libc/AOR_v20.02/math/v_cosf.c

   1 /*
   2  * Single-precision vector cos function.
   3  *
   4  * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   5  * See https://llvm.org/LICENSE.txt for license information.
   6  * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   7  */
   8
   9 #include "mathlib.h"
  10 #include "v_math.h"
  11 #if V_SUPPORTED
  12
  13 static const float Poly[] = {
  14   /* 1.886 ulp error */
  15   0x1.5b2e76p-19f,
  16   -0x1.9f42eap-13f,
  17   0x1.110df4p-7f,
  18   -0x1.555548p-3f,
  19 };
  20 #define Pi1 v_f32 (0x1.921fb6p+1f)
  21 #define Pi2 v_f32 (-0x1.777a5cp-24f)
  22 #define Pi3 v_f32 (-0x1.ee59dap-49f)
  23 #define A3 v_f32 (Poly[3])
  24 #define A5 v_f32 (Poly[2])
  25 #define A7 v_f32 (Poly[1])
  26 #define A9 v_f32 (Poly[0])
  27 #define RangeVal v_f32 (0x1p20f)
  28 #define InvPi v_f32 (0x1.45f306p-2f)
  29 #define Shift v_f32 (0x1.8p+23f)
  30 #define AbsMask v_u32 (0x7fffffff)
  31 #define HalfPi v_f32 (0x1.921fb6p0f)
  32
  33 VPCS_ATTR
  34 static v_f32_t
  35 specialcase (v_f32_t x, v_f32_t y, v_u32_t cmp)
  36 {
  37   /* Fall back to scalar code.  */
  38   return v_call_f32 (cosf, x, y, cmp);
  39 }
  40
  41 VPCS_ATTR
  42 v_f32_t
  43 V_NAME(cosf) (v_f32_t x)
  44 {
  45   v_f32_t n, r, r2, y;
  46   v_u32_t odd, cmp;
  47
  48   r = v_as_f32_u32 (v_as_u32_f32 (x) & AbsMask);
  49   cmp = v_cond_u32 (v_as_u32_f32 (r) >= v_as_u32_f32 (RangeVal));
  50
  51   /* n = rint((|x|+pi/2)/pi) - 0.5 */
  52   n = v_fma_f32 (InvPi, r + HalfPi, Shift);
  53   odd = v_as_u32_f32 (n) << 31;
  54   n -= Shift;
  55   n -= v_f32 (0.5f);
  56
  57   /* r = |x| - n*pi  (range reduction into -pi/2 .. pi/2) */
  58   r = v_fma_f32 (-Pi1, n, r);
  59   r = v_fma_f32 (-Pi2, n, r);
  60   r = v_fma_f32 (-Pi3, n, r);
  61
  62   /* y = sin(r) */
  63   r2 = r * r;
  64   y = v_fma_f32 (A9, r2, A7);
  65   y = v_fma_f32 (y, r2, A5);
  66   y = v_fma_f32 (y, r2, A3);
  67   y = v_fma_f32 (y * r2, r, r);
  68
  69   /* sign fix */
  70   y = v_as_f32_u32 (v_as_u32_f32 (y) ^ odd);
  71
  72   if (unlikely (v_any_u32 (cmp)))
  73     return specialcase (x, y, cmp);
  74   return y;
  75 }
  76 VPCS_ALIAS
  77 #endif