204 lines
5.5 KiB
NASM
204 lines
5.5 KiB
NASM
;
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; Command & Conquer Red Alert(tm)
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; Copyright 2025 Electronic Arts Inc.
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;
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; This program is free software: you can redistribute it and/or modify
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; it under the terms of the GNU General Public License as published by
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; the Free Software Foundation, either version 3 of the License, or
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; (at your option) any later version.
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;
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; This program is distributed in the hope that it will be useful,
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; but WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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; 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 License
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; along with this program. If not, see <http://www.gnu.org/licenses/>.
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;
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; $Header: g:/library/wwlib32/system/rcs/devtable.asm 1.2 1994/04/28 12:41:29 jeff_wilson Exp $
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;***************************************************************************
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;** C O N F I D E N T I A L --- W E S T W O O D A S S O C I A T E S **
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;***************************************************************************
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;* *
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;* Project Name : LIBRARY *
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;* *
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;* File Name : DEVTABLE.ASM *
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;* *
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;* Programmer : Christopher Yates *
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;* *
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;* Last Update : 12 December, 1990 [CY] *
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;* *
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;* Updated to 32bit protected mode JAW *
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;* *
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;*-------------------------------------------------------------------------*
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;* Functions: *
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;* *
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; VOID Init_Device_Table(BYTE *table); *
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; WORD Max_Device(VOID); *
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;* *
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;* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - *
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IDEAL
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P386
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MODEL USE32 FLAT
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LOCALS ??
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DOS equ 21h
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GLOBAL Max_Device :NEAR
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GLOBAL get_max_device :NEAR
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GLOBAL Init_Device_Table :NEAR
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CODESEG
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; ----------------------------------------------------------------
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;
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; Here are prototypes for the routines defined within this module:
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;
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; VOID Init_Device_Table(BYTE *table);
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; WORD Max_Device(VOID);
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;
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; ----------------------------------------------------------------
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;----------------------------------------------------------------------------
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;
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; WORD Max_Device(VOID);
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;
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PROC Max_Device C NEAR
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call get_max_device ; get max devices in ax
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ret
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ENDP Max_Device
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;----------------------------------------------------------------------------
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;----------------------------------------------------------------------------
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;
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;
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; returns max devices in AX
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PROC get_max_device C NEAR
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USES ebx,edx
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mov ah,25 ; get current drive service
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int DOS ; drive returned in al
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mov dl,al
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mov ah,14 ; set current as current drive
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int DOS
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dec al ; al = max drives, make it n - 1
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xor ah,ah ; clear high byte
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sub edx,edx
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mov edx,eax ; use dx to go backward to find out
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; if DOS is lying (down)
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??back_loop:
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push ds
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push ebx
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mov bl,dl ; find out about the drive in dl
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inc bl
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mov eax,0440Eh ; get the physical drive associated
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int DOS ; with this letter
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pop ebx
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pop ds
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jnc short ??later ; if c clear, no error
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cmp al,0Fh ; was it invalid? (0Fh = invalid)
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jne short ??later ; yes, so LATER
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dec edx
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jmp ??back_loop ; try, try again
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??later:
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mov eax,edx ; restore ax
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ret
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ENDP get_max_device
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;----------------------------------------------------------------------------
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;----------------------------------------------------------------------------
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;
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; VOID Init_Device_Table(BYTE *table);
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;
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PROC Init_Device_Table C NEAR
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USES eax,ebx,edi,edx
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ARG table:DWORD ; Pointer to device table.
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LOCAL curr_drive:BYTE ; Copy of current drive number.
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mov edi,[table]
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call get_max_device ; get max devices in ax
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add edi,eax
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std
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mov [curr_drive],al ; save it
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??next_drive:
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mov dl,[curr_drive] ; copy current drive #
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cmp dl,0FFh ; are we done?
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je short ??later ; if so, later
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dec [curr_drive] ; dec our local drive #
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push ds
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push ebx
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mov bl,dl ; find out about the drive in dl
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inc bl
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mov eax,0440Eh ; get the physical drive associated
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int DOS ; with this letter
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pop ebx
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pop ds
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jnc short ??it_is_real ; jump if no error
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cmp al,01 ; 1 = invalid command,
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; 0F = invalid device
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je short ??set_as_current ; 1? it is ok (RAM device)
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jmp short ??invalid ; 0Fh, it was not a device
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??it_is_real:
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cmp al,0 ; was it a fixed device?
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je short ??set_as_current ; yes, it's ok
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dec al ; make it a drive #
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cmp al,dl ; is it a valid drive?
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je short ??set_as_current
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;
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; Device was logical and not active, so clear the entry
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;
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??invalid:
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xor al,al
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stosb
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cmp [curr_drive],0 ; are we done checking?
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jge ??next_drive ; no, go to next
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jmp short ??later
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??set_as_current:
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mov al,1
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stosb
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cmp dl,0 ; are we before the A drive (invalid)
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jl short ??later ; yes, we are done checking
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jmp ??next_drive ; keep processing
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??later:
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cld
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ret
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ENDP Init_Device_Table
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;----------------------------------------------------------------------------
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END
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