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/*
* Single-precision vector cos function.
*
* Copyright (c) 2019, Arm Limited.
* SPDX-License-Identifier: MIT
*/
#include "mathlib.h"
#include "v_math.h"
#if V_SUPPORTED
static const float Poly[] = {
/* 1.886 ulp error */
0x1.5b2e76p-19f,
-0x1.9f42eap-13f,
0x1.110df4p-7f,
-0x1.555548p-3f,
};
#define Pi1 v_f32 (0x1.921fb6p+1f)
#define Pi2 v_f32 (-0x1.777a5cp-24f)
#define Pi3 v_f32 (-0x1.ee59dap-49f)
#define A3 v_f32 (Poly[3])
#define A5 v_f32 (Poly[2])
#define A7 v_f32 (Poly[1])
#define A9 v_f32 (Poly[0])
#define RangeVal v_f32 (0x1p20f)
#define InvPi v_f32 (0x1.45f306p-2f)
#define Shift v_f32 (0x1.8p+23f)
#define AbsMask v_u32 (0x7fffffff)
#define HalfPi v_f32 (0x1.921fb6p0f)
VPCS_ATTR
static v_f32_t
specialcase (v_f32_t x, v_f32_t y, v_u32_t cmp)
{
/* Fall back to scalar code. */
return v_call_f32 (cosf, x, y, cmp);
}
VPCS_ATTR
v_f32_t
V_NAME(cosf) (v_f32_t x)
{
v_f32_t n, r, r2, y;
v_u32_t odd, cmp;
r = v_as_f32_u32 (v_as_u32_f32 (x) & AbsMask);
cmp = v_cond_u32 (v_as_u32_f32 (r) >= v_as_u32_f32 (RangeVal));
/* n = rint((|x|+pi/2)/pi) - 0.5 */
n = v_fma_f32 (InvPi, r + HalfPi, Shift);
odd = v_as_u32_f32 (n) << 31;
n -= Shift;
n -= v_f32 (0.5f);
/* r = |x| - n*pi (range reduction into -pi/2 .. pi/2) */
r = v_fma_f32 (-Pi1, n, r);
r = v_fma_f32 (-Pi2, n, r);
r = v_fma_f32 (-Pi3, n, r);
/* y = sin(r) */
r2 = r * r;
y = v_fma_f32 (A9, r2, A7);
y = v_fma_f32 (y, r2, A5);
y = v_fma_f32 (y, r2, A3);
y = v_fma_f32 (y * r2, r, r);
/* sign fix */
y = v_as_f32_u32 (v_as_u32_f32 (y) ^ odd);
if (unlikely (v_any_u32 (cmp)))
return specialcase (x, y, cmp);
return y;
}
VPCS_ALIAS
#endif
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