1 /*
2 * Single-precision SVE sinpi(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
14 static const struct data
15 {
16 float poly[6];
17 } data = {
18 /* Taylor series coefficents for sin(pi * x). */
19 .poly = { 0x1.921fb6p1f, -0x1.4abbcep2f, 0x1.466bc6p1f, -0x1.32d2ccp-1f,
20 0x1.50783p-4f, -0x1.e30750p-8f },
21 };
22
23 /* A fast SVE implementation of sinpif.
24 Maximum error 2.48 ULP:
25 _ZGVsMxv_sinpif(0x1.d062b6p-2) got 0x1.fa8c06p-1
26 want 0x1.fa8c02p-1. */
SV_NAME_F1(sinpi)27 svfloat32_t SV_NAME_F1 (sinpi) (svfloat32_t x, const svbool_t pg)
28 {
29 const struct data *d = ptr_barrier (&data);
30
31 /* range reduction into -1/2 .. 1/2
32 with n = rint(x) and r = r - n. */
33 svfloat32_t n = svrinta_x (pg, x);
34 svfloat32_t r = svsub_x (pg, x, n);
35
36 /* Result should be negated based on if n is odd or not. */
37 svuint32_t intn = svreinterpret_u32 (svcvt_s32_x (pg, n));
38 svuint32_t sign = svlsl_z (pg, intn, 31);
39
40 /* y = sin(r). */
41 svfloat32_t r2 = svmul_x (pg, r, r);
42 svfloat32_t y = sv_horner_5_f32_x (pg, r2, d->poly);
43 y = svmul_x (pg, y, r);
44
45 return svreinterpret_f32 (sveor_x (pg, svreinterpret_u32 (y), sign));
46 }
47
48 PL_SIG (SV, F, 1, sinpi, -0.9, 0.9)
49 PL_TEST_ULP (SV_NAME_F1 (sinpi), 1.99)
50 PL_TEST_SYM_INTERVAL (SV_NAME_F1 (sinpi), 0, 0x1p-31, 5000)
51 PL_TEST_SYM_INTERVAL (SV_NAME_F1 (sinpi), 0x1p-31, 0.5, 10000)
52 PL_TEST_SYM_INTERVAL (SV_NAME_F1 (sinpi), 0.5, 0x1p22f, 10000)
53 PL_TEST_SYM_INTERVAL (SV_NAME_F1 (sinpi), 0x1p22f, inf, 10000)
54