Machine Problem 1: Illini Union Bank

Assigned	Some time ago.
Due Date	It's too late now.
Purpose	Deal with high levels of branching. Use input strings. Manipulate arrays.
Points	75
Solution	Is here

Introduction

The University has decided that its students don't owe enough money. In order to rectify this problem, a new financial institution by the name of Illini Union Bank has been founded. In order to cut development costs, administrators have decided to use unwitting engineering students to write the bank's code.

Problem Description

The bank ledger allows ten entries to be recorded. Each entry records three fields of information: whether the transaction is a deposit or withdrawal, the amount of the transaction, and a memo tag that indicates the nature of the transaction. All of this information is stored in three bytes -- the first contains the deposit/withdrawal flag and memo tag, and the other two hold the transaction amount as a 16-bit positive integer. (That is, withdrawal amounts are still stored as a positive value!)

The bits of the first byte correspond to the following. For a valid entry, only one of bits 1 through 7 is a 1.

Bit 0: 0 if deposit, 1 if withdrawal
Bit 1: Books
Bit 2: School Supplies
Bit 3: Other Academic
Bit 4: Rent
Bit 5: Food
Bit 6: Entertainment
Bit 7: Other

The functions you will be writing will display information to the screen, interpret keyboard input, and manipulate the entry array. The program's main loop (which is provided and you need not write) repeatedly shows the main menu and calls appropriate functions as necessary. When the user chooses to quit or the entry array becomes full, the program will display the account summary one last time and then output a message depending upon the account's balance.

MP 1 Program Assignment

Your job in this assignment will be to provide rewrites of certain precompiled library routines described below. A working MP will be provided for you to get a feel for the program, as well as an .ASM file with calls to the pre-written library routines. You should go through the routines one by one, replacing these calls with your own code.

The program can be run by typing mp1 at the command prompt.

Brief Intro to PUSH and POP

Pushing and poping are stack operations and will be covered later in lecture.
Pushing a register will record onto the stack a copy of the register's data, while poping to a register removes the last added data to the register.
Since returning from a function uses the stack, every push must be matched with a pop, and the order of the registers for pushing will be the reverse of that used for popping.
Pushing and popping is, among other things, used to ensure that a called function doesn't scramble registers that the calling function uses.
You should not push and pop a register that will contain information that's supposed to be returned to the calling function. Doing so will prevent the data from being transferred.
See the provided function _DisplayMainMenu as an example.
Precocious students will examine Lecture 5 or Lockwood's lecture for thorough details.

Hints

The LIBMP1 file contains executable library functions for each of the routines that you need to implement. This allows you to run the program and understand how it works before you implement it. You can test your program by stepping through it and making sure the display and comparison functions work correctly. You will only receive credit, however, for the routines that you implement yourself.
When debugging your code in Turbo Debugger, you will find it helpful to use the memory window to show you the memory location of the file and strings. You can also use the watch window to keep track of variables in your code.
Run the program many times to get a good feel of it. Your final program with your code should resemble our version. Formatting aesthetics aren't as important as correctly operating code.
Do not forget to push and pop to avoid clobbering registers!
Remember to include function headers for and write comments in each of your functions! Headers should give a general idea of what the function does and have a list of inputs, outputs, and called functions. Commenting should be specific enough to allow a function to be understood by just reading the comments. Commenting every line, however, is excessive and may cost you some points.
START EARLY!
Monitor the newsgroup for clarifications and help.

Subroutines

This assignment has eight procedures. You will receive credit by replacing each of these eight procedures listed below with your own code. Assume these function call library routines such as dspmsg as needed.

InterpretAmount	Interprets an input from keyboard into the appropriate binary number Inputs: al = ASCII code of key pressed from AmountMenu Outputs: dx = binary representation of corresponding amount, or -1 on error Calls: dspmsg This function should first check that the input is in the proper range (a - g) If not, then it should display msg_Invalid and return dx = -1 Otherwise, it should set dx to the appropriate value. Notice the unusual increments -- You can use shifting instructions instead of a large branch statement.
InterpretTag	Interprets an input from keyboard into the appropriate flag Inputs: al = ASCII code of key pressed from TagMenu Outputs: cl = tag with only one 1 corresponding to entered type, or all 1s on error Calls: dspmsg This function should first check that the input is in the proper range (a - g) If not, then it should display msg_Invalid and return cl = -1 (all 1s) Otherwise, it should set cl to the appropriate value. Using branch statements is fine, but like with InterpretAmount, the particularly bored students will use shifts.
AddDeposit	Called when the user chooses 'a' from the Main Menu Inputs: [NumEntries] Outputs: [NumEntries], [EntryArray] Calls: DisplayAmountMenu, InterpretAmount, DisplayTagMenu, InterpretTag This function should display the appropriate menus and interpret those results. If either menu results in an error, the function should exit without affecting [NumEntries] or the array. Otherwise, add the entry to the array and increment [NumEntries]
AddWithdraw	Called when the user chooses 'b' from the Main Menu Inputs: [NumEntries] Outputs: [NumEntries], [EntryArray] Calls: DisplayAmountMenu, InterpretAmount, DisplayTagMenu, InterpretTag This function is very similar to AddDeposit. You should need to add just one line to set the proper flag to indicate a withdrawal.
DisplayEntry	Displays the information about an entry to screen Inputs: bx = offset to entry Outputs: displays to screen Calls: dspmsg, dspout, binasc This function should display a withdrawal or deposit message, dollar amount, and description tag. Use the provided msg_something strings. Notice you can't use dspmsg to display a dollar sign. You'll have to use dspout.
DisplayAllEntries	Runs through the entire array, displaying each entry Inputs: [NumEntries], [EntryArray] Outputs: displays to screen Calls: DisplayEntry, dspmsg Simply call DisplayEntry on every element in the array. If there are no entries, display msg_NoEntries instead.
DisplayAcademicEntries	Displays only entries with academic-related tags. Inputs: [NumEntries], [EntryArray] Outputs: displays to screen Calls: DisplayEntry, dspmsg You should be able to reuse (i.e. copy and paste) much of the code from DisplayEntries. The only entry types you need to print are Books, School Supplies, and Other Academic. If there are no entries or no academic entries, display msg_NoEntries.
DisplayTotal	Called by main on exit, displays the final account balance and some other silly messages. Inputs: [NumEntries], [EntryArray] Outputs: displays to screen Calls: dspmsg, dspout, binasc This function first displays msg_Total and a dollar sign. Then it totals up the account and calls binasc on that amount. Finally, it displays msg_Cookie and one of the following, depending on the final total. msg_BigDebt if total < -1000 msg_LittleDebt if -1000 <= total < 0 msg_LittlePlus if 0 <= total < 1000 msg_BigPlus if 1000 <= total

Procedure

You will begin this MP with the following files:
- MP1.ASM: Program Framework
- Makefile: Specifies how and when programs are assembled and linked.
- LIBMP1.LIB: Library functions for MP1
- LIB291.LIB: General-purpose library functions
You may copy these files from the network drive to your home directory with the following command:
xcopy /s V:\ece291\mp1 W:\mp1
or download the files from this server as mp1.zip
Add your code to MP1.ASM.
Assemble and link your program by typing
make
This command reads Makefile then invokes NASM and LINK to build an executable program.
Use Turbo Debugger (TB) to find and correct program errors.

Final Steps

1. Demonstrate your MP1.EXE to a TA. You may be asked to recompile and demo the program. Your program must work with all given input.

2. Be prepared to answer questions about any aspect of the operation of your program. The TAs will not accept an MP if you cannot fully explain your code and your implementation. Delayed MPs will be subject to late penalties as described in the course syllabus (10% pts per day).

3. The TA will complete the code submission procedure.

MP1.ASM (program framework)

; MP1 - Your Name - Today's Date
;
;
; Josh Potts, Fall 2001
; Guest Author: George Lu
; University of Illinois, Urbana-Champaign
; Dept. of Electrical and Computer Engineering
;
; Version 1.0

	BITS	16

;====== SECTION 1: Define constants =======================================

        CR          EQU 0Dh
        LF          EQU 0Ah
        BEL         EQU 07h
        MAX_ENTRIES EQU 10

;====== SECTION 2: Declare external procedures ============================

; These are functions from lib291
EXTERN  kbdine, dspout, dspmsg, dosxit,ascbin,binasc

; You will be writing your own versions of these functions
EXTERN _libDisplayEntry, _libDisplayAllEntries, _libDisplayAcademicEntries
EXTERN _libInterpretAmount, _libInterpretTag, _libAddDeposit
EXTERN _libAddWithdraw, _libDisplayTotal, mp1xit

; The _lib functions need these to work properly
GLOBAL MainHeader, MainMenu, AmountMenu, TagMenu, msg_Total, msg_NoEntries
GLOBAL msg_Invalid, msg_Deposit, msg_Withdraw, msg_Books, msg_Supply
GLOBAL msg_Academic, msg_Rent, msg_Food, msg_Entertain, msg_Other
GLOBAL msg_CRLF, msg_Cookie, msg_BigDebt, msg_SmallDebt, msg_SmallPlus
GLOBAL msg_BigPlus
GLOBAL _DisplayMainMenu, _DisplayAmountMenu, _DisplayTagMenu
GLOBAL EntryArray, NumEntries, Buffer
GLOBAL _DisplayEntry, _InterpretAmount, _InterpretTag

;====== SECTION 3: Define stack segment ===================================

SEGMENT stkseg STACK                    ; *** STACK SEGMENT ***
        resb      64*8
stacktop:

;====== SECTION 4: Define code segment ====================================

SEGMENT code                            ; *** CODE SEGMENT ***

;====== SECTION 5: Declare variables for main procedure ===================

EntryArray      resb (3*MAX_ENTRIES)
NumEntries      db 0
Buffer          resb 7

MainHeader      db CR, LF, CR, LF, 'Blah.  Witty Menu Title Here.'
                db CR, LF, '  Current Number of Entries: $'
MainMenu        db CR, LF, '------------------------------------'
                db CR, LF, ' a) Make a deposit'
                db CR, LF, ' b) Make a withdrawal'
                db CR, LF, ' c) Display all entries'
                db CR, LF, ' d) Display academic-related entries'
                db CR, LF, ' e) Exit'
                db CR, LF, CR, LF, 'Selection: $'

AmountMenu      db CR, LF
                db CR, LF, 'Select Amount of Transaction:'
                db CR, LF, '-----------------------------'
                db CR, LF, ' a) 1         b) 4'
                db CR, LF, ' c) 16        d) 64'
                db CR, LF, ' e) 256       f) 1024'
                db CR, LF, ' g) 4096'
                db CR, LF, CR, LF, 'Selection: $'

TagMenu         db CR, LF
                db CR, LF, 'Select Transaction Memo:'
                db CR, LF, '------------------------'
                db CR, LF, ' a) Books'
                db CR, LF, ' b) School Supplies'
                db CR, LF, ' c) Other Academic'
                db CR, LF, ' d) Rent'
                db CR, LF, ' e) Food'
                db CR, LF, ' f) Entertainment'
                db CR, LF, ' g) Other'
                db CR, LF, CR, LF, 'Selection: $'

msg_Total       db CR, LF, CR, LF, '     Account Balance: $'
msg_NoEntries   db CR, LF, 'There are no entries!$'
msg_Invalid     db CR, LF, '*** Invalid Selection!  Operation aborted! ***$'
msg_Deposit     db CR, LF, 'Deposit    $'
msg_Withdraw    db CR, LF, 'Withdraw   $'
msg_Books       db '   Books$'
msg_Supply      db '   School Supplies$'
msg_Academic    db '   Other Academic$'
msg_Rent        db '   Rent$'
msg_Food        db '   Food$'
msg_Entertain   db '   Entertainment$'
msg_Other       db '   Other$'
msg_CRLF        db CR, LF, '$'
msg_Cookie      db CR, LF, CR, LF
                db 'Leaving the bank, you stop by a Chinese restaurant', CR, LF
                db 'for food.  While waiting for your order, you are', CR, LF
                db 'presented with a fortune cookie.  You break it open', CR, LF
                db 'and the message inside reads...', CR, LF, CR, LF, '$'
msg_BigDebt     db 'A fortuitious fortune may fix your financial flaws.'
                db CR, LF, '  Lucky numbers: 1, 2, 8, 9, 23, 43, 45'
                db CR, LF, '$'
msg_SmallDebt   db 'You are in debt.  You are in ECE291.  Get used to both.'
                db CR, LF, '$'
msg_SmallPlus   db 'You have survived the horrors of IUB.  Enjoy your rest...'
                db CR, LF, '  Until next semester.', CR, LF, '$'
msg_BigPlus     db 'You have too much money for a college student.  The'
                db CR, LF, '  IRS and FBI have been contacted.', CR, LF, '$'

;====== SECTION 6: Program initialization =================================

..start:
        mov     ax, cs                  ; Initialize Default Segment register
        mov     ds, ax  
        mov     ax, stkseg              ; Initialize Stack Segment register
        mov     ss, ax
        mov     sp, stacktop            ; Initialize Stack Pointer register

;====== SECTION 7: Main procedure =========================================

MAIN:

.MainLoop
  cmp byte [NumEntries], MAX_ENTRIES
  jae .End

  call _DisplayMainMenu
  cmp al, 'a'
  je .AddDeposit
  cmp al, 'b'
  je .AddWithdraw
  cmp al, 'c'
  je .DisplayAll
  cmp al, 'd'
  je .DisplayAcad
  cmp al, 'e'
  je .End

  mov dx, msg_Invalid
  call dspmsg
  jmp .MainLoop

.AddDeposit
  call _AddDeposit
  jmp .MainLoop

.AddWithdraw
  call _AddWithdraw
  jmp .MainLoop

.DisplayAll
  call _DisplayAllEntries
  jmp .MainLoop

.DisplayAcad
  call _DisplayAcademicEntries
  jmp .MainLoop

.End
  call _DisplayAllEntries
  call _DisplayTotal
  call mp1xit


;--------------------------------------------------------------------------
; DisplayMainMenu
;   Inputs: none
;   Outputs: al = selection from keyboard
;   Calls: dspmsg, binasc, kbdine
;--------------------------------------------------------------------------
_DisplayMainMenu
  push bx               ; All used registers except ax are pushed because
  push cx               ;   only ax returns information.  (Notice: You can't
  push dx               ;   push or pop an 8-bit register.)

  mov dx, MainHeader
  call dspmsg           ; Display menu header
  xor ax, ax
  mov al, [NumEntries]
  mov bx, Buffer
  call binasc           ; Call binasc to convert a binary number into ASCII
  mov dx, bx
  call dspmsg           ; Display the converted number
  mov dx, MainMenu
  call dspmsg           ; Display the rest of the menu
  call kbdine           ; Wait for keyboard input

  pop dx                ; Pop all pushed registers -- notice the order
  pop cx
  pop bx
  ret

;--------------------------------------------------------------------------
; DisplayAmountMenu
;   Inputs: none
;   Outputs: al = selection from keyboard
;   Calls: dspmsg, binasc, kbdine
;--------------------------------------------------------------------------
_DisplayAmountMenu
  push dx
  mov dx, AmountMenu
  call dspmsg
  call kbdine
  pop dx
  ret

;--------------------------------------------------------------------------
; DisplayTagMenu
;   Inputs: none
;   Outputs: al = selection from keyboard
;   Calls: dspmsg, binasc, kbdine
;--------------------------------------------------------------------------
_DisplayTagMenu
  push dx
  mov dx, TagMenu
  call dspmsg
  call kbdine
  pop dx
  ret

;-------------------------------------------------------------------------
; DisplayEntry
;-------------------------------------------------------------------------
_DisplayEntry
  call _libDisplayEntry
  ret

;-------------------------------------------------------------------------
; DisplayAllEntries
;-------------------------------------------------------------------------
_DisplayAllEntries
  call _libDisplayAllEntries
  ret


;-------------------------------------------------------------------------
; DisplayAcademicEntries
;-------------------------------------------------------------------------
_DisplayAcademicEntries
  call _libDisplayAcademicEntries
  ret

;-------------------------------------------------------------------------
; InterpretAmount
;-------------------------------------------------------------------------
_InterpretAmount
  call _libInterpretAmount
  ret

;-------------------------------------------------------------------------
; InterpretTag
;-------------------------------------------------------------------------
_InterpretTag
  call _libInterpretTag
  ret

;-------------------------------------------------------------------------
; AddDeposit
;-------------------------------------------------------------------------
_AddDeposit
  call _libAddDeposit
  ret

;-------------------------------------------------------------------------
; AddWithdraw
;-------------------------------------------------------------------------
_AddWithdraw
  call _libAddWithdraw
  ret

;-------------------------------------------------------------------------
; DisplayTotal
;-------------------------------------------------------------------------
_DisplayTotal
  call _libDisplayTotal
  ret

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Fall 2001