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Fix non-portable usage of isinf' in max' and `min'

* numbers.c: Add new macros DOUBLE_IS_POSITIVE_INFINITY and
  DOUBLE_IS_NEGATIVE_INFINITY.
  (scm_max, scm_min): Use the new macros to detect particular
  infinities.  Previously we checked the return value of `isinf'
  to determine the sign of the infinity, but that is not portable.
This commit is contained in:
Mark H Weaver 2011-02-02 19:32:16 -05:00 committed by Andy Wingo
parent 9da4074189
commit 041fccf6aa

View file

@ -83,6 +83,11 @@ typedef scm_t_signed_bits scm_t_inum;
TODO: if it's available, use C99's isfinite(x) instead */
#define DOUBLE_IS_FINITE(x) (!isinf(x) && !isnan(x))
/* On some platforms, isinf(x) returns 0, 1 or -1, indicating the sign
of the infinity, but other platforms return a boolean only. */
#define DOUBLE_IS_POSITIVE_INFINITY(x) (isinf(x) && ((x) > 0))
#define DOUBLE_IS_NEGATIVE_INFINITY(x) (isinf(x) && ((x) < 0))
/*
@ -5251,9 +5256,9 @@ scm_max (SCM x, SCM y)
/* If neither (xx > yy) nor (xx < yy), then
either they're equal or one is a NaN */
else if (SCM_UNLIKELY (isnan (xx)))
return (isinf (yy) == 1) ? y : x;
return DOUBLE_IS_POSITIVE_INFINITY (yy) ? y : x;
else if (SCM_UNLIKELY (isnan (yy)))
return (isinf (xx) == 1) ? x : y;
return DOUBLE_IS_POSITIVE_INFINITY (xx) ? x : y;
/* xx == yy, but handle signed zeroes properly */
else if (double_is_non_negative_zero (yy))
return y;
@ -5411,9 +5416,9 @@ scm_min (SCM x, SCM y)
/* If neither (xx < yy) nor (xx > yy), then
either they're equal or one is a NaN */
else if (SCM_UNLIKELY (isnan (xx)))
return (isinf (yy) == -1) ? y : x;
return DOUBLE_IS_NEGATIVE_INFINITY (yy) ? y : x;
else if (SCM_UNLIKELY (isnan (yy)))
return (isinf (xx) == -1) ? x : y;
return DOUBLE_IS_NEGATIVE_INFINITY (xx) ? x : y;
/* xx == yy, but handle signed zeroes properly */
else if (double_is_non_negative_zero (xx))
return y;