mirror of
https://github.com/python/cpython.git
synced 2024-12-16 21:34:44 +08:00
97 lines
1.9 KiB
C
97 lines
1.9 KiB
C
#include "Python.h"
|
|
|
|
#ifdef X87_DOUBLE_ROUNDING
|
|
/* On x86 platforms using an x87 FPU, this function is called from the
|
|
Py_FORCE_DOUBLE macro (defined in pymath.h) to force a floating-point
|
|
number out of an 80-bit x87 FPU register and into a 64-bit memory location,
|
|
thus rounding from extended precision to double precision. */
|
|
double _Py_force_double(double x)
|
|
{
|
|
volatile double y;
|
|
y = x;
|
|
return y;
|
|
}
|
|
#endif
|
|
|
|
#ifdef HAVE_GCC_ASM_FOR_X87
|
|
|
|
/* inline assembly for getting and setting the 387 FPU control word on
|
|
gcc/x86 */
|
|
#ifdef _Py_MEMORY_SANITIZER
|
|
__attribute__((no_sanitize_memory))
|
|
#endif
|
|
unsigned short _Py_get_387controlword(void) {
|
|
unsigned short cw;
|
|
__asm__ __volatile__ ("fnstcw %0" : "=m" (cw));
|
|
return cw;
|
|
}
|
|
|
|
void _Py_set_387controlword(unsigned short cw) {
|
|
__asm__ __volatile__ ("fldcw %0" : : "m" (cw));
|
|
}
|
|
|
|
#endif
|
|
|
|
|
|
#ifndef HAVE_HYPOT
|
|
double hypot(double x, double y)
|
|
{
|
|
double yx;
|
|
|
|
x = fabs(x);
|
|
y = fabs(y);
|
|
if (x < y) {
|
|
double temp = x;
|
|
x = y;
|
|
y = temp;
|
|
}
|
|
if (x == 0.)
|
|
return 0.;
|
|
else {
|
|
yx = y/x;
|
|
return x*sqrt(1.+yx*yx);
|
|
}
|
|
}
|
|
#endif /* HAVE_HYPOT */
|
|
|
|
#ifndef HAVE_COPYSIGN
|
|
double
|
|
copysign(double x, double y)
|
|
{
|
|
/* use atan2 to distinguish -0. from 0. */
|
|
if (y > 0. || (y == 0. && atan2(y, -1.) > 0.)) {
|
|
return fabs(x);
|
|
} else {
|
|
return -fabs(x);
|
|
}
|
|
}
|
|
#endif /* HAVE_COPYSIGN */
|
|
|
|
#ifndef HAVE_ROUND
|
|
double
|
|
round(double x)
|
|
{
|
|
double absx, y;
|
|
absx = fabs(x);
|
|
y = floor(absx);
|
|
if (absx - y >= 0.5)
|
|
y += 1.0;
|
|
return copysign(y, x);
|
|
}
|
|
#endif /* HAVE_ROUND */
|
|
|
|
static const unsigned int BitLengthTable[32] = {
|
|
0, 1, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4,
|
|
5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5
|
|
};
|
|
|
|
unsigned int _Py_bit_length(unsigned long d) {
|
|
unsigned int d_bits = 0;
|
|
while (d >= 32) {
|
|
d_bits += 6;
|
|
d >>= 6;
|
|
}
|
|
d_bits += BitLengthTable[d];
|
|
return d_bits;
|
|
}
|