Category : Assembly Language Source Code
Archive   : STDLIB_A.ZIP
Filename : SHELL.ASM

;****************************************************************************
;
; SHELL.ASM-
;
; This is a "typical" piece of starting code for the stdlib package.
; Whenever you begin a new assembly language program you should start
; with this code (or something similar to it).
;
;
; Global variables go here:
;
dseg segment para public 'data'
;
; Insert your global variables in here.
;
dseg ends
;
;
;
;
cseg segment para public 'code'
assume cs:cseg, ds:dseg
;
include stdlib.a
;
; lesi- macro to do a "les di, constant"
;
lesi macro adrs
mov di, seg adrs
mov es, di
lea di, adrs
endm
;
; ldxi- macro to do a "ldx si, constant" operation.
;
ldxi macro adrs
mov dx, seg adrs
lea si, adrs
endm
;
; Variables that wind up being used by the standard library routines.
; The MemInit routine uses "PSP" and "zzzzzzseg" labels. They must be
; present if you intend to use getenv, MemInit, malloc, and free.
;
;
public PSP
PSP dw ? ;Must be in CODE segment!
;
;
; Some useful constants:
;
cr equ 13
lf equ 10
eos equ 0
;
true equ 1
false equ 0
;
;
; Main is the main program. Program execution always begins here.
;
Main proc
mov cs:PSP, es ;Save pgm seg prefix
mov ax, seg dseg ;Set up the segment registers
mov ds, ax
mov es, ax
mov dx, 0 ;Allocate all available RAM.
MemInit
;
; Insert your main program here:
;
Quit: mov ah, 4ch
int 21h
;
Main endp
;
;
;
; Insert other procedures and functions down here.
;
;
;
cseg ends
;
;
; Allocate a reasonable amount of space for the stack (2k).
;
sseg segment para stack 'stack'
stk db 256 dup ("stack ")
sseg ends
;
;
;
; zzzzzzseg must be the last segment that gets loaded into memory!
; WARNING! Do not insert any segments (or other code/data) after
; this segment.
;
zzzzzzseg segment para public 'zzzzzz'
LastBytes db 16 dup (?)
heap db 1024 dup (?) ;Gets grabbed by Mem Mgr anyway!
zzzzzzseg ends
end Main