[fpc-devel] Re: Episode 4. Addressing and it's limits Part Two

[Hans-Peter Diettrich]

steve smithers schrieb:

> The bit that provides code for VM/SP as opposed to say MVS, is the RTL,
> so if I want to open a file, there is a routine in the RTL called OpenFile
> (or whatever) that issues the VM code for open.  This lives in System.pp
> or Sysfile.pp or whatever it's called in the RTL/VMSP sub-directory
> 
> Now, in order for the compiler to function it needs access to a certain
> level of base functionality in the VM/SP RTL.

The RTL is compiled before the compiler, so that it can be used inside 
the compiler. This is required for cross-compilation, where the compiler 
has to use the file access routines of the *host* system, and is 
compiled into code for the host system.

The RTL may contain assembler code for the target machine, if you don't 
trust your own compiler to generate appropriate code.

DoDi