PAGE ,132
TITLE NTNPXEM.ASM -- Support for fielding exceptions from npx em
; Copyright (c) Microsoft Corporation 1988-1991. All Rights Reserved.
;****************************************************************
;* *
;* NTNPXEM.ASM - Exception handler for npx emulation *
;* *
;****************************************************************
;* *
;* Module Description: *
;* This module contains code to field exceptions from the *
;* Nt NPX emulator. These exceptions will only be *
;* received on machines without 387's, on which the app *
;* has set the EM bit. *
;****************************************************************
.286p
.287
; -------------------------------------------------------
; INCLUDE FILE DEFINITIONS
; -------------------------------------------------------
.xlist
.sall
include segdefs.inc
include gendefs.inc
include pmdefs.inc
include \nt\public\sdk\inc\ks386.inc
include intmac.inc
.list
; -------------------------------------------------------
; GENERAL SYMBOL DEFINITIONS
; -------------------------------------------------------
; -------------------------------------------------------
; EXTERNAL SYMBOL DEFINITIONS
; -------------------------------------------------------
extrn PmFaultEntryVector:near
; -------------------------------------------------------
; DATA SEGMENT DEFINITIONS
; -------------------------------------------------------
DXDATA segment
extrn rgw0stack:word
DXDATA ends
; -------------------------------------------------------
; Exception Handler
; -------------------------------------------------------
DXPMCODE segment
assume cs:DXPMCODE
.386p
;
; N.B. The following routine will be executed on a special
; code selector. The following routine must ALWAYS
; appear at offset zero in this code selector.
;
; -------------------------------------------------------
; NpxExceptionHandler -- This function switches to the
; exception handler stack, pushes an exception frame,
; and restores the registers. It then transfers control
; the trap 7 fault handler.
;
; Input: ss:esp -> an NT CONTEXT record
; Output: all registers restored to fault time
; values, and exception frame pushed.
; Errors: none
; Uses: all
assume ds:NOTHING,es:NOTHING,ss:NOTHING,fs:NOTHING
public NpxExceptionHandler,EndNpxExceptionHandler
NpxExceptionHandler proc far
FCLI
mov ax,ss
mov ds,ax
mov ebx,esp ; ds:ebx->CONTEXT
mov ax,SEL_DXDATA OR STD_RING
mov ss,ax
mov esp,offset DXDATA:rgw0Stack ; ss:esp->exception stack
;
; Push exception frame on exception stack
;
movzx eax,word ptr [ebx].CsSegSs
push eax
push dword ptr [ebx].CsEsp
push dword ptr [ebx].CsEFlags
movzx eax,word ptr [ebx].CsSegCs
push eax
push dword ptr [ebx].CsEip
;
; Restore registers
;
mov gs,[ebx].CsSegGs
mov fs,[ebx].CsSegFs
mov es,[ebx].CsSegEs
mov ebp,[ebx].CsEbp
mov edi,[ebx].CsEdi
mov esi,[ebx].CsEsi
mov edx,[ebx].CsEdx
mov ecx,[ebx].CsEcx
mov ax,[ebx].CsSegDs
push ax
push dword ptr [ebx].CsEbx
mov eax,[ebx].CsEax
pop ebx
pop ds
db 0eah
dw (offset PmFaultEntryVector + 21)
dw SEL_DXPMCODE OR STD_RING
EndNpxExceptionHandler:
NpxExceptionHandler endp
DXPMCODE ends
end
