Help getting multiple keypresses in a DOS compiler

This is a discussion on Help getting multiple keypresses in a DOS compiler within the Game Programming forums, part of the General Programming Boards category; Ok, I need help getting multiple keypresses at once in a DOS compilier. I'm using Turbo C++ 3.1, and I ...

  1. #1
    Registered User
    Join Date
    Mar 2005
    Posts
    2

    Help getting multiple keypresses in a DOS compiler

    Ok, I need help getting multiple keypresses at once in a DOS compilier. I'm using Turbo C++ 3.1, and I need up to 4 keys at once. It's a 2 player ASCII game where little dudes fly across the center and block your bullets and there is a player at the top and bottom, and they have to hit and kill each other. I need each player to be able to move and fire while the other player may be doing the same. Thanks in advance.

  2. #2

  3. #3
    Budding Synth Programmer samGwilliam's Avatar
    Join Date
    Feb 2002
    Location
    Trefforest
    Posts
    368
    Code:
    // Codes for ISR redirect
    
    #define KEYB_INT 0x09
    #define KEYB_BUF 0x60
    #define KEYB_CONT 0x61
    #define INT_CONT 0x20
    
    #define MAX_SCANS 89
    
    // List of scan codes (make only):
    
    #define K_ESC            1
    #define K_1              2
    #define K_2              3
    #define K_3              4
    #define K_4              5
    #define K_5              6
    #define K_6              7
    #define K_7              8
    #define K_8              9
    #define K_9             10
    #define K_0             11
    #define K_MINUS         12
    #define K_EQUALS        13
    #define K_BACK_SPACE    14
    #define K_TAB           15
    #define K_Q             16
    #define K_W             17
    #define K_E             18
    #define K_R             19
    #define K_T             20
    #define K_Y             21
    #define K_U             22
    #define K_I             23
    #define K_O             24
    #define K_P             25
    #define K_LEFT_BRACKET  26
    #define K_RIGHT_BRACKET 27
    #define K_ENTER         28
    #define K_CONTROL       29
    #define K_A             30
    #define K_S             31
    #define K_D             32
    #define K_F             33
    #define K_G             34
    #define K_H             35
    #define K_J             36
    #define K_K             37
    #define K_L             38
    #define K_SEMI_COLON    39
    #define K_APOSTROPHE    40
    #define K_LEFT_SHIFT    42
    #define K_BACK_SLASH    43
    #define K_Z             44
    #define K_X             45
    #define K_C             46
    #define K_V             47
    #define K_B             48
    #define K_N             49
    #define K_M             50
    #define K_COMMA         51
    #define K_FULL_STOP     52
    #define K_FORWARD_SLASH 53
    #define K_RIGHT_SHIFT   54
    #define K_PRINT_SCREEN  55
    #define K_ALT           56
    #define K_SPACE         57
    #define K_CAPS_LOCK     58
    #define K_F1            59
    #define K_F2            60
    #define K_F3            61
    #define K_F4            62
    #define K_F5            63
    #define K_F6            64
    #define K_F7            65
    #define K_F8            66
    #define K_F9            67
    #define K_F10           68
    
    #define K_F11           87
    #define K_F12           88
    
    #define K_NUM_LOCK      69
    #define K_SCROLL_LOCK   70
    #define K_HOME          71
    #define K_UP            72
    #define K_PAGE_UP       73
    #define K_NUM_MINUS     74
    #define K_LEFT          75
    #define K_NUM_5         76
    #define K_RIGHT         77
    #define K_NUM_PLUS      78
    #define K_END           79
    #define K_DOWN          80
    #define K_PAGE_DOWN     81
    #define K_INSERT        82
    #define K_DELETE        83
    
    unsigned char keyPressed = FALSE;			// Flags the press of a key.
    unsigned char rawKey;								// The last scan code generated.
    unsigned char keySet [MAX_SCANS]; 		// One for every key on the board.
    
    // Various functions delaing with the keyboard input.
    
    void interrupt newKeybInt (...);			// For the keyboard.
    void interrupt (*oldKeybInt) (...);			// Keep copy of old one.
    
    inline char isPressed (unsigned char scanCode, unsigned char turnOff);
    Code:
    void interrupt newKeybInt (...)
    {
    	// This asm code courtesy of 'Tricks of the Game Programming Gurus' book:
    
    	asm
    	{
    		sti
    		in al, KEYB_BUF
    		xor ah, ah
    		mov rawKey, al
    		in al, KEYB_CONT
    		or al, 0x82
    		out KEYB_CONT, al
    		and al, 0x7f
    		out KEYB_CONT, al
    		mov al, 0x20
    		out INT_CONT, al
    	}
    
    	if (rawKey < MAX_SCANS)        			// If a make code.
    	{
    		keySet [rawKey] = TRUE;			// Turn that key flag on.
    		keyPressed = TRUE;
    	}
    
    	else                             		// Else must be a break code,
    	{
    		keySet [rawKey - 128] = FALSE;		// so turn it off.
    		keyPressed = FALSE;
    	}
    }
    
    inline char isPressed (unsigned char scanCode, unsigned char turnOff)
    {
    	if (keySet [scanCode])
    	{
    		if (turnOff)
    			keySet [scanCode] = FALSE;
    
    		return TRUE;
    	}
    
    	return FALSE;
    }
    And in your main:
    Code:
    void interrupt (*oldKeybInt) (...);		// Old keyboard interrupt.
    void interrupt newKeybInt (...);			// New one.
    .
    .
    .
    oldKeybInt = getvect (KEYB_INT);		// Re-direct ISR:
    setvect (KEYB_INT, newKeybInt);
    .
    .
    .
    setvect (KEYB_INT, oldKeybInt);  // When you're done, put it back

    Back from when I wrote DOS games.

    Use the #defined symbols to find out whether a key is held:

    Code:
    if (isPressed (K_SPACE, true))
       fireMissile ();
    The turnOff argument (here set to true) means that the player cannot simply hold down this particular key and constantly fire missiles. He has to let go and press it again and again. Obviously, if you want a control hold-downable (i.e. an accelerator in a race game) set this to false.
    Last edited by samGwilliam; 04-01-2005 at 09:20 PM.

Popular pages Recent additions subscribe to a feed

Similar Threads

  1. Which Compiler?
    By Bladactania in forum C Programming
    Replies: 10
    Last Post: 02-11-2009, 12:32 AM
  2. winver, winminor, winmajor can it be found from dos?
    By ronin in forum A Brief History of Cprogramming.com
    Replies: 2
    Last Post: 10-02-2002, 10:32 AM
  3. Digital Mars Compiler: compiling for DOS?
    By Waldo2k2 in forum C++ Programming
    Replies: 1
    Last Post: 09-15-2002, 02:06 PM
  4. Keyboard INT 9 handler (Handles multiple keypresses!) Problem
    By zhopon in forum A Brief History of Cprogramming.com
    Replies: 0
    Last Post: 12-16-2001, 09:39 AM
  5. Replies: 0
    Last Post: 12-16-2001, 09:36 AM

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21