newlib-cygwin/winsup/mingw/mingwex/fesetround.c

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#include <fenv.h>
#include "cpu_features.h"
/* 7.6.3.2
The fesetround function establishes the rounding direction
represented by its argument round. If the argument is not equal
to the value of a rounding direction macro, the rounding direction
is not changed. */
int fesetround (int mode)
{
unsigned short _cw;
if ((mode & ~(FE_TONEAREST | FE_DOWNWARD | FE_UPWARD | FE_TOWARDZERO))
!= 0)
return -1;
__asm__ volatile ("fnstcw %0;": "=m" (_cw));
_cw &= ~(FE_TONEAREST | FE_DOWNWARD | FE_UPWARD | FE_TOWARDZERO);
_cw |= mode;
__asm__ volatile ("fldcw %0;" : : "m" (_cw));
if (__HAS_SSE)
{
__asm__ volatile ("stmxcsr %0" : "=m" (_cw));
_cw &= ~ 0x6000;
_cw |= (mode << __MXCSR_ROUND_FLAG_SHIFT);
__asm__ volatile ("ldmxcsr %0" : : "m" (_cw));
}
return 0;
}