workbench/libs/mathieeesingtrans/ieeesptan.c

   1 /*
   2     Copyright © 1995-2003, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include "mathieeesingtrans_intern.h"
   7
   8 /*****************************************************************************
   9
  10     NAME */
  11
  12         AROS_LH1(float, IEEESPTan,
  13
  14 /*  SYNOPSIS */
  15         AROS_LHA(float, y, D0),
  16
  17 /*  LOCATION */
  18         struct Library *, MathIeeeSingTransBase, 8, MathIeeeSingTrans)
  19
  20 /*  FUNCTION
  21         Calculate the tangens of a given IEEE single precision number in radians
  22
  23     INPUTS
  24
  25     RESULT
  26         IEEE single precision floating point number
  27
  28         flags:
  29         zero     : result is zero
  30         negative : result is negative
  31         overflow :
  32
  33     BUGS
  34
  35     INTERNALS
  36
  37 *****************************************************************************/
  38 {
  39     AROS_LIBFUNC_INIT
  40
  41     LONG z,SIN,Res,ysquared,yabs,tmp;
  42     yabs = y & (IEEESPMantisse_Mask + IEEESPExponent_Mask);
  43
  44     if (IEEESP_Pinfty == yabs)
  45     {
  46         SetSR(Overflow_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  47         return IEEESP_NAN;
  48     }
  49
  50     z = IEEESPFloor(IEEESPDiv(yabs, pi));
  51     tmp  = IEEESPMul(z,pi);
  52     tmp |= IEEESPSign_Mask; /* tmp = -tmp; */
  53     yabs = IEEESPAdd(yabs, tmp);
  54     if (yabs > pio2)
  55     {
  56         yabs |= IEEESPSign_Mask;
  57         yabs  =IEEESPAdd(pi, yabs);
  58         tmp = TRUE;
  59     }
  60     else
  61     {
  62         tmp = FALSE;
  63     }
  64
  65     ysquared = IEEESPMul(yabs,yabs);
  66     SIN = IEEESPMul(yabs,
  67           IEEESPAdd(sinf1,
  68           IEEESPMul(ysquared,
  69           IEEESPAdd(sinf2,
  70           IEEESPMul(ysquared,
  71           IEEESPAdd(sinf3,
  72           IEEESPMul(ysquared,
  73           IEEESPAdd(sinf4,
  74           IEEESPMul(ysquared,
  75           IEEESPAdd(sinf5,
  76           IEEESPMul(ysquared, sinf6)))))))))));
  77     /* cos: */
  78     z   = IEEESPAdd(cosf1,
  79           IEEESPMul(ysquared,
  80           IEEESPAdd(cosf2,
  81           IEEESPMul(ysquared,
  82           IEEESPAdd(cosf3,
  83           IEEESPMul(ysquared,
  84           IEEESPAdd(cosf4,
  85           IEEESPMul(ysquared,
  86           IEEESPAdd(cosf5,
  87           IEEESPMul(ysquared, cosf6))))))))));
  88
  89     Res = IEEESPDiv(SIN, z);
  90
  91     if (y < 0 )      Res ^= IEEESPSign_Mask;
  92     if (TRUE == tmp) Res ^= IEEESPSign_Mask;
  93
  94     if (0 == Res)
  95     {
  96         SetSR(Zero_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  97         return 0;
  98     }
  99
 100     if (Res < 0) SetSR(Negative_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
 101
 102     return Res;
 103
 104     AROS_LIBFUNC_EXIT
 105 }