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|
/* Copyright (C) 1995,1996 Robert de Bath <rdebath@cix.compulink.co.uk>
* This file is part of the Linux-8086 C library and is distributed
* under the GNU Library General Public License.
*/
#include <errno.h>
/****************************************************************************/
#ifdef L_errno
int errno = 0; /* libc error value */
#endif
/****************************************************************************/
#ifdef __AS386_16__
#ifdef L___brk_addr
#asm
.data
export brk_addr
brk_addr: .word __end ! This holds the current return for sbrk(0)
.text
#endasm
#endif
/****************************************************************************/
#ifdef L_sbrk
int sbrk(brk_off)
int brk_off;
{
#asm
mov bx,sp
#if !__FIRST_ARG_IN_AX__
mov ax,[bx+2] ! Fetch the requested value
#endif
test ax,ax
jnz has_change
mov ax,[brk_addr] ! Simple one, read current - can`t fail.
jmp eof
has_change:
js go_down
add ax,[brk_addr] ! Goin up!
jc Enomem
sub bx,#511 ! Safety space 512 bytes
cmp bx,ax ! Too close ?
jb Enomem
sbrk_ok:
#ifndef __MSDOS__
push ax ! MSDOS `kernel` doesn`t care
call ___brk ! Tell the kernel
test ax,ax
pop ax ! ASSUME ___brk doesn`t alter stack!
jnz Enomem ! Ugh! kernel didn`t like the idea!
#endif
xchg [brk_addr],ax ! Save away new val
jmp eof ! Return it
go_down:
add ax,[brk_addr]
jnc Enomem
cmp ax,#__end
jae sbrk_ok
Enomem:
mov ax,#12 ! This should be ENOMEM not a magic.
mov [_errno],ax
mov ax,#-1
eof:
#endasm
}
#endif
/****************************************************************************/
#ifdef L_brk
int
brk(new_brk)
char * new_brk;
{
#asm
mov bx,sp
#if !__FIRST_ARG_IN_AX__
mov ax,[bx+2] ! Fetch the requested value
#endif
sub bx,#512 ! Safety space 512 bytes
cmp bx,ax ! Too close ?
jb Enomem
cmp ax,#__end
jae brk_ok
Enomem:
mov ax,#12 ! This should be ENOMEM not a magic.
mov [_errno],ax
mov ax,#-1
ret
brk_ok:
#ifndef __MSDOS__
push ax
call ___brk ! Tell the kernel
test ax,ax
pop bx ! ASSUME ___brk doesn`t alter stack!
jnz Enomem ! Ugh! kernel didn`t like the idea!
mov [brk_addr],bx ! Save away new val
#else
mov [brk_addr],ax ! MSDOS `kernel` doesn`t care
mov ax,#0
#endif
#endasm
}
#endif
#endif
/****************************************************************************/
#ifdef __AS386_32__
extern char * __brk_addr;
extern char * __brk();
#ifdef L___brk_addr
char * __brk_addr = 0; /* This holds the current return for sbrk(0) */
char *
__brk(val)
{
#asm
#if __FIRST_ARG_IN_AX__
mov ebx,eax
#else
mov ebx,[esp+4]
#endif
mov eax,#45
int $80
#endasm
}
__brk_addr_init()
{
if( __brk_addr == 0 && (__brk_addr = __brk(0)) == 0 )
{
errno = ENOMEM;
return -1;
}
return 0;
}
#endif
#ifdef L_sbrk
char *
sbrk(brk_off)
int brk_off;
{
char * new_brk;
if( __brk_addr_init() ) return (char*)-1;
if( brk_off == 0 ) return __brk_addr;
new_brk = __brk_addr + brk_off;
__brk_addr = __brk(new_brk);
if( __brk_addr != new_brk )
{
errno = ENOMEM;
return (char*)-1;
}
return __brk_addr - brk_off;
}
#endif
#ifdef L_brk
int
brk(new_brk)
char * new_brk;
{
if( __brk_addr_init() ) return -1;
__brk_addr = __brk(new_brk);
if( __brk_addr == new_brk ) return 0;
errno = ENOMEM;
return -1;
}
#endif
#endif
|
