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#
# Copyright (c) 1998 Robert Nordier
# All rights reserved.
#
# Redistribution and use in source and binary forms are freely
# permitted provided that the above copyright notice and this
# paragraph and the following disclaimer are duplicated in all
# such forms.
#
# This software is provided "AS IS" and without any express or
# implied warranties, including, without limitation, the implied
# warranties of merchantability and fitness for a particular
# purpose.
#
# $FreeBSD$
#
# BTX V86 interface.
#
#
# Globals.
#
.global __v86int
#
# Fields in V86 interface structure.
#
.set V86_CTL,0x0 # Control flags
.set V86_ADDR,0x4 # Int number/address
.set V86_ES,0x8 # V86 ES
.set V86_DS,0xc # V86 DS
.set V86_FS,0x10 # V86 FS
.set V86_GS,0x14 # V86 GS
.set V86_EAX,0x18 # V86 EAX
.set V86_ECX,0x1c # V86 ECX
.set V86_EDX,0x20 # V86 EDX
.set V86_EBX,0x24 # V86 EBX
.set V86_EFL,0x28 # V86 eflags
.set V86_EBP,0x2c # V86 EBP
.set V86_ESI,0x30 # V86 ESI
.set V86_EDI,0x34 # V86 EDI
#
# Other constants.
#
.set INT_V86,0x31 # Interrupt number
.set SIZ_V86,0x38 # Size of V86 structure
#
# V86 interface function.
#
__v86int: popl __v86ret # Save return address
pushl $__v86 # Push pointer
call __v86_swap # Load V86 registers
int $INT_V86 # To BTX
call __v86_swap # Load user registers
addl $0x4,%esp # Discard pointer
pushl __v86ret # Restore return address
ret # To user
#
# Swap V86 and user registers.
#
__v86_swap: xchgl %ebp,0x4(%esp,1) # Swap pointer, EBP
xchgl %eax,V86_EAX(%ebp) # Swap EAX
xchgl %ecx,V86_ECX(%ebp) # Swap ECX
xchgl %edx,V86_EDX(%ebp) # Swap EDX
xchgl %ebx,V86_EBX(%ebp) # Swap EBX
pushl %eax # Save
pushf # Put eflags
popl %eax # in EAX
xchgl %eax,V86_EFL(%ebp) # Swap
pushl %eax # Put EAX
popf # in eflags
movl 0x8(%esp,1),%eax # Load EBP
xchgl %eax,V86_EBP(%ebp) # Swap
movl %eax,0x8(%esp,1) # Save EBP
popl %eax # Restore
xchgl %esi,V86_ESI(%ebp) # Swap ESI
xchgl %edi,V86_EDI(%ebp) # Swap EDI
xchgl %ebp,0x4(%esp,1) # Swap pointer, EBP
ret # To caller
#
# V86 interface structure.
#
.comm __v86,SIZ_V86
.comm __v86ret,4
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