1 ; :ts=8
2 ;Copyright (C) 1983 by Manx Software Systems
3 dataseg	segment	para public 'data'
4 	extrn	$MEMRY:word
5 	extrn	_mbot_:word, sbot:word
6 	extrn	errno_:word
7 dataseg	ends
8 codeseg	segment	para public 'code'
9 	assume	cs:codeseg,ds:dataseg,es:dataseg,ss:dataseg
10 ;
11 ; sbrk(size): return address of current top & bump by size bytes
12 ;
13 	public sbrk_
14 sbrk_	proc	near
15 	mov	bx,sp
16 	push	di
17 	mov	ax,2[bx]
18 	mov	di,$MEMRY
19 	add	ax,di
20 	push	ax
21 	call	brk_
22 	pop	cx
23 	jnz	brk_error
24 	mov	ax,di		;return original value of the break
25 brk_error:
26 	pop	di
27 	test	ax,ax		;set flags for C
28 	ret
29 ;
30 ; brk(addr):	set current top address to addr
31 ;		returns 0 if ok, -1 if error
32 ;
33 	public	brk_
34 brk_:
35 	mov	bx,sp
36 	mov	ax,2[bx]
37 	cmp	ax,sbot			;check for stack/heap overflow
38 	jae	brk_ov
39 	cmp	ax,bx			;double check with sp for saftey
40 	jae	brk_ov
41 ;	cmp	ax,_mbot_		; ** DISABLED FOR ROGUE
42 ;	jb	brk_ov			; ** DISABLED FOR ROGUE
43 	mov	$MEMRY,ax	;new value is good so save it away
44 	sub	ax,ax
45 	ret
46 ; invalid request
47 brk_ov:
48 	mov	errno_,-4
49 	mov	ax,-1
50 	test	ax,ax
51 	ret
52 ;
53 ; rsvstk(size):		set saftey margin for stack
54 ;			this will make sure that at least size
55 ;			bytes of stack below the current level remain.
56 ;
57 rsvstk_:
58 	mov	bx,sp
59 	sub	bx,2[bx]
60 	mov	sbot,bx
61 	ret
62 sbrk_	endp
63 codeseg	ends
64 	end
65 ÿ