xref: /freebsd/contrib/arm-optimized-routines/pl/math/sv_sinpif_2u5.c (revision f126890ac5386406dadf7c4cfa9566cbb56537c5)
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.  */
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