1 files changed, 14 insertions, 0 deletions
diff --git a/lib/libm/sqrt_data.h b/lib/libm/sqrt_data.h
new file mode 100644
index 00000000..f5929b8d
--- /dev/null
+++ b/lib/libm/sqrt_data.h
@@ -0,0 +1,14 @@
+#ifndef _SQRT_DATA_H
+#define _SQRT_DATA_H
+
+#include <stdint.h>
+
+#define hidden __attribute__((visibility("hidden")))
+
+/* if x in [1,2): i = (int)(64*x);
+   if x in [2,4): i = (int)(32*x-64);
+   __rsqrt_tab[i]*2^-16 is estimating 1/sqrt(x) with small relative error:
+   |__rsqrt_tab[i]*0x1p-16*sqrt(x) - 1| < -0x1.fdp-9 < 2^-8 */
+extern hidden const uint16_t __rsqrt_tab[128];
+
+#endif