1 /* 2 * Single-precision cos function. 3 * 4 * Copyright (c) 2018-2024, 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 #include "test_defs.h" 13 #include "test_sig.h" 14 15 /* Fast cosf implementation. Worst-case ULP is 0.5607, maximum relative 16 error is 0.5303 * 2^-23. A single-step range reduction is used for 17 small values. Large inputs have their range reduced using fast integer 18 arithmetic. */ 19 float 20 cosf (float y) 21 { 22 double x = y; 23 double s; 24 int n; 25 const sincos_t *p = &__sincosf_table[0]; 26 27 if (abstop12 (y) < abstop12 (pio4f)) 28 { 29 double x2 = x * x; 30 31 if (unlikely (abstop12 (y) < abstop12 (0x1p-12f))) 32 return 1.0f; 33 34 return sinf_poly (x, x2, p, 1); 35 } 36 else if (likely (abstop12 (y) < abstop12 (120.0f))) 37 { 38 x = reduce_fast (x, p, &n); 39 40 /* Setup the signs for sin and cos. */ 41 s = p->sign[n & 3]; 42 43 if (n & 2) 44 p = &__sincosf_table[1]; 45 46 return sinf_poly (x * s, x * x, p, n ^ 1); 47 } 48 else if (abstop12 (y) < abstop12 (INFINITY)) 49 { 50 uint32_t xi = asuint (y); 51 int sign = xi >> 31; 52 53 x = reduce_large (xi, &n); 54 55 /* Setup signs for sin and cos - include original sign. */ 56 s = p->sign[(n + sign) & 3]; 57 58 if ((n + sign) & 2) 59 p = &__sincosf_table[1]; 60 61 return sinf_poly (x * s, x * x, p, n ^ 1); 62 } 63 else 64 return __math_invalidf (y); 65 } 66 67 TEST_SIG (S, F, 1, cos, -3.1, 3.1) 68 TEST_ULP (cosf, 0.06) 69 TEST_ULP_NONNEAREST (cosf, 0.5) 70 TEST_INTERVAL (cosf, 0, 0xffff0000, 10000) 71 TEST_SYM_INTERVAL (cosf, 0x1p-14, 0x1p54, 50000) 72