158     {-FLT_MIN},
159     {0.0},
160     {FLT_MIN},
161     {2.98023224e-08},
162     {5.96046E-8}, /* min positive FP16 subnormal */
163     {6.09756E-5}, /* max subnormal FP16 */
164     {6.10352E-5}, /* min positive normal FP16 */
165     {1.0},
166     {1.0009765625}, /* smallest float after 1.0 FP16 */
167     {DBL_MIN},
168     {1.3789972848607228e-308},
169     {1.4914738736681624e-308},
170     {1.0}, {2.0},
171     {M_E}, {M_PI},
172     {65503.0},
173     {65504.0}, /* max FP16 */
174     {65505.0},
175     {131007.0},
176     {131008.0}, /* max AFP */
177     {131009.0},
178     {.h = 0x41dfffffffc00000 }, /* to int = 0x7fffffff */
179     {FLT_MAX},
180     {FLT_MAX + 1.0},
181     {DBL_MAX},
182     {INFINITY},
183     {NAN},
184     {.h = 0x7ff0000000000001}, /* SNAN */
185     {SNAN},
186 };
187 
188 static const int num_f64 = ARRAY_SIZE(f64_numbers);
189 
190 int get_num_f64(void)
191 {
192     return num_f64;
193 }
194 
195 double get_f64(int i)
196 {
197     return f64_numbers[i % num_f64].d;
198 }
199 
200 char *fmt_f64(double num)
201 {
202     uint64_t double_as_hex = *(uint64_t *) &num;
203     char *fmt;
204     asprintf(&fmt, "f64(%02.20a:%#020" PRIx64 ")", num, double_as_hex);
205     return fmt;
206 }
207 
208 /*
209  * Float flags
210  */
211 char *fmt_flags(void)
212 {
213     int flags = fetestexcept(FE_ALL_EXCEPT);
214     char *fmt;
215 
216     if (flags) {
217         asprintf(&fmt, "%s%s%s%s%s",
218                  flags & FE_OVERFLOW ? "OVERFLOW " : "",
219                  flags & FE_UNDERFLOW ? "UNDERFLOW " : "",
220                  flags & FE_DIVBYZERO ? "DIV0 " : "",
221                  flags & FE_INEXACT ? "INEXACT " : "",
222                  flags & FE_INVALID ? "INVALID" : "");
223     } else {
224         asprintf(&fmt, "OK");
225     }
226 
227     return fmt;
228 }
229