diff options
Diffstat (limited to 'generic/tclStrToD.c')
| -rw-r--r-- | generic/tclStrToD.c | 88 |
1 files changed, 53 insertions, 35 deletions
diff --git a/generic/tclStrToD.c b/generic/tclStrToD.c index 9cd3811..a816062 100644 --- a/generic/tclStrToD.c +++ b/generic/tclStrToD.c @@ -49,44 +49,43 @@ * file exists only on Linux; it is missing on Cygwin and MinGW. Most gcc-isms * and ix86-isms are factored out here. */ - -#if defined(__GNUC__) +# if defined(__GNUC__) typedef unsigned int fpu_control_t __attribute__ ((__mode__ (__HI__))); -#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. */ - -#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) +#ifndef TCL_IEEE_DOUBLE_ROUNDING /* !__i386 || (!__GNUC__ && !__sun) */ +# define TCL_IEEE_DOUBLE_ROUNDING_DECL +# define TCL_IEEE_DOUBLE_ROUNDING ((void) 0) +# define TCL_DEFAULT_DOUBLE_ROUNDING ((void) 0) #endif /* @@ -1210,7 +1209,6 @@ TclParseNumber( acceptPoint = p; acceptLen = len; goto endgame; - } p++; len--; @@ -1679,7 +1677,8 @@ MakeLowPrecisionDouble( int numSigDigs, /* Number of digits in the significand */ long exponent) /* Power of ten */ { - double retval; /* Value of the number. */ + TCL_IEEE_DOUBLE_ROUNDING_DECL + mp_int significandBig; /* Significand expressed as a bignum. */ /* @@ -1687,18 +1686,25 @@ MakeLowPrecisionDouble( * 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 - * ulp, so we need to change rounding mode to 53-bits. + * ulp, so we need to change rounding mode to 53-bits. We also make + * 'retval' volatile, so that it doesn't get promoted to a register. */ - - TCL_IEEE_DOUBLE_ROUNDING; + volatile double retval; /* Value of the number. */ /* - * Test for the easy cases. + * Test for zero significand, which requires explicit construction + * of -0.0. (Unary minus returns a positive zero.) */ - if (significand == 0) { return copysign(0.0, -signum); } + + /* + * Set the FP control word for 53 bits, WARNING: It must be reset + * before returning. + */ + TCL_IEEE_DOUBLE_ROUNDING; + if (numSigDigs <= QUICK_MAX) { if (exponent >= 0) { if (exponent <= mmaxpow) { @@ -1798,7 +1804,8 @@ MakeHighPrecisionDouble( int numSigDigs, /* Number of significant digits */ long exponent) /* Power of 10 by which to multiply */ { - double retval; + TCL_IEEE_DOUBLE_ROUNDING_DECL + int machexp = 0; /* Machine exponent of a power of 10. */ /* @@ -1806,19 +1813,30 @@ MakeHighPrecisionDouble( * 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 - * ulp, so we need to change rounding mode to 53-bits. + * ulp, so we need to change rounding mode to 53-bits. We also make + * 'retval' volatile to make sure that it doesn't get promoted to a + * register. */ - - TCL_IEEE_DOUBLE_ROUNDING; + volatile double retval; /* - * Quick checks for zero, and over/underflow. Be careful to avoid - * integer overflow when calculating with 'exponent'. + * A zero significand requires explicit construction of -0.0. + * (Unary minus returns positive zero.) */ - if (mp_iszero(significand)) { return copysign(0.0, -signum); } + + /* + * Set the 53-bit rounding mode. WARNING: It must be reset before + * returning. + */ + TCL_IEEE_DOUBLE_ROUNDING; + + /* + * Make quick checks for over/underflow. Be careful to avoid + * integer overflow when calculating with 'exponent'. + */ if (exponent >= 0 && exponent-1 > maxDigits-numSigDigs) { retval = HUGE_VAL; goto returnValue; |