> otherwise it is more than a little disturbing when the source code in a high-level language takes more lines of code than doing the same thing in pure Asm
The vast majority of the code is just defining the minimal set of standard C# data types needed to compile any C# program.
There is an analog in the efi asm example in the include file [1] with its structures and defines which have a few types but is mostly concerned with defining the same structures as in the C# program.
Something that is very unique and interesting is the usage of the System.Runtime & System.Runtime.InteropService , I'm guessing that some of the contorting needed to get things working in the code lays with those functions. The other half would be the ilc and the linker having the EFI subsystem as an option.
Runtime and InteropServices are needed for .NET's P/Invoke FFI. It's used to declare the layout of structs, foreign pointers and marshalling code. You can see this being used starting at line 127, where it appears to define EFI handles, tables and headers.
The vast majority of the code is just defining the minimal set of standard C# data types needed to compile any C# program.