7bf4b77233
Because ia16-elf-gcc and the GNU linker do not understand OMF we need to use ELF everywhere. This also means we cannot use "wrt", "seg" and "call/jmp far". Most wrt's are superfluous, and seg and call/jmp far can be replaced by explicit ?GROUP references (to be defined in the linker script).
595 lines
18 KiB
NASM
595 lines
18 KiB
NASM
;
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; File:
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; io.asm
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; Description:
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; DOS-C I/O Subsystem
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;
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; Copyright (c) 1998
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; Pasquale J. Villani
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; All Rights Reserved
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;
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; This file is part of DOS-C.
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;
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; DOS-C is free software; you can redistribute it and/or
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; modify it under the terms of the GNU General Public License
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; as published by the Free Software Foundation; either version
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; 2, or (at your option) any later version.
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;
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; DOS-C is distributed in the hope that it will be useful, but
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; WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
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; the GNU General Public License for more details.
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;
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; You should have received a copy of the GNU General Public
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; License along with DOS-C; see the file COPYING. If not,
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; write to the Free Software Foundation, 675 Mass Ave,
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; Cambridge, MA 02139, USA.
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;
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; $Header$
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;
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%include "segs.inc"
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%include "stacks.inc"
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extern ConTable
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extern LptTable
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extern ComTable
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extern uPrtNo
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extern CommonNdRdExit
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;!! extern _NumFloppies
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extern blk_stk_top
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extern clk_stk_top
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extern _reloc_call_blk_driver
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extern _reloc_call_clk_driver
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extern _TEXT_DGROUP
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;---------------------------------------------------
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;
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; Device entry points
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;
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; This really should be a struct and go into a request.inc file
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;
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cmdlen equ 0 ; Length of this command
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unit equ 1 ; Subunit Specified
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cmd equ 2 ; Command Code
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status equ 3 ; Status
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media equ 13 ; Media Descriptor
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trans equ 14 ; Transfer Address
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count equ 18 ; Count of blocks or characters
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start equ 20 ; First block to transfer
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vid equ 22 ; Volume id pointer
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huge equ 26 ; First block (32-bit) to transfer
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;
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; The following is the "array" of device driver headers for the internal
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; devices. There is one header per device including special aux: and prn:
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; pseudo devices. These psuedo devices are necessary for printer
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; redirection, i.e., serial or parallel ports, and com port aux selection.
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;
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; The devices are linked into each other and terminate with a -1 next
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; pointer. This saves some time on boot up and also allows us to throw all
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; device initialization into a single io_init function that may be placed
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; into a discardable code segmemnt.
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;
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segment _IO_FIXED_DATA
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;
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; The "CON" device
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;
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; This device is the standard console device used by
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; DOS-C and kernel
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;
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global _con_dev
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_con_dev equ $
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dw _prn_dev,LGROUP
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dw 8013h ; con device (stdin & stdout)
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dw GenStrategy
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dw ConIntr
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db 'CON '
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;
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; Generic prn device that can be redirected via mode
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;
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global _prn_dev
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_prn_dev dw _aux_dev,LGROUP
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dw 0A040h
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dw GenStrategy
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dw PrnIntr
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db 'PRN '
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;
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; Generic aux device that can be redirected via mode
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;
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global _aux_dev
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_aux_dev dw _Lpt1Dev,LGROUP
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dw 8000h
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dw GenStrategy
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dw AuxIntr
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db 'AUX '
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;
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; Printer device drivers
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;
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_Lpt1Dev dw _Lpt2Dev,LGROUP
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dw 0A040h
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dw GenStrategy
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dw Lpt1Intr
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db 'LPT1 '
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_Lpt2Dev dw _Lpt3Dev,LGROUP
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dw 0A040h
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dw GenStrategy
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dw Lpt2Intr
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db 'LPT2 '
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_Lpt3Dev dw _Com1Dev,LGROUP
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dw 0A040h
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dw GenStrategy
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dw Lpt3Intr
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db 'LPT3 '
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;
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; Com device drivers
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;
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_Com1Dev dw _Com2Dev,LGROUP
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dw 8000h
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dw GenStrategy
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dw AuxIntr
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db 'COM1 '
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_Com2Dev dw _Com3Dev,LGROUP
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dw 8000h
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dw GenStrategy
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dw Com2Intr
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db 'COM2 '
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_Com3Dev dw _Com4Dev,LGROUP
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dw 8000h
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dw GenStrategy
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dw Com3Intr
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db 'COM3 '
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_Com4Dev dw _clk_dev,LGROUP
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dw 8000h
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dw GenStrategy
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dw Com4Intr
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db 'COM4 '
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;
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; Header for clock device
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;
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global _clk_dev
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_clk_dev equ $
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dw _blk_dev,LGROUP
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dw 8008h ; clock device
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dw GenStrategy
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dw clk_entry
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db 'CLOCK$ '
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;
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; Header for device
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;
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global _blk_dev
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_blk_dev equ $
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dd -1
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dw 08c2h ; block device with ioctl
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dw GenStrategy
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dw blk_entry
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db 4
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db 0,0,0,0,0,0,0
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;
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; Temporary table until next release
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;
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segment _IO_FIXED_DATA
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DiskTable db 0
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;
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; Local storage
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;
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%if 0
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segment _BSS
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blk_dos_stk resw 1
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blk_dos_seg resw 1
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clk_dos_stk resw 1
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clk_dos_seg resw 1
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%endif
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segment _IO_TEXT
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global _ReqPktPtr
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_ReqPktPtr dd 0
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uUnitNumber dw 0
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;
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; Name:
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; GenStrategy
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;
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; Function:
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; Store the pointer to the request packet passed in es:bx
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;
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; Description:
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; Generic strategy routine. Unlike the original multitasking versions,
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; this version assumes that no more thank one device driver is active
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; at any time. The request is stored into memory in the one and only
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; location available for that purpose.
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;
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global GenStrategy
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GenStrategy:
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mov word [cs:_ReqPktPtr],bx
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mov word [cs:_ReqPktPtr+2],es
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retf
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;
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; Name:
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; XXXXIntr
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;
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; Function:
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; Individual Interrupt routines for each device driver
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;
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; Description:
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; This is actually a single routine with entry points for each device.
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; The name used for the entry point is the device name with Intr
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; appended to it.
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;
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; Funtionally, each device driver has an entry and an associated
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; table. The table is a structure that consists of a control byte
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; followed by an array of pointers to C functions or assembly
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; subroutines that implement the individual device driver functions.
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; This allows the usage of common error dummy filler code to be used.
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; It also allows standardization of the calling procedure for these
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; internal device driver functions.
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;
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; Assembler call/return convention:
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; Each driver function is entered by a jump into the function and
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; exits by a jump to the appropriate success or error exit routine.
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; This speeds up the call and return and helps to minimize the stack
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; useage. The contents of the request packet are passed to each
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; routine in registers as follows:
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;
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; Register Function Description
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; -------- -------- -----------
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; al unit Subunit Specified
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; ah media Media Descriptor
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; cx count Count of blocks or characters
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; dx start First block to transfer
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; es:di trans Transfer Address
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; ds:bx reqptr Request pointer
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; cs kernel code segment
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; ds kernel data segment
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;
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; The exit routines generally set the status based on the individual
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; routine. For example, _IOSuccess will clear the count where
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; _IOErrCnt will subtract the remaining amount in cx from the original
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; count. See each utility routine for expectations.
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;
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; C call/return convention:
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; The C calling convention simply sets up the C stack and passes the
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; request packet pointer as a far pointer to the function. Although
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; the utility routine names are such that they are accesible from the
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; C name space, they are cannot used. Instead, the common interrupt
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; code expects a return status to set in the request packet. It is up
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; to the device driver function to set the appropriate fields such as
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; count when an error occurs.
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;
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; How to differntiate between the two calling conventions:
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; This code is entirely table driven. The table is a structure that
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; is generally in the _IO_FIXED_DATA segment. It consists of a flag
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; byte followed by short pointers to the driver functions. Selecting
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; a driver type is accomplished by setting the type bit in the flag
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; (see below).
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;
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; 7 6 5 4 3 2 1 0
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; +---+---+---+---+---+---+---+---+
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; | | | | | | | | |
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; +---+---+---+---+---+---+---+---+
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; | | | |--- Number of table entries
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; | | +-------------------+
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; | | |----------------------- Reserved
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; | +-------+
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; +--------------------------------- type bit (1 == C / 0 == asm)
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;
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ConIntr:
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push si
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mov si,ConTable
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jmp short CharIntrEntry
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PrnIntr:
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push si
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push ax
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xor ax,ax
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jmp short LptCmnIntr
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Lpt1Intr:
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push si
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push ax
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xor al,al
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mov ah,1
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jmp short LptCmnIntr
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Lpt2Intr:
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push si
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push ax
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mov al,1
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mov ah,2
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jmp short LptCmnIntr
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Lpt3Intr:
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push si
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push ax
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mov al,2
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mov ah,3
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LptCmnIntr:
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mov si,LptTable
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mov [cs:uPrtNo],ah
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jmp short DiskIntrEntry
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AuxIntr:
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push si
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push ax
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xor al,al
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jmp short ComCmnIntr
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Com2Intr:
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push si
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push ax
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mov al,1
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jmp short ComCmnIntr
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Com3Intr:
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push si
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push ax
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mov al,2
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jmp short ComCmnIntr
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Com4Intr:
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push si
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push ax
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mov al,3
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jmp short ComCmnIntr
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ComCmnIntr:
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mov si,ComTable
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jmp short DiskIntrEntry
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DskIntr:
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push si
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mov si,DiskTable
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CharIntrEntry:
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push ax
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DiskIntrEntry:
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push cx
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push dx
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push di
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push bp
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push ds
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push es
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push bx
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mov byte [cs:uUnitNumber],al
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lds bx,[cs:_ReqPktPtr]
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test byte [cs:si],80h
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je AsmType
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mov al,[bx+cmd]
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cmp al,[cs:si]
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ja _IOCommandError
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cbw
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shl ax,1
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add si,ax
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xchg di,ax
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push ds
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push bx
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mov bp,sp
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mov ds,[cs:_TEXT_DGROUP]
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cld
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call word [cs:si+1]
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pop cx
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pop cx
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jmp short StoreStatus
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AsmType: mov al,[bx+unit]
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mov ah,[bx+media]
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mov cx,[bx+count]
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mov dx,[bx+start]
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xchg di,ax
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mov al,[bx+cmd]
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cmp al,[cs:si]
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ja _IOCommandError
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cbw
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shl ax,1
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add si,ax
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xchg di,ax
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les di,[bx+trans]
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mov ds,[cs:_TEXT_DGROUP]
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cld
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jmp word [cs:si+1]
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;
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; Name:
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; _IOXXXXXXX
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;
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; Function:
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; Exit routines for internal device drivers.
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;
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; Description:
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; These routines are the exit for internal device drivers. _IOSuccess
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; is for read/write functions and correctly returns for a successful
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; read/write operation by setting the remainng count to zero. _IOExit
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; simply sets success bit and returns. _IODone returns complete and
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; busy status. _IOCommandError returns and error status for invalid
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; commands. _IOErrCnt corrects the remaining bytes for errors that
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; occurred during partial read/write operation. _IOErrorExit is a
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; generic error exit that sets done and error.
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;
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global _IOSuccess
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_IOSuccess:
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lds bx,[cs:_ReqPktPtr]
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xor ax,ax
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mov [bx+count],ax
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global _IOExit
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_IOExit:
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mov ah,1
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StoreStatus:
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lds bx,[cs:_ReqPktPtr]
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mov [bx+status],ax
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pop bx
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pop es
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pop ds
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pop bp
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pop di
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pop dx
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pop cx
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pop ax
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pop si
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retf
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global _IODone
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_IODone:
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mov ah,3
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jmp short StoreStatus
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global _IOCommandError
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_IOCommandError:
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mov al,3
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global _IOErrCnt
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_IOErrCnt:
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lds bx,[cs:_ReqPktPtr]
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sub [bx+count],cx
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global _IOErrorExit
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_IOErrorExit:
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mov ah,81h
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jmp short StoreStatus
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;
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; Name:
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; GetUnitNum
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;
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; Function:
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; Return the internally set unit number.
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;
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; Description:
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; Simply return the contents of uUnitNumber. This version relies on
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; no segment registers and makes a safe call regardless of driver
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; state.
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;
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global GetUnitNum
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GetUnitNum:
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mov dx,[cs:uUnitNumber]
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ret
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;
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; These are still old style DOS-C drivers. I'll replace
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; them in the next release
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;
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;
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; block device interrupt
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;
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; NOTE: This code is not standard device driver handlers
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; It is written for sperate code and data space.
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;
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blk_driver_params:
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dw blk_stk_top
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dw _reloc_call_blk_driver
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dw DGROUP
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clk_driver_params:
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dw clk_stk_top
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dw _reloc_call_clk_driver
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dw DGROUP
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; clock device interrupt
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clk_entry:
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pushf
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push bx
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mov bx, clk_driver_params
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jmp short clk_and_blk_common
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; block device interrupt
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blk_entry:
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pushf
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push bx
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mov bx, blk_driver_params
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clk_and_blk_common:
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push ax
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push cx
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push dx
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; small model
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mov ax,sp ; use internal stack
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mov dx,ss
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pushf ; put flags in cx
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pop cx
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cli ; no interrupts
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mov ss,[cs:_TEXT_DGROUP]
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mov sp,[cs:bx]
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push cx
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popf ; restore interrupt flag
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push ax ; save old SS/SP
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push dx
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; push these registers on
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push ds ; BLK_STACK
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push bp ; to save stack space
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push si
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push di
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push es
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Protect386Registers
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mov ds,[cs:_TEXT_DGROUP] ;
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push word [cs:_ReqPktPtr+2]
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push word [cs:_ReqPktPtr]
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call far [cs:bx+2]
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pop cx
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pop cx
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les bx,[cs:_ReqPktPtr] ; now return completion code
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mov word [es:bx+status],ax ; mark operation complete
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Restore386Registers
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pop es
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pop di
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pop si
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pop bp
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pop ds
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pop dx ; get back old SS/SP
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pop ax
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cli ; no interrupts
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mov ss,dx ; use dos stack
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mov sp,ax
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pop dx
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pop cx
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pop ax
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pop bx
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popf
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retf
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