Horizon Web Browser

Goals:

We will implement an x86 assembly program that can display simple HTML documents from a local NetBIOS server. The documents will be displayed on an 1024x768x256 SVGA screen using protected mode to write linear data to the screen. The browser will use buttons to navigate back and forth, have a text field to enter hyperlinks, and scrolling through the document. Our web browser will be complied under NASM and uses WDOSX for protected mode support.

A web browser has never been attempted in ECE 291 before, but the most challenging part of our program is using protected mode to display HTML documents. As far as we know, no one has ever done 1024x768x256, so we think that doing both protected mode and high color graphics will challenge our assembly language knowledge and make the program more useful in the real world.

Required to run: 80386DX or better for 32-bit protected mode, 4MB video card, 32MB RAM.

NOTE: You must run the client and server programs at the same time for Horizon to work properly.

Implementation:

• The web browser will work in the following way: SplashScreen will display the Horizon startup screen and goes right to the web browser window and calls WaitForInput to wait for the user to request a file. Two computers with HorizonS (server) and HorizonC (client) will be running synchronously. HorizonS will display a "Server Mode" screen to disable the user interface. When the user requests a file from the server computer by typing a HTML file and pressing ENTER, the program will call GetFile to retrieve the file and put it into [File_Dump]. As a side note, the server will call the serverto wait and pass files back to HorizonC. HTMLConvert on the client will then convert the HTML code into Horizon HTML code ignoring what Horizon cannot display (namely tables) and place the result into [selector_convert]. HTMLParse will then step through [selector_convert] sending the proper justification and ASCII text to ConvertData. If an image is required, HTMLParse will call GetFile to retrieve the BMP/PCX image and pass the image data to [File_Dump]. SendRawData is called to write the data header and image or ASCII data to [base_selector_file] and sends it to ConvertData]. ConvertData will be called to display the amount of data that can be currently displayed on screen. After reaching the end of ConvBuffer, the display will have all images and text on screen. WaitforInput will be called to wait for a new input.
• Scrolling will be achieved by moving the screen BMP either up or down depending on the request and redisplaying the screen.
• Horizon has two programs: Server and Horizon. All files used by Horizon are in the server directory.

Procedures:

Networking: Isaac Sanchez

The web browser will connect to a "web server" over a session level Netbios connection. The browser will send a request to the server requesting a file. The server will then send the file to the client. The client will then pass the file into a buffer, so that the data can be used by HTMLConvert.

GetFile within Horizon:

Constants:

RESET equ 032h
CANCEL equ 035h
STATUS equ 0B3h
STATUS_WAIT equ 034h
TRACE equ 0F9h
UNLINK equ 070h
ADD_NAME equ 0B0h
ADD_NAME_WAIT equ 030h
ADD_GROUP_NAME equ 0B6h
ADD_GROUP_NAME_WAIT equ 036h
DELETE_NAME equ 0B1h
DELETE_NAME_WAIT equ 031h
CALL_ equ 090h
LISTEN equ 091h
LISTEN_WAIT equ 011h
HANG_UP equ 092h
SEND equ 094h
SEND_WAIT equ 014h
CHAIN_SEND equ 097h
RECEIVE equ 095h
RECIEVE_WAIT equ 015h
RECEIVE_ANY equ 096h
SESSION_STATUS equ 0B4h
SEND_DATAGRAM equ 0A0h
SEND_BCST equ 0A2h
RECEIVE_DATA equ 0A1h
RECEIVE_BCST_DATA equ 0A3h

Structures:

NCB struc
ncb_command db ? ; command code
ncb_retcode db ? ; error return code
ncb_lsn db ? ; session number
ncb_num db ? ; name number
ncb_buf_off dw ? ; ptr to send/receive data offset
ncb_buf_seg dw ? ; ptr to send/receive data segment
ncb_buflen dw ? ; length of data
ncb_callname db 16 dup (?) ; remote name
ncb_name db 16 dup (?) ; local name
ncb_rto db 0 ; receive timeout
ncb_sto db 0 ; send timeout
ncb_post_off dw ? ; async command complete post offset
ncb_post_seg dw ? ; async command complete post segment
ncb_lana_num db ? ; adapter number
ncb_cmd_done db ? ; 0FFh until command completed
ncb_res db 14 dup (?) ; reserved
NCB ends

Inputs:

• EDX: Offset of NULL terminated string that contains the filename requested.

Outputs:

• EAX: Will return 0 on successful retrieval, -1 on failure
• File_Dump: Memory allocated to hold file data willl be overwritten with new file

Modified Variables:

• None

Purpose:

This procedure will be called by the client when it requires a file from the server. It will establish a connection, send the filename to the server and then receive the file. The file will then be written into File_Dump, which is a 1 megabyte allocation in memory.

Server Program:

Constants:

RESET equ 032h
CANCEL equ 035h
STATUS equ 0B3h
STATUS_WAIT equ 034h
TRACE equ 0F9h
UNLINK equ 070h
ADD_NAME equ 0B0h
ADD_NAME_WAIT equ 030h
ADD_GROUP_NAME equ 0B6h
ADD_GROUP_NAME_WAIT equ 036h
DELETE_NAME equ 0B1h
DELETE_NAME_WAIT equ 031h
CALL_ equ 090h
LISTEN equ 091h
LISTEN_WAIT equ 011h
HANG_UP equ 092h
SEND equ 094h
SEND_WAIT equ 014h
CHAIN_SEND equ 097h
RECEIVE equ 095h
RECIEVE_WAIT equ 015h
RECEIVE_ANY equ 096h
SESSION_STATUS equ 0B4h
SEND_DATAGRAM equ 0A0h
SEND_BCST equ 0A2h
RECEIVE_DATA equ 0A1h
RECEIVE_BCST_DATA equ 0A3h

Structures:

NCB struc
ncb_command db ? ; command code
ncb_retcode db ? ; error return code
ncb_lsn db ? ; session number
ncb_num db ? ; name number
ncb_buf_off dw ? ; ptr to send/receive data offset
ncb_buf_seg dw ? ; ptr to send/receive data segment
ncb_buflen dw ? ; length of data
ncb_callname db 16 dup (?) ; remote name
ncb_name db 16 dup (?) ; local name
ncb_rto db 0 ; receive timeout
ncb_sto db 0 ; send timeout
ncb_post_off dw ? ; async command complete post offset
ncb_post_seg dw ? ; async command complete post segment
ncb_lana_num db ? ; adapter number
ncb_cmd_done db ? ; 0FFh until command completed
ncb_res db 14 dup (?) ; reserved
NCB ends

PPROCEDURES:

MAIN:

Inputs:

• None

Outputs:

• None

Modified Variables:

The ReadIn buffer is used to temporarily hold data that is readin from the files and then sent to the client.

Purpose:

The web server will initialize itself, listen for a connection, and then service client's requests. The server will open the file, read in the data into the ReadIn buffer, then send the data over the network. The procedure will then close the file and connection, and wait for another request.

MouseIntsall:

Inputs:

• None

Outputs:

• None

Modified Variables:

• None

Purpose:

Installs the Mouse handler

MouseUninstall:

Inputs:

• None

Outputs:

• None

Modified Variables:

• None

Purpose:

Uninstalls the mouse handler

MouseHandler:

Inputs:

• None

Outputs:

• None

Modified Variables:

• exiting set to 1

Purpose:

Sets the exiting variable to indicate exiting

HTML Conversion: George Neurauter

This part of the program takes the incoming HTML file from HTMLBuffer and converts the ASCII into a series of predefined opcodes and ASCII text that will allow HTMLParse to allow the network to get images and sends palette entries and ASCII text to the graphic routines for display.

HTMLConvert:

• This function will take a HTML encoded document and convert it into ASCII text and defined functions that Horizon will display on the screen. It will do this by taking the HTML data passed into [File_Dump] by GetFile and scanning for HTML tags in either upper or lower case text. Every tag that cannot be shown or implemented will be ignored. When a tag is found, the tag is checked to make sure it can be used by Horizon and, if so, it will scan the data from the tags and prefix and suffix the data with 'tags' we set (see below). If plain text is found, it will simply write it to [selector_convert]. It will go through until the whole HTML file is scanned.
• Inputs: [File_Dump] - HTML Data
• Outputs: [selector_convert] - converted data
• External Procedures Used: SCANHTML, IGNOREHTML, VerifyWord, WriteColor
• HTML Tags used: <BODY>, <BODY BGCOLOR="#RRGGBB">, <BODY TEXT="#RRGGBB>, <BODY BGCOLOR="#RRGGBB" TEXT="#RRGGBB>, <FONT COLOR="#RRGGBB">, <IMG SRC="filename">, <A HREF="#filename> (disabled in our implementation), <H1>, <H2>, <H3>, <P>, <BR>, </HTML>, <CENTER> (disabled in our implementation)
• Constants used to convert HTML (opcodes that prefix and append ASCII text, hyperlinks, and other significant data):

BGColor equ 14
ImgSource equ 1
LinkRef equ 2
Head1 equ 3
EndHead1 equ 4
Head2 equ 5
EndHead2 equ 6
Head3 equ 7
EndHead3 equ 8
Paragraph equ 9
EndParagraph equ 10
Break equ 11
FontColor equ 12
EndFontColor equ 13
DefaultFont equ 15
EndHTML equ 16
Center equ 20
EndCenter equ 21

 

HTMLParse:

• This function will be called by the main function when a HTML document is be processed. It will iterate through [selector_convert] which is converted by HTMLConvert to find which tags are being used. Variables are updated for tags that update screen colors and justification. If there is text to be written, the ASCII is written to TextBuffer. If the text line in TextBuffer is full depending on the size of FontType, it will call SendRawData to send the line of text to ConvertData. If an image is to be written, SendRawData is called with FontType set to 0. Normally, FontType is set to 1 for text data. It continues to scan until the EndHTML tag is found.
• Inputs: [selector_convert]
• Outputs: Screen display of HTML document
• External Procedures Used: SendRawData, SCANCONV
• Data Header used in [base_selector_file] when sending data to ConvertData:

;DataHeader db 20 dup(0) ; Header for all data passed to
; RawBuffer
;The data header to be sent to the screen display
;is defined to be:
;===============

DataType db 1 ;defines data passed
; 0 = BMP
; 1 = Text (default)

LineNumber dd ? ;Current line in RawBuffer

HyperLink db ? ;(text only) - denotes if
; text is hyperlink

; 0 = Not HyperLink
; 1 = Hyperlink (different color)

DefaultFontRGB db 4 dup (0) ;(text only) - gives default font
; color - black by default
; Format - 00(Red)(Green)(Blue) - 00000000 = black by default
; 00000000 = black
; FF000000 = red ,etc.,etc.

FontType db 1 ;(text only) - denotes font size
; passed - 1 default
; 1 = normal(default)
; 2 = Heading 3 (bold?? normal)
; 3 = Heading 2 (2x bold?? normal)
; 4 = Heading 1 (3x bold?? normal)

NumChars db ? ;(text only) - number of chars
; in text packet

BackgroundColor db 0
db 3 dup (0FFh) ; color of background - white by
; default
; 4 bytes reserved

VerifyWord:

• This function is called by HTMLConvert and tests whether the two consecutive bytes in [File_Dump:ESI] are equal to the values in AX.
• Inputs: AX = ASCII values to check
• Outputs: VerifyFlag = 0 if check fails, 1 if check passes

CenterText:

• This function is called by SendRawData and finds out how many spaces to tab centered text in when writing the text to [base_selector_file]. The number of spaces depends on FontType since so many characters of different font sizes can fit on the screen. It also depends on NumChars which denotes how many characters there are in TextBuffer.
• Inputs: FontType, NumChars
• Outputs: NumSpaces

SCANHTML:

• This function is called by HTMLConvert and writes HTML data from [File_Dump] to [selector_convert] until the character in AL is reached.
• Inputs: [File_Dump], AL = character to scan for
• Outputs: updated [File_Dump] and [selector_convert] offsets ESI and EDI, ASCII written to [selector_convert]

SCANCONV:

• This function is called by HTMLParse and scans [selector_convert] for the character in AL and returns CX which has the number of bytes scanned until the character was reached.
• Inputs: [selector_convert], AL = character to scan for
• Outputs: CX = number of bytes scanned

IGNOREHTML:

• This function is called by HTMLConvert and scans [FIle_Dump] until the character in AL if found.
• Inputs: [File_Dump], AL = character to scan for
• Outputs: updated [File_Dump] offset ESI

SendRawData:

Data used to write data buffer:

;DataHeader db 20 dup(0) ; Header for all data passed to
; RawBuffer
;The data header to be sent to the screen display
;is defined to be:
;===============

DataType db 1 ;defines data passed
; 0 = BMP
; 1 = Text (default)

LineNumber dd ? ;Current line in RawBuffer

HyperLink db ? ;(text only) - denotes if
; text is hyperlink

; 0 = Not HyperLink
; 1 = Hyperlink (different color)

DefaultFontRGB db 4 dup (0) ;(text only) - gives default font
; color - black by default
; Format - 00(Red)(Green)(Blue) - 00000000 = black by default
; 00000000 = black
; FF000000 = red ,etc.,etc.

FontType db 1 ;(text only) - denotes font size
; passed - 1 default
; 1 = normal(default)
; 2 = Heading 3 (bold?? normal)
; 3 = Heading 2 (2x bold?? normal)
; 4 = Heading 1 (3x bold?? normal)

NumChars db ? ;(text only) - number of chars
; in text packet

BackgroundColor db 0
db 3 dup (0FFh) ; color of background - white by
; default

; 4 bytes reserved

WriteColor:

• This function is called by HTMLConvert and writes the passed in background color or font color from [File_Dump] and converts the ASCII values to hex values and writes them to [selector_convert]. A hex value of zero is added to the front of the data to make the data accessible bby using double variables (OverrideFontColor, DefaultColorRGB, BackgroundColor)
• Inputs: [File_dump]
• Outputs: [selector_convert] with hex values of passed in font/background colors

Graphics, Design, and Program Implementation: Chris Wissing and Adil Hussain

One task of a web browser is to display text and graphics on the screen, but to do this in mode 13h the text would have to be almost one half inch high in order to read, which would not allow many things to be displayed on the screen. In order to overcome this limitation we decided to use protected mode to address more memory and effectively allow us to display text and graphics at 1024X768x16.7M resolution. 

InitVideo:

• This Procedure Initializes the video to 1024x768x16.7M
• Inputs - Selector to video memory
• Outputs - None

MakeMem:

• This procedure allocates dos memory and upper memory
• Inputs - None
• Outputs - Saves selectors to allocated memory

ConvertData:

• This function is called from the WaitforInput function. It distinguishes between BMP and Text for different font sizes.
• Inputs - None
• Outputs - Call to function to display BMP or display Text. also stores the pixel location to draw at in variable pixelloc

KillRawBuffer:

• Sets RawBuffer memory to white color. Basically used to wash screen color.
• Inputs - Selector to RawBuffer
• Outputs - Sets RawBuffer variable

ConvertBMP:

• Converts BMP's from the memory at selector, base_selector_file and stores the data the the memory at RawBuffer
• Inputs - base_selector_file which holds text or graphics data to be displayed to the screen
• Outputs - Memory at selector RawBuffer is modified so that the BMP or text will be able to be properly displayed to the screen

FillScreen:

• Writes to the screen in 1024x768x16.7M
• Inputs - Uses scroll variable to determine where to write to screen
• Outputs - Outputs directly to the screen in the Linear Frame Buffer through the base_selector_vid selector

SplashScreen:

• Loads local BMP and Writes initial splash screen with credits of the programmers and the top title bar which remains on the screen always.
• Inputs - Selectors to memory
• Outputs - Modifies base_selector_file with BMP on local computer and modifies RawBuffer with converted image data from local BMP

DeInitVideo:

• Deinitializes the video mode and returns to text mode
• Inputs - None
• Outputs - Returns to text mode

PrintURL:

• Displays the characters in the URL Title Bar at the top of the screen every time a key is pressed and also cleans them from the bar when the enter key is pressed.
• Inputs - edi held the byte number to write . al held the ascii number for the actual character
• Outputs - Displayed directly to the screen

TextDisplay1:

• This procedure is called from the ConvertData procedure. It displays the size 1 text at the location of variable Pixelloc.
• Inputs - Pixelloc
• Outputs - Displays to the screen

TextDisplay2:

• This procedure is called from the ConvertData procedure. It displays the size 2 text at the location of variable Pixelloc.
• Inputs - Pixelloc
• Outputs - Displays to the screen

TextDisplay3:

• This procedure is called from the ConvertData procedure. It displays the size 3 text at the location of variable Pixelloc.
• Inputs - Pixelloc
• Outputs - Displays to the screen

TextDisplay4:

• This procedure is called from the ConvertData procedure. It displays the size 4 text at the location of variable Pixelloc.
• Inputs - Pixelloc
• Outputs - Displays to the screen

Initialize:

• Initializes the network and graphics. Uses 2 DPMI Int 31h calls to initialize the network with netbios.
• Inputs - Selectors to registers, network control block, and realmode offsets to the stored register data and network control block.
• Outputs - Initializes the network and sets the scroll variable to 0

Load_Font0:

• This procedure stores the images of characters of text size 0 in the memory sequentially. This is called from within ConvertData
• Inputs - None
• Outputs - None

Load_Font1:

• This procedure stores the images of characters of text size 1 in the memory sequentially. This is called from within ConvertData
• Inputs - None
• Outputs - None

Load_Font2:

• This procedure stores the images of characters of text size 2 in the memory sequentially. This is called from within ConvertData
• Inputs - None
• Outputs - None

Load_Font3:

• This procedure stores the images of characters of text size 3 in the memory sequentially. This is called from within ConvertData
• Inputs - None
• Outputs - None

Handlers, Installing/Uninstalling/Loop Functions: Chris Wissing and Adil Hussain

• These functions will install and handle mouse and keyboard events within the web browser.
• CREDITS: All of these functions have been programmed in real mode by each team member before coding Horizon during the course of this class, but these are all in protected mode.

WaitForInput:

• Waits for user input from the mouse and keyboard
• Inputs - new_web_page holds 1 if new web page should be loaded. ExitFlag holds value of 1 if the program should exit
• Outputs - new_web_page is set to 0 when new web page has been gotten. Scroll_changed is reset to 1 when new web page has been gotten. pixelloc is changed to 0 when new web page has been gotten

MouseInstall:

• This Procedure installs the MouseHandler to be called on mouse events. It also sets the maximum screen width and height. This function also sets the initial position of the mouse.
• Inputs - None
• Outputs - None

MouseUnInstall:

• This Procedure restores mouse driver to its original state
• Inputs - None
• Outputs - None

MouseHandler:

Description - This routine will be called by MouseInstall. It should process clicks on the screen.

Inputs -

• AX = event mask (same format as described in MouseInstall above)
• BX = mouse button status
• Bit 0: LMB activated
  Bit 1: RMB activated
  Bit 2: MMB activated
  Bits 3-15: Unused
• CX = horizontal mouse position
• DX = vertical mouse position
• SI = length of last horizontal mouse movement
• DI = length of last vertical mouse movement
• DS = data segment of the mouse driver
• my_saved_ds holds the value of the data selector
• OldPosition holds value of old mouse position on screen
• base_selector_vid holds selector to video memory
• NewMouse holds the 24bit values of the mouse cursor

Outputs -

• Scroll holds offset of where to draw in RawBuffer
• Scroll_changed holds 1 if the scroll variable has been changed
• Mouse_down holds 0 or 1. Left mouse button up or down respectively.
• Mouse_moved holds 1 if the mouse has moved
• Mouse_state holds the values of the button state from bx
• Mouse_ypos holds the mouse vertical position on screen
• Mouse_xpos holds the mouse horizontal position on the screen

KeyboardInstall:

• Installs Interrupt 9's (IRQ1's) vector to the address of KbdHandler.
• Input - none
• Output - OldKBV variable that holds old vector in interrupt table

KeyboardUninstall:

• Restore keyboard Interrupt vector to the original value.

  Input - OldKBV variable that holds old vector in interrupt table

  Output - None

KeyboardHandler:

• This routine is the Interrupt Service Routine called when the keyboard hardware reads in the scan code from the keyboard. By reading the scancode from the keyboard's hardware register the program can determine which key was pressed. Our routine should then translate this scan code into a corresponding ASCII code.
• Input - save_edi holds the offset in the netfile data array for the filename request
• Output - new_web_page holds 1 if new webpage is requested, Scroll also modified with offset of where to draw the screen from RawBuffer. Scroll_changed holds 1 if the scroll variable changed.

Contact Information:

Chris Wissing - wissing@uiuc.edu

Adil Hussain - ahussai1@uiuc.edu

George Neurauter - neurautr@uiuc.edu

Isaac Sanchez - iisanche@uiuc.edu