1 files changed, 122 insertions, 0 deletions
diff --git a/usr.bin/doscmd/redir.S b/usr.bin/doscmd/redir.S
new file mode 100644
index 0000000..4cb4e2e
--- /dev/null
+++ b/usr.bin/doscmd/redir.S
@@ -0,0 +1,122 @@
+! Copyright (c) 1997 Helmut Wirth <hfwirth@ping.at>
+! All rights reserved.
+!
+! Redistribution and use in source and binary forms, with or without
+! modification, are permitted provided that the following conditions
+! are met:
+! 1. Redistributions of source code must retain the above copyright
+!    notice immediately at the beginning of the file, witout modification,
+!    this list of conditions, and the following disclaimer.
+! 2. Redistributions in binary form must reproduce the above copyright
+!    notice, this list of conditions and the following disclaimer in the
+!    documentation and/or other materials provided with the distribution.
+! 3. The name of the author may not be used to endorse or promote products
+!    derived from this software without specific prior written permission.
+!
+! THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+! IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+! OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+! IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+! INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+! NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+! DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+! THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
+! (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+! THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+!
+!      $Id$
+
+
+!
+! This is the new redirector program, it replaces instbsdi.exe
+! The program fetches some pointers from DOS and reports them back to
+! the emulator via the emulator interrupt 0xff. It does not stay resident.
+
+use16
+
+.text
+.bss
+.data
+.align 0
+
+! Emulator interrupt entry
+EmulatorINT = 0xFF
+! Emulator redirector function
+EmulatorRED = 0x1
+
+! DOS interrupt
+DOSInt      = 0x21
+
+! DOS get list of lists call, returns pointer to system vars in ES:BX 
+DOSGetList  = 0x52
+
+! DOS get swappable area, returns DOS swappable area in DS:SI
+DOSGetSwapD = 0x5D06
+
+! DOS terminate program with return code
+DOSExit	    = 0x4C
+
+! DOS print message
+DOSMesg	    = 0x9
+
+cr      =       0xd
+lf      =       0xa
+eom     =       '$'             ! DOS end of string
+
+	.org 0x100
+
+.globl _main
+_main:
+	
+	mov 	ah, #DOSGetList
+	int 	DOSInt
+	jc	Fail
+	mov 	[_list], bx
+	mov 	ax, es
+	mov	[_list+2], ax
+	push 	ds
+	mov 	ax, #DOSGetSwapD
+	int 	DOSInt
+	mov	ax, ds
+	pop	ds
+	jc	Fail
+	mov 	[_swap], si
+	mov	[_swap+2], ax
+	push	ax
+	mov	ah, #EmulatorRED
+	mov	dx, [_list]
+	mov	bx, [_list+2]
+	mov	si, [_swap]
+	mov	di, [_swap+2]
+	int	EmulatorINT
+	xor	al, al			! return 0
+	jmp	Exit
+Fail:
+	mov	ah, #DOSMesg
+	mov	dx, #ErrorMessage
+	int	DOSInt
+	mov	al, #1			! return 1
+Exit:
+	mov	ah, #DOSExit
+	int 	DOSInt
+!
+!	Should never get to this point
+!
+	nop
+	nop
+	hlt
+
+! The two pointers are found using the DOS calls
+! and passed to the redirector interface via int FF
+! The two pointers are passed in BX:DX (list) and DI:SI (swap)
+
+.align	2
+
+_list:	.word 0
+	.word 0
+_swap:	.word 0
+	.word 0
+
+ErrorMessage:
+	.ascii	"Error installing redirector interface"
+	.byte	cr,lf,eom, 0