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glibc  2.9
s_sincosf.c
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00001 /* Compute sine and cosine of argument.
00002    Copyright (C) 1997, 2000 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004    Contributed by Ulrich Drepper <drepper@cygnus.com>, 1997.
00005 
00006    The GNU C Library is free software; you can redistribute it and/or
00007    modify it under the terms of the GNU Lesser General Public
00008    License as published by the Free Software Foundation; either
00009    version 2.1 of the License, or (at your option) any later version.
00010 
00011    The GNU C Library is distributed in the hope that it will be useful,
00012    but WITHOUT ANY WARRANTY; without even the implied warranty of
00013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00014    Lesser General Public License for more details.
00015 
00016    You should have received a copy of the GNU Lesser General Public
00017    License along with the GNU C Library; if not, write to the Free
00018    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00019    02111-1307 USA.  */
00020 
00021 #include <math.h>
00022 
00023 #include "math_private.h"
00024 
00025 
00026 void
00027 __sincosf (float x, float *sinx, float *cosx)
00028 {
00029   int32_t ix;
00030 
00031   /* High word of x. */
00032   GET_FLOAT_WORD (ix, x);
00033 
00034   /* |x| ~< pi/4 */
00035   ix &= 0x7fffffff;
00036   if (ix <= 0x3f490fd8)
00037     {
00038       *sinx = __kernel_sinf (x, 0.0, 0);
00039       *cosx = __kernel_cosf (x, 0.0);
00040     }
00041   else if (ix>=0x7f800000)
00042     {
00043       /* sin(Inf or NaN) is NaN */
00044       *sinx = *cosx = x - x;
00045     }
00046   else
00047     {
00048       /* Argument reduction needed.  */
00049       float y[2];
00050       int n;
00051 
00052       n = __ieee754_rem_pio2f (x, y);
00053       switch (n & 3)
00054        {
00055        case 0:
00056          *sinx = __kernel_sinf (y[0], y[1], 1);
00057          *cosx = __kernel_cosf (y[0], y[1]);
00058          break;
00059        case 1:
00060          *sinx = __kernel_cosf (y[0], y[1]);
00061          *cosx = -__kernel_sinf (y[0], y[1], 1);
00062          break;
00063        case 2:
00064          *sinx = -__kernel_sinf (y[0], y[1], 1);
00065          *cosx = -__kernel_cosf (y[0], y[1]);
00066          break;
00067        default:
00068          *sinx = -__kernel_cosf (y[0], y[1]);
00069          *cosx = __kernel_sinf (y[0], y[1], 1);
00070          break;
00071        }
00072     }
00073 }
00074 weak_alias (__sincosf, sincosf)