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      1 #include "Python.h"
      2 
      3 #ifdef X87_DOUBLE_ROUNDING
      4 /* On x86 platforms using an x87 FPU, this function is called from the
      5    Py_FORCE_DOUBLE macro (defined in pymath.h) to force a floating-point
      6    number out of an 80-bit x87 FPU register and into a 64-bit memory location,
      7    thus rounding from extended precision to double precision. */
      8 double _Py_force_double(double x)
      9 {
     10     volatile double y;
     11     y = x;
     12     return y;
     13 }
     14 #endif
     15 
     16 #ifdef HAVE_GCC_ASM_FOR_X87
     17 
     18 /* inline assembly for getting and setting the 387 FPU control word on
     19    gcc/x86 */
     20 
     21 unsigned short _Py_get_387controlword(void) {
     22     unsigned short cw;
     23     __asm__ __volatile__ ("fnstcw %0" : "=m" (cw));
     24     return cw;
     25 }
     26 
     27 void _Py_set_387controlword(unsigned short cw) {
     28     __asm__ __volatile__ ("fldcw %0" : : "m" (cw));
     29 }
     30 
     31 #endif
     32 
     33 
     34 #ifndef HAVE_HYPOT
     35 double hypot(double x, double y)
     36 {
     37     double yx;
     38 
     39     x = fabs(x);
     40     y = fabs(y);
     41     if (x < y) {
     42         double temp = x;
     43         x = y;
     44         y = temp;
     45     }
     46     if (x == 0.)
     47         return 0.;
     48     else {
     49         yx = y/x;
     50         return x*sqrt(1.+yx*yx);
     51     }
     52 }
     53 #endif /* HAVE_HYPOT */
     54 
     55 #ifndef HAVE_COPYSIGN
     56 double
     57 copysign(double x, double y)
     58 {
     59     /* use atan2 to distinguish -0. from 0. */
     60     if (y > 0. || (y == 0. && atan2(y, -1.) > 0.)) {
     61         return fabs(x);
     62     } else {
     63         return -fabs(x);
     64     }
     65 }
     66 #endif /* HAVE_COPYSIGN */
     67 
     68 #ifndef HAVE_ROUND
     69 double
     70 round(double x)
     71 {
     72     double absx, y;
     73     absx = fabs(x);
     74     y = floor(absx);
     75     if (absx - y >= 0.5)
     76         y += 1.0;
     77     return copysign(y, x);
     78 }
     79 #endif /* HAVE_ROUND */
     80