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/*
* gcc on x86 needs access to rounding controls, because of a questionable
* feature where it retains intermediate results as IEEE 'long double' values
* somewhat unpredictably. It is tempting to include fpu_control.h, but that
* file exists only on Linux; it is missing on Cygwin and MinGW. Most gcc-isms
* and ix86-isms are factored out here.
*/
#define _FPU_GETCW(cw) __asm__ __volatile__ ("fnstcw %0" : "=m" (*&cw))
#define _FPU_SETCW(cw) __asm__ __volatile__ ("fldcw %0" : : "m" (*&cw))
# define FPU_IEEE_ROUNDING 0x027F
# define ADJUST_FPU_CONTROL_WORD
#define TCL_IEEE_DOUBLE_ROUNDING \
# define _FPU_GETCW(cw) __asm__ __volatile__ ("fnstcw %0" : "=m" (*&cw))
# define _FPU_SETCW(cw) __asm__ __volatile__ ("fldcw %0" : : "m" (*&cw))
# define FPU_IEEE_ROUNDING 0x027F
# define ADJUST_FPU_CONTROL_WORD
# define TCL_IEEE_DOUBLE_ROUNDING_DECL \
fpu_control_t roundTo53Bits = FPU_IEEE_ROUNDING; \
fpu_control_t oldRoundingMode; \
fpu_control_t oldRoundingMode;
# define TCL_IEEE_DOUBLE_ROUNDING \
_FPU_GETCW(oldRoundingMode); \
_FPU_SETCW(roundTo53Bits)
#define TCL_DEFAULT_DOUBLE_ROUNDING \
# define TCL_DEFAULT_DOUBLE_ROUNDING \
_FPU_SETCW(oldRoundingMode)
/*
* Sun ProC needs sunmath for rounding control on x86 like gcc above.
*/
#elif defined(__sun)
#include <sunmath.h>
#define TCL_IEEE_DOUBLE_ROUNDING \
# elif defined(__sun)
# include <sunmath.h>
# define TCL_IEEE_DOUBLE_ROUNDING_DECL
# define TCL_IEEE_DOUBLE_ROUNDING \
ieee_flags("set","precision","double",NULL)
#define TCL_DEFAULT_DOUBLE_ROUNDING \
# define TCL_DEFAULT_DOUBLE_ROUNDING \
ieee_flags("clear","precision",NULL,NULL)
# endif
#endif
/*
* Other platforms are assumed to always operate in full IEEE mode, so we make
* the macros to go in and out of that mode do nothing.
*/
#ifndef TCL_IEEE_DOUBLE_ROUNDING /* !__i386 || (!__GNUC__ && !__sun) */
#else /* !__GNUC__ && !__sun */
#define TCL_IEEE_DOUBLE_ROUNDING ((void) 0)
#define TCL_DEFAULT_DOUBLE_ROUNDING ((void) 0)
#endif
#else /* !__i386 */
#define TCL_IEEE_DOUBLE_ROUNDING ((void) 0)
#define TCL_DEFAULT_DOUBLE_ROUNDING ((void) 0)
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static double
MakeLowPrecisionDouble(
int signum, /* 1 if the number is negative, 0 otherwise */
Tcl_WideUInt significand, /* Significand of the number */
int numSigDigs, /* Number of digits in the significand */
long exponent) /* Power of ten */
{
TCL_IEEE_DOUBLE_ROUNDING_DECL
mp_int significandBig; /* Significand expressed as a bignum. */
/*
* With gcc on x86, the floating point rounding mode is double-extended.
* This causes the result of double-precision calculations to be rounded
* twice: once to the precision of double-extended and then again to the
* precision of double. Double-rounding introduces gratuitous errors of 1
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static double
MakeHighPrecisionDouble(
int signum, /* 1=negative, 0=nonnegative */
mp_int *significand, /* Exact significand of the number */
int numSigDigs, /* Number of significant digits */
long exponent) /* Power of 10 by which to multiply */
{
TCL_IEEE_DOUBLE_ROUNDING_DECL
int machexp; /* Machine exponent of a power of 10. */
/*
* With gcc on x86, the floating point rounding mode is double-extended.
* This causes the result of double-precision calculations to be rounded
* twice: once to the precision of double-extended and then again to the
* precision of double. Double-rounding introduces gratuitous errors of 1
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