1 /*
2 * Single-precision vector cos function.
3 *
4 * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 * See https://llvm.org/LICENSE.txt for license information.
6 * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 */
8
9 #include "mathlib.h"
10 #include "v_math.h"
11 #if V_SUPPORTED
12
13 static const float Poly[] = {
14 /* 1.886 ulp error */
15 0x1.5b2e76p-19f,
16 -0x1.9f42eap-13f,
17 0x1.110df4p-7f,
18 -0x1.555548p-3f,
19 };
20 #define Pi1 v_f32 (0x1.921fb6p+1f)
21 #define Pi2 v_f32 (-0x1.777a5cp-24f)
22 #define Pi3 v_f32 (-0x1.ee59dap-49f)
23 #define A3 v_f32 (Poly[3])
24 #define A5 v_f32 (Poly[2])
25 #define A7 v_f32 (Poly[1])
26 #define A9 v_f32 (Poly[0])
27 #define RangeVal v_f32 (0x1p20f)
28 #define InvPi v_f32 (0x1.45f306p-2f)
29 #define Shift v_f32 (0x1.8p+23f)
30 #define AbsMask v_u32 (0x7fffffff)
31 #define HalfPi v_f32 (0x1.921fb6p0f)
32
33 VPCS_ATTR
34 static v_f32_t
specialcase(v_f32_t x,v_f32_t y,v_u32_t cmp)35 specialcase (v_f32_t x, v_f32_t y, v_u32_t cmp)
36 {
37 /* Fall back to scalar code. */
38 return v_call_f32 (cosf, x, y, cmp);
39 }
40
41 VPCS_ATTR
42 v_f32_t
V_NAME(cosf)43 V_NAME(cosf) (v_f32_t x)
44 {
45 v_f32_t n, r, r2, y;
46 v_u32_t odd, cmp;
47
48 r = v_as_f32_u32 (v_as_u32_f32 (x) & AbsMask);
49 cmp = v_cond_u32 (v_as_u32_f32 (r) >= v_as_u32_f32 (RangeVal));
50
51 /* n = rint((|x|+pi/2)/pi) - 0.5 */
52 n = v_fma_f32 (InvPi, r + HalfPi, Shift);
53 odd = v_as_u32_f32 (n) << 31;
54 n -= Shift;
55 n -= v_f32 (0.5f);
56
57 /* r = |x| - n*pi (range reduction into -pi/2 .. pi/2) */
58 r = v_fma_f32 (-Pi1, n, r);
59 r = v_fma_f32 (-Pi2, n, r);
60 r = v_fma_f32 (-Pi3, n, r);
61
62 /* y = sin(r) */
63 r2 = r * r;
64 y = v_fma_f32 (A9, r2, A7);
65 y = v_fma_f32 (y, r2, A5);
66 y = v_fma_f32 (y, r2, A3);
67 y = v_fma_f32 (y * r2, r, r);
68
69 /* sign fix */
70 y = v_as_f32_u32 (v_as_u32_f32 (y) ^ odd);
71
72 if (unlikely (v_any_u32 (cmp)))
73 return specialcase (x, y, cmp);
74 return y;
75 }
76 VPCS_ALIAS
77 #endif
78