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64 lines
1.4 KiB
64 lines
1.4 KiB
7 months ago
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/*
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* Single-precision cos function.
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*
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* Copyright (c) 2018-2019, Arm Limited.
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* SPDX-License-Identifier: MIT
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*/
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#include <stdint.h>
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#include <math.h>
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#include "math_config.h"
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#include "sincosf.h"
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/* Fast cosf implementation. Worst-case ULP is 0.5607, maximum relative
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error is 0.5303 * 2^-23. A single-step range reduction is used for
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small values. Large inputs have their range reduced using fast integer
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arithmetic. */
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float
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cosf (float y)
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{
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double x = y;
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double s;
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int n;
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const sincos_t *p = &__sincosf_table[0];
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if (abstop12 (y) < abstop12 (pio4))
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{
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double x2 = x * x;
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if (unlikely (abstop12 (y) < abstop12 (0x1p-12f)))
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return 1.0f;
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return sinf_poly (x, x2, p, 1);
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}
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else if (likely (abstop12 (y) < abstop12 (120.0f)))
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{
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x = reduce_fast (x, p, &n);
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/* Setup the signs for sin and cos. */
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s = p->sign[n & 3];
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if (n & 2)
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p = &__sincosf_table[1];
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return sinf_poly (x * s, x * x, p, n ^ 1);
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}
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else if (abstop12 (y) < abstop12 (INFINITY))
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{
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uint32_t xi = asuint (y);
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int sign = xi >> 31;
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x = reduce_large (xi, &n);
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/* Setup signs for sin and cos - include original sign. */
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s = p->sign[(n + sign) & 3];
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if ((n + sign) & 2)
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p = &__sincosf_table[1];
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return sinf_poly (x * s, x * x, p, n ^ 1);
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}
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else
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return __math_invalidf (y);
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}
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