tutorials/logging.md

+There are various ways to log information in the sac2c compiler.
+
+There are kinds of ways to log information during compilation.
+`src/libsac2c/support/debug.h` and `src/libsac2c/global/ctinfo.h`
+
+
+
+1. `debug.h` is for compiler debugging for the compiler developers.
+2. The functions in `ctinfo.h` which are used to actually give feedback to the caller of the compiler.
+
+
+# debug.h 
+
+A modified version of the `debug.h` file by `Fred Fish`. 
+Modify a lot by the sac team. 
+
+These macros are for compiler debugging for the compiler developers.
+Only present in a DEBUG build of the compiler.
+
+This system allows you to print debug information to the console at different levels and for different tags.
+
+You can get these debug messages for the entire compiler by using the `-#d` flag.
+If you want to only get messages for a certain compiler phase you can specify the debug prefix of the messages you want to see `-#d,EX` for a traversal with `#define DBUG_PREFIX "EX"`.
+This is possible because the `debug.h` file allows you to only print messages with a certain prefix if you want.
+
+You set the prefix by doing `#define DBUG_PREFIX "TSM"` at the top of the file you want to debug.
+
+# ctinfo functions
+
+These functions actually provide feedback to the caller of the compiler.
+This messages are present in both debug builds and release builds of the compiler.
+
+The logging follows different levels of verbosity. 
+The caller sets the verbosity levels by using the `-v` flag.
+This info is from the top of the `ctinfo.c` file:
+
+```
+* Verbose level 0:
+*
+* Only error messages are printed.
+*
+* Verbose level 1:
+*
+* Error messages and warnings are printed.
+*
+* Verbose level 2:
+*
+* Error messages, warnings and basic compile time information, e.g. compiler
+* phases,  are printed.
+*
+* Verbose level 3:
+*
+* Error messages, warnings and full compile time information are printed.
+*
+* Verbose level 4+:
+*
+* Additional compile time information is provided that typically is only
+* of interest in certain situation.
+*
+* Default values are 1 for the product version and 3 for the developer version.
+```
+
+However `ctinfo.c` holds more logging functions like `InternalCompilerErrorBreak` which produces the `OOOOOOOPS, your program crashed the compiler 8-((` message.
+Or for instance `CTIerror` which is used to print an error messages or `CTIwarn` to show warnings etc.
+
+