first commit of the new libm!

[musl] / src / math / ilogbl.c

diff --git a/src/math/ilogbl.c b/src/math/ilogbl.c
new file mode 100644 (file)
index 0000000..ed9ddcb
--- /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