[et] first draft

README.md

@@ -13,3 +13,44 @@ make
 ```
 
 then run any example binary, located inside the `build/examples/` directory.
+
+## Remarks
+
+### Assembler code
+
+Some examples are meant to show the assembler code they generate.
+To see that, one can use for example https://godbolt.org/ or GDB.
+With GDB:
+```bash
+gdb -q -ex 'disassemble main' -ex q "${program_to_execute}"
+```
+
+Important note:
+if using `cmake` to produce the Makefile, you must call it with at least:
+```bash
+cmake -DCMAKE_BUILD_TYPE=Release ..
+```
+or the examples will be compiled without the optimization level 2.
+
+### use of `volatile`
+
+When a value is required to show something, it is necessary to prevent the compiler to
+optimize out this value. To achieve this, one can read the value from a file, for example,
+but it will generate more assembler code.
+Another solution is the `volatile` type modifier that forbids optimization like caching or
+other optimizations like:
+```cpp
+int main() {
+	int volatile v0 = 5, v1 = 7;
+	return v0 + v1;
+}
+```
+
+Without `volatile`, the addition is done by the compiler and `main` returns directly `12`.
+With `volatile`, the generated assembler code will contain an `add` instruction, even with `-O2`.
+
+### `std::printf` instead of `std::cout`
+
+C++ iostreams cause lots of assembler code, for that reason, when an example is expected to be
+possibly used by looking at its generated assembler code, iostreams are avoided and replaced by
+`printf`.