From f8e05f3850e51673522216f23533bf7146359dcd Mon Sep 17 00:00:00 2001 From: Bernhard Reutner-Fischer Date: Mon, 15 Dec 2014 16:13:01 +0100 Subject: stdio: Fix printing 0.0 We were relying on FE_DIVBYZERO being turned off when printing "%f", +-.0 Avoid the whole issue by looking at the sign-bit (in a rough approximation). Note that we do not handle gracefully: printf ("\n%llf\n", -0.0); printf ("\n%llf\n", 0.0); nor %Lf for both when NOT cast to long double. Avoiding an FPE due to broken numbers like these does not make sense to me. Signed-off-by: Bernhard Reutner-Fischer --- libc/stdio/_fpmaxtostr.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/libc/stdio/_fpmaxtostr.c b/libc/stdio/_fpmaxtostr.c index f7ea792c4..35805844a 100644 --- a/libc/stdio/_fpmaxtostr.c +++ b/libc/stdio/_fpmaxtostr.c @@ -45,11 +45,6 @@ */ #define isnan(x) ((x) != (x)) -/* Without seminumerical functions to examine the sign bit, this is - * about the best we can do to test for '-0'. - */ -#define zeroisnegative(x) ((1./(x)) < 0) - /*****************************************************************************/ /* Don't change anything that follows peroid!!! ;-) */ /*****************************************************************************/ @@ -262,7 +257,13 @@ ssize_t _fpmaxtostr(FILE * fp, __fpmax_t x, struct printf_info *info, if (x == 0) { /* Handle 0 now to avoid false positive. */ #ifdef __UCLIBC_HAVE_SIGNED_ZERO__ - if (zeroisnegative(x)) { /* Handle 'signed' zero. */ + union { + double x; + struct { + unsigned int l1, l2; + } i; + } u = {x}; + if (u.i.l1 ^ u.i.l2) { /* Handle 'signed' zero. */ *sign_str = '-'; } #endif /* __UCLIBC_HAVE_SIGNED_ZERO__ */ -- cgit v1.2.3