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/*
* Single-precision vector cos function.
*
* Copyright (c) 2019-2023, Arm Limited.
* SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
*/
#include "mathlib.h"
#include "v_math.h"
static const struct data
{
float32x4_t poly[4];
float32x4_t range_val, inv_pi, half_pi, shift, pi_1, pi_2, pi_3;
} data = {
/* 1.886 ulp error. */
.poly = { V4 (-0x1.555548p-3f), V4 (0x1.110df4p-7f), V4 (-0x1.9f42eap-13f),
V4 (0x1.5b2e76p-19f) },
.pi_1 = V4 (0x1.921fb6p+1f),
.pi_2 = V4 (-0x1.777a5cp-24f),
.pi_3 = V4 (-0x1.ee59dap-49f),
.inv_pi = V4 (0x1.45f306p-2f),
.shift = V4 (0x1.8p+23f),
.half_pi = V4 (0x1.921fb6p0f),
.range_val = V4 (0x1p20f)
};
#define C(i) d->poly[i]
static float32x4_t VPCS_ATTR NOINLINE
special_case (float32x4_t x, float32x4_t y, uint32x4_t odd, uint32x4_t cmp)
{
/* Fall back to scalar code. */
y = vreinterpretq_f32_u32 (veorq_u32 (vreinterpretq_u32_f32 (y), odd));
return v_call_f32 (cosf, x, y, cmp);
}
float32x4_t VPCS_ATTR V_NAME_F1 (cos) (float32x4_t x)
{
const struct data *d = ptr_barrier (&data);
float32x4_t n, r, r2, r3, y;
uint32x4_t odd, cmp;
#if WANT_SIMD_EXCEPT
r = vabsq_f32 (x);
cmp = vcgeq_u32 (vreinterpretq_u32_f32 (r),
vreinterpretq_u32_f32 (d->range_val));
if (unlikely (v_any_u32 (cmp)))
/* If fenv exceptions are to be triggered correctly, set any special lanes
to 1 (which is neutral w.r.t. fenv). These lanes will be fixed by
special-case handler later. */
r = vbslq_f32 (cmp, v_f32 (1.0f), r);
#else
cmp = vcageq_f32 (x, d->range_val);
r = x;
#endif
/* n = rint((|x|+pi/2)/pi) - 0.5. */
n = vfmaq_f32 (d->shift, d->inv_pi, vaddq_f32 (r, d->half_pi));
odd = vshlq_n_u32 (vreinterpretq_u32_f32 (n), 31);
n = vsubq_f32 (n, d->shift);
n = vsubq_f32 (n, v_f32 (0.5f));
/* r = |x| - n*pi (range reduction into -pi/2 .. pi/2). */
r = vfmsq_f32 (r, d->pi_1, n);
r = vfmsq_f32 (r, d->pi_2, n);
r = vfmsq_f32 (r, d->pi_3, n);
/* y = sin(r). */
r2 = vmulq_f32 (r, r);
r3 = vmulq_f32 (r2, r);
y = vfmaq_f32 (C (2), C (3), r2);
y = vfmaq_f32 (C (1), y, r2);
y = vfmaq_f32 (C (0), y, r2);
y = vfmaq_f32 (r, y, r3);
if (unlikely (v_any_u32 (cmp)))
return special_case (x, y, odd, cmp);
return vreinterpretq_f32_u32 (veorq_u32 (vreinterpretq_u32_f32 (y), odd));
}
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