Loadstar 128 #32

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Text File | 1992-01-01 | 16.4 KB | 317 lines

M O U S E 8 0 Program and Text by Maurice Randall MOUSE 80 is a device driver for the Commodore 1351 mouse or compatibles. It is designed to be used with the 128 in 80 column 'text mode' only. This driver will fill a void that most people do not realize existed. The 1351 mouse has been around for a while now, and there are mouse drivers for it. The demo disk that comes with the mouse has an assortment of drivers for the 64 mode and the 128 mode, but the 128 mode driver is only for 40-column use. It makes use of a sprite for the pointer that is visible on the screen. Sprites are not available on the 80-column screen. Sprites are easily simulated on the 128's 80-column graphic screen, but then you are limited to creating 'graphic text'. GEOS works this way, and GEOS is an excellent system, but there is still a need for applications written to use the 128's native text mode. What makes this driver different is the fact that it moves the pointer about the text screen smoothly. There have been other mouse drivers for the 80-column text screen, but these move the mouse pointer around the screen a full character at a time. They work fine, but the smoothness of movement isn't there. The only smooth mouse pointer I'm aware of for the 128 is incorporated into the Pocket Series software from Digital Solutions. But their mouse routines are not available to the public. Therefore, I have designed MOUSE 80 so that other software developers might make use of the 1351 mouse with a smooth moving pointer in their programs. Any new development for the 128 should definitely make use of the new hardware that is available, and MOUSE 80 will help give a more professional appearance to the program. MOUSE 80 can be used with a BASIC or ML program. It uses a jump table to call its routines and you can also read or change various variables that are used by MOUSE 80. To use MOUSE 80, you would include the following statement in a BASIC loader: bload"mouse80.o"onu(dv) where dv is the current drive number NOTE: For card games use "c80c-mouse.2300" and set MO = 8960. Once your main program begins, you can use the various jump addresses and variables locations to initially install the mouse wedge into the IRQ interrupt sequence, turn the mouse pointer on and off, or to find or set the pointer on the screen. You can locate the pointer according to its pixel location. You can also confine the mouse to a defined region or 'window'. You can tell if either button is being pressed. You can also instruct MOUSE 80 to set up a jump address for the application to call if one of the buttons is pressed. If you don't like the looks of the mouse pointer, you can change its appearance by altering the eight bytes that make up its picture. There are four graphic characters from the upper/lower case set that are used by MOUSE 80. If you need to use these characters, you can choose any other four characters instead. It would be a very rare program that would have to use each of the 512 characters that are available. Whenever you are accessing the screen, you should 'hide' the mouse pointer to prevent garbage from appearing on the screen. The 80-column VDC chip is very touchy, and does not like the mouse when the screen is scrolling, or if you are typing characters into the same location that the mouse is occupying. So, just call 'HIDEMOUS' before any screen access and call 'SHOWMOUS' when finished. When the mouse is hidden, the pointer is not displayed, but movement is still possible. So, you could use this to your advantage for various things such as menus. As the mouse is moved up and down, you could highlight the menu item that is being pointed at, much like what is usually done with the CRSR keys. If you call the routine, 'STOPMOUS', then the pointer is not only hidden, but its location also is not updated. It will remain frozen in the spot it was in when the routine was called. The buttons are still active so that you can still check for either button being pressed. Either 'SHOWMOUS' or 'HIDEMOUS' will then make the mouse active again. 'HIDEMOUS' will leave the pointer hidden. The following is a list of available routines and variables along with their locations in memory: Name BASIC Description ------------------------------------------------------ INSTALL MO+0 Initially installs the mouse wedge REMOVE MO+3 Removes mouse wedge from the system. HIDEMOUS MO+6 Hides the pointer from view. SHOWMOUS MO+9 Displays the pointer on the screen. STOPMOUS MO+12 Stops the mouse and hides it. CKSTATUS MO+15 Check location of mouse on screen. USERJUMP MO+18 User callable according to buttons. (Locations $1315-$1317 are not used. They are reserved for future use.) There are a number of variables that may be read or set. Here is a listing of those variables, their location offset in relation to the starting address and a brief description. The following bytes define the region in which to confine the mouse pointer. The default settings are for the entire screen. LTXLIMIT +24,25 Left border (lsb,msb) (0-319) UPYLIMIT +26 Upper border (0-199) RTXLIMIT +27,28 Right border (lsb,msb) (0-319) LOYLIMIT +29 Lower border (0-199) The following locations define the present location of the mouse. These are best checked by machine language. When using BASIC, the mouse could move between the time it takes to check the X position and the Y position. XCHAR +30 Column location of the mouse. YCHAR +31 Row location of the mouse. CXPOS +32,33 Horizontal pixel location of the mouse. CYPOS +34 Vertical pixel location of the mouse From BASIC, (or ML) you could check these locations after accessing the routine called 'CKSTATUS'. The exact location of the mouse when 'CKSTATUS' is accessed is saved here until the next time the routine is accessed. BXCHAR +35 Column location. BYCHAR +36 Row location. BCXPOS +37,38 Horizontal pixel location. BCYPOS +39 Vertical pixel location. These next two locations may be set in order to place the mouse pointer at a specific location on the screen. 'SETXPOS' should be set to a two-byte value ranging from 0-319, and 'SETYPOS' should be 0-199. Always POKE the value into SETXPOS+1 last, because after MOUSE 80 checks these bytes, bit 7 of SETXPOS+1 will be set which makes MOUSE 80 ignore these values. If you were to set this location before the other three (from BASIC), they would most likely be read before you are done setting the other bytes and so the mouse would not be placed in the desired location. From machine language, it is not a problem since you can disable the interrupts first. SETXPOS +40,41 Place pointer at this X location. SETYPOS +42 Place pointer at this Y location. LTBUTTON +43 Current status of left button. RTBUTTON +44 Current status of right button. LTCHECK +45 Latched status of left button. RTCHECK +46 Latched status of right button. These next four bytes are used as user defined addresses that may be called in machine language whenever a button is pressed. They are described in better detail later. LTADDR +47,48 Address for left button. RTADDR +49,50 Address for right button. LTINT +51,52 Interrupt address. RTINT +53,54 Interrupt address. MSEPORT +55 Active joystick port (1 or 2) MOUSEPIC +56-63 This is the picture of the pointer. These next four bytes designate the screencodes of the characters that will be used for the mouse pointer. You may use the default characters or change these bytes to select different characters. If you should happen to use a character that is displayed elsewhere on the screen, then the mouse pointer will appear at that location also. This may not be too desirable, but could possibly be used for a special effect. ULCORNER +64 Character that is used for upper left. (Default is ASCII 113) URCORNER +65 Character that is used for upper right. (Default is ASCII 114) LLCORNER +66 Character that is used for lower left. (Default is ASCII 115) LRCORNER +67 Character that is used for lower right. (Default is ASCII 116) And these four bytes are the attribute bytes for the characters that are to be redefined. The default setting for each one is $80, which would select the character from the upper/lower case set. Set the locations to $00 if you wish to use characters from the uppercase/graphics set. ULMSATTR +68 Attribute byte for upper left. URMSATTR +69 Attribute byte for upper right. LLMSATTR +70 Attribute byte for lower left. LRMSATTR +71 Attribute byte for lower right. The mouse picture located at 'MOUSEPIC' is made up of eight bytes. These eight bytes and their values look like this: BYTE BINARY HEXADECIMAL DECIMAL ------------------------------------------- byte 0 11000000 $C0 192 byte 1 11111000 $F8 248 byte 2 11111110 $FE 254 byte 3 11111000 $F8 248 byte 4 10011100 $9C 156 byte 5 00001110 $0E 14 byte 6 00000111 $07 7 byte 7 00000000 $00 0 If you study the 'ones' in the binary representation, you will see the picture of the mouse. By changing these eight bytes, you can change the appearance of the mouse pointer. One thing to keep in mind whenever you are making reference to the mouse location in the horizontal axis, is that the mouse is moved two pixels at a time, horizontally. Even though there are 640 pixels on the X- axis, the mouse will be referenced at points ranging from 0 to 319. So, if the mouse is at location 100, it is actually sitting at pixel 200 on the screen. You can have MOUSE 80 set up a user callable jump address in the jump table according to the values placed at LTADDR and RTADDR. For instance, if you place a two-byte value at LTADDR, it will be transferred to MOUSE 80's jump table at MO+18 whenever the left button is pressed. You may then JSR MO+18 to your own routine. If you place a two-byte address at LTINT, then that address will be called by MOUSE 80 during the interrupt sequence whenever the left button is pressed. The address at MO+18 is not affected by the setting at LTINT. LTINT is transferred to an internal location within MOUSE 80. MOUSE 80 calls this routine for you whenever the button is pressed. To block either of these features, simply zero out the locations. The same idea applies for RTADDR and RTINT and the right button. By using this feature, you never have to check the status of the buttons yourself. If you do need to check the buttons, there is more than one way to do it. You can test the location at 'LTBUTTON'. If bit 7 is set or if the location contains any value greater than 127, then this means that the left button is being pressed. If the location contains any value greater than zero, then the button was pressed sometime during the last eight interrupt sequences. Bit 7 always represents the button's status for the most recent interrupt, bit 6 for the previous one and so forth on down to bit 0. So, if bit 3 at 'LTBUTTON' is 'off', then the left button was not pressed 5 interrupts ago. By allowing you to read the status of the button for a period of eight interrupts, you might be able to catch a button press even after the user lets up on the button. 'RTBUTTON' contains the status for the right button. For the curious, here is how MOUSE 80 works. It is really quite simple when you think about it. First of all, the 80-column text screen is just that, a text screen. Graphics are not possible, which means that we cannot address individual pixel locations. We have to address character locations, so we are limited to displaying objects (or characters) in a matrix that is 80 columns wide and 25 rows high. So, whenever you see what looks like graphics on the text screen, you are seeing either the graphic characters that Commodore has provided us or you are seeing redefined characters that are being displayed about the screen. MOUSE 80 uses four redefined characters and so it actually occupies four character locations on the screen at all times. The four locations are always attached to each other in a matrix that is two characters wide and two characters high. Reference is always made to the upper left character. For instance, if the mouse is located at column 0 and row 0, it is occupying the following four locations: column 0, row 0 column 0, row 1 column 1, row 0 column 1, row 1 Now, to get the mouse displayed on the screen, MOUSE 80 creates its own little bitmap in memory. Once it knows where it is located on the screen, it then determines where within this bitmap that it should be located. For instance, if the mouse is at the upper left of the screen, it would be at column 0 and row 0. Let's say that the actual pixel location of the mouse is at pixel 3 horizontally and pixel 5 vertically. These locations fall within the upper left character location of the screen. Now we draw the mouse pointer in our own little bitmap at position 3 on the X axis and position 5 on the Y axis. The bitmap is 16 pixels by 16 pixels but we keep the entire mouse picture within the bitmap and we keep the upper left pixel of the mouse within the upper left quarter of the bitmap. This means that the X coordinate can be from 0-7 and the Y coordinate can be from 0-6. (Remember, the x coordinates move two pixels at a time). Now that we have drawn the mouse into the bitmap, it is time to fetch the character definitions from the four locations that the mouse is occupying on the screen. First the character from column 0, row 0 is fetched and drawn to the upper left quarter of the bitmap. Each bit when drawn is actually EOR'D with the picture of the mouse. The remaining three characters are then drawn in the other three quarters of the bitmap in the same manner. By Exclusive ORing each bit with the mouse picture, the mouse and the character are each visible. If bits that are 'on' are overlapping each other, then the bits will be 'off'. This makes the mouse visible if the character it passes over should be a solid block. Now that our little bitmap is completely drawn, we send each quarter of it to the four different character definitions that MOUSE 80 uses for its pointer. Then it is drawn to the screen by sending those four characters to the screen. Each time the mouse moves, this bitmap is redrawn. So the effect of a smooth moving mouse is not through the use of sprites or graphics, but actually through the use of four redefined characters. This is why you must call 'HIDEMOUS' or 'STOPMOUS' before any screen access in the area that the pointer is, or if the entire screen is going to scroll. These routines will remove the mouse picture from the screen, and replace the actual characters that should be residing in the four locations of the screen where the mouse is. Things to remember: * Call 'INSTALL' to initially install the mouse. 'INSTALL' initializes numerous variables, so you must set any desired variables after this call. 'INSTALL' leaves the mouse in a frozen and hidden state. * Call 'SHOWMOUS' to make the pointer visible and active. * Call 'HIDEMOUS' or 'STOPMOUS' during any screen activity in the area of the mouse. * 'HIDEMOUS' leaves the mouse active, but makes it invisible. * 'STOPMOUS' makes the mouse invisible and also freezes its position. * 'X' coordinates range from 0-319 because the mouse is moved two pixels at a time horizontally. * Call 'REMOVE' to remove MOUSE 80 from the IRQ sequence before ending your application. 'REMOVE' calls 'STOPMOUS' and then resets the IRQ vector to its original state. MOUSE 80 should open up a whole new avenue of professional appearing applications for the 128. \\\\\ RETURN - Menu \\\\\