* Re: bcc question
2002-05-26 1:25 bcc question Ken Martwick
@ 2002-05-26 12:03 ` Harry Kalogirou
2002-05-28 19:14 ` Robert de Bath
1 sibling, 0 replies; 3+ messages in thread
From: Harry Kalogirou @ 2002-05-26 12:03 UTC (permalink / raw)
To: Ken Martwick; +Cc: Linux 8086
Την Κυρ, 26-05-2002 στις 04:25, ο/η Ken Martwick έγραψε:
> How does one write inline assembly code in "bcc" to move
> a register value to a "C" variable? The following code
> is acceptable to "bcc", but "ld86" fails with something
> about undefined variables. I couldn't find any examples.
>
> --------------------------------------------------------
>
> int main()
> {
> int codeseg, datseg;
>
> #asm
> push cs
> pop ax
> mov codeseg,ax
> push ds
> pop ax
> mov datseg,ax
> #endasm
>
> --------------------------------------------------------
>
> Ken Martwick
>
Replace "mov codeseg,ax" with "mov _codeseg,ax" and
"mov datseg,ax" with "mov _datseg,ax" and it should be fine...
Harry
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: bcc question
2002-05-26 1:25 bcc question Ken Martwick
2002-05-26 12:03 ` Harry Kalogirou
@ 2002-05-28 19:14 ` Robert de Bath
1 sibling, 0 replies; 3+ messages in thread
From: Robert de Bath @ 2002-05-28 19:14 UTC (permalink / raw)
To: Ken Martwick; +Cc: Linux 8086
[-- Attachment #1: Type: TEXT/PLAIN, Size: 1211 bytes --]
On Sat, 25 May 2002, Ken Martwick wrote:
> How does one write inline assembly code in "bcc" to move
> a register value to a "C" variable? The following code
> is acceptable to "bcc", but "ld86" fails with something
> about undefined variables. I couldn't find any examples.
Because until recently it didn't work with local variables.
For the most recent version I've found a way of fixing the old bug where
mixed C & assembler may get out of sequence and added some more 'magic'
symbols for frame pointer offsets to the local variables (as opposed to
the existing stack pointer relative offsets).
The general method is something like this:
void mem_check()
{
/* Try int $15 EAX=$E801 */
{
unsigned int mem_64, mem_16; /* For int $15,AX=$E801 */
#asm
mov ax,#$E801
int $15
jc no_e801
mov .mem_check.mem_16[bp],ax
mov .mem_check.mem_64[bp],bx
#endasm
main_mem_top = ((unsigned long)mem_64<<6) + mem_16;
#asm
no_e801:
#endasm
}
}
I've attached the whole function which has a couple of other bits too.
--
Rob. (Robert de Bath <robert$ @ debath.co.uk>)
<http://www.cix.co.uk/~mayday>
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: Type: TEXT/X-C-SOURCE; NAME="mem_check.c", Size: 1777 bytes --]
void mem_check()
{
#ifndef __STANDALONE__
main_mem_top = 16384;
return; /* If not standalone don't try */
#else
#asm
int 0x12 ! Amount of boot memory
mov cl,#6
sal ax,cl ! In segments
mov [_boot_mem_top],ax
! Next check for extended
mov al,[_x86] ! If we ain't got a 286+ we can't access it anyway
cmp al,#2
jl is_xt
mov ah,#0x88 !
int 0x15
jnc got_ext ! Error!? This should _not_ happen ... but ...
is_xt:
xor ax,ax
got_ext:
mov word ptr [_main_mem_top+2],#0
mov [_main_mem_top],ax
#endasm
/* Rest are big memory for 80386+ */
if( x86 < 3 ) return;
/* Try int $15 EAX=$E820 */
{
struct e820_dat {
unsigned long base_lo, base_hi;
unsigned long len_lo, len_hi;
long addr_type;
} e820_item;
long epoll = 0;
do
{
e820_item.addr_type = 0;
#asm
mov eax,#$E820
mov ebx,.mem_check.epoll[bp]
mov ecx,#20
mov edx,#$534D4150
push ds
pop es
lea di,.mem_check.e820_item[bp]
int $15
jnc got_e820
xor ebx,ebx
got_e820:
mov .mem_check.epoll[bp],ebx
#endasm
if (e820_item.addr_type == 1
&& e820_item.base_hi == 0
&& e820_item.base_lo == 0x100000L)
{
/* XXX Later ... */
if (e820_item.len_hi) main_mem_top = 0x40000;
else
main_mem_top = (e820_item.len_lo >> 10);
return;
}
}
while(epoll);
}
/* Try int $15 EAX=$E801 */
{
unsigned int mem_64, mem_16; /* For int $15,AX=$E801 */
#asm
mov ax,#$E801
int $15
jc no_e801
mov .mem_check.mem_16[bp],ax
mov .mem_check.mem_64[bp],bx
#endasm
main_mem_top = ((unsigned long)mem_64<<6) + mem_16;
#asm
no_e801:
#endasm
}
#endif
}
^ permalink raw reply [flat|nested] 3+ messages in thread