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The C Users' Group Library 1994 August
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wc-cdrom-cusersgrouplibrary-1994-08.iso
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v_07_04
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v7n4079a.txt
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1989-03-10
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7KB
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279 lines
page 60, 132
name startup
title ROM System Startup Code for Turbo C 2.0
;
; ROM System Startup Code for Turbo C 2.0
; Copyright (C) 1987, 1988, 1989 by Paradigm Systems.
; All rights reserved.
;
; Assemble with MASM as follows:
;
; masm tc /mx /d__MODEL__ ;
;
; where
; __MODEL__ is one of the following:
;
; __SMALL__ Small memory model
; __COMPACT__ Compact memory model
; __MEDIUM__ Medium memory model
; __LARGE__ Large memory model
;
; If no memory model is specified, the small memory
; model is assumed and a warning is issued.
;
;
; Segment and group declarations. The order of these
; declarations is used to control the order of
; segments in the .EXE file since the Microsoft and
; Borland linkers copy segments in the same order
; they are encountered in the object files.
;
; The default Borland model is to have the stack
; after the heap in the small and medium memory
; models. This startup assumes that the stack
; will follow immediately after the BSS area.
;
; Make sure that this startup module is specified
; first when linking the application. Requires
; MASM 5.10 to assemble.
;
_text segment byte public 'CODE'
_text ends
_etext segment para public 'CODEEND'
_etext ends
_data segment para public 'DATA'
_data ends
_bss segment para public 'BSS'
_bss ends
_bssend segment byte public 'BSSEND'
_bssend ends
_stack segment para stack 'STACK'
_stack ends
romdata segment para public 'ROMDATA'
romdata ends
IFDEF __SMALL__
dgroup group _data, _bss, _bssend, _stack
assume cs:_text, ds:dgroup, es:nothing, ss:dgroup
ELSEIFDEF __COMPACT__
dgroup group _data, _bss, _bssend
assume cs:_text, ds:dgroup, es:nothing, ss:_stack
ELSEIFDEF __MEDIUM__
dgroup group _data, _bss, _bssend, _stack
assume cs:_text, ds:dgroup, es:nothing, ss:dgroup
ELSEIFDEF __LARGE__
dgroup group _data, _bss, _bssend
assume cs:_text, ds:dgroup, es:nothing, ss:_stack
ELSE
dgroup group _data, _bss, _bssend, _stack
assume cs:_text, ds:dgroup, es:nothing, ss:dgroup
ENDIF
;
; Make up the correct external references that
; depend on the memory model
;
.xlist
IF1 ; Only expand these
IFDEF __SMALL__ ; on pass 1
extrn _main : near
%out Assembling for small memory model
ELSEIFDEF __COMPACT__
extrn _main : near
%out Assembling for compact memory model
ELSEIFDEF __MEDIUM__
extrn _main : far
%out Assembling for medium memory model
ELSEIFDEF __LARGE__
extrn _main : far
%out Assembling for large memory model
ELSE
%out Warning: No model - small model assumed
extrn _main : near
ENDIF
ENDIF
.list
subttl Startup code for Turbo C V2.0
page
_text segment
public start
start proc far
cli ; Disable interrupts
cld
;
; Set up the stack according to the memory model.
;
IFDEF __SMALL__
mov ax, dgroup
mov ss, ax
mov sp, offset DGROUP:tos
ELSEIFDEF __MEDIUM__
mov ax, dgroup
mov ss, ax
mov sp, offset DGROUP:tos
ELSEIFDEF __COMPACT__
mov ax, _stack
mov ss, ax
mov sp, offset tos
ELSEIFDEF __LARGE__
mov ax, _stack
mov ss, ax
mov sp, offset tos
ELSE
mov ax, dgroup
mov ss, ax
mov sp, offset DGROUP:tos
ENDIF
;
; Prepare the segment registers for initialization.
;
mov ax, dgroup ; Get the target segment
mov es, ax ; for DGROUP
mov ax, romdata ; Get the segment for the
mov ds, ax ; copy of DGROUP
;
; Copy DGROUP from its position in ROM (just after
; the code class) to the target address in RAM
;
mov si, offset DGROUP:idata
mov di, si
mov cx, offset DGROUP:bdata
sub cx, di
rep movsb
push es
pop ds
;
; Zero out the BSS area
;
xor al, al
mov di, offset DGROUP:bdata
mov cx, offset DGROUP:edata
sub cx, di
rep stosb
;
; Call the C language entry point
;
sti
call _main ; Call the Turbo C main()
;
; Restart the process should main() return
;
jmp start
start endp
;
; These routines are defined to satisfy any error
; handling routines that might need to give up on
; an error. An example of this would be the
; stack checking routine calling abort if a stack
; overflow has been detected.
;
public _exit, __exit, _abort
_abort proc ; User customized
jmp start
_abort endp
_exit proc ; User customized
jmp start
_exit endp
__exit proc ; User customized
jmp start
__exit endp
;
; This is code given control when Turbo C detects
; a stack overflow. It simply sets up a new stack
; (it assumes that BP contains the original value
; of the stack) and exits.
;
public OVERFLOW@
OVERFLOW@ proc
jmp start
OVERFLOW@ endp
_text ends
subttl Segment Declarations
page
_etext segment
public tend
tend label byte ; Mark the segment end
db ?
_etext ends
romdata segment
public rdata
rdata label byte
romdata ends
_data segment
public idata, _errno
idata label byte
_errno dw 0
IFDEF __SMALL__
public ___brklvl
___brklvl dw offset DGROUP:edata
ELSEIFDEF __MEDIUM__
public ___brklvl
___brklvl dw offset DGROUP:edata
ELSEIFDEF __COMPACT__
public __stklen
__stklen dw offset tos
ELSEIFDEF __LARGE__
public __stklen
__stklen dw offset tos
ELSE
public __brklvl
__brklvl dw offset DGROUP:edata
ENDIF
_data ends
_bss segment
public bdata
bdata label byte ; Mark the start of
; the _BSS (and the
_bss ends ; end of _DATA
_bssend segment
public edata
edata label byte ; Mark the end of
IFDEF __COMPACT__ ; the BSS
db ?
ELSEIFDEF __LARGE__
db ?
ENDIF
_bssend ends
_stack segment
public tos ; Make the TOS visible
dw 256 dup (?) ; Declare the stack size
tos label word ; Define the top of stack
_stack ends
end start