1 //===-- Single-precision cos function -------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #include "math_utils.h"
10 #include "sincosf_utils.h"
11
12 #include "src/__support/common.h"
13 #include <math.h>
14
15 #include <stdint.h>
16
17 namespace __llvm_libc {
18
19 // Fast cosf implementation. Worst-case ULP is 0.5607, maximum relative
20 // error is 0.5303 * 2^-23. A single-step range reduction is used for
21 // small values. Large inputs have their range reduced using fast integer
22 // arithmetic.
LLVM_LIBC_ENTRYPOINT(cosf)23 float LLVM_LIBC_ENTRYPOINT(cosf)(float y) {
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 double x2 = x * x;
31
32 if (unlikely(abstop12(y) < abstop12(as_float(0x39800000))))
33 return 1.0f;
34
35 return sinf_poly(x, x2, p, 1);
36 } else if (likely(abstop12(y) < abstop12(120.0f))) {
37 x = reduce_fast(x, p, &n);
38
39 // Setup the signs for sin and cos.
40 s = p->sign[n & 3];
41
42 if (n & 2)
43 p = &__sincosf_table[1];
44
45 return sinf_poly(x * s, x * x, p, n ^ 1);
46 } else if (abstop12(y) < abstop12(INFINITY)) {
47 uint32_t xi = as_uint32_bits(y);
48 int sign = xi >> 31;
49
50 x = reduce_large(xi, &n);
51
52 // Setup signs for sin and cos - include original sign.
53 s = p->sign[(n + sign) & 3];
54
55 if ((n + sign) & 2)
56 p = &__sincosf_table[1];
57
58 return sinf_poly(x * s, x * x, p, n ^ 1);
59 }
60
61 return invalid(y);
62 }
63
64 } // namespace __llvm_libc
65