1 /*
2 * Single-precision vector tanpif(x) function.
3 *
4 * Copyright (c) 2024, Arm Limited.
5 * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
6 */
7
8 #include "sv_math.h"
9 #include "test_defs.h"
10 #include "test_sig.h"
11
12 const static struct v_tanpif_data
13 {
14 float c0, c2, c4, c6;
15 float c1, c3, c5, c7;
16 } tanpif_data = {
17 /* Coefficients for tan(pi * x). */
18 .c0 = 0x1.921fb4p1f, .c1 = 0x1.4abbcep3f, .c2 = 0x1.466b8p5f,
19 .c3 = 0x1.461c72p7f, .c4 = 0x1.42e9d4p9f, .c5 = 0x1.69e2c4p11f,
20 .c6 = 0x1.e85558p11f, .c7 = 0x1.a52e08p16f,
21 };
22
23 /* Approximation for single-precision vector tanpif(x)
24 The maximum error is 3.34 ULP:
25 _ZGVsMxv_tanpif(0x1.d6c09ap-2) got 0x1.f70aacp+2
26 want 0x1.f70aa6p+2. */
SV_NAME_F1(tanpi)27 svfloat32_t SV_NAME_F1 (tanpi) (svfloat32_t x, const svbool_t pg)
28 {
29 const struct v_tanpif_data *d = ptr_barrier (&tanpif_data);
30 svfloat32_t odd_coeffs = svld1rq (pg, &d->c1);
31 svfloat32_t n = svrintn_x (pg, x);
32
33 /* inf produces nan that propagates. */
34 svfloat32_t xr = svsub_x (pg, x, n);
35 svfloat32_t ar = svabd_x (pg, x, n);
36 svbool_t flip = svcmpgt (pg, ar, 0.25f);
37 svfloat32_t r = svsel (flip, svsub_x (pg, sv_f32 (0.5f), ar), ar);
38
39 svfloat32_t r2 = svmul_x (pg, r, r);
40 svfloat32_t r4 = svmul_x (pg, r2, r2);
41
42 /* Order-7 Pairwise Horner. */
43 svfloat32_t p01 = svmla_lane (sv_f32 (d->c0), r2, odd_coeffs, 0);
44 svfloat32_t p23 = svmla_lane (sv_f32 (d->c2), r2, odd_coeffs, 1);
45 svfloat32_t p45 = svmla_lane (sv_f32 (d->c4), r2, odd_coeffs, 2);
46 svfloat32_t p67 = svmla_lane (sv_f32 (d->c6), r2, odd_coeffs, 3);
47 svfloat32_t p = svmad_x (pg, p67, r4, p45);
48 p = svmad_x (pg, p, r4, p23);
49 p = svmad_x (pg, p, r4, p01);
50 svfloat32_t poly = svmul_x (pg, r, p);
51
52 svfloat32_t poly_recip = svdiv_x (pg, sv_f32 (1.0), poly);
53 svfloat32_t y = svsel (flip, poly_recip, poly);
54
55 svuint32_t sign
56 = sveor_x (pg, svreinterpret_u32 (xr), svreinterpret_u32 (ar));
57 return svreinterpret_f32 (svorr_x (pg, svreinterpret_u32 (y), sign));
58 }
59
60 #if WANT_TRIGPI_TESTS
61 TEST_DISABLE_FENV (SV_NAME_F1 (tanpi))
62 TEST_ULP (SV_NAME_F1 (tanpi), 2.84)
63 TEST_SYM_INTERVAL (SV_NAME_F1 (tanpi), 0, 0x1p-31, 50000)
64 TEST_SYM_INTERVAL (SV_NAME_F1 (tanpi), 0x1p-31, 0.5, 100000)
65 TEST_SYM_INTERVAL (SV_NAME_F1 (tanpi), 0.5, 0x1p23f, 100000)
66 TEST_SYM_INTERVAL (SV_NAME_F1 (tanpi), 0x1p23f, inf, 100000)
67 #endif
68 CLOSE_SVE_ATTR
69