1/*
2 * Single-precision SVE cospi(x) function.
3 *
4 * Copyright (c) 2023, Arm Limited.
5 * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
6 */
7
8#include "mathlib.h"
9#include "sv_math.h"
10#include "pl_sig.h"
11#include "pl_test.h"
12#include "poly_sve_f32.h"
13
14static const struct data
15{
16  float poly[6];
17  float range_val;
18} data = {
19  /* Taylor series coefficents for sin(pi * x).  */
20  .poly = { 0x1.921fb6p1f, -0x1.4abbcep2f, 0x1.466bc6p1f, -0x1.32d2ccp-1f,
21	    0x1.50783p-4f, -0x1.e30750p-8f },
22  .range_val = 0x1p31f,
23};
24
25/* A fast SVE implementation of cospif.
26   Maximum error: 2.60 ULP:
27   _ZGVsMxv_cospif(+/-0x1.cae664p-4) got 0x1.e09c9ep-1
28				    want 0x1.e09c98p-1.  */
29svfloat32_t SV_NAME_F1 (cospi) (svfloat32_t x, const svbool_t pg)
30{
31  const struct data *d = ptr_barrier (&data);
32
33  /* Using cospi(x) = sinpi(0.5 - x)
34     range reduction and offset into sinpi range -1/2 .. 1/2
35     r = 0.5 - |x - rint(x)|.  */
36  svfloat32_t n = svrinta_x (pg, x);
37  svfloat32_t r = svsub_x (pg, x, n);
38  r = svsub_x (pg, sv_f32 (0.5f), svabs_x (pg, r));
39
40  /* Result should be negated based on if n is odd or not.
41     If ax >= 2^31, the result will always be positive.  */
42  svbool_t cmp = svaclt (pg, x, d->range_val);
43  svuint32_t intn = svreinterpret_u32 (svcvt_s32_x (pg, n));
44  svuint32_t sign = svlsl_z (cmp, intn, 31);
45
46  /* y = sin(r).  */
47  svfloat32_t r2 = svmul_x (pg, r, r);
48  svfloat32_t y = sv_horner_5_f32_x (pg, r2, d->poly);
49  y = svmul_x (pg, y, r);
50
51  return svreinterpret_f32 (sveor_x (pg, svreinterpret_u32 (y), sign));
52}
53
54PL_SIG (SV, F, 1, cospi, -0.9, 0.9)
55PL_TEST_ULP (SV_NAME_F1 (cospi), 2.08)
56PL_TEST_SYM_INTERVAL (SV_NAME_F1 (cospi), 0, 0x1p-31, 5000)
57PL_TEST_SYM_INTERVAL (SV_NAME_F1 (cospi), 0x1p-31, 0.5, 10000)
58PL_TEST_SYM_INTERVAL (SV_NAME_F1 (cospi), 0.5, 0x1p31f, 10000)
59PL_TEST_SYM_INTERVAL (SV_NAME_F1 (cospi), 0x1p31f, inf, 10000)
60