elks-enhanced - XT-Emporium

File editor

The code is written in K&R C, although header files do provide function
prototypes if __STDC__ is defined. See <linuxmt/types.h>

Header files can be found as follows:

<linuxmt/xxx.h>	[source]/include/linuxmt/xxx.h
<arch/xxx.h>	[source]/include/arch/xxx.h	(arch/i86/include is a symlink
						to this directory)

ints are 2 bytes. To work with K&R compilers you can't assume that type
conversion of function arguments will take place - so you must cast ints to
longs and vice versa if necessary.

CALLING CONVENTIONS

bcc pushes parameters right-to-left. Hence when a function is entered the
stack looks like this:

               ---+-----+-----+-----+-----+-----+-----+-----
                  | ret addr  |  param 1  |  param 2  | ...
               ---+-----+-----+-----+-----+-----+-----+-----
                     ^
                    sp

The normal entry code would then do PUSH BP; MOV BP,SP which leaves:

   ---+-----+-----+-----+-----+-----+-----+-----+-----+-----
      |  old bp   | ret addr  |  param 1  |  param 2  | ...
   ---+-----+-----+-----+-----+-----+-----+-----+-----+-----
         ^
       sp,bp

so parameters can be accessed as [bp+4], [bp+6] etc. (The 8086 does not have
an [sp+const] addressing mode)

*** THE FOLLOWING NEEDS TO BE CHECKED! ***

The function return value is in AX. Functions are expected to preserve only
the following registers when they return:

        BP, DI, SI

Additionally, BCC assumes that DS=ES=SS, so any function which alters these
needs to restore them before returning.

BCC _can_ be switched (-Mf) so that the first parameter is in AX, and that
SI/DI are saved by the caller not the callee. However since there is much
machine code which assumes the default behaviour, this should be left alone.

Commit message

This repository is read-only for this account.

Repository snapshot

Current branch
master
Visibility
public
Your access
Read
Remote
Configured

File activity

View file history