fpedos4g.asm

来自「开放源码的编译器open watcom 1.6.0版的源代码」· 汇编 代码 · 共 141 行

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;
; FPE387        : connect/disconnect 80x87 interrupt handler under rational
;               : dos extender
;
; For the IBM PC, we use IRQ13 (math coprocessor exception)
; Level     Function
; NMI       Parity, Watchdog Timer,
;           Arbitration time-out,
;           Channel Check
; IRQ 0     Timer
; IRQ 1     Keyboard
; IRQ 2     Cascaded Interrupt Control -- IRQ  8 Real Time Clock
;                                         IRQ  9 Redirect Cascade
;                                         IRQ 10 Reserved
;                                         IRQ 11 Reserved
;                                         IRQ 12 Mouse
;                                         IRQ 13 Math Coprocessor Exception
;                                         IRQ 14 Fixed Disk
;                                         IRQ 15 Reserved
; IRQ 3     Serial Alternate
; IRQ 4     Serial Primary
; IRQ 5     Reserved
; IRQ 6     Diskette
; IRQ 7     Parallel Port
; IRQ 8 through 15 are cascaded through IRQ 2
;
; IRQ 0 through  7 map to INT 08 through INT 0F
; IRQ 8 through 15 map to INT 70 through INT 77
;
;
; For the NEC PC (286, 386), we use IRQ 8 (math coprocessor exception)
; Level     Function                                Vector Number
; IRQ  0     Timer                                  08
; IRQ  1     Keyboard                               09
; IRQ  2     CTRV                                   0A
; IRQ  3     Expansion bus INT0                     0B
; IRQ  4     Serial Primary (RS-232C ch0)           0C
; IRQ  5     Expansion bus INT1                     0D
; IRQ  6     Expansion bus INT2                     0E
; IRQ  7     Slave                                  0F
; IRQ  8     Math coprocessor (286, 386, ...)       10
; IRQ  9     Expansion bus INT3 (HD, HDLC)          11
; IRQ 10     Expansion bus INT41 (640KB FD)         12
; IRQ 11     Expansion bus INT42 (1MB FD)           13
; IRQ 12     Expansion bus INT5 (RS-232C ch1, ch2)  14
; IRQ 13     Expansion bus INT6 (mouse)             15
; IRQ 14     Reserved (math coprocessor in 70116)   16
; IRQ 15     Reserved                               17
;
; IRQ 0 through  7 map to INT 08 through INT 0F
; IRQ 8 through 15 map to INT 10 through INT 17

.8087
.386p

include struct.inc
include mdef.inc
include extender.inc


        xref            __FPE2Handler_  ; handle exceptions w/o OUT's

        modstart fpedos4g

        datasegment

        extrn   "C",__PMAddr    : dword
        extrn   "C",__PMSeg     : word
        extrn   "C",__FPE_int   : byte  ; defined in \clib\math\c\fpeint.c

        enddata

        xdefp __DOS4G_hook_init_
defp    __DOS4G_hook_init_
        push    DS                      ; save DS
        mov     AH,35h                  ; get interrupt handler for
        mov     AL,__FPE_int            ; for INT 2 (INT 10 on NEC)
        int     21h                     ; ...
        mov     __PMAddr,EBX            ; save protected-mode interrupt vector
        mov     __PMSeg,ES              ; ...
        mov     AH,25h                  ; set new FPE handler
        mov     AL,__FPE_int            ; get interrupt number
        mov     DX,CS                   ; set DS:EDX pointing to handler
        mov     DS,DX                   ; ...
        lea     EDX,__FPE2Handler_      ; ...
        int     21h                     ; set it
        pop     DS                      ; restore DS
        ret                             ; return
endproc __DOS4G_hook_init_

;
;/* Disconnect */
;

        xdefp __DOS4G_hook_fini_
defp    __DOS4G_hook_fini_
        push    DS                      ; save DS
        mov     AH,25h                  ; set old FPE handler
        mov     AL,__FPE_int            ; get interrupt number
        mov     EDX,__PMAddr            ; set DS:EDX pointing to old handler
        mov     DS,__PMSeg              ; ...
        int     21h                     ; restore previous interrupt handler
        pop     DS                      ; restore DS
        ret                             ; return
endproc __DOS4G_hook_fini_

        endmod
        end