1 /*
2 * Single-precision cos function.
3 *
4 * Copyright (c) 2018, Arm Limited.
5 * SPDX-License-Identifier: MIT
6 */
7
8 #if WANT_SINGLEPREC
9 #include "single/s_cosf.c"
10 #else
11
12 #include <stdint.h>
13 #include <math.h>
14 #include "math_config.h"
15 #include "sincosf.h"
16
17 /* Fast cosf implementation. Worst-case ULP is 0.5607, maximum relative
18 error is 0.5303 * 2^-23. A single-step range reduction is used for
19 small values. Large inputs have their range reduced using fast integer
20 arithmetic. */
21 float
cosf(float y)22 cosf (float y)
23 {
24 double x = y;
25 double s;
26 int n;
27 const sincos_t *p = &__sincosf_table[0];
28
29 if (abstop12 (y) < abstop12 (pio4))
30 {
31 double x2 = x * x;
32
33 if (unlikely (abstop12 (y) < abstop12 (0x1p-12f)))
34 return 1.0f;
35
36 return sinf_poly (x, x2, p, 1);
37 }
38 else if (likely (abstop12 (y) < abstop12 (120.0f)))
39 {
40 x = reduce_fast (x, p, &n);
41
42 /* Setup the signs for sin and cos. */
43 s = p->sign[n & 3];
44
45 if (n & 2)
46 p = &__sincosf_table[1];
47
48 return sinf_poly (x * s, x * x, p, n ^ 1);
49 }
50 else if (abstop12 (y) < abstop12 (INFINITY))
51 {
52 uint32_t xi = asuint (y);
53 int sign = xi >> 31;
54
55 x = reduce_large (xi, &n);
56
57 /* Setup signs for sin and cos - include original sign. */
58 s = p->sign[(n + sign) & 3];
59
60 if ((n + sign) & 2)
61 p = &__sincosf_table[1];
62
63 return sinf_poly (x * s, x * x, p, n ^ 1);
64 }
65 else
66 return __math_invalidf (y);
67 }
68
69 #endif
70