[libc] [llvm] [libc][math][c23] Implement higher math function `cbrtf16` in LLVM libc (PR #132484)

[via llvm-commits]

================
@@ -94,10 +94,9 @@ LLVM_LIBC_FUNCTION(float16, cbrtf16, (float16 x)) {
   float xf = static_cast<float>(x);
   FloatBits xf_bits(xf);
 
-  unsigned x_e = static_cast<unsigned>(xf_bits.get_exponent());
-  unsigned out_e = x_e / 3 + 127;
-
-  unsigned shift_e = x_e % 3;
+  uint32_t x_e = xf_bits.get_biased_exponent();
----------------
lntue wrote:

Please add the comments to explain how we derived the exponent computations.

https://github.com/llvm/llvm-project/pull/132484