#
# 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.
#

#
# 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