1 /* 2 * Single-precision cos function. 3 * 4 * Copyright (c) 2018-2021, Arm Limited. 5 * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception 6 */ 7 8 #include <stdint.h> 9 #include <math.h> 10 #include "math_config.h" 11 #include "sincosf.h" 12 13 /* Fast cosf implementation. Worst-case ULP is 0.5607, maximum relative 14 error is 0.5303 * 2^-23. A single-step range reduction is used for 15 small values. Large inputs have their range reduced using fast integer 16 arithmetic. */ 17 float 18 cosf (float y) 19 { 20 double x = y; 21 double s; 22 int n; 23 const sincos_t *p = &__sincosf_table[0]; 24 25 if (abstop12 (y) < abstop12 (pio4f)) 26 { 27 double x2 = x * x; 28 29 if (unlikely (abstop12 (y) < abstop12 (0x1p-12f))) 30 return 1.0f; 31 32 return sinf_poly (x, x2, p, 1); 33 } 34 else if (likely (abstop12 (y) < abstop12 (120.0f))) 35 { 36 x = reduce_fast (x, p, &n); 37 38 /* Setup the signs for sin and cos. */ 39 s = p->sign[n & 3]; 40 41 if (n & 2) 42 p = &__sincosf_table[1]; 43 44 return sinf_poly (x * s, x * x, p, n ^ 1); 45 } 46 else if (abstop12 (y) < abstop12 (INFINITY)) 47 { 48 uint32_t xi = asuint (y); 49 int sign = xi >> 31; 50 51 x = reduce_large (xi, &n); 52 53 /* Setup signs for sin and cos - include original sign. */ 54 s = p->sign[(n + sign) & 3]; 55 56 if ((n + sign) & 2) 57 p = &__sincosf_table[1]; 58 59 return sinf_poly (x * s, x * x, p, n ^ 1); 60 } 61 else 62 return __math_invalidf (y); 63 } 64