work on chapter 14 (test)

learning_go/14_reflection_unsafe_cgo/README.md

@@ -15,7 +15,38 @@
     - when you define `Foo` struct, it has:
         - `Kind` -> `reflect.Struct`
         - `Type` -> `packetname.Foo`
+* `reflect.New` is reflective version of `new` operator
+* there are also equivalents of `make` 
+* it's possible to create custom marshalling and unmarshalling functions using `reflect` package and reflection mechanism
 
 ### Unsafe
+* truly unsafe
+* weird
+* 1 type -> `Pointer`
+* 3 functions
+    - `Sizeof` -> returns size of the variable
+    - `Offsetof` -> returns offset of the field in the struct
+    - `Alignof` -> returns alignment of the field in the struct
+* based on [this empirical study from arxiv](https://arxiv.org/pdf/2006.09973.pdf) some colorful stuff
 
-### Cgo
+> [!TIP]
+> Correct way to convert `float64` to `uint64` using `unsafe` package (conversion must appear in the same line s operations, otherwise the pointer could be collected by garbage collector before dereferencing) 
+> ```go
+> import unsafe
+> 
+> func Float64(f float64) uint64 {
+>    return *(*uint64)(unsafe.Pointer(&f))
+> }
+> ```
+
+> [!CAUTION]
+> Incorrect way, contrary to explained above
+> ```go
+> import unsafe
+> 
+> u := uintptr(p)
+> p = unsafe.Pointer(u + offset)
+> ```
+
+
+### Cgo