85 lines
2.5 KiB
C
85 lines
2.5 KiB
C
/*
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* Single-precision SVE sin(x) function.
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*
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* Copyright (c) 2019-2023, Arm Limited.
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* SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
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*/
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#include "sv_math.h"
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#include "pl_sig.h"
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#include "pl_test.h"
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#if SV_SUPPORTED
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#define A3 (sv_f32 (__sv_sinf_data.coeffs[3]))
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#define A5 (sv_f32 (__sv_sinf_data.coeffs[2]))
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#define A7 (sv_f32 (__sv_sinf_data.coeffs[1]))
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#define A9 (sv_f32 (__sv_sinf_data.coeffs[0]))
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#define NegPi1 (sv_f32 (-0x1.921fb6p+1f))
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#define NegPi2 (sv_f32 (0x1.777a5cp-24f))
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#define NegPi3 (sv_f32 (0x1.ee59dap-49f))
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#define RangeVal (sv_f32 (0x1p20f))
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#define InvPi (sv_f32 (0x1.45f306p-2f))
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#define Shift (sv_f32 (0x1.8p+23f))
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#define AbsMask (0x7fffffff)
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static NOINLINE sv_f32_t
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__sv_sinf_specialcase (sv_f32_t x, sv_f32_t y, svbool_t cmp)
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{
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return sv_call_f32 (sinf, x, y, cmp);
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}
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/* A fast SVE implementation of sinf.
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Maximum error: 1.89 ULPs.
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This maximum error is achieved at multiple values in [-2^18, 2^18]
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but one example is:
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__sv_sinf(0x1.9247a4p+0) got 0x1.fffff6p-1 want 0x1.fffffap-1. */
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sv_f32_t
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__sv_sinf_x (sv_f32_t x, const svbool_t pg)
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{
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sv_f32_t n, r, r2, y;
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sv_u32_t sign, odd;
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svbool_t cmp;
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r = sv_as_f32_u32 (svand_n_u32_x (pg, sv_as_u32_f32 (x), AbsMask));
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sign = svand_n_u32_x (pg, sv_as_u32_f32 (x), ~AbsMask);
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cmp = svcmpge_u32 (pg, sv_as_u32_f32 (r), sv_as_u32_f32 (RangeVal));
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/* n = rint(|x|/pi). */
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n = sv_fma_f32_x (pg, InvPi, r, Shift);
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odd = svlsl_n_u32_x (pg, sv_as_u32_f32 (n), 31);
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n = svsub_f32_x (pg, n, Shift);
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/* r = |x| - n*pi (range reduction into -pi/2 .. pi/2). */
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r = sv_fma_f32_x (pg, NegPi1, n, r);
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r = sv_fma_f32_x (pg, NegPi2, n, r);
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r = sv_fma_f32_x (pg, NegPi3, n, r);
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/* sin(r) approx using a degree 9 polynomial from the Taylor series
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expansion. Note that only the odd terms of this are non-zero. */
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r2 = svmul_f32_x (pg, r, r);
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y = sv_fma_f32_x (pg, A9, r2, A7);
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y = sv_fma_f32_x (pg, y, r2, A5);
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y = sv_fma_f32_x (pg, y, r2, A3);
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y = sv_fma_f32_x (pg, svmul_f32_x (pg, y, r2), r, r);
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/* sign = y^sign^odd. */
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y = sv_as_f32_u32 (
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sveor_u32_x (pg, sv_as_u32_f32 (y), sveor_u32_x (pg, sign, odd)));
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/* No need to pass pg to specialcase here since cmp is a strict subset,
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guaranteed by the cmpge above. */
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if (unlikely (svptest_any (pg, cmp)))
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return __sv_sinf_specialcase (x, y, cmp);
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return y;
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}
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PL_ALIAS (__sv_sinf_x, _ZGVsMxv_sinf)
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PL_SIG (SV, F, 1, sin, -3.1, 3.1)
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PL_TEST_ULP (__sv_sinf, 1.40)
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PL_TEST_INTERVAL (__sv_sinf, 0, 0xffff0000, 10000)
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PL_TEST_INTERVAL (__sv_sinf, 0x1p-4, 0x1p4, 500000)
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#endif
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