Machine Problem 4

Introduction

Over the course of the next two machine problems, we will implement the game of tag in a virtual environment. The rules of tag are simple. The person that is it chases after everyone else. Upon tagging someone, that person become it.

Our game will be played in the safety of the ECE291 lab using Ethernet and VGA video graphics. For MP4, we will implement the graphic functions to represent ourself in the game as a bitmapped image (BMP). Our program will allow us to move our icon over a mode-13h VGA graphics display.

For MP5 (the 2nd half of this assignment), we will use NetBIOS's datagram group service to transmit our images and movements to the other players on the network. Each player sees an identical view of the game from their own machine. Up to 63 players can play the game at once.

Video Graphics Implementation

For this machine problem, we will write the following routines to load, store, and draw these images on the screen. A screen dump of the running program is shown below:

Video Graphic Routines

• All routines should preserve the values of any registers modified
• Use proper segments where needed

• DrawBox
  • Purpose: Draw a filled square on the screen
  • Inputs:
    • AL: Color
    • DI: Screen location (top-left corner)
  • Output: Writes directly to screen
  • Description: This routine draws a 32x32 filled square on the screen using the palette number specified in AL.
  • Notes:
    • This will be a frequently-used routine for this MP.
      It should be optimized for performance using a 32-bit register (386, 486) and string operations.

• DrawEmptyBox
  • Purpose: Draw an empty square box on the screen
  • Inputs:
    • AL: Color
    • DI: Screen location (top-left corner)
  • Output: Writes directly to screen
  • Description: This routine draws an empty 32x32 square box on the screen using the palette number specified in AL. Pixels inside the box should not be affected by this call.
  • Notes:
    • This will be a frequently-used routine for this MP.
      It should be optimized for performance using a 32-bit register (386, 486) and string operations where possible.

• DrawBMP
  • Purpose: Write an image to the screen
  • Inputs:
    • AX: Image Number (0..63)
    • DI: Screen location (top-left corner)
    • Variable ImageArray
  • Output: Writes directly to screen
  • Description: This routine draws the AXth image from ImageArray to the VGA display.
    DI is specified as a offset on a mode-13h screen.
  • Notes:
    • This will be a frequently-used routine for this MP.
      It should be optimized for performance using a 32-bit variant of the repeating string operations.

• LoadBMP
  • Purpose: Load a BMP file from disk to memory
  • Input: DX: Pointer to the null-terminated string with the file name
  • Output: Contents of file stored in Variable BMP
  • Description: This routine uses DOS INT 21h services to open and read a file from the disk. The contents of the file should be stored in the variable called BMP.
  • Notes:
    • The variable BMP is located in a different segment.
      The segment can be accessed as Seg BMP.
    • The structure of the BMP file is given to you in the source code.
    • Null-terminated strings end with ASCII 0.
    • If the file cannot be read, switch back to text-mode video and print an error message and terminate the program.

• StoreBMP
  • Purpose: Convert BMP data and store to image array.
  • Inputs:
    • AX: Image Number (0..63)
    • DS:SI: Pointer to BMP data (Segment:Offset)
  • Output: 1024 bytes written to AXth element of ImageArray
  • Description: This routine converts a 16-color, 32x32-pixel BMP image to a VGA mode-13h formatted array of bytes and stores the data in an array.
  • Notes:
    • The variable ImageArray is located in a different segment
    • BMP files store rows from the bottom up.
    • ImageArray uses consecutive memory locations to store 64 images of 1024 bytes in row-column format.
    • The 16-color palette of the BMP images map directly into the default 256-color palette of the VGA.

• MyImage.bmp
  • Purpose: Your virtual representation
  • Inputs: Artistic creation skills
  • Output: 32x32, 16-color BMP image
  • Description: Use the Corel PhotoPaint program (or another other graphic editing program of your choice), to create an accurate image that represents yourself in the network tag game. This image should resemble yourself and be suitable for display to all members of the class.
  • Notes:
    • It is required that your image resemble your face
      to the degree that everyone in the class will be able
      to match your image with your face.
    • Your image must have the exact size of Height=32 pixels, Width=32 pixels
    • Your image must use the same 16-color palette as the given images in this MP.
    • Save your image as an uncompressed windows BMP file called MyImage.bmp.
    • The length of your image file must be exactly
      = 118 header bytes + (32*32 image pixels)/(2 pixels/byte)
      = 118 header bytes + 512 image bytes
      = 630 bytes.
  • Hints:
    • By loading an existing image from the MP4 directory, Corel PhotoPaint will be initialized with an image template that has the right size, correct palette, and proper color depth.
    • In Corel PhotoPaint, you can view the palette from the
      Image--ColorTable menu.
      You should not change the palette entries from the values given.
    • You can cut-and-paste images into your tempplate window. Be aware, however, that some work is needed to resample the image resolution and remap the palette.

Points

• DrawBox: 8 pts
• DrawEmptyBox: 8 pts
• DrawBMP: 8 pts
• LoadBMP: 8 pts
• StoreBMP: 8 pts
• Myimage.bmp: 10 pts

Preliminary Procedure

• You will begin MP4 with the following files:
  • MP4.EXE: Fully functional program using library functions
  • MP4.ASM: Graphic Functions Framework
  • LIBMP4.LIB: Working versions of all routines
  • LIB291.LIB: Useful (and free) routines
  • MYIMAGE.BMP: A really ugly BMP file
  • DOG.BMP: Picture of a dog
  • Makefile
• You can obtain these files via one of the methods listed below:
  • In lab, copy all files from the MP4 directory to your directory with the following command:
    xcopy /s V:\ece291\mp4\ W:\mp4
    
  • Alternatively, download all files as: MP4.ZIP

MP4.ASM