diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/lib9/fmt/nan64.c | 57 |
1 files changed, 31 insertions, 26 deletions
diff --git a/src/lib9/fmt/nan64.c b/src/lib9/fmt/nan64.c index 7d719157..9c0cc7bf 100644 --- a/src/lib9/fmt/nan64.c +++ b/src/lib9/fmt/nan64.c @@ -6,6 +6,7 @@ */ #include "plan9.h" +#include <assert.h> #include "fmt.h" #include "fmtdef.h" @@ -13,31 +14,43 @@ static uvlong uvnan = ((uvlong)0x7FF00000<<32)|0x00000001; static uvlong uvinf = ((uvlong)0x7FF00000<<32)|0x00000000; static uvlong uvneginf = ((uvlong)0xFFF00000<<32)|0x00000000; +/* gcc sees through the obvious casts. */ +static uvlong +d2u(double d) +{ + union { + uvlong v; + double d; + } u; + assert(sizeof(u.d) == sizeof(u.v)); + u.d = d; + return u.v; +} + +static double +u2d(uvlong v) +{ + union { + uvlong v; + double d; + } u; + assert(sizeof(u.d) == sizeof(u.v)); + u.v = v; + return u.d; +} + double __NaN(void) { - uvlong *p; - - /* gcc complains about "return *(double*)&uvnan;" */ - p = &uvnan; - return *(double*)p; + return u2d(uvnan); } int __isNaN(double d) { - /* - * Used to just say x = *(uvlong*)&d, - * but gcc miscompiles that! - */ - union { - uvlong i; - double f; - } u; uvlong x; - u.f = d; - x = u.i; + x = d2u(d); /* IEEE 754: exponent bits 0x7FF and non-zero mantissa */ return (x&uvinf) == uvinf && (x&~uvneginf) != 0; } @@ -45,23 +58,15 @@ __isNaN(double d) double __Inf(int sign) { - uvlong *p; - - if(sign < 0) - p = &uvinf; - else - p = &uvneginf; - return *(double*)p; + return u2d(sign < 0 ? uvneginf : uvinf); } int __isInf(double d, int sign) { uvlong x; - double *p; - - p = &d; - x = *(uvlong*)p; + + x = d2u(d); if(sign == 0) return x==uvinf || x==uvneginf; else if(sign > 0) |