reactos/subsys/win32k/misc/math.c

   1 /* Math functions for i387.
   2    Copyright (C) 1995, 1996, 1997 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by John C. Bowman <bowman@ipp-garching.mpg.de>, 1995.
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Library General Public License as
   8    published by the Free Software Foundation; either version 2 of the
   9    License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Library General Public License for more details.
  15
  16    You should have received a copy of the GNU Library General Public
  17    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  18    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21 #include <windows.h>
  22
  23 double atan (double __x);
  24 double atan2 (double __y, double __x);
  25 double ceil (double __x);
  26 double cos (double __x);
  27 double fabs (double __x);
  28 double floor (double __x);
  29 long _ftol (double fl);
  30 double log (double __x);
  31 double __log2 (double __x);
  32 double pow (double __x, double __y);
  33 double sin (double __x);
  34 double sqrt (double __x);
  35 double tan (double __x);
  36
  37
  38 double atan (double __x)
  39 {
  40   register double __value;
  41   __asm __volatile__
  42     ("fld1\n\t"
  43      "fpatan"
  44      : "=t" (__value) : "0" (__x));
  45
  46   return __value;
  47 }
  48
  49 double atan2 (double __y, double __x)
  50 {
  51   register double __value;
  52   __asm __volatile__
  53     ("fpatan\n\t"
  54      "fld %%st(0)"
  55      : "=t" (__value) : "0" (__x), "u" (__y));
  56
  57   return __value;
  58 }
  59
  60 double ceil (double __x)
  61 {
  62   register double __value;
  63   __volatile unsigned short int __cw, __cwtmp;
  64
  65   __asm __volatile ("fnstcw %0" : "=m" (__cw));
  66   __cwtmp = (__cw & 0xf3ff) | 0x0800; /* rounding up */
  67   __asm __volatile ("fldcw %0" : : "m" (__cwtmp));
  68   __asm __volatile ("frndint" : "=t" (__value) : "0" (__x));
  69   __asm __volatile ("fldcw %0" : : "m" (__cw));
  70
  71   return __value;
  72 }
  73
  74 double cos (double __x)
  75 {
  76   register double __value;
  77   __asm __volatile__
  78     ("fcos"
  79      : "=t" (__value): "0" (__x));
  80
  81   return __value;
  82 }
  83
  84 double fabs (double __x)
  85 {
  86   register double __value;
  87   __asm __volatile__
  88     ("fabs"
  89      : "=t" (__value) : "0" (__x));
  90
  91   return __value;
  92 }
  93
  94 double floor (double __x)
  95 {
  96   register double __value;
  97   __volatile unsigned short int __cw, __cwtmp;
  98
  99   __asm __volatile ("fnstcw %0" : "=m" (__cw));
 100   __cwtmp = (__cw & 0xf3ff) | 0x0400; /* rounding down */
 101   __asm __volatile ("fldcw %0" : : "m" (__cwtmp));
 102   __asm __volatile ("frndint" : "=t" (__value) : "0" (__x));
 103   __asm __volatile ("fldcw %0" : : "m" (__cw));
 104
 105   return __value;
 106 }
 107
 108 long _ftol (double fl)
 109 {
 110   return (long)fl;
 111 }
 112
 113 double log (double __x)
 114 {
 115   register double __value;
 116   __asm __volatile__
 117     ("fldln2\n\t"
 118      "fxch\n\t"
 119      "fyl2x"
 120      : "=t" (__value) : "0" (__x));
 121
 122   return __value;
 123 }
 124
 125 double __log2 (double __x)
 126 {
 127   register double __value;
 128   __asm __volatile__
 129     ("fld1\n\t"
 130      "fxch\n\t"
 131      "fyl2x"
 132      : "=t" (__value) : "0" (__x));
 133
 134   return __value;
 135 }
 136
 137 double pow (double __x, double __y)
 138 {
 139   register double __value, __exponent;
 140   long __p = (long) __y;
 141
 142   if (__x == 0.0 && __y > 0.0)
 143     return 0.0;
 144   if (__y == (double) __p)
 145     {
 146       double __r = 1.0;
 147       if (__p == 0)
 148         return 1.0;
 149       if (__p < 0)
 150         {
 151           __p = -__p;
 152           __x = 1.0 / __x;
 153         }
 154       while (1)
 155         {
 156           if (__p & 1)
 157             __r *= __x;
 158           __p >>= 1;
 159           if (__p == 0)
 160             return __r;
 161           __x *= __x;
 162         }
 163       /* NOTREACHED */
 164     }
 165   __asm __volatile__
 166     ("fmul      %%st(1)         # y * log2(x)\n\t"
 167      "fst       %%st(1)\n\t"
 168      "frndint                   # int(y * log2(x))\n\t"
 169      "fxch\n\t"
 170      "fsub      %%st(1)         # fract(y * log2(x))\n\t"
 171      "f2xm1                     # 2^(fract(y * log2(x))) - 1\n\t"
 172      : "=t" (__value), "=u" (__exponent) :  "0" (__log2 (__x)), "1" (__y));
 173   __value += 1.0;
 174   __asm __volatile__
 175     ("fscale"
 176      : "=t" (__value) : "0" (__value), "u" (__exponent));
 177
 178   return __value;
 179 }
 180
 181 double sin (double __x)
 182 {
 183   register double __value;
 184   __asm __volatile__
 185     ("fsin"
 186      : "=t" (__value) : "0" (__x));
 187
 188   return __value;
 189 }
 190
 191 double sqrt (double __x)
 192 {
 193   register double __value;
 194   __asm __volatile__
 195     ("fsqrt"
 196      : "=t" (__value) : "0" (__x));
 197
 198   return __value;
 199 }
 200
 201 double tan (double __x)
 202 {
 203   register double __value;
 204   register double __value2 __attribute__ ((unused));
 205   __asm __volatile__
 206     ("fptan"
 207      : "=t" (__value2), "=u" (__value) : "0" (__x));
 208
 209   return __value;
 210 }
 211
 212 //FIXME! Is there a better algorithm. like FT_MulDiv
 213 INT STDCALL EngMulDiv(
 214              INT nMultiplicand,
 215              INT nMultiplier,
 216              INT nDivisor)
 217 {
 218 #if SIZEOF_LONG_LONG >= 8
 219     long long ret;
 220
 221     if (!nDivisor) return -1;
 222
 223     /* We want to deal with a positive divisor to simplify the logic. */
 224     if (nDivisor < 0)
 225     {
 226       nMultiplicand = - nMultiplicand;
 227       nDivisor = -nDivisor;
 228     }
 229
 230     /* If the result is positive, we "add" to round. else, we subtract to round. */
 231     if ( ( (nMultiplicand <  0) && (nMultiplier <  0) ) ||
 232          ( (nMultiplicand >= 0) && (nMultiplier >= 0) ) )
 233       ret = (((long long)nMultiplicand * nMultiplier) + (nDivisor/2)) / nDivisor;
 234     else
 235       ret = (((long long)nMultiplicand * nMultiplier) - (nDivisor/2)) / nDivisor;
 236
 237     if ((ret > 2147483647) || (ret < -2147483647)) return -1;
 238     return ret;
 239 #else
 240     if (!nDivisor) return -1;
 241
 242     /* We want to deal with a positive divisor to simplify the logic. */
 243     if (nDivisor < 0)
 244     {
 245       nMultiplicand = - nMultiplicand;
 246       nDivisor = -nDivisor;
 247     }
 248
 249     /* If the result is positive, we "add" to round. else, we subtract to round. */
 250     if ( ( (nMultiplicand <  0) && (nMultiplier <  0) ) ||
 251          ( (nMultiplicand >= 0) && (nMultiplier >= 0) ) )
 252       return ((nMultiplicand * nMultiplier) + (nDivisor/2)) / nDivisor;
 253
 254     return ((nMultiplicand * nMultiplier) - (nDivisor/2)) / nDivisor;
 255
 256 #endif
 257 }