minix/lib/libc/arch/i386/math/arch_round.c

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2009-12-24 21:22:41 +01:00
#include <errno.h>
#include <fenv.h>
#include <math.h>
#include "fpu_cw.h"
#include "fpu_round.h"
static double rndint(double x, u16_t cw_bits, u16_t cw_mask)
{
u16_t cw;
/* set FPUCW to the right value */
cw = fpu_cw_get();
fpu_cw_set((cw & cw_mask) | cw_bits);
/* perform the round */
fpu_rndint(&x);
/* restore FPUCW */
fpu_cw_set(cw);
return x;
}
double nearbyint(double x)
{
/* round, disabling floating point precision error */
return rndint(x, FPUCW_EXCEPTION_MASK_PM, ~0);
}
double remainder(double x, double y)
{
int xclass, yclass;
/* check arguments */
xclass = fpclassify(x);
yclass = fpclassify(y);
if (xclass == FP_NAN || yclass == FP_NAN)
return NAN;
if (xclass == FP_INFINITE || yclass == FP_ZERO)
{
errno = EDOM;
return NAN;
}
/* call the assembly implementation */
fpu_remainder(&x, y);
return x;
}
double trunc(double x)
{
/* round in truncate mode, disabling floating point precision error */
return rndint(x,
FPUCW_EXCEPTION_MASK_PM | FPUCW_ROUNDING_CONTROL_TRUNC,
~FPUCW_ROUNDING_CONTROL);
}