workbench/libs/mathieeedoubtrans/ieeedpcos.c

   1 /*
   2     Copyright © 1995-2003, The AROS Development Team. All rights reserved.
   3     $Id$
   4 */
   5
   6 #include "mathieeedoubtrans_intern.h"
   7
   8 /*****************************************************************************
   9
  10     NAME */
  11
  12         AROS_LHQUAD1(double, IEEEDPCos,
  13
  14 /*  SYNOPSIS */
  15         AROS_LHAQUAD(double, y, D0, D1),
  16
  17 /*  LOCATION */
  18         struct MathIeeeDoubTransBase *, MathIeeeDoubTransBase, 7, MathIeeeDoubTrans)
  19
  20 /*  FUNCTION
  21         Calculate the cosine of a given IEEE double precision number in radians
  22
  23     INPUTS
  24
  25     RESULT
  26         IEEE double precision floating point number
  27
  28         flags:
  29         zero     : result is zero
  30         negative : result is negative
  31         overflow : 0
  32
  33     BUGS
  34
  35     INTERNALS
  36         cos (x) = sin (x+ pi/2);
  37
  38 *****************************************************************************/
  39 {
  40     AROS_LIBFUNC_INIT
  41
  42     LONG tmp;
  43     QUAD z,Res, ysquared, yabs, Qtmp;
  44     AND64C
  45     (
  46         yabs, y,
  47         (IEEEDPMantisse_Mask_Hi | IEEEDPExponent_Mask_Hi),
  48         (IEEEDPMantisse_Mask_Lo | IEEEDPExponent_Mask_Lo)
  49     );
  50
  51     if (is_eqC(yabs, IEEEDPPInfty_Hi, IEEEDPPInfty_Lo))
  52     {
  53         SetSR(Overflow_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  54         Set_Value64C(Res, IEEEDPNAN_Hi, IEEEDPNAN_Lo);
  55         return Res;
  56     }
  57
  58     z = IEEEDPFloor(IEEEDPDiv(yabs, pi));
  59     Qtmp  = IEEEDPMul(z,pi);
  60     OR64QC(Qtmp, IEEEDPSign_Mask_Hi, IEEEDPSign_Mask_Lo) /* Qtmp=-Qtmp */
  61     yabs = IEEEDPAdd(yabs, Qtmp);
  62     if (is_greaterC(yabs, pio2_Hi, pio2_Lo))
  63     {
  64         OR64QC(Qtmp, IEEEDPSign_Mask_Hi, IEEEDPSign_Mask_Lo) /* Qtmp=-Qtmp */
  65         yabs  =IEEEDPAdd(pi, yabs);
  66         tmp = TRUE;
  67     }
  68     else
  69     {
  70         tmp = FALSE;
  71     }
  72
  73     ysquared = IEEEDPMul(yabs,yabs);
  74     Res = IEEEDPAdd(cosf1,
  75           IEEEDPMul(ysquared,
  76           IEEEDPAdd(cosf2,
  77           IEEEDPMul(ysquared,
  78           IEEEDPAdd(cosf3,
  79           IEEEDPMul(ysquared,
  80           IEEEDPAdd(cosf4,
  81           IEEEDPMul(ysquared,
  82           IEEEDPAdd(cosf5,
  83           IEEEDPMul(ysquared,
  84           IEEEDPAdd(cosf6,
  85           IEEEDPMul(ysquared,
  86           IEEEDPAdd(cosf7,
  87           IEEEDPMul(ysquared, cosf8))))))))))))));
  88
  89     if (is_eqC(Res, 0x0, 0x0))
  90     {
  91         SetSR(Zero_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
  92         Set_Value64C(Res, 0x0, 0x0);
  93         return Res;
  94     }
  95
  96     if (TRUE == intern_IEEEDPisodd(z))
  97     {
  98         XOR64QC(Res, IEEEDPSign_Mask_Hi, IEEEDPSign_Mask_Lo);
  99     }
 100
 101     if (TRUE == tmp)
 102     {
 103         XOR64QC(Res, IEEEDPSign_Mask_Hi, IEEEDPSign_Mask_Lo);
 104     }
 105
 106     if (is_lessSC(Res, 0x0, 0x0))
 107     {
 108         SetSR(Negative_Bit, Zero_Bit | Negative_Bit | Overflow_Bit);
 109     }
 110
 111     return Res;
 112
 113     AROS_LIBFUNC_EXIT
 114 }