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-rw-r--r--src/math/logbl.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/src/math/logbl.c b/src/math/logbl.c
new file mode 100644
index 00000000..5d04abd7
--- /dev/null
+++ b/src/math/logbl.c
@@ -0,0 +1,19 @@
+#include <limits.h>
+#include "libm.h"
+#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024
+long double logbl(long double x)
+{
+ return logb(x);
+}
+#else
+long double logbl(long double x)
+{
+ int i = ilogbl(x);
+
+ if (i == FP_ILOGB0)
+ return -1.0/fabsl(x);
+ if (i == FP_ILOGBNAN || i == INT_MAX)
+ return x * x;
+ return i;
+}
+#endif