author | Rich Felker <dalias@aerifal.cx> | 2012年03月13日 01:17:53 -0400 |
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committer | Rich Felker <dalias@aerifal.cx> | 2012年03月13日 01:17:53 -0400 |
commit | b69f695acedd4ce2798ef9ea28d834ceccc789bd (patch) | |
tree | eafd98b9b75160210f3295ac074d699f863d958e /src/math/ilogbl.c | |
parent | d46cf2e14cc4df7cc75e77d7009fcb6df1f48a33 (diff) | |
download | musl-b69f695acedd4ce2798ef9ea28d834ceccc789bd.tar.gz |
-rw-r--r-- | src/math/ilogbl.c | 28 |
diff --git a/src/math/ilogbl.c b/src/math/ilogbl.c new file mode 100644 index 00000000..ed9ddcbc --- /dev/null +++ b/src/math/ilogbl.c @@ -0,0 +1,28 @@ +#include <limits.h> +#include "libm.h" + +#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024 +int ilogbl(long double x) +{ + return ilogb(x); +} +#elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384 +int ilogbl(long double x) +{ + union ldshape u = {x}; + uint64_t m = u.bits.m; + int e = u.bits.exp; + + if (!e) { + if (m == 0) + return FP_ILOGB0; + /* subnormal x */ + for (e = -0x3fff+1; m < (uint64_t)1<<63; e--, m<<=1); + return e; + } + if (e == 0x7fff) + /* in ld80 msb is set in inf */ + return m & (uint64_t)-1>>1 ? FP_ILOGBNAN : INT_MAX; + return e - 0x3fff; +} +#endif |