add circuitpython code

1 files changed, 11 insertions, 0 deletions

diff --git a/circuitpython/lib/libm/thumb_vfp_sqrtf.c b/circuitpython/lib/libm/thumb_vfp_sqrtf.c
new file mode 100644
index 0000000..12ffebf
--- /dev/null
+++ b/circuitpython/lib/libm/thumb_vfp_sqrtf.c
@@ -0,0 +1,11 @@
+// an implementation of sqrtf for Thumb using hardware VFP instructions
+
+#include <math.h>
+
+float sqrtf(float x) {
+    asm volatile (
+            "vsqrt.f32  %[r], %[x]\n"
+            : [r] "=t" (x)
+            : [x] "t"  (x));
+    return x;
+}