1 /* 2 * Single-precision vector cos function. 3 * 4 * Copyright (c) 2019, Arm Limited. 5 * SPDX-License-Identifier: MIT 6 */ 7 8 #include "mathlib.h" 9 #include "v_math.h" 10 #if V_SUPPORTED 11 12 static const float Poly[] = { 13 /* 1.886 ulp error */ 14 0x1.5b2e76p-19f, 15 -0x1.9f42eap-13f, 16 0x1.110df4p-7f, 17 -0x1.555548p-3f, 18 }; 19 #define Pi1 v_f32 (0x1.921fb6p+1f) 20 #define Pi2 v_f32 (-0x1.777a5cp-24f) 21 #define Pi3 v_f32 (-0x1.ee59dap-49f) 22 #define A3 v_f32 (Poly[3]) 23 #define A5 v_f32 (Poly[2]) 24 #define A7 v_f32 (Poly[1]) 25 #define A9 v_f32 (Poly[0]) 26 #define RangeVal v_f32 (0x1p20f) 27 #define InvPi v_f32 (0x1.45f306p-2f) 28 #define Shift v_f32 (0x1.8p+23f) 29 #define AbsMask v_u32 (0x7fffffff) 30 #define HalfPi v_f32 (0x1.921fb6p0f) 31 32 VPCS_ATTR 33 static v_f32_t 34 specialcase (v_f32_t x, v_f32_t y, v_u32_t cmp) 35 { 36 /* Fall back to scalar code. */ 37 return v_call_f32 (cosf, x, y, cmp); 38 } 39 40 VPCS_ATTR 41 v_f32_t 42 V_NAME(cosf) (v_f32_t x) 43 { 44 v_f32_t n, r, r2, y; 45 v_u32_t odd, cmp; 46 47 r = v_as_f32_u32 (v_as_u32_f32 (x) & AbsMask); 48 cmp = v_cond_u32 (v_as_u32_f32 (r) >= v_as_u32_f32 (RangeVal)); 49 50 /* n = rint((|x|+pi/2)/pi) - 0.5 */ 51 n = v_fma_f32 (InvPi, r + HalfPi, Shift); 52 odd = v_as_u32_f32 (n) << 31; 53 n -= Shift; 54 n -= v_f32 (0.5f); 55 56 /* r = |x| - n*pi (range reduction into -pi/2 .. pi/2) */ 57 r = v_fma_f32 (-Pi1, n, r); 58 r = v_fma_f32 (-Pi2, n, r); 59 r = v_fma_f32 (-Pi3, n, r); 60 61 /* y = sin(r) */ 62 r2 = r * r; 63 y = v_fma_f32 (A9, r2, A7); 64 y = v_fma_f32 (y, r2, A5); 65 y = v_fma_f32 (y, r2, A3); 66 y = v_fma_f32 (y * r2, r, r); 67 68 /* sign fix */ 69 y = v_as_f32_u32 (v_as_u32_f32 (y) ^ odd); 70 71 if (unlikely (v_any_u32 (cmp))) 72 return specialcase (x, y, cmp); 73 return y; 74 } 75 VPCS_ALIAS 76 #endif 77