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