Hi!
20-Ноя-2005 16:57 [EMAIL PROTECTED] (Kenneth Davis) wrote to
[EMAIL PROTECTED]:
> --- NEW FILE: intwrap.asm ---
> reloc_call_int13_handler:
> cli ; disable other interrupts for now
INT instruction already disables IFlag.
> stc ; force error unless BIOS clears
?! This is issue of caller to set or reset CFlag.
> push dx ; store BIOS drive # for error handling usage
> push ds ; get segment of kernel DATA
> mov ds, [cs:_DGROUP_]
> pushf ; simulate int call so returns back here (flags+cs:ip on
> stack)
> call far [ds:_UserInt13]
Bug!!! Here DS register is garbaged, whereas it used by some functions
(for example, INT13/42).
> pop ds ; restore ds
> jc int13err ; test if error, if not return to caller
> int13iret:
> inc sp ; clean up stack
> inc sp
> sti ; ensure int's are renabled
> retf 2 ; return to caller leaving flags asis
I don't think that this is right way, because caller may disable
interrupts for own purposes, whereas here interrupts enabled.
> int13wrap:
> %IF XCPU < 186
> push ax ; preserve registers, setup stack frame
> push bp
> mov bp, sp
> mov ax, 13h ; want to push 0x13 onto stack
> xchg ax, [bp+2] ; so restore pushed ax value and put 0x13 on stack
> pop bp ; clean up stack frame (leaving just 0x13 pushed on stack)
push bp
push bp
mov bp,sp
mov word [bp+2],13h
pop bp
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